Characterization of Bacteria from a Swine Manure Digester

One-hundred thirty bacteria isolated from a swine manure digester were predominately gram-positive anaerobes which were tentatively classified into the following genera: Peptostreptococcus, Eubacterium, Bacteroides, Lactobacillus, Peptococcus, Clostridium, and Streptococcus plus two unidentified groups. The major fermentation products formed by these organisms included acetate, propionate, succinate, lactate, and ethanol, singly or in various combinations. Acetate was the sole end product of several groups. Few of the isolates (14%) reduced the pH below 6.0. The predominate bacteria appear to differ from the predominate organisms isolated from other anaerobic ecosystems.