ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • LUNAR AND PLANETARY EXPLORATION  (7.080)
  • Biochemistry and Biotechnology  (4.892)
  • Industrial Chemistry
  • Seismology
  • 1990-1994  (7.806)
  • 1980-1984  (5.295)
  • 1950-1954  (1.353)
Sammlung
Schlagwörter
Erscheinungszeitraum
Jahr
  • 101
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1081-1086 
    ISSN: 0006-3592
    Schlagwort(e): solvation ; organic media ; kinetics ; subtilisin ; thermodynamics ; solubility ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Subtilisin Carlsberg adsorbed on silica particles has been used to catalyze the transesterification of CBZ-Ala-ONp and CBZ-Leu-ONp with 1-butanol in organic systems preequilibrated to water activity of 0.93. Initial reaction rates are conveniently followed by extraction of the released nitrophenol into an alkaline aqueous phase. Kinetic parameters were determined for varied ester concentrations in toluene, isopropyl ether, and hexane. The effect of solvent on substrate solvation was determined by solubility measurements. Much of the observed effect of solvent on Vm/Km may be accounted for by solvation differences. The residual effect of solvent on Km, after discounting solvation differences, is completely opposite to the apparent trend. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 102
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1146-1152 
    ISSN: 0006-3592
    Schlagwort(e): biodegradation ; benzene ; toluene ; p-xylene ; hybrid strain ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: For the complete biodegradation of a mixture of benzene, toluene, and p―xylene (BTX), a critical metabolic step that can connect two existing metabolic pathways of aromatic compounds (the tod and the tol pathways) was determined. Toluate―cis-glycol dehydrogenase in the tol pathway was found to attack benzene―cis―glycol, toluene―cis―glycol, and p―xylene―cis―glycol, which are metabolic intermediates of the tod pathway. Based on this observation, a hybrid strain, Pseudomonase putida TB101, was constructed by introduction of the TOL plasmid pWW0 into P. putida F39/D, a derivative of P. putida F1, which is unable to transform cis―glycol compounds to corresponding catechols. The metabolic flux of BTX into the tod pathway was redirected to the tol pathway at the level of cis―glycol compounds by the action of toluate―cis―glycol dehydrogenase in P. putida TB101, resulting in the simultaneous mineralization of BTX mixture without accumulation of any metabolic intermediates. The profile of specific degradation rates showed a similar pattern as that of the specific growth rate of the microorganism, and the maximum specific degradation rates of benzene, toluene, and p-xylene were determined to be about 0.27, 0.86, and 2.89 mg/mg biomass/h, respectively. P. putida TB101 is the first reported microorganism that mineralizes BTX mixture simultaneously. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 103
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 379-382 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Several techniques for protein extraction were tested for recovering penicillin acylase from a recombinant strain of Escherichia coli. These techniques include chemical [guanidine hydrochloride, Triton X-100, ethylenediaminetetraacetic acid (EDTA), ethanol/toluene], physical (sonication, freeze-and-thawing), and enzymatic (lysozyme) treatments. Best results were obtained with the combined use of guanidine and EDTA. This extraction procedure was optimized, and it was found that 95% of the enzyme was extracted after a 10 m/M EDTA plus 10 mM guanidine treatment at room temperature for 10 h. The purification factor was 25 when compared to disruption by sonication. This extraction method could avoid purification steps for particular applications. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 104
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 387-391 
    ISSN: 0006-3592
    Schlagwort(e): diffusion limitation ; layer thickness ; sulfate reducing bacteria ; methanogenic bacteria ; competition ; UASB granule ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The role of mass transfer limitation of sulfate as a factor governing the competition between sulfate reducing and methane producing bacteria in methanogenic aggregates was theoretically evaluated by the calculation of steady-state sulfate microprofiles using a reference set of parameters obtained from the literature. The shooting method was used as a numerical technique for solving the mathematical model. The effect of the parameters on mass transport limitation was tested by varying each reference value of the parameters with a factor of 3. Sulfate limitation within granules prevailed at moderate (0.1 kg m-3) and low sulfate concentrations in the bulk liquid, at high maximum sulfate utilization rates (3.73 × 10-5 kg SO42- kg-1 VSS S-1 or biomass concentrations (40 KG VSS m-3), and in large aggregates (radius of 7.5 10-4 m). The effective diffusion coefficient of sulfate and the affinity constant were less determinative for the penetration depth of sulfate within a granule. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 105
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 429-435 
    ISSN: 0006-3592
    Schlagwort(e): dynamic experiments ; ethanol ; xylose ; microaerobic fermentation ; oxygen limitation ; on-line monitoring ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new experimental technique, called oxygen programmed fermentation (OPF), was used to study microbial cultures of the years Pichia stipitis and Candida utilis growing on xylose as carbon and energy source. In the oxygen programmed fermentation, the inlet oxygen mole fraction was continuously changed to scan through a wide range of oxygen uptake rates in a continuous culture. The largest ethanol yields and productivities of P. stipitis were found at oxygen transfer rates below 1.5 mmol L-1 h-1. It was found that the ratio between the culture fluorescence and near-IR absorbance increased at oxygen transfer rates lower than 1.5 mmol L-1 h-1. Small amounts of ethanol were produced also by C. utilis when the oxygen transfer rate was between 0 and 3 mmol L-1 h-1. It is suggested that OPF will form a nice complement to ordinary, microaerobic chemostat experiments, by making the identification of interesting regions of oxygen transfer rates possible in an efficient and time-saving initial experiment. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 106
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 453-459 
    ISSN: 0006-3592
    Schlagwort(e): NAD(P)H fluorescene ; on-line monitoring ; amino acid fermentation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The amino acid fermentation by Corynebacterium glutamicum was monitored with an new technique that uses the first derivative of the NAD(P)H fluorescene signal. The rate of change of NAD(P)H pools is indicative of intracellular redox balance variations that correspond to metabolic changes. The profile of this signal showed several characteristics that coincided with major metabolic events during fermentation. We show here that the derivative fluorescence signal can accurately estimate points of threonine depletion, viable cell count, and the end of amino acid formation. Furthermore, on-line optimization strategies can be developed by using the derivative fluorescene signal. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 107
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 489-497 
    ISSN: 0006-3592
    Schlagwort(e): Bacillus licheniformis ; bacterial transport ; porous media ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The convective transport of concentrated suspension of bacteria in porous media is of interest for several processes such as microbial enhanced oil recovery and in situ bioremediation. The parameters which affect the transport of the bacterium Bacillus licheniformis JF-2, a candidate microorganism for microbial enhanced oil recovery, were investigated experimentally in sandpacks. Bacteria retention and permeability reduction occurred primarily in the first few centimeters upon entering the porous medium. In downstream sections of the sandpack, the permeability reduction was low, even in cases in which high cell concentrations (108 cfu/mL) were detected in the effluent. The effect of (i) addition of a dispersant, (ii) linear velocity of injection, (iii) cell concentration, (iv) salinity (v) temperature, and (vi) the presence of a residual oleic phase were determined experimentally. A lower reduction in permeability and a higher effluent bacterial concentration were obtained in the presence of dispersant, high injection velocities, low salinities, and at a higher temperature. Macroscopic measurements at different linear velocities and in the presence or absence of dispersants suggest that the formation of reversible microaggregates and multiparticle hydrodynamic exclusion may be the primary mechanisms for bacterial retention and permeability reduction. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 108
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 509-522 
    ISSN: 0006-3592
    Schlagwort(e): affinity precipitation ; antibody purification ; bioseparation ; phospholipids, ligand-modified ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new method for the selective precipitation of proteins is applied to the isolation and purification of an antibody. Ligand-modified phospholipids (LMPs) are solubilized by the nonionic ethoxylated alcohol detergent, resulting in small (50 to 100 Å) micellar aggregates of LMPs and surfactant. When introduced into protein solutions containing an antibody for which the LMP has specific affinity, the ligand binds to the protein. Hydrophobic interactions between phospholipid tail groups bound to the protein molecules result in an insoluble precipitate. Polyclonal and monoclonal antibiotin antibody (pABA and mABA) are shown to be selectively precipitated using ratios of dimyristoylphosphatidylethanolamidobiotin (DMPE-B) to ABA ranging from 1:1 to 19:1. The kinetics and yield of the precipitation achieve a maximum at a ratio of DMPE-B to ABA of approximately 7:1. The kinetics and magnitude of the turbidity change are modeled using the Mie theory of light scattering coupled with the smoluchowski theory of aggregation. The kinetics are shown to be enhanced significantly by the addition of salt. In particular, the addition of 0.5 M ammonium sulfate salt increases the rate of precipitation by more than an order of magnitude. It is demonstrated that pABA can be recovered with total activity yields of 60% to 70% from mixtures containing nonspecific lgG antibodies in very high purity (〉99%). © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 109
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 539-548 
    ISSN: 0006-3592
    Schlagwort(e): cross-flow filtration ; Escherichia coli ; cell harvesting ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Cross-flow filtration of Escherichia coli strains was examined at the laboratory and pilot scales using Romicon 500,000 molecular-weight-cutoff hollow fiber membranes. Both the series resistance and macrosolute polarization models were employed to compare performances. Total dissolved solids content above 90 g/L and viscosity above 1.1 × 10-3 paċ s of cell-free culture media were found to decrease average filtration fluxes by over 60% both in the absence and presence of cells. Broth filtration with culture media of dissolved solids levels below 80 g/L were influenced to a greater extent by harvest cell density. The collodial nature of the complex nutrient responsible for the total solids increase affected prediction of filtration performance. Differences in strain filterability were observed with JM109 preferred over DH5 in high solids-containing media and RR1 preferred over JM109 in low dissolved solids-containing media. Their research demonstrates the importance of cell strain and media selection in the performance of early downstream processing steps. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 110
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 586-594 
    ISSN: 0006-3592
    Schlagwort(e): sulphate-reducing bacteria ; biofilm ; granulation ; gas-lift reactor ; hydrogen sulphide toxicity ; mass transfer ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Feasibility and engineering aspects of biological sulphate reduction in gas-lift reactors were studied. Hydrogen and carbon dioxide were used as energy and carbon source. Attention was paid to biofilm formation, sulphide toxicity, sulphate conversion rate optimization, and gasliquid mass transfer limitations. Sulphate-reducing bacteria formed stable biofilms on pumice particles. Biofilm formation was not observed when basalt particles were used. However, use of basalt particles led to the formation of granules of sulphate-reducing biomass. The sulphate-reducing bacteria, grown on pumice, easily adapted to free H2S concentrations up to 450 mg/L. Biofilm growth rate then equilibrated biomass loss rate. These high free H2S concentrations caused reversible inhibition rather than acute toxicity. When free H2S concentrations were kept below 450 mg/L, a maximum sulphate conversion rate of 30 g SO42-/L · d could be achieved after only 10 days of operation. Gas-to-liquid hydrogen mass transfer capacity of the reactor determined the maximum sulphate conversion rate. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 111
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 617-625 
    ISSN: 0006-3592
    Schlagwort(e): oxygen profiles ; oxygen microprobe ; Po2-microelectrode ; artifacts ; alginate beads ; Saccharomyces cerevisiae ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Polarographic microcoaxial needle electrodes were used to measure internal profiles of dissolved oxygen tension (Po2) within single Ca-alginate beads of different diameter containing entrapped cells of Saccharomyces cerevisiae. For the investigations, single beads coming from variable growing conditions and distinct cultivation stages were fixed in a special holding device. In dependence on microbial growth steep oxygen gradients were observed. The Oxygen penetration depth at steady state lay between 50 and 100 μm. After 8 h of cultivation time, the anaerobic space within the beads (φ 2 mm; cultivation in a packed bed reactor) is beginning at ∼ 130 μm, whereas the anaerobic space within the beads (φ 2 mm) coming from the shaker flask culture is located ∼440 μm below the bead surface. Surprisingly, steep gradients were also observed, when recording profiles from cell-free Ca-alginate beads of different diameter and alginate concentrations. The steep oxygen gradients apparently had to be interpreted as pseudo-Po2-gradients. These results were borne by several effects, such as formation of artifacts and diffusion barriers in front of the electrode tip or oxygen “availability” at the tip and consumption of oxygen by the electrode itself. These phenomena could be documented by microscopic observation and photography. Thus, to obtain real Po2-profiles it is important to be exactly informed about the physical, chemical, and biological properties of the material to be investigated. Furthermore, it is necessary to apply a special stepwise puncture technique with distinct step-in/step-out movements of the electrode: e.g., unidirectional or contradirectional puncture techniques. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 112
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 661-666 
    ISSN: 0006-3592
    Schlagwort(e): biomass ; biosurfactant ; molasses ; mixed culture ; emulsification capacity ; surface tension ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Non-aseptic production of biosurfactant from molasses by a mixed culture was investigated in stirred batch reactors. Biosurfactant production was quantified by surface tension reduction, critical micelle dilution (CMD), and emulsification capacity (EC). Biosurfactant production was directly correlated with biomass production, and was improved by pH control and addition of yeast extract. Centrifugation of the whole broth increased emulsifying capacity and reduced surface tension. Acidification of the whole broth increased the emulsification capacity but reduced the apparent biosurfactant concentration (CMD), without affecting the surface tension. The emulsification capacity of the cell-free broth was equivalent to that of a 100 mg/L solution of sodium dodecyl sulfate. The emulsification capacity of the whole broth and cell-free broth were reduced by about 50% at and above NaCl concentrations of 100mM. Preliminary characterization suggests that the biosurfactant activity is primarily associated with one or more protease-sensitive species, released from cells in larger quantities after more vigorous centrifugation. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 113
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 674-681 
    ISSN: 0006-3592
