Affiliation:
1. Laboratoire de Microbiologie de l'Environnement, Université de Caen, EA956 USC INRA2017 IFR 146, 14032 Caen Cedex, France
Abstract
ABSTRACT
Enterococcus faecalis
is equipped with two pathways of glycerol dissimilation. Glycerol can either first be phosphorylated by glycerol kinase and then oxidized by glycerol-3-phosphate oxidase (the
glpK
pathway) or first be oxidized by glycerol dehydrogenase and then phosphorylated by dihydroxyacetone kinase (the
dhaK
pathway). Both pathways lead to the formation of dihydroxyacetone phosphate, an intermediate of glycolysis. It was assumed that the
glpK
pathway operates during aerobiosis and that the
dhaK
pathway operates under anaerobic conditions. Because this had not been analyzed by a genetic study, we constructed mutants of strain JH2-2 affected in both pathways. The growth of these mutants on glycerol under aerobic and anaerobic conditions was monitored. In contrast to the former model, results strongly suggest that glycerol is catabolized simultaneously by both pathways in the
E. faecalis
JH2-2 strain in the presence of oxygen. In accordance with the former model, glycerol is metabolized by the
dhaK
pathway under anaerobic conditions. Comparison of different
E. faecalis
isolates revealed an impressive diversity of growth behaviors on glycerol. Analysis by BLAST searching and real-time reverse transcriptase PCR revealed that this diversity is based not on different gene contents but rather on differences in gene expression. Some strains used preferentially the
glpK
pathway whereas others probably exclusively the
dhaK
pathway under aerobic conditions. Our results demonstrate that the species
E. faecalis
cannot be represented by only one model of aerobic glycerol catabolism.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
63 articles.
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