Clostridium acetireducens sp nov, a novel amino acid-oxidizing, acetate-reducing anaerobic bacterium

Strain 30A(T) (T = type strain), which was isolated from an anaerobic bioreactor fed on waste from a potato starch factory in De Krim, The Netherlands, is a nonmotile, gram-positive, anaerobic, rod-shaped organism that is able to degrade various amino acids, including alanine, leucine, isoleucine, valine, serine, and threonine. Acetate is required as an electron acceptor for the utilization of alanine, valine, leucine, and isoleucine. Other grow th substrates, including pyruvate, alpha-ketobutyrate, alpha-ketoisocaproate, alpha-keto-3-methylvalerate, alpha-ketoisovalerate, and peptone, are intermediates in amino acid catabolism. Strain 30A(T) utilizes neither the branched-chain amino acids nor alanine via interspecies hydrogen transfer with methanogenic and sulfate-reducing bacteria or via the Stickland reaction with proline or glycine as an electron acceptor. No growth occurs with the following electron accepters: fumarate, nitrate, nitrite, sulfite, sulfate, and oxygen. Yeast extract is required for growth. Sugars are not degraded. The optimal temperature and optimal pH for growth are 39 to 43 degrees C and 6.4 to 7.6, respectively. The results of a 16S rRNA sequence analysis phylogenetically placed strain 30A(T) in Clostridium group I (genus Clostridium sensu stricto), where it forms a new and distinct line of descent.