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  • Biochemistry and Biotechnology  (231)
  • Wiley-Blackwell  (231)
  • 1990-1994  (231)
  • 1
    Electronic Resource
    Electronic Resource
    Engineering cellulase mixtures by varying the mole fraction of Thermomonospora fusca E5 and E3, Trichoderma reesei CBHI, and Caldocellum saccharolyticum β-glucosidase (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1019-1028 
    Details
    ISSN: 0006-3592
    Keywords: Caldocellum saccharolyticum ; cellulose ; binding ; β-glucosidase ; hydrolysis ; mole fraction ; synergism ; Thermomonospora fusca ; Trichoderma reesei ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, different mole fractions of pure Thermomonospora fusca E5 and E3, plus Trichoderma reesei CBHI were studied for reducing sugar production at 2 h, degree of synergism, and cellulose binding. In addition, the effects of introducing the Caldocellum saccharolyticum β-glucosidase into this cellulase system were investigated. The cellulases used were purified to homogeneity. Avicel PH 102 (4% w/w solution in 0.05 sodium acetate pH 5.5 buffer) was the substrate. Reactions were run at 50°C for 2 h using total cellulase concentrations of 8.3 or 12.2 μM. A bimixture of T. fusca E3 and T. reesei CBHI was very effective in hydrolyzing microcrystalline cellulose (9.1% conversion). The addition of endoglucanase E5 to the mixture only increased conversion to 9.8%. However, when both E5 and β-glucosidase were added, conversion increased to 14%. It was also observed that increasing total cellulase concentration beyond 8.3 μM did little to increase percent conversion of cellulose into glucose. The results of the binding studies indicate no competition for binding sites between the endo- and exocellulases. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420902
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  • 2
    Electronic Resource
    Electronic Resource
    Continuous culture system for production of biopolymer levan using erwinia herbicola (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 557-560 
    Details
    ISSN: 0006-3592
    Keywords: levan ; continuous culture ; molecular weight ; Erwinia herbicola ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The optimal production of the fructan biopolymer levan by the bacterium Erwinia herbicola was investigated, including variations in nitrogen, carbon and phosphorous sources, pH, incubation time, culture yields up to 19% by weight produced based on conversion of sucrose as the carbon source when grown in a continuous culture system and processed by tangential flow filtration. Product identity was confirmed with gas chromatography (GC) and 13C nuclear magnetic resonance (NMR). Gel permeation chromatography (GPC) and low-angle laser light scattering (LALLS) determination of the molecular weight of the product showed a significant difference in molecular weight values dependent on the method of analysis. Analysis by GPC resulted in molecular weight one order of magnitude lower than LALLS independent of sample, underscoring the unusual nature of this biopolymer.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380515
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  • 3
    Electronic Resource
    Electronic Resource
    Correlating the effect of pretreatment on the enzymatic hydrolysis of straw (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 113-116 
    Details
    ISSN: 0006-3592
    Keywords: enzymic hydrolysis models ; pretreated lignocellulosics hydrolysis ; Fusarium oxysporum cellulases ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Avicell, Alkali-treated straw cellulose (ATSC), and wheat straw were ball-milled to reduce crystallinity; wheat straw was delignified by hot (120°C) sodium hydroxide solutions of various concentrations. The physically and chemically pretreated cellulosic materials were hydrolyzed by the cellulases of Fusarium oxysporum strain F3. Enzymic hydrolysis data were fitted by the hyperbolic correlation of Holtzapple, which involves two kinetic parameters, the maximum conversion (Xmax), and the enzymic hydrolysis time corresponding to 50% of Xmax (t1/2). An empirical correlation between Xmax and cellulose crystallinity, lignin content, and degree of delignification has been found under our experimental conditions. Complete cellulose hydrolysis is shown to be possible at less than 60% crystallinity indices or less than 10% lignin content.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260390116
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  • 4
    Electronic Resource
    Electronic Resource
    Fragmentation of cellulose by the major Thermomonospora fusca cellulases, Trichoderma reesei CBHI, and their mixtures (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1019-1026 
    Details
    ISSN: 0006-3592
    Keywords: cellulases ; cellulose ; fragmentation ; hydrolysis ; synergism ; Thermomonospora fusca ; Trichoderma reesei ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, the fragmentation activities of Thermomonospora fusca cellulases E2, E3, E5, Trichoderma reesei CBHI, and their mixtures were measured to study synergism in fragmentation. Fragmentation studies revealed that only two pure cellulases, T. fusca E2 and E5 had significant fragmentation activity. T. fusca E3 shows strong synergism in fragmentation both in the production of reducing sugars and in fragmentation with both T. fusca endoglucananses and with T. reesei CBHI. Most mixtures containing CBHI produced higher rates of fragmentation than comparable mixtures containing E3. The highest rate and extent of reducing sugar formation and the highest fragmentation activity were obtained with a mixture of E2, E3, and CBHI. © 1992 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260400905
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of dilution rate on growth, productivity, cell cycle and size, and shear sensitivity of a hybridoma cell in a continuous culture (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 429-439 
    Details
    ISSN: 0006-3592
    Keywords: shear ; air-lift loop reactor ; growth rate ; cell size ; hybridoma cell ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To study the effects of the growth rate of the hybridoma cell Mn12 on productivity, cell cycle, cell size, and shear sensitivity, six continuous cultures were run at dilution rate of 0.011, 0.021, 0.023, 0.030, 0.042, and 0.058 h-1. This particular hybridoma cell appeared to be unstable in continuous culture with respect to specific productivity, as a sudden drop occurred after about 30 generations in continuous culture, accompanied by the appearance of two populations with respect to the cytoplasmic lgG content. The specific productivity increased with increasing growth rate. The shear sensitivity of the cell, as measured in a small air-lift loop reactor, increased with increasing growth rate. The mean relative cell size, as determined with a flow cytometer, increased with increasing growth rates. Furthermore, the fraction of cells in the S phase increased, and the fraction of cells in the G1/G0 phase decreased with increasing growth rates. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260410406