    Schlagwort(e): reverse micelles ; extraction ; horseradish peroxidase purification ; AOT ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Phase transfer studies were carried out on the solubilization of horseradish peroxidase (HRP) (E.C. 1.11.1.7) in reverse micelles formed in isooctane using the anionic surfactant, aerosol OT, at concentrations between 50 and 110mM. The selectivity of this methodology was tested, because the HRP used comprised a mixture of seven different isoenzymes with a wide range of isoelectric points. Forward and backward transfers were carried out in wellstirred vessels until equilibrium was reached. Significant protein partitioning could only be obtained by using NaCl to adjust ionic strength in pH range between 1.5 and 3.5, with a maximum at pH 3. The back transfer process was best at pH 8 with 80mM phosphate buffer and 1 M KCI. A loss of 1% to 3% of the surfactant through precipitation at the interface at pH〈4 was observed, which may be due to instability in this pH region, because, even without protein, a similar precipitate was noticed. Protein partitioning was approximately constant when the ionic strength was increased up to 1 MNaCl at pH 3, but protein recovery in back transfer decreased accordingly. Hydrophobic interactions together with association between the protein and surfactant might be responsible for that behavior. Protein partitioning remained the same when the surfactant concentration was decreased to 50 mM, at the expense of higher variability. HPLC chromatograms showed no apparent damage to the protein after reverse micellar extraction. Protein partitioning is best when the temperature is kept at 25×C. The amount of protein and specific activity recovered strongly depends on the phase ratio used during forward transfer. Overall activity recovery varied from 87% to 136% when the phase ratio was increased from 1:1 to 30:1 in forward transfer. This behavior may be due to a change in the ratio of the three isoenzymes recovered after the backward transfer process, with the most active one being increasingly enriched at higher phase ratios. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 114
    ISSN: 0006-3592
    Schlagwort(e): monoclonal antibody ; glycosylation ; cell culture ; fed-batch ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Many mammalian cell fed-batch processes rely on maintaining the cells in a viable and productive state for extended periods of time in order to reach high final concentrations of secreted protein. In the work described herein, a nonamplified NSO cell line was transfected with a vector expressing a recombinant human anti-HIV gp 120 monoclonal antibody (Mab) and a selectable marker, glutamine synthetase. A fed-batch process was developed which improved product yields tenfold over the yields reached in batch culture. In this case, the clone was cultured for a period of 22 days and produced 0.85 g Mab/L. To gauge the effect of extended culture lifetime on product quality, biochemical characteristics of MAb isolated from different time points in the fed-batch culture were determined. The apparent molecular weight of the MAb was constant throughout the course of the culture. Isoelectric focusing revealed four major charged species, with a fifth more acidic species appearing later in the culture. The antigen binding kinetics were constant for MAb isolated throughout the culture period. Glycosylation analysis, on the other hand, revealed that MAb produced later in the culture contained greater percentages of truncated N-acetylglucosamine and highmannose N-glycans. Possible contributions to this underglycosylated material from either cell lysis or synthesis from noviable cells were found to be negligible. Instead, the viable cells appeared to be secreting more truncated and high mannose MAb glycoforms as the culture progressed. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 115
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 765-771 
    ISSN: 0006-3592
    Schlagwort(e): membrane bioreactors ; two-phase ; surfactant adsorption ; membrane wettability ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Surface-active components, both reactants and products, are frequently encountered in two-phase, aqueous-organic, biocatalytic reactions, When such reaction are carried out in a membrane reactor, employing a membrane selectively wetted by one of the two reactants, changes in the content of these surfactants- as a consequence of the progress of the reaction-can lead to wetting transitions at the two membrane-liquid interfaces as a result of adsorption of the tenside. This can lead to a decrease in the pressure required to cause the, initially, nonwetting phase to break through the membrane. Such effects render difficult the operation of two-phase membrane bioreactors. Hence, it is necessary to make a careful selection of the membrane material and type by considering factors such as UF versus MF and low MWCO versus high MWCO to enable the reactor to be operated without breakthrough, but without significantly compromising the reaction rates that can be maintained.The phenomena leading to breakthrough effects are discussed in this paper, and experimental results for the hydrolysis of ethyl laurate by lipase from Candida rugosa in a batch flat sheet membrane reactor are presented with the reactor operated with a variety of membranes. An experimental result showing the decrease in the pressure required to cause breakthrough of the organic phase (for the system ethyl laurate-lauric acid-water) as the content of the highly surface-active lauric acid in the organic phase is increased is also presented for an asymmetric, hydrophilic meta-aramid ultrafiltration membrane. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 116
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 801-807 
    ISSN: 0006-3592
    Schlagwort(e): foaming ; fermentations ; biochemical basis ; biosurfactants ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A detailed physico-chemical analysis of two foaming fungal fermentations was carried out to identify that key groups of compounds responsible for foam formation. Fermentations were carried out on a 20-L scale in a stirred aerated tank, over 7 days, using a commercial, defined medium. The organisms investigated were Penicillium herqueii, a hyphomycete, and an unidentified Ingoldian fungus. Samples of broth and, where possible, foam were analyzed to determine which groups of compounds were concentrated into generated foams. Surface tension, bulk viscosity, and antifoam A concentration were additionally determined in broth samples. To date the cause of foaming in fermentations has been attributed to the surfactant properties of extracellular proteins. This assumption was tested and found to be incomplete as many additional groups of biochemicals were found to be enriched into the foam. The results of the investigation revealed the presence of proteins, carbohydrates, α-keto acids, and lipophilic biosurfactants, particularly extracellular pigments, enriched within stable foams. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 117
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 830-836 
    ISSN: 0006-3592
    Schlagwort(e): reverse micelles ; protein precipitation ; amino acid precipitation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new method is presented to precipitate proteins and amino acids from reverse micelles by dehydrating the micelles with molecular sieves. Nearly complete precipitation is demonstrated for α-chymotrypsin, cytochromec, and trytophan from 2-ethylhexyl sodium sulfosuccinate (AOT)/isooctane/water reverse micelle solutions. The products precipitate as a solid powder, which is relatively free of surfactant. The method does not require any manipulation of pH, ionic strength, temperature, pressure, or solvent composition, and is applicable over a broad range of these properties. This general approach is compared with other techniques. This general approach is compared with other techniques for the recovery of biomolecules from reverse micelles. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 118
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 131-137 
    ISSN: 0006-3592
    Schlagwort(e): oxygen uptake ; oxygen transfer ; Candida lipolytica ; citric acid ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The rates of oxygen uptake and oxygen transfer during cell growth and citric acid production by Candida lipolytica Y 1095 were determined. The maximum cell growth rate, 1.43 g cell/L · h, and volumetric oxygen uptake rate, 343 mg O2/L · h, occurred approximately 21 to 22 h after inoculation. At the time of maximum oxygen uptake, the biomass concentration was 1.3% w/v and the specific oxygen uptake rate was slightly greater than 26 mg O2/g cell · h. The specific oxygen uptake rate decreased to approximately 3 mg O2/g cell · h by the end of the growth phase.During citric acid production, as the concentration of dissolved oxygen was increased from 20% to 80% saturation, the specific oxygen uptake and specific citric acid productivity (mg citric acid/g cell · h) increased by 160% and 71%, respectively, at a biomass concentration of 3% w/v. At a biomass concentration of 5% w/v, the specific oxygen uptake and specific citric acid productivity increased by 230% and 82%, respectively, over the same range of dissolved oxygen concentrations.The effect of dissolved oxygen on citric acid yields and productivities was also determined. Citric acid yields appeared to be independent of dissolved oxygen concentration during the initial production phase; however, volumetric productivity (g citric acid/L · h) increased sharply with an increase in dissolved oxygen. During the second or subsequent production phase, citric acid yields increased by approximately 50%, but productivities decreased by roughly the same percentage due to a loss of cell viability under prolonged nitrogen-deficient conditions. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 119
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 138-148 
    ISSN: 0006-3592
    Schlagwort(e): cell population ; cytometry ; segregated model ; cytometry ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A fresh quest is made of segregated cell models of microbial populations with a view to determine whether the multivarite distribution of physiological states, during transient growth, can attain self-similar forms (i.e., become time invariant) when each physiological state variable is scaled with respect to its population average. Such self-similar growth situations are believed to be more general than those of balanced growth. The conditions under which self-similarity is possible are investigated. Thus conditions are stipulated on the synthesis rates of different physiological entities, cell division rate, and the partitioning of the parent cell's components among the daughter cells (assuming binary division) in order for self-similar growth to be attained. Subject to the attainment of self-similar growth, it is shown that cytometric data can be analyzed systematically to determine how the rates of syntheses of various biochemical entities and cell division rates vary with the physiological entities that are measured. Inverse problems, represented by algebraic systems, are identified which will potentially allow flow cytometric data to be inverted to yield quantitative information on the absolute rates of cellular growth and reproductory processes as a function of the cell states chosen for measurement. It is suggested that the methods become more effective when cytometry can be used to make direct observations on dividing cells so that the number of unknowns in the inverse problem can be reduced, thus facilitating its more complete solution. Preliminary analysis of cytometric data obtained in the literature show promise of self-similarity and thus the possibility of application of the methods discussed here. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 120
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 186-187 
    ISSN: 0006-3592
    Schlagwort(e): copper ; biosorption ; biopolymers ; diffusion ; alginate gel ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Calculations of the diffusivity of Cu2+ in calcium alginate gel beads using the shrinking core model were checked by us. Corrected results are reported here. Diffusivity was still found to increase with increasing alginate concentration, but at a lower rate than reported in the cited paper. The diffusivity increased by a factor of 2 over the range of alginate concentrations studied rather than 10. The original data is included with sample calculations. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 121
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 529-532 
    ISSN: 0006-3592
    Schlagwort(e): whey proteins ; proteases ; enzymatic hydrolysis ; peptides ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Using high-pressure liquid chromatography we studied the distribution of molecular weights in whey-protein hydrolysates using the following commercially obtained proteases: Alcalasa 0.6 L and Protease 660 L, both bacterial in origin, and PEM 2500 S, of animal origin. In each of the systems, the range of molecular weights in the hydrolysate depended solely on the degree of hydrolysis (DH) achieved. For DH ≥ 20, between 65% and 95% of the hydrolysate is made up of peptides with a molecular weight of less than 1,000 Da. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 122
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 549-556 
    ISSN: 0006-3592
    Schlagwort(e): lipase ; water activity control ; esterification ; equilibrium constants ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A technique of continuous water activity control was used to examine the effects of water activity on enzyme catalysis in organic media. Esterification catalyzed by Rhizopus arrhizus lipase was preferably carried out at a water activity of 0.33, which resulted in both maximal initial reaction rate and a high yield. When Pseudomonas lipase was used as catalyst it was beneficial to start the reaction at high water activity (giving the optimal reaction rate with this enzyme) and then shift to a lower water activity toward the end of the reaction to obtain a high yield. The apparent equilibrium constant of the reaction was influenced by the water activity of the organic solvent. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 123
    ISSN: 0006-3592
    Schlagwort(e): α-amylase production ; recombinant Saccharomyces cerevisiae ; PGK promoter ; SUC2 promoter ; fuzzy controller ; on-line glucose-ethanol analyzer ; effect of ethanol on cloned gene expression ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effect of ethanol concentration on cloned gene expression in recombinant Saccharomyces cerevisiae strain 20B-12 containing one of two plasmids, pNA3 and pNA7, was investigated in batch cultures. Plasmids pNA3 and pNA7 contain the α-amylase gene under the control of the SUC2 or PGK promoter, respectively. When the ethanol concentration was controlled at 2 to 5 g/L, the gene expressions were two times higher than those at 20 g/L ethanol. The increase the gene expression by maintaining both the ethanol and glucose concentrations at low levels, a fuzzy ontroller was developed. The concentrations of glucose and ethanol were controlled simultaneously at 0.15 and 2 g/L, respectively, in the production phase using the fuzzy controller in fed-batch culture. The synthesis of α-amylase was induced by the low glucose concentration and maintained at a high level of activity by regulating the ethanol concentration at 2 g/L. The secretory α-amylase was induced by the low glucose concentration and maintained at a high level of activity by regulating the ethanol concentration at 2 g/L. The secretory α-amylase activities of cells harboring plasmids pNA3 and pNA7 in fed-batch culture were 175 and 395 U/mL, and their maximal specific activities 7.7 and 12.4 U/mg dry cells, respectively. These values are two to three times higher in activity and three to four times higher in specific activity than those obtained when glucose only was controlled. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 124
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1089-1098 
    ISSN: 0006-3592
    Schlagwort(e): bubble breakup ; animal cells ; stress ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Two flow parameters are proposed for the analysis of flows that have potential to damage animal cells. They are the state of stress (characterized by the second invariant of the stress tensor) and the flow classification parameter RD (which is related to the possibility of stress relaxation). We consider the flow that occurs when a 1.7-mm bubble collapses at a liquid interface. Using these two parameters, we show the regions in which the flow is strong in terms of high hydrodynamic stresses and elongation characteristics. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 125
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994) 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 126
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 690-698 
    ISSN: 0006-3592
