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  • 1
    Electronic Resource
    Electronic Resource
    On-line and in-situ monitoring technology for cell density measurement in microbial and animal cell cultures (1994)
    Springer
    Bioprocess and biosystems engineering 10 (1994), S. 195-207 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Commercially available on-line and in-situ devices for monitoring cell density are reviewed in this article. Principles of operation are described as well as capabilities of these probes in specific measurement applications based on literature reports. Pilot-scale experimental observations from three optical density probes, the Cerex, Monitek and Wedgewood designs, have been included for Escherichia coli fermentations. Requirements for future on-line and in-situ instruments are discussed as well as the impact of current limitations on widespread application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369530
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Reversed-phase high-performance liquid chromatography assay for recombinant acidic fibroblast growth factor in E. coli cell suspensions and lysate samples
    Amsterdam : Elsevier
    Journal of Chromatography A 663 (1994), S. 43-51 
    Details
    ISSN: 0021-9673
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0021-9673(94)80494-X
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  • 3
    Electronic Resource
    Electronic Resource
    Biodiversity processing (1995)
    Springer
    World journal of microbiology and biotechnology 11 (1995), S. 251-252 
    Details
    ISSN: 1573-0972
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00367093
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of medium sterilization on the production of zaragozic acids by the fungusLeptodontidium elatius (1995)
    Springer
    Journal of industrial microbiology and biotechnology 15 (1995), S. 503-508 
    Details
    ISSN: 1476-5535
    Keywords: medium sterilization ; fermentation development ; squalene synthase inhibitors ; Leptodontidium elatius ; zaragozic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The production of zaragozic acids by fermentation of the fungusLeptodontidium elatius was examined at the 800-L fermentor scale under two different production medium batch sterilization conditions. Low production-medium heat input (R0=33.4 min) resulted in a 4′-desacetoxy zaragozic acid C:4′-O-desacetyl zaragozic acid C:zaragozic acid C ratio of 0.53:0.60:1.0. At a higher heat input (R0=50.5 min), the ratio shifted to 1.0:0.66:1.0 with a corresponding 26% increase in total zaragozic acid production. This higher total zaragozic acid titer resulted from an increase in the amount of 4′-desacetoxy zaragozic acid C produced while the levels of the other two analogues remained unchanged. Batch sterilization conditions also resulted in differences in growth, carbon substrate consumption, and oxygen uptake rates. The structures of the zaragozic acids produced suggest a precursor/end product relationship. A biosynthetic model describing the synthesis of the three zaragozic acids listed above is postulated and used to explain the effects of production-medium heat input during sterilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01570022
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  • 5
    Electronic Resource
    Electronic Resource
    Interactions of cell morphology and transport processes in the lovastatin fermentation (1992)
    Springer
    Bioprocess and biosystems engineering 8 (1992), S. 1-7 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The cholesterol lowering drug, Lovastatin (Mevacor), acts as an inhibitor of HMGCoA reductase, and is produced from an Aspergillus terreus fermentation. Pilot scale studies were carried out in 800 liter fermenters to determine the effects of cell morphology on the oxygen transport properties of this fermentation. Specifically, parallel fermentations giving (i) filamentous mycelial cells, and (ii) discrete mycelial pellets, were quantitatively characterized in terms of broth viscosity, availability of dissolved oxygen, oxygen uptake rates and the oxygen transfer coefficient under identical operating conditions. The growth phase of the fermentation, was operated using a cascade control strategy which automatically changed the agitation speed with the goal of maintaining dissolved oxygen at 50% saturation. Subsequently stepwise changes were made in agitation speed and aeration rate to evaluate the response of the mass transfer parameters (DO, OUR, and k L a). The results of these experiments indicate considerable potential advantages to the pellet morphology from the standpoint of oxygen transport processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369257
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  • 6
    Electronic Resource
    Electronic Resource
    Bioconversion of avermectin into 27-OH avermectin (1990)
    Springer
    Journal of industrial microbiology and biotechnology 6 (1990), S. 279-284 
    Details
    ISSN: 1476-5535
