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  • 1
    Electronic Resource
    Electronic Resource
    The kinetics of cholesterol oxidase synthesis by Nocardia rhodocrous (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 18 (1976), S. 601-621 
    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 production of cholesterol oxidase by 3 liter batch cultures of Nocardia rhodocrous growing on a glycerol/yeast extract medium was investigated. Cholesterol was shown to be a good inducer of the enzyme. The optimum time for cholesterol addition and the quantity to be added were determined, resulting in a 15-fold yield increase. Cholesterol oxidase synthesis was influenced by the dissolved oxygen tension. Maximum cholesterol oxidase production was obtained at 30-40% air saturation. The effect of growth conditions on the extraction of cholesterol oxidase by Triton X-100 was investigated. The scale-up of the fermentation to 800 liters in a pilot-plant fermenter is described.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260180502
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  • 2
    Electronic Resource
    Electronic Resource
    On-line analysis of avermectin fermentation cell growth kinetics in an industrial pilot plant (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 34 (1989), S. 234-241 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental data are presented which show that on-line calculation of oxygen uptake rate can be used to estimate the cell concentration of Streptomyces avermitilis during the active growth phase of this fermentation. Moreover, by dividing the oxygen uptake rate by the total oxygen consumed, an on-line estimate of specific growth rate of this culture can be generated. A theoretical basis is provided for this model. Use of a mass spectrometer for vent gas analysis coupled with computer data acquisition has made this information both very accurate and readily available. Examples are given which illustrate the kinetics of the avermectin fermentation as well as the effect of a temperature shift on the specific growth rate.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260340212
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  • 3
    Electronic Resource
    Electronic Resource
    The influence of dissolved oxygen tension on the synthesis of the antibiotic difficidin by bacillus subtilis (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1007-1012 
    Details
    ISSN: 0006-3592
    Keywords: difficidin ; oxydifficidin ; Bacillus subtilis ; dissolved oxygen tension ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The antibiotic, difficidin, and its hydroxylated derivative oxydifficidin, were synthesized by cultures of Bacillus subtilis grown on a complex medium. Maximum titers of about 200 and 130 mg/L, respectively, were obtained. In fermentations where the dissolved oxygen tension (DOT) was controlled, the maximum specific growth rate was only reduced below 5% air saturation. DOT had little effect on the volumetric rateof synthesis of oxydifficidin but greatly influenced the rate for difficidin, which was reduced at DOT values below 40% air saturation. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440818
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  • 4
    Electronic Resource
    Electronic Resource
    The enzymatic transformation of water-insoluble reactants in nonaqueous solvents. Conversion of cholesterol to cholest-4-ene-3-one by a Ncardia sp. (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 815-826 
    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 rapid conversion of cholesterol to cholestenone by Nocardia in the presence of high proportions of water-immiscible solvent has been demonstrated. At high agitator speeds, the reaction rate was not limited by the rates of transfer of oxygen or cholesterol to the microorganisms. Using 100 g of thawed cells in 200 ml of carbon tetrachloride containing 16% (w/v) cholesterol, at 20°C cholestenone was formed at 7 g/hr. Cells could be separated easily from the organic solvent and reused. After 7 runs (69 hr) the reaction rate had fallen only to half the value for the first run.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260170604
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  • 5
    Electronic Resource
    Electronic Resource
    Improved performance in viscous mycelial fermentations by agitator retrofitting (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 31 (1988), S. 737-742 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For viscous mycelial fermentations it was demonstrated at the pilot-plant scale that the replacement of standard radial flow Rushton turbines with larger diameter axial-flow Prochem hydrofoil impellers significantly improved oxygen transfer efficiency. It was also determined that the Streptomyces broth under evaluation is highly shear thinning. Separate experiments using a Norcardia broth with similar Theological properties demonstrated that the oxygen transfer coefficient, KLa, can be greatly increased by use of water additions to reduce broth viscosity. These observations are consistent with the hypothesis that the improvement in oxygen transfer by changing agitator types is primarily due to an improvement in bulk mixing. A model is presented, based on the concepts of Bajpai and Reuss, which explains this improvement in performance in terms of enlargement of the well mixed micromixer region for viscous mycelial broths.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260310717
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  • 6
    Electronic Resource
    Electronic Resource
    Development of a large-scale continuous substrate feed process for the biotransformation of simvastatin by Nocardia s.p. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 1101-1107 
    Details
    ISSN: 0006-3592
