Aminobacterium thunnarium sp nov., a mesophilic, amino acid-degrading bacterium isolated from an anaerobic sludge digester, pertaining to the phylum Synergistetes

A new Gram-staining-positive, non-sporulating, mesophilic, amino acid-degrading anaerobic bacterium, designated strain OTA 102(T), was isolated from an anaerobic sequencing batch reactor treating wastewater from cooking tuna. The cells were curved rods (0.6-2.5x0.5 mu m) and occurred singly or in pairs. The strain was motile by means of one lateral flagellum. Strain OTA 102(T) grew at temperatures between 30 and 45 degrees C (optimum 40 degrees C), between pH 6.0 and 8.4 (optimum pH 7.2) and NaCl concentrations between 1 and 5% (optimum 2%, w/v). Strain OTA 102(T) required yeast extract for growth. Serine, threonine, glycine, cysteine, citrate, fumarate, alpha-ketoglutarate and pyruvate were fermented. When co-cultured with Methanobacterium formicicum as the hydrogen scavenger, strain OTA 102(T) oxidized alanine, valine, leucine, isoleucine, aspartate, tyrosine, methionine, histidine and asparagine. The genomic DNA G + C content of strain OTA 102(T) was 41.7 mol%. The main fatty acid was iso-C-15:0. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain OTA 102(T) was related to Aminobacterium colombiense and Aminobacterium mobile (95.5 and 95.2% similarity, respectively), of the phylum Synergistetes. On the basis of phylogenetic, genetic and physiological characteristics, strain OTA 102(T) is proposed to represent a novel species of the genus Aminobacterium, Aminobacterium thunnarium sp. nov. The type strain is OTA 102(T) (=DSM 27500(T)=JCM 19320(T)).