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  • 1
    Electronic Resource
    Electronic Resource
    Lactase and other enzymes bound to chitin with glutaraldehyde (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 315-326 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Acid tolerant lactase (I), α-chymotrypsin (II), and acid phosphatase (III) were immobilized on chitin with glutaraldehyde. Pretreatments of the chit in with acid, alkali, ammonia, and pronase were compared with respect to release of titratable amino groups and ability to retain lactase activity. Shrimp chitin appeared to be more sensitive to pretreatment conditions and so effort was concentrated on crab. An acid-alkali pretreatment was selected as most practical and economical, and the properties of enzymes fixed on crab chitin were studied intensively. The pH optima of the fixed enzymes were shifted about one pH unit; the shift for I was toward more acid pH, for II was toward alkaline pH, and for III was toward acid pH. The retained activity of immobilized I was approximately 60% that of the native enzyme. A column in continuous operation with I on chitin-glutaraldehyde gave an apparent activity half-life of 27 days.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260170303
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  • 2
    Electronic Resource
    Electronic Resource
    Cultivation of a filamentous mold in a glass pilot-scale airlift fermentor (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 863-877 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Results of pilot plant studies using a glass airlift fermentation device (55 liter fermentation volume) have proven the relative merits of such a system in the fermentation of a filamentous mold, Monascus purpureus, on 4% (w/w) starch media. The resultant overall yield of cell mass (Yx/s) of 0.38 was an appreciable increase over the 0.32 obtained with a pilot scale stirred tank fermentor previously studied. Power requirements of the airlift fermentor were approximately 50% of those for the mechanically agitated system. The lack of mechanical shear in the airlift system provides a more gentle environment or the cultivation of organisms than does the high degree of shear prevalent in the mechanically agitated vessels. Mass transfer of oxygen to the aqueous phase of the fermentation volume is improved significantly through use of the airlift device. Mass transfer coefficients in the range of 200 reciprocal hr were obtained to approximately 80 reciprocal hr in the stirred tank fermentor.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260230416
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  • 3
    Electronic Resource
    Electronic Resource
    Flow characteristics of a pilot-scale airlift fermentor (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 2421-2431 
    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 effects of aeration on the flow characteristics of water in a glass pilot-scale airlift fermentor have been examined. The 55-L capacity fermentor consisted of a 15.2-cm-i.d. riser column with a 5.1-cm-i.d. downcomer tube. It was found that the average bubble size diminished with increased aeration. Typically, average bubble sizes ranged from 4.32 mm at a superficial gas velocity of 0.64 cm/s to 1.92 mm at 10.3 cm/s. A gas holdup of 0.19 was attained with superficial gas velocities (vs) on the order of 10 cm/s, indicating the highly gassed nature of the fluid in the riser section of the fermentor. Circulation velocities of markers placed in the fermentor decreased with increasing aeration rates due to increased turbulence and axial liquid back mixing within the riser section. Actual volumetric liquid circulation rates remained relatively constant (0.36-0.49 L/s) for values of (vs) up to 10 cm/s. Based on theoretical calculations, the ascending velocity of bubbles in a swarm reached 54 cm/s in the range of (vs) values studied.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260231104
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetic modeling of a multiple immobilized enzyme system. I. Development and testing of the model (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 2447-2464 
    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 kinetic model for the reaction sequence catalyzed by coimmobilized invertase and glucose oxidase with a sucrose substrate in a tubular reactor has been developed. The computerized mathematical model employs and orthogonal collection technique for solving oxidase were coimmobilized in poly(2-hydroxyethlmethacrylate) gels and used in a continuous flow packed-bed tubular reactor system. In addition to describing the development of the kinetic model, this article compares experimentally determined reactor effluent concentrations for various sucrose feed solutions to those predicted by the model. Variations between experimental and predicted reactor effluent concentrations were found to be on the micromolar level for sucrose feed concentrations as low as 1.38mM.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260231106
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetic modeling of a multiple immobilized enzyme system. II. Application of the model (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 2465-2481 
    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 mathematical model for the reaction sequence catalyzed by immobilized invertase and glucose oxidase discussed in the preceding article has been used successfully to duplicate experimental findings. In addition, it has been used as a tool for the simulation and prediction of effects derived from alterations to system-related and gel-related parameters. The effects of gel diffusivity on the overall conversion of sucrose substrate to reaction products was investigated through use of this model. Changes in the enzyme loading within a gel and the results of varying the ration of invertase activity to glucose activity were also evaluated. Through use of concentrations of the molecular species determined at the collocation points within a gel particle and in the bulk liquid phase, an estimate of the thickness of the diffusion boundary layer around the gel particle was determined which was in close agreement with values obtained from classical mass transfer relationships. For most of this study, the enzymes were coimmobilized within the same polymeric matrix. However, a number of tests were run with the enzymes immobilized individually and placed in separate reactors in a sequential reactor system. The experimental results from these tests were duplicated successfully by means of the model with little modification to the basic computer program. Such an example illustrates the potential flexibility of the model and its overall versatility.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260231107
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  • 6
    Electronic Resource
    Electronic Resource
    Growth rate effects on fundamental transport properties of bacterial populations (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1277-1286 
    Details
    ISSN: 0006-3592
    Keywords: chemotaxis ; growth rate ; migration ; bacteria ; transport coefficients ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In many natural environments, bacterial populations experience suboptimal growth due to the competition with other microorganisms for limited resources. The chemotactic response provides a mechanism by which bacterial populations can improve their situation by migrating toward more favorable growth conditions. For bacteria cultured under suboptimal growth conditions, evidence for an enhanced chemotactic response has been observed previously. In this article, for the first time, we have quantitatively characterized this behavior in terms of two macroscopic transport coefficients, the random motility and chemotactic sensitivity coefficients, measured in the stopped-flow diffusion chamber assay. Escherichia coli cultured over a range of growth rates in a chemostat exhibits a dramatic increase in the chemotactic sensitivity coefficient for D-fucose at low growth rates, while the random motility coefficient remains relatively constant by comparison. The change in the chemotactic sensitivity coefficient is accounted for by an independently measured increase in the number of galactose-binding proteins which mediate the chemotactic signal. This result is consistent with the relationship between macroscopic and microscopic parameters for chemotaxis, which was proposed in the mathematical model of Rivero and co-workers. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260421104
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