ABSTRACT
Various anaerobic hydrolytic and methanogenic bacteria active in cattle dung biogas plants are reported in the literature. Anaerobic bacteria with ability to use volatile fatty acids constitute a vital bridge between hydrolytic bacteria and methanogenic bacteria. The present paper describes the isolation of Syntrophobacter wolinii a propionate degrading bacterium in co-culture with a hydrogen utilizing methanogen viz., Methanobacterium formicicum from the fermenting slurry of cattle dung biogas plant. Earlier studies on propionate and butyrate degradation indicated Μethanospirillum hungatei as the hydrogen utilizing partner of the co-culture whereas in the present studies this was not the case. Temperature 35o C, pH 7·5 and 20 mM of propionate were found optimal for growth and activity of co-culture.