Accueil > Publications > Recherche par années > Années 1990 > 1996

Bernalier, A ; Lelait, M ; Rochet, V ; Grivet, JP ; Gibson, GR ; Durand, M

Acetogenesis from H-2 and CO2 by methane- and non-methane-producing human colonic bacterial communities

Fems Microbiology Ecology 19 (3) 193-202

par Administrateur - publié le

Abstract :

The purpose of the study was to define the potential for reductive acetogenesis of colonic microflora from six non-methane- and four methane-excreting human subjects in relation to numbers of the different H-2-utilizing microorganisms. Faecal bacterial suspensions were incubated in the presence of (NaHCO3)-C-13, and under a gas phase composed of either 100% N-2 (control) or 80% H-2-20% N-2. The effects of a specific methanogenesis inhibitor or of sulfate supplementation were also determined. Quantitative nuclear magnetic resonance showed the presence of both single- and double-labelled acetate in all incubations under hydrogen. H-2/CO2-acetogenesis appears to be a quantitatively important activity only in the presence of very low numbers of methanogens. Inhibition of methanogenesis induced a large increase in (CO2)-C-13 incorporation into acetate in CH4-producing samples. These results showed that methanogens can efficiently outcompete acetogens in human colonic contents. In contrast, no clear-cut competition for H-2 between acetogenesis and dissimilatory sulfate-reduction could be demonstrated. A slight reduction of the acetogenic activity was only observed at the highest sulfate addition (100 mM).