Pleomorphochaeta caudata gen. nov., sp nov., an anaerobic bacterium isolated from an offshore oil well, reclassification of Sphaerochaeta multiformis MO-SPC2T as Pleomorphochaeta multiformis MO-SPC2T comb. nov as the type strain of this novel genus and emended description of the genus Sphaerochaeta

A strictly anaerobic Gram-stain-negative bacterium, designated strain SEBR 4223(T), was isolated from the production water of an offshore Congolese oil field. Cells were non-motile, pleomorphic and had spherical, annular or budding shapes, often exhibiting long stalks. Strain SEBR 4223(T) grew on a range of carbohydrates, optimally at 37 degrees C and pH 7, in a medium containing 40 g l(-1) NaCl. Predominant fatty acids were C-14 : 0, C-14 : 0 DMA, C-16 : 0 and C-16 : 1 omega 7c and the major polar lipids were phosphoglycolipids, phospholipids, glycolipids and diphosphatidylglycerol. The G+ C content of the DNA was 28.7 mol%. Phylogenetic analysis, based on the 16S rRNA gene sequence, showed that strain SEBR 4223(T) and Sphaerochaeta multiformis MO-SPC2(T) formed a cluster with similarity to other species of the genus Sphaerochaeta of of less than 86 %. On the basis of the phenotypic characteristics and taxonomic analyses, we propose a novel genus, Pleomorphochaeta gen. nov., to accommodate the novel species Pleomorphochaeta caudata sp. nov., with SEBR 4223(T) (= DSM 103077(T) = JCM 31 475(T)) as the type strain. We also propose the reclassification of Sphaerochaeta multiformis MO SPC2(T) as Pleomorphochaeta multiformis MO-SPC2(T) comb. nov., the type strain of this novel genus and emend description of the genus Sphaerochaeta.