    Schlagwort(e): micellar-enhanced ; enantiomers ; stereoselectivity ; amino acids ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Micellar-enhanced ultrafiltration (MEUF) is investigated as a large-scale technique for separating amino acid enantiomers. Specifically, L-5-cholesterol glutamate, a chiral ligand-exchange cosurfactant, is used together with a nonionic surfactant to form mixed micelles that preferentially bind D-phenylalanine over L-phenylalanine in the presence of copper(II). Operational selectivities as high as 4.2 are obtained. Potentiometric titrations using a water-soluble model compound similar to the chiral cosurfactant indicate that the ternary copper complex with phenylalanine has a stereoselectivity for the D enantiomer which is significantly smaller than that observed in the MEUF system. Thus, the selectivity of the chiral legend's local solvent and structural environment. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 127
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 720-726 
    ISSN: 0006-3592
    Schlagwort(e): cell death ; apoptosis ; hybridoma cells ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The incidence of apoptotic and necrotic cell death was compared in CHO, SF9 insect cells and murine plasmacytoma (J558L) and hybridoma (TB/C3) cells during in vitro cultivation in batch cultures. Acridine orange staining and fluorescence microscopy enabled the visualization of a classic morphological feature of apoptotic cell, the presence of condensed and/or fragmented chromatin. DNA gel electrophoresis was employed to show an additional characteristic of the process, the endonuclease-mediated fragmentation of DNA into multiples of 180 base pairs. The levels of apoptosis at the end of batch cultures of plasmacytoma and hybridoma cell lines were found to be 60% and 90% of total dead cells, respectively. However, employing the above-mentioned techniques, the biochemical and morphological features of apoptosis were not found in CHO and SF9 insect cells. Some factors affecting the induction of apoptosis during the batch culture of the hybridoma and plasmacytoma cell lines were identified. The most effective inducer was found to be glutamine limitation, followed by (in order of importance) serum limitation, glucose limitation, and ammonia toxicity. Blockage of the cell cycle of the plasmacytoma and hybridoma cells using thymidine resulted in the induction of apoptosis. This has important implications for the development of cell culture processes that minimize cell division and thereby increase specific productivity. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 128
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994) 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 129
    ISSN: 0006-3592
    Schlagwort(e): error diagnosis ; filtering technique ; data reconciliation ; measurement error detection ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This article presents a method to test the presence of relatively small systematic measurement errors; e.g., those caused by inaccurate calibration or sensor drift. To do this, primary measurements - flow rates and concentrations - are first translated into observed conversions, which should satisfy several constraints, like the laws of conservation of chemical elements. This study considers three objectives: 1.Modification of the commonly used balancing technique to improve error sensitivity to be able to detect small systematic errors. To this end, the balancing technique is applied sequentially in time.2.Extension of the method to enable direct diagnosis of errors in the primary measurements instead of diagnosing errors in the observed conversions. This was achieved by analyzing how individual errors in the primary measurements are expressed in the residual vector.3.Derivation of a new systematic method to quantitatively determine the sensitivity of the error, is that error size at which the expected value of the chisquare test function equals its critical value.The method is applied to industrial data demonstrating the effectiveness of the approach. It was shown that, for most possible error sources, a systematic errors of 2% to 5% could be detected. In given application, the variation of the N-content of biomass was appointed to be the cause of errors. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 130
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 819-829 
    ISSN: 0006-3592
    Schlagwort(e): on-line HPLC ; fed batch ; closed loop control ; Escherichia coli fermentation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This article describes a fully automated system for the on-line monitoring and closed-loop control of a fed-batch fermentation of recombinant Escherichia coli, and presents two case studies of its used in limiting production of unwanted byproducts such as acetic in fed-batch fermentations. The system had two components. The first components, on-line monitoring, comprised an aseptic sampling device, a microcentrifuge, and HPLC System. These instruments removed a Sample from a fermentor, spun it at high speed to separate solid and liquid components, and then automatically injected the supernatant onto an HPLC column for analysis. The second component consisted of control algorithms programmed using the LabView visual programming environment in a control computer that was linked via a remote components were linked so that results from the on-line HPLC were captured and used by the control algorithm was designed to demonstrate coarse feedback control to confirm the operability of the controller. The second case study showed how the system could be used in a more sophisticated feedings strategy providing fine control and limiting acetate concentration to a low level throughout the fermentation. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 131
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 854-858 
    ISSN: 0006-3592
    Schlagwort(e): cyanobacterium ; energy conversion efficiency ; hydrogen production ; nitrogen-fixing strain ; Synechococcus sp. ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The capability of hydrogen photoproduction under high cell density conditions was examined using synchronously grown cells of nitrogen-fixing Synechococcus sp. Miami BG 043511. Optimum hydrogen yield was obtained when vessels (25 ml) contained 0.2 to 0.3 mg chlorophyll a in 3-mL cell suspension. During a 24-h incubation period, an initial phase of hydrogen and carbon dioxide production and a subsequent phase of carbon dioxide uptake and oxygen accumulated as major products after 24 h. after the initial 24-h. After the initial 24-h incubation, as high as 7.4 and 3.7 L (at standard condition) of hydrogen and oxygen, respectively, accumulated in vessels with 22-ml gas phase. This indicated that the pressure in the flask increased to 1.5 atmosphere. Energy conversion efficiency based on photosynthetically active radiation (25 W/m2) was about 2.6%. However, increased pressure somehow reduced the duration of hydrogen production. Duration of hydrogen and oxygen production was prolonged by periodical (24-h interval) gas replacement during incubation. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 132
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1031-1039 
    ISSN: 0006-3592
    Schlagwort(e): polyampholytes ; block copolymers ; proteins ; complexation ; protein separation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The interaction of dilute mixtures of proteins and ABC triblock methacrylic polyampholytes at different values of pH was investigated turbidimetrically. The onset of interaction was manifested by large changes in turbidity at certain critical pHs which lie close to the isoelectric points of the two interacting components. Protein precipitation yields in protein-polyampholyte binary mixtures followed the corresponding turbidity profiles and varied from 10% to 90%. The synthetic polyampholytes self-aggregate around their isoelectric point. The kinetics of precipitation of one of the same polymer with soybean trypsin inhibitor were studied, with turbidity-based characteristic times (exponential fit) of 2-3 min. The kinetics of precipitation of the protein-polymer mixture are slower than that of pure polymer because a small, but steady, long-term increase in turbidity is observed in the former case. The pH-dependence of the turbidity of binary mixtures of one protein and one synthetic polyampholyte, as well as a tertiary mixture of two proteins and one polyampholyte, were measured 30 min after the pH adjustment. The observations in these experiments along with the measured protein precipitation yields in the binary mixtures and the polyampholyte self-aggregation can be used for polymer removal and recycling. The latter constitutes a significant advantage over the use of homopolyelectrolytes which cannot easily be recycled. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 133
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1265-1269 
    ISSN: 0006-3592
    Schlagwort(e): subtilisin ; organic solvents ; immobilized enzyme ; aquaphilicity ; hydrophilicity ; enantioselectivity ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Subtilisin Carlsberg was covalently attached to five macroporous acrylic supports of varying aquaphilicity (a measure of hydrophilicity). Kinetic parameters of the transesterification of S and R enantiomers of secphenethyl alcohol with vinyl butyrate, catalyzed by various immobilized subtilisins, were determined in anhydrous dioxane and acetonitrile. Enzyme enantioselectivity in acetonitrile, but not in dioxane, correlated with the aquaphilicity of the support; a mechanistic rationale for this phenomenon was proposed. Although the catalytic activity of immobilized subtilisin in anhydrous solvents strongly depended on enzyme pretreatment, the enantioselectivity was essential conserved. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 134
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1295-1305 
    ISSN: 0006-3592
    Schlagwort(e): Escherichia coli ; fusion proteins ; Cellulomonas fimi ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Fusion of the leader peptide and the cellulose-binding domain (CBD) of endoglucanase A (CenA) from Cellulomonas fimi, with of without linker sequences, to the N-terminus of alkaline phosphatase (PhoA) from Escherichia coli leads to the accumulation of significant amounts of the CBD-PhoA fusion proteins in the supernatants of E. coli cultures. The fusion proteins can be purified from the supernatants by affinity chromatography on cellulose. The fusion protein can be desorbed from the cellulose with water or guanidine-HCl. If the sequence IEGR in present between the CBD and PhoA, the CBD can be cleaved from the PhoA with factor Xa. The efficiency of hydrolysis by factor Xa is strongly in fluenced by the amino acids on either side of the IEGR sequence. The CBD released by factor Xa is removed by adsorption to cellulose. A nonspecific proteases from C. fimi, which hydrolyzes native CenA between the CBD and the catalytic domain, may be useful for removing the CBD from some fusion proteins. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 135
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1331-1336 
    ISSN: 0006-3592
    Schlagwort(e): Streptomyces aureofaciens ; self cycling fermentation ; tetracycline production ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The self-cycling frementation (;rSCF) technique was applied to culture of Streptomyces aureofaciens. SCF is a method of continuous fermentation in which the metabolism of a microorganism is monitored by a measurement such as dissolved oxygen. These data are sent to a computer to allow it to control the system. Tetracycline production was observed only at exceedingly low iron concentrations in the growth medium. Repeatability of cycles was found to be dependent upon the presence of tetracycline in the fermentation broth as well as the strain of microorganism grown in the fermentor. Tetracycline was produced by an improved specific rate when compared to results in the literature for this organism grown using the batch method. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 136
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1355-1361 
    ISSN: 0006-3592
    Schlagwort(e): enzyme inactivation ; immiscible organic solvents ; interfacial area ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new technique with controlled interface generation allows separation and quantitation of enzyme inactivation by both solvent/aqueous interface and dissolved solvent. This has now been used in n-butanol, isopropylether, 2-octanone, n-hexane, n-butylbenzene, and n-tridecane. Ribonuclease was stable with all the solvent/aqueous interfaces studied. Chymotrypsin was mainly inactivated by the more hydrophobic solvent/aqueous interfaces, whereas lipase was only inactivated by the less hydrophobic solvent/aqueous interfaces. Urease was inactivated by some interfaces, but not all, without an obvious trend. Thus, the commonly expected simple relationship with solvent polarity (e.g., log P) does not apply when interfacial inactivation is determined specifically. Greater dissolved solvent inactivation occurred with the more polar solvents, though only a general trend was apparent with log P. A better correlation was noted with the Hilde-brand solubility parameter. Interfacial effects are discussed with reference to enzyme molecular weight, denaturation temperature, hydrophobicity, and adiabatic compressibility. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 137
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1337-1347 
    ISSN: 0006-3592
    Schlagwort(e): poly-(3-hydroxybutyric acid) ; PHB ; Escherichia coli ; morphology ; plasmid ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A stable high-copy-number plasmid pSYL105 containing the Alcaligenes eutrophus polyhydroxyalkanoic acid (PHA) biosynthesis genes was constructed. This plasmid was transferred to seven Escherichia coli strains (K12, B, W, XL1-Blue, JM109, DH5α, and HB101), which were subsequently compared for their ability to synthesize and accumulate ploy- (3-hydroxybutyric acid) (PHB). Growth of recombinant cells and PHB synthesis were investigated in detail in Luria-Bertani (LB) medium containing 20 g/L glucose. Cell growth, the rate of PHB synthesis, the extent of PHB accumulation, the amount of glucose utilized, and the amount of acetate formed varied from one strain to another. XL1-Blue (pSYL105) and B (pSYL105) synthesized PHB at the fastest rate, which was ca. 0.2 g PHB/g true cell mass-h, and produced PHB up to 6-7 g/L. The yields of cell mass, true cell mass, and PHB varied considerably among the strains. The PHB yield of XL1-Blue (pSYL105) in LB plus 20 g/L glucose was as high as 0.369 g PHB/g glucose. Strains W (pSYL105) and K12 (pSYL105) accumulated the least amount of PHB with the lowest PHB yield at the lowest synthesis rate. JM109 (pSYL105) accumulated PHB to the highest extent (85.6%) with relatively low true cell mass (0.77 g/L). Considerable filamentation of cells accumulating PHB was observed for all strains except for K12 and W, which seemed to be due either to the overexpression of the foreign PHA biosynthesis enzymes or to the accumulation of PHB. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 138
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1367-1370 
    ISSN: 0006-3592
    Schlagwort(e): CHO cells ; Cloned proteins ; VHb hemoglobin ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Previous studies suggest that secretion of cloned proteins synthesized by recombinant Chinese hamster ovary (CHO) cells can be adenosine triphosphate (ATP) limited. Other research indicates that the presence of cloned Vitreoscilla hemoglobin (VHb) enhances ATP production in oxygen-limited Escherichia coli. To evaluate the influence of VHb expression on recombinant CHO cell productivity, the vhb gene has been fused to the mouse mammary tumor virus (MMTV) promoter and cloned in a CHO cell line previously engineered to express human tissue plasminogen activator (tPA). Western blot analysis confirms dexamethasone-inducible VHb expression in all of the clones tested. Batch cultivation experiments with one VHb-expressing clone and the parental CHO-tPA expressing cells. The VHb-expressing clone exhibits specific tPA production 40 to 100% greater than the parental CHO-tPA culture. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 139
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1140-1154 
    ISSN: 0006-3592
