These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Regulation of Clostridium acetobutylicum metabolism as revealed by mixed-substrate steady-state continuous cultures: role of NADH/NAD ratio and ATP pool.
    Author: Girbal L, Soucaille P.
    Journal: J Bacteriol; 1994 Nov; 176(21):6433-8. PubMed ID: 7961393.
    Abstract:
    Glycerol-glucose-fed (molar ratio of 2) chemostat cultures of Clostridium acetobutylicum were glucose limited but glycerol sufficient and had a high intracellular NADH/NAD ratio (I. Vasconcelos, L. Girbal, and P. Soucaille, J. Bacteriol. 176:1443-1450, 1994). We report here that the glyceraldehyde-3-phosphate dehydrogenase, one of the key enzymes of the glycolytic pathway, is inhibited by high NADH/NAD ratios. Partial substitution of glucose by pyruvate while maintaining glycerol concentration at a constant level allowed a higher consumption of glycerol in steady-state continuous cultures. However, glycerol-sufficient cultures had a constant flux through the glyceraldehyde-3-phosphate dehydrogenase and a constant NADH/NAD ratio. A high substitution of glucose by pyruvate [P/(G+P) value of 0.67 g/g] provided a carbon-limited culture with butanol and butyrate as the major end products. In this alcohologenic culture, the induction of the NADH-dependent butyraldehyde and the ferredoxin-NAD(P) reductases and the higher expression of alcohol dehydrogenases were related to a high NADH/NAD ratio and a low intracellular ATP concentration. In three different steady-state cultures, the in vitro phosphotransbutyrylase and butyrate-kinase activities decreased with the intracellular ATP concentration, suggesting a transcriptional regulation of these two genes, which are arranged in an operon (K. A. Walter, R. V. Nair, R. V. Carry, G. N. Bennett, and E. T. Papoutsakis, Gene 134:107-111, 1993).
    [Abstract] [Full Text] [Related] [New Search]