    Keywords: simvastatin ; microbial ; hydroxylation ; fermentation ; biotransformation ; scale-up ; dissolved oxygen ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article describes a process for microbial hydroxylation of simvastatin by a Nocardia sp. Simvastatin (Zocor) belongs to the family of HMGCoA reductase inhibitors used as cholesterol-lowering drugs. Studies at 14 L scale showed that high substrate (simvastatin) concentrations inhibited product formation; consequently, continuous slow feeding of the substrate was introduced to maintain low residual simvastatin concentrations. Dissolved oxygen levels above 50% air saturation were desirable for the biotransformation. The process was scaled up to 19,000-L fermentors using an on-line filter sterilization system for substrate feeding. The feed rate was regulated by off-line high-pressure liquid chromatography (HPLC) assays to keep the substrate concentration below 20 mg/L. Intermittent addition of nutrients helped to boost the bioconversion rate to give final titers of 400 mg/L 6-β-hydroxymethyl simvastatin. Enrichment of the nutrient medium led to bioconversion titers of 800 mg/L 6-β-hydroxymethyl simvastatin. Bioconversion efficiencies (desired product/substrate) of 22-25% with a ratio of desired product/side products of 0.7 were obtained by this process.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260371116
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  • 7
    Electronic Resource
    Electronic Resource
    Cultivation of virus antigen in fibroblast cells using a glass fiber bed reactor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 635-642 
    Details
    ISSN: 0006-3592
    Keywords: MRC-5 ; anchorage-dependent ; fibers ; cell culture ; hepatitis A ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The anchorage-dependent cell line, MRC-5, was cultivated successfully on glass fibers with diameters ranging from 24 to 120 μm, despite vast differences in substrate curvature. Multilayer cell growth was observed, particularly for fiber diameters 30 μm and below, which differed from the typical monolayer growth observed in T-flask cultivations. Cells were maintainable at a reduced incubation temperature and were demonstrated to support virus replication for the 21-day antigen production period. Direct microscopic observation, along with indirect calculations, indicated that only a small fraction (about 10%) of the total available fiber surface area was occupied by cells. Thus, productivity per unit surface area was replaced by productivity per unit medium volume when evaluating fiber bed performance. Antigen and protein yields, as well as nutrient uptakes, were 1.5- to 2.5-fold greater than parallel T-flask cultures when compared on this basis. Corresponding available surface area-based values were 10- to 15-fold lower for the fiber bed reactor. The multilayer cell morphology obtained in the fiber bed was attractive for antigen production when immobilized in a column reactor system. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420512
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  • 8
    Electronic Resource
    Electronic Resource
    Cultivation of attenuated hepatitis A virus antigen in a titanium static mixer reactor (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1315-1324 
    Details
    ISSN: 0006-3592
    Keywords: static mixer ; MRC-5 ; anchorage dependent ; hepatitis A ; animal cell culture ; bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: 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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260441107
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  • 9
    Electronic Resource
    Electronic Resource
    Thienamycin production by immobilized cells of Streptomyces cattleya in a bubble column (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 2399-2411 
    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 novel 2.0-L columnar reactor has been developed for the production of thienamycin by cells of Streptomyces cattleya attached to celite particles. Successful immobilization of cells was achieved by operating the column continuously at a high dilution rate during the growth phase. Scanning electron micrographs of the celite particles indicate the involvement of subcellular fibrils in the attachment of cells to the solid surfaces. Reactor operation was divided into two distinct phases-a growth phase and a production phase. The kinetics of attached growth and thienamycin production were found to be strongly influenced by nutrient concentrations. The influences of nutrient concentration on CO2 production and thienamycin production during both the growth phase and the production phase are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260251010
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  • 10
    Electronic Resource
    Electronic Resource
    Development of a recovery and recycle process for a pseudomonas lipase used for large-scale enzymatic synthesis (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 487-493 
    Details
    ISSN: 0006-3592
    Keywords: enzyme ; lipase ; recovery ; recycle ; filtration ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Enzymes are potential catalysts for a wide range of large-scale chemical synthesis steps, particularly when the creation of a specific chiral center is desired. The efficient recycling of the enzyme catalyst and the removal of carryover impurities were crucial factors in the improvement of a stereoselective ester hydrolysis step used in the synthesis of a selective leukotriene antagonist. In this enzymatic reaction step, the substrate and product were both largely insoluble, while the enzyme was soluble in the aqueous reaction mixture. Microfiltration and ultrafiltration of the slurry reaction mother liquor indicated near 100% enzyme protein recovery, while activity recovery was about 70% to 80%. These activity losses might be accounted for by enzyme degradation (1 to 2 mg/L · h) during the 40-hour reaction period. Dissolved impurities, principally a diacid byproduct, in the enzyme recycling stream were reduced 60% to 70% by either lowering the solution pH to 4.0 or raising the solution ionic strength to 1 M. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420412
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