    Schlagwort(e): ammonia ; apoptosis ; hybridoma ; lactate ; myeloma ; nutrient deprivation ; programmed cell death ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In the present study, cell death was investigated in cultures of NS/0 myelomas and SP2/0-derived D5 hybridomas through morphological examination of cells stained with acridine orange and ethidium bromide. The relative contribution of elevated levels of lactic acid and ammonia, as well as deprivation of glutamine, cystine, and glucose on the induction of necrosis or apoptosis, was investigated. In batch culture of D5 hybridoma cells, induction of apoptotic cell death correlated with the exhaustion of glutamine, while in the case of NS/0 myelomas, it coincided with exhaustion of cystine. To determine whether limiting nutrients were the actual triggering factors for apoptosis in batch culture, exponentially growing cells were resuspended in glutamine or cystine-free media. Within 30 to 40 h, viability decreased to 50% and the nonviable cell population displayed typical apoptotic morphology, with crescents of condensed chromatin around the periphery of the nucleus, or with the entire nucleus present as one or a group of featureless, brightly staining spherical beads. Similarly, D5 hybridomas and NS/0 myelomas cultivated in glucose-free medium died mainly from apoptosis. Cells were also cultivated in fresh medium supplemented with elevated concentrations of ammonia (3.0 mM) and/or lactate (35 mM, 50 mM). This resulted in decreased viabilities and necrotic death in both cell lines. From these results, we conclude that D5 hybridomas and NS/0 myelomas deprived of essential nutrients die by apoptosis, whereas incubation in the presence of elevated levels of metabolic byproducts such as ammonia and lactate will induce necrotic cell death in these cells. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 140
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1168-1176 
    ISSN: 0006-3592
    Schlagwort(e): estimators ; biomass measurement ; lactic acid bacteria ; software sensors ; inhibition ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Indirect measurement of lactose, galactose, lactic acid, and biomass concentration from on-line sodium hydroxide weight measurements have been obtained for pure and mixed batch cultures of Streptococcus salivarius ssp. thermophilus 404 and Lactobacillus delbrueckii subsp. bulgaricus 398 conducted at controlled pH and temperature. Linear correlations were established between the equivalent sodium hydroxide concentration and the lactose (substrate), galactose and lactic acid (products) concentrations while nonlinear relationships were developed between biomass and lactic acid concentrations. These nonlinear relationships took into account the inhibitory effect of lactic acid on growth and acidification. The indirect measurements of biomass concentration were introduced into a nonlinear estimator of the state variables and of the specific growth and lactic acid production rates. Good agreement was found between estimated and measured biomass concentrations (error index ranging from 10.8% to 12.6%). The results showed the feasibility of on-line estimation of biomass concentration and of the specific kinetics from NaOH addition weight measurements and its applicability for monitoring lactic acid fermentations. Using off-line measurements of L(+) and D(-) lactic acid concentrations, the evolution of the concentration of each strain in mixed cultures was obtained from the relationships proposed for the mixed cultures. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 141
    ISSN: 0006-3592
    Schlagwort(e): microencapsulation ; polyacrylate ; submerged jet ; mammalian cell ; HepG2 cells ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An interfacial precipitation process to encapsulate mammalian cells in hydroxyethyl methacrylate-methyl methacrylate (HEMA-MMA) microcapsules of ∼ 750 in ∼m diameter was previously described. It was not possible to produce smaller capsules due to low shearing force. A new droplet generation scheme was developed by suspending the cell and polymer co-extrusion nozzle in a uniform co-axial fluid jet which enabled the production of 300 to 600-µm diameter capsules. HepG2 hepatoma cells in 400-µm-diameter HEMA-MMA capsules were able to retain their metabolic activity during and after the encapsulation process. The in vitro secretion of plasma proteins α1-acid glycoprotein, α1-antitrypsin, and fibrinogen by the encapsulated cells was retained. The encapsulated cells secreted less fibrinogen (340 kD) relative to α1-acid glycoprotein (42kD), indicating the sieving effect (but not absolute cut-off) of the HEMA-MMA membrane. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 142
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1228-1234 
    ISSN: 0006-3592
    Schlagwort(e): broth recycle ; water reuse ; Apiotrichum curvatum ; fermentation ; microbial lipid ; inhibition ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Fermentation is a water-intensive process requiring treatment of large amounts of effluent broth. It is desirable to increase the ratio of product produced to the volume of effluent by minimizing the discharge of effluent from the fermentation process. A study of recycling spent fermentation process. A study of recycling spent fermentation broth for the subsequent fermentation was carried out with Apiotrichum curvatum an oleaginous yeast, as the working culture. Spent broth from a defined medium was recycled t replace as much as 75% of the water and salts for subsequent batches and this was repeated for seven sequential batches without affecting cell mass and lipid production. A 64% vlume reduction of wastewater was achieved in this manner. However, when using whey permeate as the medium, lipid production dropped after three consecutive recycle operations at 50% recycle, and after two consecutive recycle operations at 75% and 100% recycle. Accumulation of ions in the broth appeared to be responsible for the inhibition. An ion exchange step was able to eliminate the ion buildup and restore fermentation performance. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 143
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1261-1264 
    ISSN: 0006-3592
    Schlagwort(e): foam fractionation ; differential foam fractionation ; protein purification ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Commercially available beer, which is a dilute solution containing components of yeast, malt, and hop used in the manufacture of the beer, was used as a model system to demonstrate the potential of foam fractionation beyond the primary foaming stage. Most of the components present in the beer concentrated in the initial foam, but they drained differentially in the subsequent collapsed foam collected over a period of 30 min. This resulted in further enrichment, in particular, of components which were present in low concentration in the original beer, Preferential drainage from foam, hence, might provide a novel way of fractionating further the proteins concentrated initially in the liquid films of foam. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 144
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1271-1278 
    ISSN: 0006-3592
    Schlagwort(e): fermentation ; state estimation ; kalman filter ; multirate systems ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This article discusses issues related to estimation and monitoring of fermentation processes that exhibit endogenous metabolism and time-varying maintenance activity. Such culture-related activities hamper the use of traditional, software sensor-based algorithms, such as the extended kalman filter (EKF). In the approach presented here, the individual effects of the endogenous decay and the true maintenance processes have been lumped to represent a modified maintenance coefficient, mc. Model equations that relate measurable process outputs, such as the carbon dioxide evolution rate (CER) and biomass, to the observable process parameters (such as net specific growth rate and the modified maintenance coefficient) are proposed. These model equations are used in an estimator that can formally accommodate delayed, infrequent measurements of the culture states (such as the biomass) as well as frequent, culture-related secondary measurements (such as the CER). The resulting multirate software sensor-based estimation strategy is used to monitor biomass profiles as well as profiles of critical fermentation parameters, such as the specific growth for a fed-batch fermentation of Streptomyces clavuligerus. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 145
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1288-1294 
    ISSN: 0006-3592
    Schlagwort(e): D-amino acid oxidase ; bioreactor ; α-keto acid ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The study reports on the development of a bioreactor for the production of α-keto acids from D,L- or D-amino acids using Rhodotorula gracilis D-amino acid oxidase. D-Amino acid oxidase was co-immobilized with catalase on Affi-Gel 10 matrix, and the reactor was operated as a continuous-stirred tank reactor (CSTR) or stirred tank with medium recycling conditions. The optimum substrate concentration and quantity of biocatalyst were determined (5 mM and 1.2 mg/L, respectively). Under optimum operating conditions, product formation was linearly related to both substrate and enzyme concentration, showing the system to be highly flexible. Under these conditions, in a stirred tank, over 90% conversion was achieved in 30 min with a maximum production of 0.23 g of pyruvic acid/day/enzyme units. Product was recovered by ion exchange chromatography. The operational stability of the reactor was high (up to 9.5 h of operation without loss of activity) and the inactivation half-life was not reached even after 18 h or 36 bioconversion cycles. This represents the first case of a reactor developed successfully with a D-amino acid oxidase. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 146
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1315-1324 
    ISSN: 0006-3592
    Schlagwort(e): static mixer ; MRC-5 ; anchorage dependent ; hepatitis A ; animal cell culture ; bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The titanium static mixer reactor, demonstrated for a variety of vaccine processes during the late 197s, was investigated for the production of attenuated hepatitis A virus antigen from anchorage-dependent MRC-5 cells. This reactor system used Charles River Biotechnological Services cabinets for monitoring and process control. Cell inoculation protocols, using 6000-10,000 cells/cm2, resulted on over 95% attachment at both the laboratory and pilot scales. Indirect monitoring techniques using oxygen, glucose, L-serine, and L-glutamine uptake rates were indicative of cell growth prior to virus inoculation as well as environmental and/or nutrient limitations. Seven laboratory-scale (3900 cm2) runs and one pilotscale (265,000 cm2) run were conducted to investigate refeeding regiments, parallel versus perpendicular element orientation, increased element surface area per unit volume, and scale-up performance. In general, lysate antigen yields achieved were similar to those of parallel T-flasks cultivated under similar conditions. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 147
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1348-1354 
    ISSN: 0006-3592
    Schlagwort(e): streptavidin ; galactosidase ; fusion proteins ; plasmid vector ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Covalently immobilized biotin was used as a biospecific adsorbant to investigate the application of streptavidin as an affinity domain for simultaneous purification and immobilization of recombinant proteins. A streptavidin-β-galactosidase fusion protein was constructed and tested as a model system. The gene for streptavidin from Streptomyces avidinii was modified by polymerase chain reaction to mutate the stop codon and to facilitate cloning into an Escherichia coli expression vector yielding a versatile plasmid with 37 unique restriction enzyme sites at the 3' end. E. coli β-galactosidase was cloned in-frame to the streptavidin gene. Analysis of lysates of induced recombinant E. coli cells by SDS-PAGE and Western blots indicated that the 133.6-kDa fusion protein was expressed. Sulfosuccinimidyl-6-(biotinamido) hexanoate was covalently immobilized on 3-aminopropyl-controled-pore glass beads. Exposure of recombinant cell lysates to this support indicated that streptavidin-β-galactosidase was bioselectively adsorbed. The resulting biocatalyst contained 300 mg protein per gram of beads and exhibited a specific activity of 306 βmol/min per milligram protein with o-nitrophenyl-β-D-galactopyranoside as substrate corresponding to approximately 50% of that observed for commercially pure E. coli β-galactosidase. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 148
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1362-1366 
    ISSN: 0006-3592
    Schlagwort(e): Saccharomyces cerevisiae ; bioaccumulation ; gel immobilization ; cross-flow microfiltration ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Cross-flow microfiltration was shown to retain Saccharomyces cerevisiae biomass utilized for heavy metal bioaccumulation. The passage of metal-laden influent through a series of sequential bioaccumulation systems allowed for further reductions in the levels of copper, cadmium, and cobalt in the final effluent than that afforded by a single bioaccumulation process. Serial bioaccumulation systems also allowed for partial separation of metals from dual metal influents. More than one elemental metal cation could be accumulated simultaneously and in greater quantities than when a single metal was present in the effluent (Cu2+ 0.43 mmol, Cu2+ + Cd2+ 0.67 mmol, and Cu2+ + Co2+ 0.83 mmol/g yeast dry mass when the initial concentration of each of the metal species was 0.2 mmol·L-1). Co-accumulation of two different metal cations allowed higher total levels of bioaccumulation than found with a single metal. The flux rate was 2.9 × 102 L·h-2μm-2 using a polypropylene microfiltration membrane (0.1 μm pore size) at 25°C. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 149
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 368-378 
    ISSN: 0006-3592
    Schlagwort(e): Daucus carota L. ; embryos ; kinetics ; morphology ; pattern recognition ; image analysis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The environmental effects on developing somatic embryos should be characterized not only by the growth based on biomass, but also by the morphological properties and size. We have previously developed a discrete classifier to separate developing embryos into distinct morphological classes. In this study, a continuous descriptor using the distributions of magnitude of features representing morphological characteristics and size information was used to describe the developing embryo populations. The identity of the population was examined by comparing either the distributions of all features or key features. The method was applied to characterize the kinetics of carrot embryo populations cultivated in the presence and absence of triiodobenzoic acid(TIBA), an inhibitor of auxin polar transport. Optimal sample size for morphological characterization was determined by the invariance of feature distributions with further increase in sample size. The overall growth and substrate consumption kinetics were only slightly affected by the presence of TIBA. However, the distribution of morphological features was significantly affected. The features showing the highest statistical significance were related to those corresponding to the roughness. The continuous descriptor for characterizing developing embryo population is potentially useful for quality control in large-scale operations. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 150
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994) 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 151
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 419-427 
    ISSN: 0006-3592
    Schlagwort(e): dynamic experiments ; oxygen limitation ; microaerobic fermentation ; mathematical modeling ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An experimental method for studying microaerobic fermentation, called oxygen programmed fermentation, is introduced. The method if based on a chemostat. The mathematical equations governing the dynamics of the system are derived and simulations are made for two principally different cases: a purely respirative organism, and an organism capable of fermentation during oxygen limitation. It is shown that at a suitably chosen ramp rate, the dissolved oxygen concentration in the broth can be made to decrease almost linearly. It is suggested that the greatest use of oxygen programmed fermentation will be in initial experiments. Compared with chemostat studies, a scan of different oxygenation rates will provide a time-saving method of finding the interacting regions for metabolic transitions. Furthermore it is shown that the methods makes it possible to study cell physiology at condition which would normally lead to washout. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 152
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 445-451 
    ISSN: 0006-3592
    Schlagwort(e): aqueous two-phase systems ; pristinamycins ; fatty acid esters of PEG ; hydrophobic affinity partitioning ; extractive fermentation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The partitioning of pristinamycins was studied in dextran and polyethylene glycol (PEG) aqueous two-phases systems. Pristinamycins partitioned preferentially into the PEG-rich top phase. The partition coefficient was independent of molar mass of PEG and dextran and of antibiotic concentration, but, increased exponentially with the tieline length of the system. Partition of pristinamycins was greatly improved when fatty acids esters of PEG were mixed with PEG. In such mixtures, the partition of coefficient increased up to a value of 24, dependent on the carbon chain length of fatty acids and the modified PEG concentrations. Moreover, in such system, the two groups of pristinamycins, I and II, were extracted in accordance with their hydrophobicity. Recovery of pristinanamycins produced by Streptomyces pritinaespiralis in a fermentation broth was achieved with a dextran/PEG system. Cells were confined into the bottom phase and pristinamycins partitioned in the top phase. However, due to binding of the pristinamycins to the cells, the partition coefficient was slightly lower than of pure antibiotics solutions. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 153
