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  • 1
    Electronic Resource
    Electronic Resource
    Temperature dependence of a diffusion-limited immobilized enzyme reaction (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 18 (1976), S. 95-104 
    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 apparent activation energy of N-α-benzoyl-L-arginine-ethyl ester (BAEE) hydrolysis by immobilized trypsin varies with the bulk substrate concentration from its maximum value, comparable to that of the free enzyme, to considerably lower values. Thus, with a concentration change from 3 × 10-2 to 10-4 M the apparent activation energy diminishes from 9.5 to 4.5 kcal/mol. This experimental finding is interpreted to be due to Michaelis-type kinetics in a heterogeneous system, in one case reflecting the temperature dependence of the maximal enzyme reaction rate, in another case illustrating the diffusion limited overall reaction at low substrate concentrations. As a consequence it may not be feasible to operate a reaction at elevated temperatures in a high conversion range, since diffusion limitation may restrict the enhancement of the overall reaction rate. Some further data are given concerning the buffer effect on the reaction rate, which should occur due to its limitation by proton transfer in the buffer-free system.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260180108
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Macrokinetics and operational stability of immobilized glucose oxidase and catalase (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 1201-1220 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Glucose oxidation by immobilized glucose oxidase (GlO) and catalase (Cat) has been investigated in batch and continuous reactions for operational studies. The macrokinetics of the process depend on coupled reaction steps and diffusion rates. The problem may be approximated by a simple pseudohomogeneous model taking into account both substrates of glucose oxidase and the intermediate reaction product H2O2. The effectiveness of both enzymes is enhanced in the coupled reaction path, the overall effectiveness nevertheless is very low. H2O2 causes the inactivation of both GlO and Cat. The rates of deactivation depend on the oxidation rates of glucose that give different quasistationary levels of H2O2 concentration. As a first approximation, the deactivation rates may be described by first-order reactions with respect to H2O2.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260200807
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of the coupled transport, reaction, and deactivation phenomena in the immobilized glucose oxidase and catalase system (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 21 (1979), S. 2061-2081 
    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 a previous paper, the overall or macrokinetics of the immobilized glucose oxidase-catalase system has been presented. In this paper a detailed analysis of the interaction of diffusion and reaction in this system will be presented. The mathematical treatment includes two consecutive reactions with two-substrate kinetics. Furthermore, the deactivation of both enzymes due to the intermediate product peroxide is taken into account. The predicted results suggest that the efficiency of the glucose oxidase reaction depends on the concentration ranges of the two substrates. Furthermore, the external mass-transfer rate may cause a shift from glucose limitation to oxygen limitation. The efficiency of the coupled system is always higher than that predicted for the uncoupled reaction path. The calculations show that the economics of the coupled system depend a great deal on the deactivation of the enzymes.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260211112
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  • 4
    Electronic Resource
    Electronic Resource
    Identification of mass-transfer parameters and process simulation of SCP production process in airlift tower reactors with an external loop (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 817-835 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A distributed parameter model for simulation of SCP-production processes in tower reactors with an outer loop was developed by considering substrate, cell, and CO2 balances in the liquid phase, and O2 and CO3 balances in the ges phase and taking into account variations of dissolved oxygen concentration, pressure, and kLa along the column, as well as double substrate Monod kinetics. This model was used to describe the cultivation of Hansenula polymorpha in a tower-loop reactor (height 275 cm, diameter 15 cm). Parameter identification and process simulation were carried out by a hybrid computer. The variation of identified mass transfer parameters with fermentation time and operation mode is considered employing ethanol and glucose substrate, respectively. Relationships among kLa, substrate concentration, and superficial gas velocity were developed to facilitate the layout and simulation of pilot-plant reactors.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260240406
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetics of leucrose formation from sucrose by dextransucrase (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 856-864 
    Details
    ISSN: 0006-3592
    Keywords: dextransucrase ; leucrose formation ; kinetic model ; acceptor site ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: 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.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430904
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetic of leucrose formation from sucrose by dextransucrase (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 392-394 
    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: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440319
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  • 7
    Electronic Resource
    Electronic Resource
    Kinetic studies of C. pyrenoidosa using 94% 13C CO2 (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 819-829 
    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 alga Chlorella pyrenoidosa has been grown in mass quantities on 94 at. % 13CO2. The algal cells have been labeled to the 90 at. % 13C level. Neither inhibition nor a requirement for adaptation was encountered; changes in morphology were not evident. A statistically significant increase in mass of cells produced in the presence of 13CO2 was observed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140511
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  • 8
    Electronic Resource
    Electronic Resource
    Improved biocatalyst effectiveness by controlled immobilization of enzymes (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 727-736 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nonuniform enzyme distributions can be obtained by kinetic control of the immobilization process. Such heterogeneous biocatalysts exhibit higher effectiveness compared to conventional immobilization procedures, when the mass transfer of substrates or products is limiting. Model calculations provide some insight into the relative weight of the immobilization parameters with respect to optimal control of the enzyme distribution. Experimental results and model calculations show that considerably improved effectiveness of biocatalysts can be obtained. The role of external mass transfer is emphasized.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260260715
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  • 9
    Electronic Resource
    Electronic Resource
    Process optimization of a continuous airlift tower-loop reactor (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 1851-1869 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Based on the experimental investigations with H. polymorpha and Methylomonas M 15 in bench-scale airlift tower-loop reactors, a general distributed parameter model was developed and used to simulate to cultivation process in a 40-m-high production reactor. This general model was simplified with regard to the gas phase and loop balances and was employed to optimize cell productivity and/or profit in a 20-m-high pilot-plant airlift tower-loop reactor. Maximum cell productivity always occurs in the oxygen-transfer-limited growth range. In case of a high “penalty factor” for nonconsumed substrate, maximum profit is attained at the boundary between substrate and oxygen-transfer-limited growth. Oxygen-transfer limitation exists in the lower half of the tower, whereas in the upper half, substrate limitation prevails. The longitudinal dissolved oxygen concentration passes a minimum in this case as has been determined experimentally in the bench-scale column. The simulation results agree fairly well with the data measured in the pilot plant.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260240811
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