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  • Biochemistry and Biotechnology  (4)
  • 2020-2022
  • 1995-1999
  • 1960-1964  (4)
  • 1960  (4)
  • 1
    ISSN: 0368-1467
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dextran, a polymer of glucose, has been widely used as a blood-plasma volume expander. In whole culture fermentations most dextran-producing organisms elaborate dextrans that have molecular weights of many millions and must be depolymerized and fractionated to obtain a product suitable for clinical use. An exception however is Streptococcus sp. (Strain DS-50) NRRL B-1351. In the work described here, this organism is used to produce clinical-size dextran in high yields, both on a laboratory- and a pilot-plant scale. With this process, fractionation is required but depolymerization is not. Fermentations of media containing 15 per cent sucrose are complete in less than 48 hours with 0·2 per cent inoculum. Yields of native dextran and clinical-size dextran by methanol precipitation are 68 and 43 per cent of the theory, respectively. The structurally heterogeneous dextran formed by NRRL B-1351 has a higher viscosity for a given molecular weight than does NRRL B-512 dextran. The viscosity-molecular weight relationship for the former may be expressed by the equation [η] = 6·51 × 10-4Mw0·554. The high-molecular weight fraction had approximately 75 per cent of 1,6-like linkages, as compared with 87 per cent for the clinical fraction. All fractions had a lower ratio of 1,6 to non-1,6 linkages than did NRRL B-512 dextrans.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Biochemical and Microbiological Technology and Engineering 2 (1960), S. 419-430 
    ISSN: 0368-1467
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of low-level radiotracer techniques permits rapid, precise estimation of yields and material balances for processing steps. This is a great advantage for development work with Vitamin B12 because the conventional methods using microbiological assays are slow and lack precision. Release of the vitamin from S. griseus cells, selection of absorbing resins, and screening of eluting agents were followed using cobalt-60 cyanocobalamin. The method is most valuable when supplemented by microbiological assays because the yields of radioactivity are misleading in conditions which inactivate the vitamin.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Biochemical and Microbiological Technology and Engineering 2 (1960), S. 81-91 
    ISSN: 0368-1467
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Development of a foam breaker which operates on the principle of rapid acceleration of foam through a nozzle has allowed large-scale aerobic fermentations to be run without addition of antifoam agents. Fermentations have been investigated over a wide range of aeration levels in which oxygen supplied to the organisms was the limiting growth factor.With Torulopsis utilis grown in a 5 per cent molasses medium. oxygen utilization followed an exponential pattern during the early phase of growth, with carbon dioxide production equal to the consumption of oxygen. At the point where oxygen supply to the organism became limiting, anaerobic fermentation began, and the consumption of oxygen remained constant. The level of oxygen absorption beyond which the respiratory quotient exceeded unity was used as a measure of limiting oxygen supply.Addition of three types of antifoam compounds to T. utilis fermentations resulted in a marked depression of oxygen consumption, and a decrease in cell production. Incremental addition of small quantities of antifoam to maintain a constant foam level in the fermentor depressed the oxygen absorption rate to a lesser extent. Sulphite oxidation rates did not reflect the true value of oxygen absorption rates found for fermentations without addition of antifoam.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Biochemical and Microbiological Technology and Engineering 2 (1960), S. 165-175 
    ISSN: 0368-1467
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The broths of four important industrial fermentations, namely nystatin, penicillin, and streptomycin fermentations, and a fermentation used for steroid hydroxylation, were examined rheologically. Considerable variation in rheological properties was demonstrated among these fermentations as well as throughout the course of the nystatin and streptomycin fermentations. These latter fermentations, employing Streptomyces strains, were mostly Newtonian in behaviour. Departures from this behaviour twice in the streptomycin fermentation resulted in plastic characteristics. The other two fermentations employing moulds were found to be markedly non-Newtonian, either plastic or pseudo-plastic in their behaviour.Rheological properties of most fermentation broths change appreciably during the course of fermentation. These properties influence the nature of the fluid regime in fermentors and, as a consequence, are important factors when considering mass and heat transfer. Therefore, a knowledge of the rheological behaviour of fermentation broths is an important prerequisite for an intelligent understanding of these transport processes. This paper briefly reviews some of the mathematical flow models used to characterize fluids and reports the rheological examination and analysis of several industrially important fermentation broths containing filamentous micro-organisms.
    Additional Material: 9 Ill.
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