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 481-488 
    ISSN: 0006-3592
    Schlagwort(e): plant cell cultures ; foaming ; Atropa belladonna ; cell flotation ; antifoam ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Foam development and stability in Atropa belladonna suspensions were investigated as a function of culture conditions. Foaming was due mainly to properties of the cell-free broth and was correlated with protein content; effects due to presence of cells increased towards the end of batch culture. Highest foam levels were measured 11 days after inoculation. Air flow rate was of major importance in determining foam volume; foam volume and stability were also strongly dependent on pH. Foam flotation of plant cells was very effective. After 30 min foaming, ca. 55% of cells were found in the foam; this increased to ca. 75% after 90 min. Polypropylene glycol 1025 and 2025, Pluronic PE 6100, and Antifoam-C emulsion were tested as chemical antifoams. Polypropylene glycol 1025 and Antifoam C at concentrations up to 600 ppm had no adverse effect on growth in shake flasks; Pluronic PE 6100 has an inhibitory effect at all levels tested. Concentrations of polypropylene glycol 2025 and Pluronic PE 6100 as low as 20 ppm reduced foam volumes by a factor of ca. 10. Addition of antifoam reduced kLa values in bubble-column and stirred-tank bioreactors. After operation of a stirred reactor for 2 days using Antifoam C for foam control, cell production was limited by oxygen due to the effect of antifoam on mass transfer. Theoretical analysis showed that maximum cell concentrations and biomass levels decline with increasing reactors working volume due to greater consumption of antifoam to prevent foam overflow. The results indicate that when chemical foam control is used in plant cell cultures, head-space volume and tolerable foam levels must be considered to optimize biomass production. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 154
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 499-508 
    ISSN: 0006-3592
    Schlagwort(e): bacterial transport ; porous media ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A model is presented for the coupled processes of bacterial growth and convective transport of bacteria has been modeled using a fractional flow approach. The various mechanisms of bacteria retention can be incorporated into the model through selection of an appropriate shape of the fractional flow curve. Permeability reduction due to pore plugging by bacteria was simulated using the effective medium theory. In porous media, the rates of transport and growth of bacteria, the generation of metabolic products, and the consumption of nutrients are strongly coupled processes. Consequently, the set of governing conservation equations form a set of coupled, nonlinear partial differential equations that were solved numerically. Reasonably good agreement between the model and experimental data has been obtained indicating that the physical processes incorporated in the model are adequate. The model has been used to predict the in situ transport and growth of bacteria, nutrient consumption, and metabolite production. It can be particularly useful in simulating laboratory experiments and in scaling microbial-enhanced oil recovery or bioremediation processes to the field. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 155
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 533-538 
    ISSN: 0006-3592
    Schlagwort(e): benzene ; toluene ; p-xylene ; competitive inhibition ; biodegradation kinetics ; cometabolic transformation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A microbial consortium and Pseudomonas strain (PPO1) were used in studying biodegradation of benzene, toluene, and p-xylene under aeorbic conditions. Studies involved removal of each compound individually as well as in mixture with the others. Both cultures exhibited a qualitatively similar behavior toward each compound. Both the pure culture and the consortium grew on benzene following Monod kinetics, on toluene following inhibitory (Andrews) kinetics, whereas neither could grow on P-xylene. Benzene and toluene mixtures were removed under cross-inhibitory (competitive inhibition) kinetics. In the presence of benzene and/or toluene, p-xylene was cometabolically utilized by both cultures, but was not completely mineralized. Metabolic intermediates of p-xylene accumulated in the medium and were identified. Benzene and toluene were completely mineralized. Cometabolic removal of p-xylene reduced the yields on both benzene and toluene. Except for cometabolism, kinetic constants were determined from data analysis and are compared with values published recently by other researchers. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 156
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 557-562 
    ISSN: 0006-3592
    Schlagwort(e): membrane-fixed enzymes ; invertase ; amyloglucosidase ; enzyme distribution ; enzyme reactor ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Invertase as well as as amyloglucosidase were immobilized within asymmetyric ultrafiltration membranes that were prepared from polysulfone or homogeneously modified polysulfone. The chemical modification was carried out by sulfonation and halomethylation. This additional change of the surface properties of the capillaries within the membrane offers the possibilities for various types of enzyme fixation, namely adsorption, charge interactions, or covalent bonding. By variation of the immobilization conditions the distribution of the enzyme could be adjusted over the membrane's cross section. At a distinct enzyme concentration in the loading solution a homogeneous enzyme distribution within the membrane could be verified. This was shown by diffusion experiments. Under ultrafiltration conditions using a solution that contains membrane-impermeable macromolecules as well as a membrane-permeable solute like saccharose the residence time within the membrane was increased due to gel formation atop the membrane yet the kinetic was no affected. The nonpermeable soluble starch was not reacted by the amyloglucosidase membrane, indicating that the skin layer was free of enzymes. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 157
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 595-608 
    ISSN: 0006-3592
    Schlagwort(e): biofilm ; aerobic waste water treatment ; airlift reactor ; waste water ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In this article, the conditions for aerobic biofilm formation on suspended particles, the dynamics of biofilm formation, and the biomass production during the start-up of a Biofilm Airlift Suspension reactor (BAS reactor) have been studied. The dynamics of biofilm formation during start up in the biofilm airlift suspension reactor follows three consecutive stages: bare carrier, microcolonies or patchy biofilms on the carrier, and biofilms completely covering the carrier. The effect of hydraulic retention time and of substrate loading rate on the formation of biofilms were investigated. To obtain in a BAS reactor a high biomass concentration and predominantly continuous biofilms, which completely surround the carrier, the hydraulic retention time must be shorter than the inverse of the maximum growth rate of the suspended bacteria. At longer hydraulic retention times, a low amount of attached biomass can be present on the carrier material as patchy biofilms. During the start-up at short hydraulic retention times the bare carrier concentration decreases, the amount of biomass per biofilm particle remains constant, and biomass increase in the reactor is due to increasing numbers of biofilm particles. The substrate surface loading rate has effect only on the amount of biomass on the biofilm particle. A higher surface load leads to a thicker biofilm.A strong nonlinear increase of the concentration of attached biomass in time was observed. This can be explained by a decreased abrasion of the biofilm particles due to the decreasing concentration of bare carriers. The detachment rate per biofilm area during the start-up is independent of the substrate loading rate, but depends strongly upon the bare carrier concentration.The Pirt-maintenance concept is applicable to BAS reactors. Surplus biomass production is diminished at high biomass concentrations. The average maximal yield of biomass on substrate during the experiments presented in this article was 0.44 ± 0.08 C-mol/C-mol, the maintenance value 0.019 ± 0.012 C-mol/(C-mol h). The lowest actual biomass yield measured in this study was 0.15 C-mol/C-mol. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 158
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 655-660 
    ISSN: 0006-3592
    Schlagwort(e): morphology ; vacuolation ; hyphal fragmentation ; Penicillium chrysogenum ; image analysis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A link between vacuolation and fragmentation of Penicillium chrysogenum mycelia in stirred tank submerged fermentations is reported. Quantitative information on vocuolation and morphology was obtained by image analysis. In fed-batch fermentations the coincidence of the events of rapid vacuolation and the fall of the mean total and main hyphal lengths suggests that hyphal fragmentation is not necessarily due to “shear” alone. The physiological state of the hyphae, characterized by the proportions of vaccuoles, was found to have a significant influence on the breakage of mycelial hyphae, It was found that the fragmentation was greater when the hyphae became heavily vacuolated following nutrient limitation in the culture, i.e., during the switch from the rapid growth to the production phase. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 159
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 649-654 
    ISSN: 0006-3592
    Schlagwort(e): anthocyanin production ; bioreactor cultivation ; Perilla frutescens ; plant cell culture ; shear effects ; metabolism ; secondary ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The short-time effects of shear on suspended cells of Perilla frutescens were quantitatively analyzed by exposing the cells to a well-defined flow field in a rotating drum reactor. It was found that both shear rate and shearing time significantly affected cell viability. The quantitative effects of shear on cell growth and the production of anthocyanin, a secondary metabolite, by the cell cultures were further investigated in a series of batch cultivations using a 5-L plant cell bioreactor with a marine impeller. The results indicated that there was an optimum range of shear rate; i.e., an average shear rate of 20 to 30 s-1 or an impeller tip speed of 5 to 8 dm/s, which maximized all the values of the following parameters: the specific growth rate, the maximum cell concentration, the (specific) production and productivity of anthocyanin, and the cell and anthocyanin yields. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 160
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 667-673 
    ISSN: 0006-3592
    Schlagwort(e): growth kinetics ; solid substrate ; bacterial adsorption ; Thiobacillus ferrooxidans ; sulfur ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The kinetics of oxidation of elemental sulfur by Thiobacillus ferrooxidans in a batch reactor was followed by measuring the concentration of adsorbed cells on the sulfur surface, the concentration of free cells in liquid medium, and the amount of sulfur oxidized. As the elemental sulfur was oxidized to sulfate, the liquid-phase concentration of free cells continued to increase with time, whereas the surface concentration of adsorbed cells per unit weight of sulfur approached a limiting value, i.e., the maximum adsorption capacity. During sulfur oxidation, there was a close correlation between the concentrations of adsorbed and free cells, and these data were well correlated with the Langmuir isotherm. The observed rates of batch growth and sulfur oxidation were consistent with a kinetic model, assuming that the growth rate of batch growth and sulfur oxidation were consistent with a kinetic model. Assuming that the growth rate of adsorbed bacteria is proportional to the product of the concentration of adsorbed cells and the fraction of adsorption sites unoccupied by cells. The kinetic and stoichiometric parameters appearing in the model were evaluated using the experimental data and were compared with parameters determined previously for a few metal sulfides. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 161
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 699-709 
    ISSN: 0006-3592
    Schlagwort(e): spores ; Penicillium roquefortii ; bioconversion ; methyl ketone ; germination ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The bioconversion of octanoic acid into 2-heptanone by spores of Penicillium roquefortii is performed using a fed-batch technique with pH control by addition of the liquid substrate itself. The early stage of this process takes place with a high bioconversion rate and high yield. These values then decrease as a result of germination and growth the biocatalyst. An optimization strategy for the process would thus be to improve the characteristics of this first period, i.e., increase its duration and the reaction rate. An increase in duration is evidenced in two cases: (I) under oxygen limitation: and (ii) when the spore content in the medium is less than 107 spores/mL. These conditions give insufficient overall bioconversion rates: better optimization should be achieved without oxygen limitation and with high spore content. Characterization of the first period by material and bioenergetic balances suggests that an increase in the ethanol content of the medium, which acts as an energy source and a permeabilizer, and the use of specific inhibitor of the Krebs cycle, may be a way to further improve the biocatalyst performance and stability. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 162
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 736-744 
    ISSN: 0006-3592
    Schlagwort(e): disruption kinetics ; Saccharomyces cerevisiae ; virus-like particles ; recombinant cells ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Recombinant cells of Saccharomyces cerevisiae, expressing virus-like particles (Ty-VLPs), can be readily disrupted in a high pressure homogenizer and show identical disruption kinetics to the untransformed host strain. When the cells are freeze/thawed before disruption, they become about four times more resistant to homogenization. This effect increases with the number of freeze/thaw cycles, but is independent of the time the cells remain frozen. The freeze/thaw effect is observed with cells harvested during both the logarithmic and stationary phase of growth, and occurs with the untransformed host strain as well as the transformed one. Freeze/thawed cells are twice as resistant to disruption in the bead mill as fresh cells. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 163
    ISSN: 0006-3592
    Schlagwort(e): hybridoma ; subclone ; continuous culture ; batch culture ; igG-mRNA ; biosynthetic activities ; antibody production ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: During long-term continuous culture of the hybridoma cell line 11317, a better-producing subclone (I1317-SF11), giving improved productivity, has been selected. The comparison of the original cell line (I1317-DC) with this subclone revealed that although the growth patterns of both clones were similar, both in continuous and in batch cultures, considerable differences could be seen between the clones with respect to monoclonal antibody (MAB) accumulation, MAB production rate, the levels of mRNA coding for heavy and light chains of IgG, and some metabolic activities. In continuous culture as well as in batch culture, I1317-SF11 showed increased levels of mRNA coding for kappa and gamma chains compared with I1317-DC and/or a modified ratio of the mRNA species when compared to that in I1317-DC. Using pulse experiments, it could be established that the biosynthesis of both chains was augmented in I1317-SF11. Although the kappa and gamma mRNA levels were modified or inversed for I1317-SF11, the cells always synthesized more kappa than gamma chains. The overall increase in the synthetic activity of I1317-SF11 is suggested as one reason for the considerable increase of IgG productivity and product accumulation in continuous culture as well as in repeated batch cultures. Tests concerning metabolic activity revealed that I1317-SF11 had a predominantly glycolytic metabolism independent of growth requirements, whereas for I1317-DC the metabolism became increasingly glycolytic with increased growth. The antibody yield coefficient of I1317-SF11 on glutamine was significantly higher than that of I1317-DC for the continuous culture, whereas the antibody coefficients on glucose were almost similar for both clones under the different culture conditions used. Both antibody coefficients were considerablly influenced by the specific growth rate.All these facts together lead to the conclusion that subclone I1317-SF11 uses more of the energy available, or it was the energy and/or precursors available for the synthesis and production of MAB more efficiently than the thesis and production of MAB more efficiently than the original cell line. Although the levels of mRNA coding for heavy and light chains of IgG were modified, it could be confirmed that the overall regulation of MAB-synthesis and -production occurs post-translationally and that at higher growth rates, more biosynthetic activity is diverted to biomass production. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 164
