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  • 1
    Electronic Resource
    Electronic Resource
    Immobilization of Brevibacterium flavum cells on collagen for the production of glutamic acid in a recycle reactor (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 899-916 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, live cells of Brevibacterium flavum were immobilized for the production of glutamic acid. The reason for such a choice was that glutamic acid fermentation is an extensively studied fermentation and one which requires the viability of entire cellular faculties for the acid production. Brevibacterium flavum was chosen because it is an industrially used bacterium, and is very potent via a vis glutamic acid production. Studies were performed to find aeration and agitation conditions for optimal growth and glutamic acid productivity. Experiments were also done to find the optimum harvesting time. The cell activity peaks during the run of fermentation, and the time at which the peak occurs, was found. Conventional methods for immobilizing the cells on collagen were found to be lacking. The pH and drying were the two main reasons for loss of viability of the cells; the latter being more important. A modified immobilization procedure has been devised, which can immobilize live cells at any given pH and ionic strength, in contrast to the conventional method which requires the pH to be above 11 or below 3. This new method involves dialysis of collagen in suitable dialysis bags against water at pH7 (or buffer at any desired pH). The dialysed collagen blended at 20,000 rpm, resulted in a very smooth dispersion, unnoticeably different from collagen dispersion prepared at pH 11. The dispersed collagen was then cast and dried at an elevated temperature, and high air flow rate over the cast membrane, decreasing the time of drying from 6-8 hr ( in the conventional method) to 1.5-2 hr. The membrane has been tested for glutamic acid producing capabilities in a column reactor with the membrane spirally wound. The reactor has been operated under continuous conditions for 5-10 days with stable activities.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260230419
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  • 2
    Electronic Resource
    Electronic Resource
    Steady-state and transient behavior in microbial methanification: II. Mathematical modeling and verification (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1199-1207 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been shown that the Upflow Anaerobic Sludge Bed (UASB) system data reported earlier1 cannot be explained by simple Monod-type substrate consumption patterns. An autoinhibition model was also ruled out because the substrate concentration range over which hysteresis was observed was much larger than such a model would predict. However, propionic and acetic acids were found to inhibit each other's conversion machineries. Since in the UASB system the biocatalyst is flocculated, it was found that a model additionally incorporating this facet of the reactor set-up could explain the steady-state data very well. Using the parameters generated from steady-state data and data from butyric acid step change,1 i.e., the entire set of parameters (Table I), a very good agreement between predicted and observed data was found. International Mathematical and Statistical Libraries (IMSL) and Upjohn's NONLIN library combined with various root-finding and integrating subroutines were used for parameter estimation. The model thus described was used to predict the response of the UASB system when acetic acid and propionic acid influent concentrations were stepped-up/down. The agreement between the predicted and observed data was found to be excellent in each case during the step-up schedule. During the step-down the data seemed to indicate that the UASB system, like any other chemostat, responded faster than predicted. This could be due to the fact that when the culture has to “gear up” part of the lag time is the time required for the cell to produce the requisite amount of enzymes. In the case of “gearing down” this time is not required and the system responds faster.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260270815
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  • 3
    Electronic Resource
    Electronic Resource
    Lysozyme activity in the presence of nonionic detergent micelles (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 737-752 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of a nonionic surfactant, polyoxyethylenesorbitan monolaurate (Tween 20), on the hen egg-white lysozyme catalyzed lysis of a dried cell suspension of Micrococcus lysodeikticus is analysed. A rate enhancement of up to 70% is observed in the presence of surfactant at concentrations above the critical micelle concentration. This activity increase may be explained by postulating the existence of a micelle-enzyme complex in which enzyme molecules are bound to micelles with preferential orientation of their active sites.The reaction is found to be second order with respect to substrate. A mechanism is postulated in which a substrate particle is assumed to be an energy-furnishing collision partner to the enzyme-substrate complex. This mechanism correlated data over a wide range of enzyme and substrate concentrations.Data from kinetic, ultrafiltration, ultraviolet, and fluorescence studies provide convincing evidence for the existence of a micelle-lysozyme complex. The results suggest that it is possible that immobilized enzymes mat in general be more reactive than corresponding free enzymes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140505
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  • 4
    Electronic Resource
    Electronic Resource
    Collagen-enzyme complex membranes and their performance in biocatalytic modules (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 93-115 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Collagen was used as carrier for the immobilization of invertase, lysozyme, urease, glucose oxidase, penicillin amidase, and glucose isomerase. Immobilization was accomplished by either impregnation of a preswollen collagen membrane with enzyme solution or electrocodeposition of collagen and enzyme from a collagen dispersion containing dissolved enzyme. The collagen-enzyme complexes prepared are in membrane form.Membranous collagen-enzyme complexes were used to construct biocatalytic reactors such as the capillaric coil modular reactor. Such biocatalytic reactors were used in a recirculation system for the conversion of substrates. The biocatalytic reactors showed initial decreases of activity to stable limits which are maintained over a large number of reactor volume replacements. The stable limits correspond to approximately 35% of the initial activities for lysozyme and invertase, 25% for urease, 15% for glucose oxidase.The mechanism of complex formation between collagen and enzyme involves multiple salt linkages, hydrogen bonds, and van der Waals interactions. This protein-protein interaction which leads to stable complexes by both impregnation and electrocodeposition processes is unique among the enzyme immobilization methods currently available.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260150108
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  • 5
    Electronic Resource
    Electronic Resource
