Enumeration studies on methanogenic bacteria

Various media for the enumeration of methanogenic bacteria were compared statistically. It is suggested that a reduced medium containing mineral salts, vitamins, small amounts of fatty acids, carbon dioxide (20 per cent) and hydrogen (80 per cent) should be used for the enumeration of methanogenic bacteria from natural habitats. The addition of rumen fluid and digester fluids to media seemed to have stimulated the growth of more colonies, some of which may have been non-methanogenic in origin. Repressive effects of formate and acetate on colony counts in certain circumstances were observed.