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 808-818 
    ISSN: 0006-3592
    Schlagwort(e): fed batch ; substrate limitation ; energy metabolism ; kinetics ; overflow metabolism ; growth rate ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Substrate limited fed batch cultures were used to study growth and overflow metabolism in hybridoma cells. A glucose limited fed batch, a glutamine limited fed batch, and a combined glucose and glutamine limited red batch culture were compared with batch cultures. In all cultures μ reaches its maximum early during growth and decreases thereafter so that no exponential growth and decreases thereafter so that no exponential growth rate limiting, although the glutamine concentration (〉0.085mM) was lower than reported Ks vales and glucose was below 0.9mM; but some other nutrients (s) was the cause as verified by simulations. Slightly more cells and antibodies were produced in the combined fed batch compared with the batch culture. The specific rates for consumption of glucose and glutamine were dramatically influenced in fed batch cultures resulting in major metabolic changes. Glucose limitation decreased lactate formation, but increased glutamine consumption and ammonium formation. Glutamine limitation decreased ammonium and alanine formation of lactate, alanine, and ammonium was negligible in the dual-substrate limited fed batch culture. The efficiency of the energy metabolism increased, as judged by the increase in the cellular yield coefficient for glucose by 100% and for glutamine by 150% and by the change in the metabolic ratios lac/glc, ala/ln, and NHx/ln, in the combined fed culture. The data indicate that a larger proportion of consumed glutamine enters the TCA cycle through the glutamate dehydrogenase pathway, which releases more energy from glutamine than the transamination pathway. We suggest that the main reasons for these changes are decreased uptake rates of glucose and glutamine, which in turn lead to a reduction of the pyruvate pool and a restriction of the flux through glutaminase and lactate dehydrogenase. There appears to be potential for further cell growth in the dual-substrate-limited fed batch culture as judged by a comparison of μ in the different cultures. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 165
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 837-848 
    ISSN: 0006-3592
    Schlagwort(e): phosphorus removal ; metabolic models ; stoichiometry ; polyphosphate ; poly-β-hydroxybutyrate ; glycogen ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In the aerobic phase of the biological phosphorus removal process, poly-β-hydroxybutyrate, produced during anaerobic conditions, is used for cell growth, phosphate uptake, and glycogen formation. A metabolic model of this process has been developed. The yields for growth, polyphosphate and glycogen formation are quantified using the coupling of all these conversions to the oxygen consumption. The uptake of phosphate and storage as polyphosphate is shown to have a direct effect on the observed oxygen consumption in the aerobic phase. The overall energy requirements for the P-metabolism are substantial: 25% of the acetate consumed during anaerobic conditions and 60% of the oxygen consumptions is used for the synthesis of polyphosphate and glycogen. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 166
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 888-894 
    ISSN: 0006-3592
    Schlagwort(e): Rhodotorula glutinis ; Lactobacillus helveticus ; yeast ; whey ; carotenoids ; carotenogenesis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The growth and carotenoid biosynthesis of the yeast Rhodotorula glutinis was studied by cocultivation with Lactobacillus helveticus in cheese ultrafiltrate containing 3.9% and 7.1% lactose. By growing this mixed culture in a 15-L fermentor MBR AG (Switzerland) at an air flow rate of 0.5 L/L min and agitation at 220 rpm for 6 days, a total yield of carotenoids of 268 μg/g dry cells wasobtained. Carotenoids were formed almost parallel with the cell growth, anda maximum production was reached at an early stationary phase. A high-performance liquid chromatographic system (HPLC) permitting simultaneous determination of major carotenoid pigments was used. The three main pigments (torularhodin, β-carotene, and torulene) were formed in Rhodotorula glutinis, and reached a maximum concentration as follows: 182.0, 43.9, 23.0 μg,g dry cells. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 167
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 902-911 
    ISSN: 0006-3592
    Schlagwort(e): product inhibition ; growth modeling ; glycerol fermentation ; 1,3-propanediol ; C. butyricum ; K. pneumoniae ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The inhibition potentials of products and substrate on the growth ofClostridium butyricum and Klebsiella pneumoniae in the glycerol fermentation are examined from experimental data and with a mathematicalmodel. Whereas the inhibition potential of externally added and self-produced 1,3-propanediol is essentially the same, butyric acid produced by the culture is more toxic than that externally added. The same seems to apply for acetic acid. The inhibitory effect of butyric acid is due tothe total concentration instead of its undissociated form. For acetic acid, it cannot be distinguished between the total concentration and the undissociated formThe inhibition effects of products and substrate in the glycerol fermentation are irrespective of the strains, and, therefore, the same growth model can be used. The maximum product concentrations tolerated (critical concentrations C*pi) are 0.35 g/Lfor undissociated acetic acid, 10.1 g/L for total butyric acid, 16.6 g/L for ethanol, 71.4 g/L for 1,3-propanediol, and 187.6 g/L for glycerol, which are applicable to C. butyricum and K. pneumoniae grown under a variety of conditions. For 55 steady-states, which were obtained from different types of continuous cultures over a pHrange of 5.3-8.5 and under both substrate limitation and substrate excess, the proposed growth model fits the experimental data with an average deviation of 17.0%. The deviation of model description from experimental values reduces of 11.4% if only the steady-states with excessive substrate are considered. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 168
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 930-943 
    ISSN: 0006-3592
    Schlagwort(e): Eschscholtzia californica ; embryogenesis ; somatic embryos ; bioreactor ; macronutrients ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Embryogenic cultures of a transformed Eschscholtzia californica cell line were carried out in a 11-L helical ribbon impeller bioreactor operated under various conditions to evaluate the performance of this equipment for somatic embryo (SE) production. All bioreactor cultures produced SE suspensions with maximum concentrations at least comparable to those obtained from flask control cultures (∼8-13 SE · mL-;1). However, an increase of the mixingspeed, from 60 to 100 rpm, and low sparging rate (∼0.05 VVM, kL a ∼ 6.1 h-;1) for dissolved oxygen concentration (DO) control yielded poorer quality embryogenic cultures. The negative effects on SE production were attributed mainly to the low but excessive shear experienced by the embryogenic cells and/or embryoforming aggregates. High DO (∼60% of air saturation) conditions favored undifferentrated biomass production and high nutrient uptake rates at the expense of the slower SE differentiation process in both flask and bioreactor cultures. Too low DO (-5-10%) inhibited biomass and SE production. The best production of SE (∼44 SE · mL-1 or ∼757 SE · g dw-1 · d-1) was achieved by operating the bioreactor at 60 rpm while controlling DO at ∼20%by surface oxygenation only (0.05 VVM, kL a ∼ 1.4 h-;1). This production was found to be a biomass production/growth-associated process and was mainly limited by the availability of extracellular phosphate, magnesium, nitrogen salts, and carbohydrates. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 169
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 11-20 
    ISSN: 0006-3592
    Schlagwort(e): conservation equations ; linear constraints ; data reconciliation ; balancing technique ; gross error detection ; error diagnosis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Conservation equations derived from elemental balances, heat balances, and metabolic stoichiometry, can be used to constrain the values of conversion rates of relevant components. In the present work, their use will be discussed for detection and localization of significant errors of the following types: 1.At least one of the primary measurements has a significant error (gross measurement error).2.The system definition is incorrect: a component a.is not included in the system description.b.has a composition different from that specified.3.The specified variances are too small, resulting in a too-sensitive test.The error diagnosis technique presented here, is based on the following: given the conservation equations, for each set of measured rates, a vector of residuals of these equations can be constructed, of which the direction is related to the error source, as its length is a measure of the error size. The similarity of the directions of such a residual vector and certain compare vectors, each corresponding to a specific error source, is considered in a statistical test. If two compare vectors that result from different error sources have (almost) the same direction, errors of these types cannot be distinguished from each other. For each possible error in the primary measurements of flows and concentrations, the compare vector can be constructed a priori, thus allowing analysis beforehand, which errors can be observed. Therefore, the detectability of certain errors likely to occur can be insured by selecting a proper measurement set. The possibility of performing this analysis before experiments are carried out is an important advantage, providing a profound understanding of the detectability of errors. The characteristics of the method with respect to diagnosis of simultaneous errors and error size estimation are discussed and compared to those of the serial elimination method and the serial compensation strategy, published elsewhere. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 170
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 46-56 
    ISSN: 0006-3592
    Schlagwort(e): enzymatic lysis ; homogenization, high-pressure ; Candida utilis ; cell wall disruption ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The enhancement of the overall disruption of a native strain of Candida utilis (ATCC 9226) was studied using a combination of two methods, namely, pretreatment in the form of partial enzymatic lysis by Zymolyase followed by mechanical disruption in a Microfluidizer high-pressure homogenizer. The cells were grown in both batch and continuous cultures to examine the effect of specific growth rate on disruption. Cell suspensions ranging in concentration from 7 to 120 g DW/L were disrupted with and without enzymatic pretreatment. For yeast grown in batch culture, final total disruption obtained using the combined protocol approached 95% with four passes at a pressure of 95 MPa, as compared with only 65% disruption using only mechanical homogenization. A modified model was developed to predict the fraction disrupted by the enzymatic pretreatment-mechanical homogenization two-stage process. Predicted disruptions agreed favorably with experimental observations (maximum deviation of 20%) over a wide range of operating conditions. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 171
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 69-76 
    ISSN: 0006-3592
    Schlagwort(e): airlift ; fermentor, airlift ; hydrodynamics ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Fermentations of the yeast Saccharomyces cerevisiae were carried out in a 90 to 250-L working volume concentric tube airlift fermentor. Measurements of liquid circulation velocity, gas hold-up, and liquid mixing were made under varying conditions of gas flowrate, vessel height, and top-section size. Both liquid circulation velocity and mixing time increased with vessel height. Liquid velocity varied approximately in proportion to the square root of column height, supporting a theoretically based relationship. The effect of vessel height on gas hold-up was negligible. The height of the top-section had a significant effect on liquid mixing. Mixing time decreased with increasing size of the top-section up to a critical height. As the top-section was expanded beyond this height, little improvement in mixing was seen. This indicated the presence of a two-zone flow pattern in the top-section. Liquid velocity and gas hold-up were essentially independent of top-section height. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 172
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 429-433 
    ISSN: 0006-3592
    Schlagwort(e): disinfection ; Escherichia coli ; water disinfection ; activated carbon fiber ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A novel electrochemical reactor employing activated carbon fiber (ACF) electrodes was constructed for disinfecting bacteria in drinking water. Escherichia coli adsorbed preferentially onto ACF rather than to carbon-cloth or granular-activated carbon. E. coli cells, which adsorbed onto the ACF, were killed electrochemically when a potential of 0.8 V vs. a saturated calomel electrode (SCE) was applied. Drinking water was passed through the reactor in stop-flow mode: 2mL/min for 12 h, o L/min for 24 h, and 1 mL/min for 6 h. At an applied potential of 0.8 V vs, SCE, viable cell concentration reamined below 30 cells/mL. In the absence of an applied potential, bacteria grew to a maximum concentration of 9.5 × 103 cells/mL. After continuous operation at 0.8 V vs. SCE, cells adsorbed onto the ACF could not be observed by scanning electron microscopy. In addition, chlorine in drinking water was completely removed by the reactor. Therefore, clean and efficient inactivation of bacteria in drinking water was successfully performed. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 173
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 461-470 
    ISSN: 0006-3592
    Schlagwort(e): phosphorus removal ; metabolic model ; stoichiometry ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In the anaerobic phase of a biological phosphorus removal process, acetate is taken up and converted to PHB utilizing both energy generated in the degradation of polyphosphate to phosphate, which is released, and energy generated in the conversion of glycogen to poly-β-hydroxy butyrate (PHB). The phosphate/acetate ratio cannot be considered a metabolic constant, because the energy requirement for the uptake of acetate is strongly influenced by the pH value. The observed phosphate/acetate ratio shows a variation of 0.25 to 0.75 P-mol/C-mol in a pH range of 5.5 to 8.5. It is shown that stored glycogen takes part in the metabolism to provide reduction equivalents and energy for the conversion of acetate to PHB. A structured metabolic model, based on glycogen as the source of the reduction equivalents in the anaerobic phase and the effect of the pH on the energy requirement of the uptake of acetate, is developed. The model explains the experimental results satisfactorily. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 174
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 483-489 
    ISSN: 0006-3592
    Schlagwort(e): microbial fermentation control ; neural network simulation ; backpropagation ; network topology design ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This article discusses the development of a prototype neural network-based supervisory control system for Bacillus thuringiensis fermentations. The input pattern to the neural network included the type of inoculum, operation temperature, pH value, accumulated process time, optical density in fermentation medium, and change in optical density. The output from the neural network was the predicted optical density for the next sampling time. The control system has been implemented in both a computer simulation and a laboratory fermentation experiment with promising results. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 175