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  • 6
    Electronic Resource
    Electronic Resource
    Construction, expression, and analysis of recombinant HIV gp41 constructs containing a novel cellular binding domain (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 81-86 
    Details
    ISSN: 0006-3592
    Keywords: human immunodeficiency virus ; gp41 ; recombinant fusion protein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The gp41 polypeptide of human immunodeficiency virus (HIV) contains an immunosuppressive domain, an epitope which elicits specific cytolytic T cell responses to HIV, and a complement Clq interactive domain. In addition, a synthetic peptide called CS3, derived from gp41 (amino acids 576-593 of gp160) and contiguous with the major immunodominant domain, binds to cellular proteins and may be important in HIV entry/fusion. In order to further investigate the role of the CS3 region of gp41 in cellular binding and to investigate other properties of gp41, sufficient quantities of this polypeptide must be readily available. We have therefore cloned the region of the HIV genome between nucleotides 7891 and 8188 (corresponding to amino acids 541-639 of gp160) into a series of procaryotic expression vectors. The resulting clones express a recombinant polypeptide of gp41 (r41). Two of these recombinants, pMAL-cRl/r41 and pGEMEX-2/r41, expressed the highest and most consistent levels of r41 as judged by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. With the pMAL-cRl/r41 construct, r41 was expressed as a fusion to the maltose-binding protein (MBP) and, following purification by affinity chromatography, was cleaved from MBP by factor Xa protease digestion. MBP/r41 may be useful for studies of a reported gp41 cellular binding domain and may facilitate studies involving other functions ascribed to this region of gp41. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420111
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  • 7
    Electronic Resource
    Electronic Resource
    Cultivation of an L-lactate dehydrogenase mutant of Bacillus stearothermophilus in continuous culture with cell recycle (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 21-28 
    Details
    ISSN: 0006-3592
    Keywords: cell recycle ; thermophilic ethanol fermentation ; Bacillus ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous fermentation with cell recycle proved very effective in increasing the ethanol volumetric productivity of the thermophilic facultative anaerobe, Bacillus stearothermophilus strain LLD-15, on sucrose at 70°C. When complete cell recycle was used, cell viability decreased after a few residence times and sucrose consumption was reduced. Operation using a constant bleed rate resulted in greater stability and higher ethanol volumetric productivities. A mathematical model based on maintenance energy requirements provided an adequate description of the system. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440105
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  • 8
    Electronic Resource
    Electronic Resource
    Enzyme activity and shikonin production in Lithospermum erythrorhizon cell cultures (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 69-74 
    Details
    ISSN: 0006-3592
    Keywords: Lithospermum erythrorhizon ; nitrate ; PAL and HMGR activity ; shikonin dervative production ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The activities of the biosynthetic enzmes phenylalanine ammonia lyase (PAL) and 3-hydroxy-3-methylglutaryl-CoA-reductase (HMGR) were measured in cells transferred from growth to production medium in a two-stage batch culture. It was found that both these enzymes showed transient increases, PAL (three- to fourfold) and HMGR (two- to four-fold), at or near the point of exhaustion of nitrogen source (NO3). Production of shikonin derivatives also started at this time. The addition of excess nitrate to the medium shortly before nitrate exhaustion (days 6-8) markedly reduced the final product yield (by 70-80%) while addition of excess nitrate in the later stationary growth phase (days 14-16) had no significant effect. When the production rate of shikonin derivatives was correlated with PAL activity, it was observed that production rate is very low (less than 1 mg/L · day) at low levels of PAL activity (below 0.1 unit/mg protein). Once a threshold level of PAL activity (about 0.15 unit/mg protein) is reached, the biosynthetic rate of shikonin derivatives increases. Such a relationship could not be deduced for HMGR activity. It was concluded that the production of shikonin derivatives may be limited at the phenylalanine deaminating step at low levels of PAL activity.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260400111
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of a recombinant antibody produced in the course of a high yield fed-batch process (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 727-735 
    Details
    ISSN: 0006-3592
    Keywords: monoclonal antibody ; glycosylation ; cell culture ; fed-batch ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: 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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440609
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  • 10
    Electronic Resource
    Electronic Resource
    Gluco-oligosaccharide synthesis by free and immobilized β-glucosidase (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 303-308 
    Details
    ISSN: 0006-3592
    Keywords: gluco-oligosaccharides ; sorbitol ; glucose ; disaccharides ; immobilized enzymes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gluco-oligosaccharides were synthesized through the enzymatic condensation of D-glucose at high concentration using a commercial almond β-glucosidase. The synthesis reactions were carried out with both free and immobilized enzyme, with or without sorbitol, an efficient depressor of water activity (aw) in the presence of different glucose concentrations. The yield and the composition of the gluco-oligosaccharides produced changed with the reaction mixture and the form of the enzyme used (free or immobilized). The use of 5 M glucose solution permitted only disaccharides to be obtained, whereas with a glucose concentration of 7.5 M glucose, di-, tri-, and tetrasaccharides were produced. A 7.5 M glucose solution used with 4.4 M sorbitol gave three times more disaccharides than the same solution without sorbitol. Moreover, the immobilized enzyme was much more active in synthesis. The synthesis yield (oligomers mg/mL · mg of enzyme) after immobilization was 573% compared to that of the free enzyme, when a 7.5 M glucose solution was tested. The effects of substrate concentration, sorbitol addition and enzyme immobilization were investigated. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420306
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