    Regulation of lac operon expression in mixed sugar chemostat cultures (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 29 (1987), S. 1003-1014 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Expression of the lactose (lac) operon in the Escherichia coli chromosome has been studied in mixed-sugar chemostat cultures under steady-state and transient conditions. A unified model has been formulated which involves regulation of active inducer (lactose) transport, promoter-operator regulated expression of the lac operon, glucose-mediated inducer exclusion, and catabolite repression. The model of the lac operon control system focuses on the molecular interactions among the regulatory species and the genetic control elements for the initiation of transcription. The role of catabolite modulator factor (CMF) in the regulation of transcription is described. The modeling of glucose-mediated regulation of intracellular cyclic adenosine monophosphate (cAMP) and inducer exclusion is based on the recently elucidated mechanisms of the involvement of the PTS (phosphoen-olpyruvate dependent sugar transport system) enzymes, in the presence of glucose, in regulation of adenylate cyclase and non-PTS sugar transport proteins (i.e. per-meases). The adequacy of the unified model was verified with experimental data.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260290812
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  • 6
    Electronic Resource
    Electronic Resource
    Fermentation of lactose to ethanol with recombinant yeast in an immobilized yeast membrane bioreactorIssued as NRCC No. 32515. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 587-590 
    Details
    ISSN: 0006-3592
    Keywords: Saccharomyces ; lactose fermentation ; glucose fermentation ; reverse osmosis membrane ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel concept of membrane bioreactor in which living cells are sandwiched between ultrafiltration (UF) and reverse osmosis (RO) membranes was applied for lactose fermentation to ethanol by genetically engineered yeast cells. The productivity of the Lactophile 13B strains was higher than that of the Lactophile 13D strains. In both cases performance data similar to those for glucose fermentation to ethanol by Saccharomyces cerevisiae were obtained. However, the operational stability of recombinant yeast cells was improved in the new bioreactor in comparison to the stability of these cells in a shake flask.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260370614
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  • 7
    Electronic Resource
    Electronic Resource
    Mass transfer and biochemical reaction with semipermeable microcapsules (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 467-481 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Enzymes can be encapsulated within a semipermeable membrane which allows reactants to enter and the products to diffuse out. The mass transport from the external fluid to the membrane and the combined mass transport and biochemical reaction from the membrane inwards can be modeled with recognized formulations; measurements of the overall reaction rate lead then to estimates of the permeability of the membrane itself.With capsules enclosing catalase, the permeability of collodion membranes to H2O2 is found to be large (〈2 × 10-2cm/sec) in comparison to rates in the other two diffusion zones. For this first-order reaction system, an analytical solution to the transient case of the well-stirred finite bath is found using the Laplace transform. With capsules enclosing urease, the nonlinear Michaelis-Menten kinetics apply to the enzymatic step. The steady-state operation of a column packed with urease microcapsules is analyzed with the aid of numerical computation and the membrane permeability for urea is found to be 10-3cm/sec.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260150304
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  • 8
    Electronic Resource
    Electronic Resource
    Active transport of inducer in enzyme biosynthesis (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 1455-1460 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260240617
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  • 9
    Electronic Resource
    Electronic Resource
    Enzymatic modification of vegetable protein: Immobilization of Penicillium duponti enzyme on reconstituted collagen and the use of the immobilized-enzyme complex for solubilizing vegetable protein in a recycle reactor (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 2609-2627 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Penicillium duponti enzyme was immobilized on reconstituted collagen by macromolecular complication, impregnation, and covalent crosslinking techniques. The immobilization of the enzyme on collagen has a twofold purpose: (1) providing a protein microenvironment for the proteolytic enzyme; and (2) extending the useful life the enzyme once immobilized on the collagen matrix. Two types of collagen were used, one produced by the United States Department of Agriculture and the other produced by FMC. The USDA collagen contained unhydrolyzed telepeptide linkages and required pretreatment to reduce collagenaselike activity of the enzyme. Activity analysis of the immobilized enzyme complex showed that membranes with enzyme loading less than 10 mg enzyme/g of wet membrane in the reactor were dimensionally stable. The degree of crosslinking was an important parameter. Membranes with structural opening up to three times the initial dry thickness were found to be the maximum limit for controlled release of enzyme from the collagen membrane during enzymatic reaction. Higher activities and better stability of the enzyme in collagen membrane were found for covalent crosslinking of the enzyme to treated collagen films. The hydrolysis of soybean vegetable protein with the immobilized enzyme in a recycle reactor at enzyme loading of mg/g of wet membrane at 40°C, pH 3.4, produced 56.5% of soluble protein in 10h. The production is equivalent to 1.84 h total contact time between the substrate and the immobilized enzyme. The average productivity based on a stable enzyme activity and 20g of dry membrane was 329 mg of protein/g/mg of active enzyme immobilized. The productivity of the free enzyme in a batch reactor was 62.5 mg protein/h/mg enzyme.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260231117
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  • 10
    Electronic Resource
    Electronic Resource
    Steady-state and transient behavior in microbial methanification: I. Experimental results (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1192-1198 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The process of methanification of volatile fatty acids (VFA) was studied to elucidate its kinetics. An upflow anaerobic sludge bed (UASB) system was used to perform the experiments. At residence times of less than 2.5 h the UASB system was found to exhibit hysteresis with respect to acetic and propionic acid consumption but not with respect to butyric acid consumption. These hysteretic effects could be attributed to the manner in which the various VFA-consuming cultures were structured inside the flocculated biomass in light of the cross-inhibitory effects of the acetic- and propionic-acid-consuming fractions of the total culture. (Butyric acid proved to be non-interactive.) Production of methane was found to respond almost instantaneously to changes in the inlet conditions of the UASB system. This indicated that methane is not primarily growth associated, as has often been assumed, but is related to changes in the culture's maintenance energy requirements. Reactor operation was found to be stable even when the concentration of each VFA in the feed was simultaneously changed by 50%. Even at very high organic throughput rates (35 kg COD/day m3-reactor) conversions of 82% were observed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260270814
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