    Keywords: Fermentation ; Nocardia ; Bioconversion ; Avermectin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The bioconversion of avermectin to its 27-hydroxy derivative is achieved withNocardia autotrophica subsp.canberrica. The approach of increasing bioconversion productivity rather than efficiency was adopted in these studies. Process improvement studies focused on the physico-chemical conditions of the fermentation, examined initially at the shake-flask scale. Bioconversion yields were affected by pH, substrate concentration, time of substrate addition, substrate solubilization, carbon to nitrogen ratio, and medium strength. Optimization of these parameters resulted in a 8-fold process improvement. During pre scale-up studies, the sensitivity of this bioconversion to the antifoam employed was demonstrated and lard oil was selected as giving the best results. Additional process changes were required during scale-up efforts in larger vessels, including replacement of the original substrate solvent with dimethylsulfoxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01575874
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of strain and medium composition on filtration of escherichia coli suspensions (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 539-548 
    Details
    ISSN: 0006-3592
    Keywords: cross-flow filtration ; Escherichia coli ; cell harvesting ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cross-flow filtration of Escherichia coli strains was examined at the laboratory and pilot scales using Romicon 500,000 molecular-weight-cutoff hollow fiber membranes. Both the series resistance and macrosolute polarization models were employed to compare performances. Total dissolved solids content above 90 g/L and viscosity above 1.1 × 10-3 paċ s of cell-free culture media were found to decrease average filtration fluxes by over 60% both in the absence and presence of cells. Broth filtration with culture media of dissolved solids levels below 80 g/L were influenced to a greater extent by harvest cell density. The collodial nature of the complex nutrient responsible for the total solids increase affected prediction of filtration performance. Differences in strain filterability were observed with JM109 preferred over DH5 in high solids-containing media and RR1 preferred over JM109 in low dissolved solids-containing media. Their research demonstrates the importance of cell strain and media selection in the performance of early downstream processing steps. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440418
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  • 8
    Electronic Resource
    Electronic Resource
    Secondary metabolite scale-up to minimize homolog impurity levels (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 595-604 
    Details
    ISSN: 0006-3592
    Keywords: secondary metabolite ; scale-up ; Streptomyces ; impurity analog ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mutant strain of Streptomyces hygroscopicus was found to produce up to 9.0 units/L of an immunoregulant precursor, immunomycin, with up to 3.5% of a lower homolog impurity under either dual fed-batch or batch conditions. Glycerol and valine were key nutrients influencing productivity and impurity levels. Soybean oil was successfully substituted for glycerol as a carbon source to minimize shot additions to batch culture. The remainder of the production medium was composed largely of defined components with the exception of yeast extract.Valine limitation increased lower homolog formation while decreasing higher homolog formation; excess valine decreased lower homolog formation below 2-3% while increasing higher homolog formation. Higher homolog formation in the presence of valine seemed to be slower than lower homolog formation in the absence of valine. Valine was believed to be the major butyrate precursor; consequently its availability influenced the impurity profile. A preliminary cost analysis suggests that elimination of added valine from the cultivation and replacement of glycerol with soybean oil can result in a 6.6-fold reduction in media costs relative to the original fed-batch process. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:595-604, 1998.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    On-line and in-situ monitoring technology for cell density measurement in microbial and animal cell cultures (1994)
    Springer
    Bioprocess engineering 10 (1994), S. 195-207 
    Details
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Commercially available on-line and in-situ devices for monitoring cell density are reviewed in this article. Principles of operation are described as well as capabilities of these probes in specific measurement applications based on literature reports. Pilot-scale experimental observations from three optical density probes, the Cerex, Monitek and Wedgewood designs, have been included for Escherichia coli fermentations. Requirements for future on-line and in-situ instruments are discussed as well as the impact of current limitations on widespread application
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369530
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 10
    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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