The Experts below are selected from a list of 6162 Experts worldwide ranked by ideXlab platform

Gilles Reysset - One of the best experts on this subject based on the ideXlab platform.

H. Azeddoug - One of the best experts on this subject based on the ideXlab platform.

Brigitte Zickner - One of the best experts on this subject based on the ideXlab platform.

  • Transcriptional regulation of solventogenesis in Clostridium acetobutylicum.
    Journal of molecular microbiology and biotechnology, 2002
    Co-Authors: Stephan Nakotte, Steffen Schaffer, Brigitte Zickner
    Abstract:

    Solvent synthesis in Clostridium acetobutylicum is induced in concert with sporulation to counteract the dangerous effects of produced butyric and acetic acids and to provide the cell with sufficient time to complete endospore formation. Cardinal transcription units for butanol and acetone production are the sol and adc operons encoding butyraldehyde/butanol dehydrogenase and coenzyme A transferase as well as acetoacetate decarboxylase. Induction is achieved by a decreased level of DNA supercoiling and the transcription factor Spo0A, possibly in cooperation with other regulatory proteins. A number of other operons is also turned on during this metabolic switch, whose physiological relevance, however, is only partly understood. The recent completion of C. acetobutylicum genome sequencing will pave the way for transcriptional profiling and thus allow comprehension of the coherent regulatory networks of solventogenesis and sporulation.

Philippe Soucaille - One of the best experts on this subject based on the ideXlab platform.

  • Complete activity profile of Clostridium acetobutylicum [FeFe]-hydrogenase and kinetic parameters for endogenous redox partners
    FEMS microbiology letters, 2007
    Co-Authors: Marie Demuez, Philippe Soucaille, Laurent Cournac, Olivier Guerrini, Laurence Girbal
    Abstract:

    In Clostridium acetobutylicum, [FeFe]-hydrogenase is involved in hydrogen production in vivo by transferring electrons from physiological electron donors, ferredoxin and flavodoxin, to protons. In this report, by modifications of the purification procedure, the specific activity of the enzyme has been improved and its complete catalytic profile in hydrogen evolution, hydrogen uptake, proton/deuterium exchange and para-H2/ortho-H2 conversion has been determined. The major ferredoxin expressed in the solvent-producing C. acetobutylicum cells was purified and identified as encoded by ORF CAC0303. Clostridium acetobutylicum recombinant holoflavodoxin CAC0587 was also purified. The kinetic parameters of C. acetobutylicum [FeFe]-hydrogenase for both physiological partners, ferredoxin CAC0303 and flavodoxin CAC0587, are reported for hydrogen uptake and hydrogen evolution activities.

  • Regulation of solvent production in Clostridium acetobutylicum
    Trends in Biotechnology, 1998
    Co-Authors: Laurence Girbal, Philippe Soucaille
    Abstract:

    The production of acetone and butanol by Clostridium acetobutylicum was once one of the largest fermentation processes but, once it was no longer competitive with chemical synthesis, it was discontinued. However, the combined efforts of several laboratories have increased our knowledge of the molecular basis of solvent production and this, combined with a better understanding of the regulation of the genes responsible for solvent formation, should enable a more pragmatic approach to the construction of C. acetobutylicum strains producing high yields of specific metabolites in a selective manner.

  • Autolysis of Clostridium acetobutylicum ATCC 824.
    Journal of general microbiology, 1992
    Co-Authors: Christian Croux, Bruno Canard, Gérard Goma, Philippe Soucaille
    Abstract:

    SUMMARY: The optimum conditions for autolysis of Clostridium acetobutylicum ATCC 824 were determined. Autolysis was optimal at pH 6.3 and 55 °C in 0.1 M-sodium acetate/phosphate buffer. The ability of cells to autolyse decreased sharply at the end of the exponential phase of growth. Lysis was stimulated by monovalent cations and compounds that complex divalent cations, and inhibited by divalent cations. The autolysin of C. acetobutylicum, which was mainly cytoplasmic, was purified to homogeneity and characterized as a muramidase. The enzyme was identical to the extracellular muramidase in terms of Mr , isoelectric point and NH2-terminal amino acid sequence. The autolysin was inhibited by lipoteichoic acids and cardiolipin but not by phosphatidylethanolamine and phosphatidylglycerol. A mechanism of regulation and fixation involving lipoteichoic acid, cardiolipin and divalent cations is proposed.

  • Bioconversion of Biogenic and Abiogenic Volatile Fatty Acids Into the Corresponding Alcohols by Clostridium acetobutylicum
    Recent Advances in Biotechnology, 1992
    Co-Authors: I. Vasconcelos, Philippe Soucaille, G. Goma
    Abstract:

    Significant improvements to the economic feasibility of acetone-butanol fermentation could be envisaged if low cost organic acid mixtures were used as co-substrates with sugars, during growth of Clostridium acetobutylicum.

Laurence Girbal - One of the best experts on this subject based on the ideXlab platform.

  • Complete activity profile of Clostridium acetobutylicum [FeFe]-hydrogenase and kinetic parameters for endogenous redox partners
    FEMS microbiology letters, 2007
    Co-Authors: Marie Demuez, Philippe Soucaille, Laurent Cournac, Olivier Guerrini, Laurence Girbal
    Abstract:

    In Clostridium acetobutylicum, [FeFe]-hydrogenase is involved in hydrogen production in vivo by transferring electrons from physiological electron donors, ferredoxin and flavodoxin, to protons. In this report, by modifications of the purification procedure, the specific activity of the enzyme has been improved and its complete catalytic profile in hydrogen evolution, hydrogen uptake, proton/deuterium exchange and para-H2/ortho-H2 conversion has been determined. The major ferredoxin expressed in the solvent-producing C. acetobutylicum cells was purified and identified as encoded by ORF CAC0303. Clostridium acetobutylicum recombinant holoflavodoxin CAC0587 was also purified. The kinetic parameters of C. acetobutylicum [FeFe]-hydrogenase for both physiological partners, ferredoxin CAC0303 and flavodoxin CAC0587, are reported for hydrogen uptake and hydrogen evolution activities.

  • Regulation of solvent production in Clostridium acetobutylicum
    Trends in Biotechnology, 1998
    Co-Authors: Laurence Girbal, Philippe Soucaille
    Abstract:

    The production of acetone and butanol by Clostridium acetobutylicum was once one of the largest fermentation processes but, once it was no longer competitive with chemical synthesis, it was discontinued. However, the combined efforts of several laboratories have increased our knowledge of the molecular basis of solvent production and this, combined with a better understanding of the regulation of the genes responsible for solvent formation, should enable a more pragmatic approach to the construction of C. acetobutylicum strains producing high yields of specific metabolites in a selective manner.