INTERACTIONS BETWEEN AMINO-ACID-DEGRADING BACTERIA AND METHANOGENIC BACTERIA IN ANAEROBIC-DIGESTION

Certain amino acids were degraded oxidatively by dehydrogenation, with methanogenic bacteria acting as H//2 acceptors. The inhibition of methanogenesis by chloroform also inhibited the degradation of these amino acids and and/or caused variations in the composition of volatile acids produced from them. The presence of glycine reduced the inhibitory effect caused by chloroform, probably because glycine acted as an H//2 acceptor in place of methanogenic bacteria. This fact suggested that the coupled oxidation-reduction reactions between two amino acids - one acting as the H//2 donor and the other acting as the H//2 acceptor - may occur in the anaerobic digestion of proteins or amino-acid mixtures.