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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 16 (1996), S. 29-35 
    ISSN: 1476-5535
    Keywords: spores ; fatty acid ; internal concentrations ; transport ; biotransformation ; Penicillium roquefortii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Internal substrate concentrations were monitored during biotransformation of octanoic acid into 2-heptanone by spores ofPenicillium roquefortii. The fatty acid rapidly enters the spores in its undissociated form, and a Collander-type relation shows that it strongly accumulates in the spore wall and membrane; this accumulation is reversible. The reaction takes place with cytoplasmic substrate concentrations that quickly fall to zero, and the process is limited by octanoic acid penetration into the cells. This entry is accompanied by proton efflux and involves an active transport process with a H+-ATPase system that exhibits Michaelian behavior. The driving force is postulated to be ΔpH, which takes a value set by the initial substrate concentration through the stoichiometry of the H+/octanoic acid exchange.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology techniques 12 (1998), S. 899-903 
    ISSN: 1573-6784
    Keywords: spectrophotometry ; Pseudomonas fluorescens ; exopolymer ; biomass ; material balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A simple and rapid spectrophotometric method based on a single optical density measurement was developed to quantify biomass in the presence of a growth - associated exopolymer. It allowed the determination of both cell and polymer concentrations in a cultivation broth without the need for separation of these two elements. Cultivations of Pseudomonas fluorescens NCIMB 11671 in a fermenter were taken as examples to demonstrate the validity of this approach. © Rapid Science Ltd. 1998
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 699-709 
    ISSN: 0006-3592
    Keywords: spores ; Penicillium roquefortii ; bioconversion ; methyl ketone ; germination ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The bioconversion of octanoic acid into 2-heptanone by spores of Penicillium roquefortii is performed using a fed-batch technique with pH control by addition of the liquid substrate itself. The early stage of this process takes place with a high bioconversion rate and high yield. These values then decrease as a result of germination and growth the biocatalyst. An optimization strategy for the process would thus be to improve the characteristics of this first period, i.e., increase its duration and the reaction rate. An increase in duration is evidenced in two cases: (I) under oxygen limitation: and (ii) when the spore content in the medium is less than 107 spores/mL. These conditions give insufficient overall bioconversion rates: better optimization should be achieved without oxygen limitation and with high spore content. Characterization of the first period by material and bioenergetic balances suggests that an increase in the ethanol content of the medium, which acts as an energy source and a permeabilizer, and the use of specific inhibitor of the Krebs cycle, may be a way to further improve the biocatalyst performance and stability. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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