Thermosynergistes pyruvativorans gen. nov., sp. nov., an anaerobic, pyruvate-degrading bacterium from Shengli oilfield, and proposal of Thermosynergistaceae fam. nov. in the phylum Synergistetes.

A strictly anaerobic, thermophilic, Gram-stain-negative bacterium, named as strain S15T, was isolated from oily sludge of Shengli oilfield in PR China. Cells of strain S15T were straight or slightly curved rods with 0.4-0.8 µm width × 1.4-3 µm length and occurred mostly in pairs or short chains. Endospore-formation was not observed. The strain grew optimally at 55 °C (range from 30-65 °C), pH 6.5 (pH 6.0-8.5) and 0-30 g l-1 NaCl (optimum with 10 g l-1 NaCl). Yeast extract was an essential growth factor for strain S15T. The major cellular fatty acid was iso-C15 : 0 (58.2 %), and the main polar lipids were amino phospholipid (APL), glycolipids (GLs) and phosphatidylethanolamine (PE). The G+C content of DNA of strain S15T was 52.2 mol%. Strain S15T shared 89.8 % 16S rRNA gene similarity with the most related organism Acetomicrobium hydrogeniformans DSM 22491T in the phylum Synergistetes. The paired genomic average amino acid identity (AAI) and percentage of conserved proteins (POCP) values showed relatedness of less than 58.0 and 39.7 % with type strains of the species in the phylum Synergistetes. On the basis of phenotypic, phylogenetic and phylogenomic evidences, strain S15T constitutes a novel species in a novel genus, for the name Thermosynergistes pyruvativorans gen. nov., sp. nov. is proposed. The type strain is S15T (=CCAM 583T=JCM 33159T). Thermosynergistaceae fam. nov. is also proposed.