Format

Send to:

Choose Destination
See comment in PubMed Commons below
Microbiology. 2003 Jul;149(Pt 7):1935-44.

Transcriptional, translational and metabolic regulation of glycolysis in Lactococcus lactis subsp. cremoris MG 1363 grown in continuous acidic cultures.

Author information

  • 1Laboratoire Biotechnologie-Bioprocédés, UMR 5504 INSA/CNRS, UMR 792 INSA/INRA, Institut National des Sciences Appliquées, 135 Avenue de Rangueil, 31077 Toulouse Cedex 4, France.

Abstract

The physiological behaviour of Lactococcus lactis subsp. cremoris MG 1363 was characterized in continuous culture under various acidic conditions (pH 4.7-6.6). Biomass yield was diminished in cultures with low pH and the energy dedicated to maintenance increased due to organic acid inhibition and cytoplasmic acidification. Under such acidic conditions, the specific rate of glucose consumption by the bacterium increased, thereby enhancing energy supply. This acceleration of glycolysis was regulated by both an increase in the concentrations of glycolytic enzymes (hierarchical regulation) and the specific modulation of enzyme activities (metabolic regulation). However, when the inhibitory effect of intracellular pH on enzyme activity was taken into account in the model of regulation, metabolite regulation was shown to be the dominant factor controlling pathway flux. The changes in glycolytic enzyme concentrations were not correlated directly to modifications in transcript concentrations. Analyses of the relative contribution of the phenomena controlling enzyme synthesis indicated that translational regulation had a major influence compared to transcriptional regulation. An increase in the translation efficiency was accompanied by an important decrease of total cellular RNA concentrations, confirming that the translation apparatus of L. lactis was optimized under acid stress conditions.

PMID:
12855744
[PubMed - indexed for MEDLINE]
Free full text
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Write to the Help Desk