Aminomonas paucivorans gen. nov., sp nov., a mesophilic anaerobic, amino-acid-utilizing bacterium

A novel, asaccharolytic, amino-acid-degrading bacterium, designated strain GLU-3(T), was isolated from an anaerobic lagoon of a dairy wastewater treatment plant. Strain GLU-3(T) stained Gram-negative and was an obligately anaerobic, non-spore-forming, slightly curved, rod-shaped bacterium (0.3 x 4.0-6.0 mu m) which existed singly or in pairs. The DNA G+C content was 43 mol%. Optimum growth occurred at 35 degrees C and pH 7.5 on arginine with a generation time of 16 h. Good growth was obtained on arginine, histidine, generation time of 16 h. Good growth was obtained on arginine, histidine, threonine and glycine. Acetate was the end-product formed from all these substrates, but in addition, a trace of formate was detected from arginine and histidine, and ornithine was produced from arginine. Strain GLU-3(T) grew slowly on glutamate and produced acetate, carbon dioxide, formate, hydrogen and traces of propionate as the end-products. In syntrophic association with Methanobacterium formicicum, strain GLU-3(T) oxidized arginine, histidine and glutamate to give propionate as the major product; acetate, carbon dioxide and methane were also produced. Strain GLU-3(T) did not degrade alanine and the branched-chain amino acids valine, leucine and isoleucine either in pure culture or in association with M. formicicum. The nearest phylogenetic relative of strain GLU-3(T) was the thermophile Selenomonas acidaminovorans (similarity value of 89.5 %). As strain GLU-3(T) is phylogenetically, physiologically and genotypically different from other amino-acid-degrading genera, it is proposed that it should be designated a new species of a new genus Aminomonas paucivorans gen. nov., sp. nov. (DSM 12260(T)).