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 515-520 
    ISSN: 0006-3592
    Schlagwort(e): subtilisin ; organic solvents ; transition state stabilization ; EPR spectroscopy ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Electrostatic forces are among the stabilizing interactions that contribute to the high degree of enzyme-transition state complementarity. The active-site polarity, which can differ substaintially from that of water, is thus an important determinant of transition state stabilization. Here we pose the question of whether the rate of an enzymatic reaction proceeding through a charged transition state can be increased by increasing the active-site polarity in an organic solvent. The active-site polarity of subtilisin has been reduced by dehydration and suspension in a nonpolar solvent (tetrahydrofuran), and then increased by adding water to the solvent. Enhancing the local polarity substantially increasing the rate of catalysis, implicating polarity as an important factor in stabilizing the charged tetrahedral transition state. Studies with subtilisins whose active sites have been modified by site-directed mutagenesis support the role of polarity in transition state stabilization. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 176
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 543-554 
    ISSN: 0006-3592
    Schlagwort(e): encapsulation ; nerve regeneration ; cell transplantation ; polymers ; extracellular matrix ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The nervous system presents a challenge to the field of tissue engineering because some of its complex neurochemical and neuroanatomical architecture is just beginning to be understood. A combination of advances in molecular neurobiology, gene transfer techniques, and the concomitant advances in the engineering of biomaterials at a molecular level, are making tissue engineering in the nervous system possible. Due to the vast range of fields that this highly interdisciplinary task spans, any review is bound to be somewhat limited. Given that, this review attempts to cover some solutions engineered for: (a) the functional replacement of a missing neuroactive component; (b) the rescue or regeneration of degenerated neural tissue; and (c) the building of intelligent neural cell-based biosensors and simple in vitro neural circuits based on controlled neural cell attachment to electrically relevant substrates. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 177
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 195-206 
    ISSN: 0006-3592
    Schlagwort(e): bioprocess ; stirred tank ; structured mixing model ; scale-up ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new scale-up concept based upon mixing models for bioreactors equipped with Rushton turbines using the tanks-in-series concept is presented. The physical mixing model includes four adjustable parameters, i.e., radial and axial circulation time, number of ideally mixed elements in one cascade, and the volume of the ideally mixed turbine region. The values of the model parameters were adjusted with the application of a modified Monte-Carlo optimization method, which fitted the simulated response function to the experimental curve. The number of cascade elements turned out to be constant (N = 4). The model parameter radial circulation time is in good agreement with the one obtained by the pumping capacity. In case of remaining parameters a first or second order formal equation was developed, including four operational parameters (stirring and aeration intensity, scale, viscosity). This concept can be extended to several other types of bioreactors as well, and it seems to be a suitable tool to compare the bioprocess performance of different types of bioreactors. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 178
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 242-257 
    ISSN: 0006-3592
    Schlagwort(e): genetic regulation ; gene expression ; transcriptional regulation ; translational regulation ; RNA polymerase ; rpoBc ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A theoretical method for comparing the performance of rival models of bacterial genetic regulation is presented. The particukar difficulties involved in describing the regulated synthesis of proteins that strongly influence cell growth are identiied, and the method is specifically designed to treat such cases. The method employs a mathematical description of intrinsic perturbations occurring during exponential growth to test the performance of regulatory models. Specific models of transcriptional and translational regulation are inserted into a general gene-expression framework in order to determine their control responses. Applying thhis approach to examine the regulation of RNA polymerase synthesis in Eschericia coli provides support for the hypothesis that rpoB translation is regulated by cooperative binding of multiple RNA polymerase molecules to the mRNA. The framework is of a sufficiently general form that the method can be used to study mechanisms involved in controlling synthesis of any bacterial protein. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 179
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 262-266 
    ISSN: 0006-3592
    Schlagwort(e): amperometric glucose biosensor ; oxygen electrode ; rechargeable sensor ; continuous glucose monitoring ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A potentially implantable glucose biosensor for continuous monitoring of glucose levels in diabetic patients has been developed. The glucose biosensor is based on an amperometric oxygen electrode and glucose oxidase immobilized on carbon powder held in a form of a liquid suspension. The enzyme material can be replaced (the sensor recharged) without sensor disassembly. Recharging of the biosensor is achieved by injecting fresh immobilized enzyme into the sensor using a septum. Diffusion membranes made of silastic latex-rubber coatings over a microporous polycarbonate membrane are used. Calibration curves of the amperometric signal show linearity over a wide range of glucose concentrations - up to 500 mg/dL (28 mM), covering hypoglycemic, normoglycemic, and hyperglycemic conditions. Preliminary in vitro studies of the biosensor show stable performance during several recharge cycles (of 14 days each) over a period of 4 months. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 180
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 293-300 
    ISSN: 0006-3592
    Schlagwort(e): chromium ; Escherichia coli microbial reduction ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A model based on te analysis of the mechanism of enzymatic reactions was developed to characterize the rate and extent of microbial reduction of hexavalent chromium in Escherichia coli 33456. A finite reduction capacity (Rc) was proposed and incorporated into the enzymatic model to regulate the toxicity effect on cells due to the oxidizing power of Cr(VI). The parameter values were determined by nonlinear least-square analysis using experimental data of anaerobic cultures. The obtained parameters were then used to predict Cr(VI) reduction in aerobic cultures along with a modification term of uncompetitive inhibition from molecular oxygen. The applicability of the developed model was demonstrated through excellent prediction of the results of batch studies conducted over range of initial Cr(VI) concentrations, initial cell densities, and DO levels. A sensitivity analysis revealed that the parameters obtained using the experimental data were unique, and neither change in Kc, the half-velocity constant, at high initial Cr(VI) concentrations nor change in Rc, the reduction capacity, at low initial Cr(VI) concentrations was sensitive to model prediction. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 181
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 321-330 
    ISSN: 0006-3592
    Schlagwort(e): crystalline surface layers ; Protein A ; immobilization ; affinity matrix ; Clostridium thermohydrosulfuricum ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In this article, we describe a novel type of affinity matrix which was prepared by covalently binding Protein A to crystalline cell surface layers (S-layers) from the gram-positive Clostridium thermohydrosulfuricum L111-69. S-layers were used in the form of cell wall fragments, which were obtained by breaking whole cells by ultrasonification and removing the cell content and the plasma membrane. In these thimble shaped structures, revealing a size of 1 to 2 μm, the peptidoglycan-containing layer was covered on both faces with a hexagonally ordered S-layer lattice composed of identical glycoprotein subunits. After crosslinking the S-layer protein with glutaraldehyde, carboxyl groups from acidic amino acids were activated with carbodiimide and used for immobilization of Protein A. Quantitative determination confirmed that up to two Protein A molecules were bound per S-layer subunit leading to a dense monomolecular coverage of the immobilization matrix with the ligand.Affinity microparticles were capable of adsorbing lgG from solutions of purified preparations, from artificial lgG-albumin mixtures, and from serum. The amount of lgG bound to affinity microparticles corresponded to the theoretical saturation capacity. Under appropriate conditions, up to 95% of the adsorbed lgG could be eluted again. Affinity microparticles were found to have an extremely low Protein A leakage and a high stability toward mechanical forces. Because pores in the S-layer lattice revealed a size of 4 to 5 nm, immobilization of Protein A and adsorption of lgG was restricted to the outermost surface area. This excludes mass transfer problems usually encountered with affinity matrices prepared from amorphous polymers where more than 90% of the ligands are immobilized in the interior. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 182
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 342-348 
    ISSN: 0006-3592
    Schlagwort(e): organic solvents ; reversed micelles ; protein mobility ; EPR spectra of enzymes ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: We have investigated the effect of pressure on structural properties of subtilisin solubilized in reversed micelles of Tween-85/isopropanol in hexane. Electron paramagnetic resonance (EPR) spectra of spin-labeled enzyme indicate a reduction in spin-label mobility when the enzyme is transferred from aqueous solution to the microemulsion. One explanation for the spectral broadening is a change in the protein's active-site conformation and/or dynamics. However, over a W0 range of 80 to 180, EPR spectroscopy could detect no change in the enzyme's environment, conformation, or molecular dynamics. The EPR spectra also contained a contribution from free spin label located in an environment with a polarity roughly between that of propanol and bulk water. No changes in the polarity surrounding the free spin label nor in the enzyme's structural properties were evident at pressures up to 10,000 psi. Previous work has demonstrated that pressure can be used to manipulate the size of some reversed micelles, and the EPR data indicated that for this system such pressure tuning of micellar properties will not adversely affect the structure of solubilized enzyme. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 183
    ISSN: 0006-3592
    Schlagwort(e): immune activation ; monoclonal antibody ; phorbol myristate acetate ; immunotherapy ; assay validation ; renal cell carcinoma ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An in vitro assay that measures the activation level of ex vivo activated (EVA) T cells currently being used in the adoptive immunotherapy of metastatic renal cell carcinoma has been developed. This assay is based on the ability of activated, but not resting. T cells to proliferate in response to the protein kinase C activator, phorbol myristate (PMA). To utilize this assay for in-process monitoring and control, we have begun an initial validation of the overall reproducibility of this assay. The proliferation of activated T cells in response to PMA, as measured by the mean cpm values of 3H-thymidine incorporated, was demonstrated to have intra-assay coefficients of variation (cv′s) for individual analysts that were typically less than 10% and rarely exceeded 20%. Activated T cells could be frozen and stored for at least 6 weeks with little or no deterioration in their ability to proliferate in response to PMA. Using these cells, inter-assay cv′s that were typically less than 15% were obtained by individual analysts, and overall cv′s of 10% to 25% were obtained for different samples assayed by different analysts at different times. This level of variability is very reasonable for a cellular assay. Furhter validation of this assay will address the issues of sensitivity, linearity and selectivity. To date, this assay has been used to analyze over 90 patient EVA cell samples and has revealed a broad range of proliferative responses to PMA. Taken together, these results suggest that this assay may be useful in defining the potency of the activated T cell used therapeutically.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 184
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 757-763 
    ISSN: 0006-3592
    Schlagwort(e): transposition ; microneurovascular repair ; tenotomy and repair ; muscle atrophy ; motor unit number ; mean motor unit maximum force ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: One aspect of tissue engineering of skeletal muscle involves the transposition and transplantation of whole muscles to treat muscles damaged by injury or disease. The transposition of whole muscles has been used for many decades, but since 1970, the development of techniques for microneurovascular repair has allowed the transplantation of muscles invariably result in structural and functional deficits. The deficits are of the greatest magnitude during the first month, and then a gradual recovery results in the stabilization of structural and functional variables between 90 and 120 days. In stabilized vascularized grafts ranging from 1 to 3 g in rats to 90 g in dogs, the major deficits are ∼25% decrease in muscle mass and in most grafts ∼40% decrease in maximum force. The decrease in power is more complex because it depends on both the average shortening force and the velocity of shortening. As a consequence, the deficit in maximum power may be either greater or less than the deficit in maximum force. Tenotomy and repair are the major factors responsible for the deficits.Although the data are limited, skeletal muscle grafts appear to respond to training stimuli in a manner no different from that of control muscles. The training stimuli include traditional methods of endurance and strength training, as well as chronic electrical stimulation. Transposed and transplanted muscles develop sufficient force and power to function effectively to: maintain posture; move limbs; sustain the patency of sphincters; partially restore symmetry in the face; or serve as, or drive, assist devices in parallel or in series with the heart.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 185
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 792-800 
    ISSN: 0006-3592
    Schlagwort(e): tissue engineering ; biomaterials ; surface chemistry ; cell adhesion ; cell guidance ; haptotaxis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Anisotropic cell culture surfaces patterned with amino and alkylsilanes can guide cell distribution and provide an approach to study important processes involved in tissue engineering, such as cell attachment and locomotion. By combining photolithographic and silane coupling techniques, glass coverslips were patterned with either n-octadecyldimethylchlorosilane (ODDMS) or dimethyldichlorosilane (DMS), and N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (EDS). The alkylsilanes, theoretically, have similar methyl and methylene groups exposed at the surface but different structures, with DMS being amorphous and ODDMS ordered. Neuroblastoma cells, osteosarcoma cells, and fibroblasts plated on surfaces patterned with EDS/ODDMS and EDS/DMS specifically localized on the EDS regions, but distributed randomly on ODDMS/DMS patterned surfaces. The preferential assembly of cells onto EDS regions did not depend on the structure of the adjacent alkylsilane regions and was a time-dependent process. Angle dependent x-ray photoelectron spectroscopy (XPS) and contact angle measurements indicated that EDS was imobilized on glass as a fractional hydrophilic monolayer, and ODDMS and DMS were bound as patchy amorphous hydrophobic multilayers. Neither surface coverage nor thickness of the overlayer seemed to be as important as surface chemistry, or charge, in guiding mammalian cell distribution. These results are consistent with the concept that mammalian cells attach to and are guided by positively charged surfaces.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 186
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 490-496 
    ISSN: 0006-3592
    Schlagwort(e): multifactorial optimization ; bacterial transformation ; electroporation ; Streptococcus thermophilus ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A multifactorial process was used to optimize transformation of Streptococcus thermophilus by electroporation. Simple experimental designs were applied to study three, four, or five factors in eight experiments. Four qualitative factors, growth and recovering media, and plasmid and bacterial strains, were studied empirically. Eight quantitative factors, including electrical, physiological, and chemical parameters, were studied by fractional factorial designs. Effects of individual parameters as well as interactions between them were investigated and optimized. Optimization was performed for one S. thermophilus strain, ST11, and proved to work for all other tested strains of the same species. Transformation efficiencies of 9 × 102 to 6 × 105 transformants per microgram DNA were achieved, depending on the strains and vectors used. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 187
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 521-528 
    ISSN: 0006-3592
    Schlagwort(e): carbon tetrachloride ; acetate ; nitrate ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A denitrifying consortium capable of transforming carbon tetrachloride (CCl4) was cultured from aquifer sediment from the U.S. Department of Energy's Hanford Site in southeastern Washington State. To understand the kinetics of the biological destruction of CCl4 by these microbes, a set of experiments, the conditions of which were chosen according to a fractional factorial experimental design, were completed. This article reports on the experimental design along with the results for CCl4, biomass, acetate, nitrate, and nitrite concentrations. These data indicate that growth is inhibited by high nitrite concentrations, whereas CCl4 degradation is slowed by the presence of nitrate and/or nitrite. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 188
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 541-541 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 189
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 582-585 
    ISSN: 0006-3592
    Schlagwort(e): osteoblasts ; biomaterilas ; bone-implant interface ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Well-characterized osteoblasts provide a successful in vitro model to study bone-biomaterial interactions. Knowledge of the events occurring at this tissue-biomaterial interface could lead to the design of improved orthopedic/dental biomaterials which elicit specific and desirable responses from surrounding cells/tissues, optimize function of osteoblasts (the boneforming cells), and enhance long-term bone-implant bonding. © 1994 John Wiley & Sons, Inc.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 190
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 573-581 
    ISSN: 0006-3592
    Schlagwort(e): bone ; bone remodeling ; bone interstitial fluid flow ; fluid shear stress ; osteoblasts ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: It is well established that vascularization is required for effective bone healing. This implies that blood flow and interstitial fluid (ISF) flow are required for healing and maintenance of bone. The fact that changes in bone blood flow and ISF flow are associated with changes in bone remodeling and formation support this theory. ISF flow in bone results from transcortical pressure gradients produced by vascular and hydrostatic pressure, and mechanical loading. Conditions observed to alter flow rates include increases in venous pressure in hypertension, fluid shifts occurring in bedrest and microgravity, increases in vascularization during the injury-healing response, and mechanical compression and bending of bone during exercise. These conditions also induce changes in bone remodeling. Previously, we hypothesized that interstitial fluid flow in bone, and in particular fluid shear stress, serves to mediate signal transduction in mechanical loading- and injury-induced remodeling. In addition, we proposed that a lack or decrease of ISF flow results in the bone loss observed in disuse and microgravity. The purpose of this article is to review ISF flow in bone and its role in osteogenesis. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 191
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 615-621 
    ISSN: 0006-3592
    Schlagwort(e): endothelial cell metabolism ; strain ; endothelin ; prostacyclin ; tissue plasminogen activator ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effects of cyclical expansion and elaxation of the vessel wall on endothelial cell metabolism have been modeled using a uniaxial strain device and cultured endothelial cell monolayers. Also, the effects of stopping and then restarting cyclic strain on metabolite secreation rates were determined. Secretion rates of prostacyclin (PGI2), endothelin, tissue plasminogen activator (t-PA), and plasminogen activator inhibitor-type 1 (PaI-1) by endothelial cells were constant over24-h periods The secreation of both PGI2 and endothelin was enhanced in cells exposed to high physiological levels of cyclical strain (10% at 1Hz) compared with controls, while tPA production was unaltered. These results were true for both human and bovine endothelial cells. Characterization of the response of human endothelial cells to cyclical strain made evaluation of stretch effects on PAl-1 secretion possible. A nearly twofold increase in PAl-1 secretion by cells exposed to arterial levels of strain was observed. Endothelin secretion remained elevated even after strain was stopped for 12 h, while PGl2 secretion returned to control values upon cessation of cyclic stretch. These results indicate that physiological levels of cyclic mechanical strain ca significantly modulate secretion of vasoactive metabolited form endothelial cells. The changes sen secretion are, in some cases, quite different from those caused by arterial levels of fluid shear stress exposure. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 192
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 645-653 
    ISSN: 0006-3592
    Schlagwort(e): hepatocytes ; liver failure ; bioartificial liver ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Despite recent advances in medical supportive therapy, patients with severe fulminant hepatic failure (FHF) have mortality rate approaching 90%. Investigators have attempted to improve survival by using various extracorporeal liver support systems loaded with sorbents and liver tissue preparations. None of them succeeded in gaining clinical acceptance and orthotopic liver transplantation (OLT) remains a primary therapeutic option for patients with FHF. In this study, authors discuss the systems which utilize isolated hepatocytes. Most of these devices were tested in vitro and in animals with chemically and surgically induced liver failure. In some studies, signficant levels of detoxification and liver functions were achieved. The authors describe their own hepatocyte-based artificial liver (BAL). It is based on plasma perfusion through a hollow-fiber module seeded with matrix-anchored porcine hepatocytes. The BAL was used 14 times to treat 9 patients with acute liver failure. On 10 occasions, a charcoal column was included in the plasma circuit. Each treatment lasted 7 ± 1 h. All procedures were tolerated well and 8 patients (including 6 patients with FHF) underwent OLT. Five patients with increased intracranial pressure (ICP) and evidence of decerebration had normalization of ICP and enjoyed full neurologic recovery after OLT. Laboratory data showed evidence for bilirubin conjugation, decrease in blood ammonia, maintenance of low lactic acid levels, and increase in the ration between the branched chain and aromatic amino acids. No allergic reactions to xenogeneic hepatocytes were observed. The authors conclude that BAL treatment with porcine hepatocytes appears to be safe and can help maintain patients alive and neurologically intact until a liver becomes available for transplantation. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 193
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 678-681 
    ISSN: 0006-3592
    Schlagwort(e): kidney ; bioartificial kidney ; blood ultrafiltration ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Tissue engineering is a rapidly growing field in biotechnology. The use and packaging of synthetic materials, biologic compounds, and cellular components of specific tissues can be envisioned to replace physiologic function of diseased organs. Long-term ex vivo therapy for kidney failure has been achieved, so that the kidney may be the first solid organ in which tissue engineering concepts can produce an implantable device for long-term in vivo replacement therapy. To replace the kidney's excretory function, an implantable bioartificial kidney requires both a device to replace blood ultrafiltration performed by renal glomeruli and a device to replace transport regulatory function of the renal tubule. The initial concepts for these devices are just beginning to be considered and developed. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 194
    ISSN: 0006-3592
    Schlagwort(e): renal cell carcinoma ; lymphocyte therapy ; immunotherapy ; T cells ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Autolymphocyte therapy (ALT) is outpatient-based adoptive immunotherapy using ex vivo-activated memory T-cells. To support the safe and reproducible delivery of ALT at three cell processing facilities (Boston, MA; Atlanta, GA; Orange, CA) we created a comprehensive quality assurance/quality control program compliant with recent FDA guidance relevant to activated lymphocytes and somatic cell therapies. Each facility performed extensive QC testing to ensure sterility, viability, and proper cell yield. Additonally, several QC tests were performed at Cellocr′s centralized reference laboratory to monitor cell potency and identity of the ex vivo-processed lymphocytes. We report here the successful implementation of this QA/QC program for ALT which has resulted in the safe preparation and delivery of cell infusion products amounting to over 3600 treatments at seven clinical sites nationwide. We believe this program will serve as a model for other cellular therapies.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 195
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 747-756 
    ISSN: 0006-3592
    Schlagwort(e): tissue engineering ; skin equivalent ; transplantation ; cryopreservation ; serum-free medium ; sweat gland ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An in vitro construct of human skin (living skin equivalent, LSE) has been engineered using serially passaged human epidermal keratinocytes and human dermal fibroblasts with a matrix of type I collagen. Cells are obtained from neonatal foreskin. LSE is cast, cultured, and shipped in a single culture insert. The size and shape of theinsert determines thesize and shape of the LSE. The dermal matrix consists of dermal fibroblasts within a condensed collagen lattice. The overlying epidermis is developed at the air-liquid interface to generate a protective cornified layer. Serum was not necessaryfor development of the epidermis. LSE for graft (Graftskin) has handling characteristics similar to split-thickness skin allowing it to be meshed, stapled, and sutured. LSE was cryopreserved using 65% glycerol an rapid freezing. Viability and in vivo performance on athymic mice were similar to fresh LSE. Cells derived from human eccrine gland were able to invade and form tubules rudimentary appendages may be possible.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 196
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 781-791 
    ISSN: 0006-3592
    Schlagwort(e): collagen ; biomaterials ; tissue engineering ; fiber ; fabric ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Tissue-engineered implants require appropriate biomaterials to serve the required physical function of the tissue being repaired or replaced while facilitating remodeling of the implant. We report on the development of implantable fabrics manufactured from continuous collagen threads. The collagen threads are formed by extrusion of native, acid-extracted bovine colagen into a buffered solution of polyethylene glycol, followed by rinsing and air drying. The high manufacturing rate of such threads permits the production of colagen fabrics of various configurations. The fiber diameter can be controlled, and threads with dry diameters as low as 25 μm have been produced. Braids and bundles of collagen threads implanted as a replacement of the anterior cruciate ligament in a dog model were completely remodeled into host tissue by 12 weeks. Knitted collagen fabrics implanted in a rat abdominal repair model prevented herniation, and connective tissue ingrowth was observed within the fabric by 12 weeks.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 197
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994) 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 198
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 856-864 
    ISSN: 0006-3592
    Schlagwort(e): dextransucrase ; leucrose formation ; kinetic model ; acceptor site ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Leucrose formation from sucrose and fructose by dextransucrase is of practical interest. It has been investigated at different experimental conditions, including the influence of temperature on reaction rate and selectivity. Under appropriate conditions high product yield can be obtained. Furthermore, a model is presented that allows interpretation of the experimental data.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 199
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 934-938 
    ISSN: 0006-3592
    Schlagwort(e): immobilization ; nonaqueous enzymology ; esterification ; Rhizomucor miehei lipase ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: For the commercial exploitation of lipase biocatalysis to be successful, it is essential that effective supports are selected for lipase immobilization. In this study hydrophobic controlled-pore glasses have been used as model systems for the immobilization of Rhizomucor miehei lipase. The effect of pore diameter and surface chemistry on enzyme efficiency in a typical esterification reaction under essentially nonaqueous conditions has been examined. It has been found that pore diameters of at least 35 nm are needed for the lipase to be able to utilize the internal volume of the support particles in the immobilization process. Despite the small size of the substrates in the esterification reaction, even larger pores (〉100 nm) are required for the lipase efficiency to become independent of pore diameter; below 100 nm lipase activity and efficiency are markedly reduced. It has also been shown that the chemical nature of the hydrophobic surface plays an important part in catalyst design. Although lipase will adsorb readily to a wide range of hydrophobic groups, the highest catalyst activities are obtained when the glass surface is derivatized to give long alkyl chains; the presence of unsaturated derivatives gonerally leads to a reduction in activity. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 200
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 960-968 
    ISSN: 0006-3592
    Schlagwort(e): membrane filtration ; protein separation ; albumin ; immunoglobulins ; electrostatic interactions ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Although protein fractionation by selective membrane filtration has numerous potential applications in both the downstream processing of fermentation broths and the purification of plasma proteins, the selectivity for proteins with only moderately different molecular weights has generally been quite poor. We have obtained experimental data for the transport of bovine serum albumin (BSA) and immunoglobulins (IgG) through 100,000 and 300,000 molecular weight cutoff polyethersulfone membranes in a stirred ultrafiltration device at different solution pH and ionic strength. The selectivity was a complex function of the flux due to the simultaneous convective and diffusive solute transport through the membrane and the bulk mass transfer limitations in the stirred cell. Under phsioligical conditions (pH 7.0 and 0.15 M NaCI) the maximum selectivity for the BSA-IgG separation was only about 2.0 due primarily to the effects of protein adsorption. In contrast, BSA-IgG selectivities as high as 50 were obtained with the same membranes when the protein solution was at pH 4.8 and 0.0015 M NaCl. This enhanced selectivity was a direct result of the electrosatatic contributions to both bulk and membrane transport. The membrane selectivity could actually be reversed, with higher passage of the larger IgG molecules, by using a 300,000 molecular weight cutoff membrane at pH 7.4 and an ionic strength of 0.0015 M NaCl. These results clearly demonstrate that the effectiveness of selective protein filtration can be dramatically altered by appropriately controlling electrostatic interactions through changes in pH and/or ionic strength. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...