Pelolinea submarina gen. nov., sp nov., an anaerobic, filamentous bacterium of the phylum Chloroflexi isolated from subseafloor sediment

A novel, anaerobic filamentous bacterium, strain MO-CFX1(T), was isolated from a methanogenic community, which was originally established from subseafloor sediments collected from off the Shimokita Peninsula, Japan. Cells were non-spore-forming, non-motile, Gram-stain-negative and filamentous. The filaments were longer than 10 mu m and 130-150 nm in width. Growth of the strain was observed at 10-37 degrees C (optimum 25-30 degrees C), at pH 5.5-8.5 (optimum pH 7.0) and in 0-50 g NaCl I-1 (optimum 15 g NaCl I-1). The strain was able to grow with a number of carbohydrates in the presence of yeast extract. The major cellular fatty acids were monounsaturated C-18:1 omega 9, C-16:1 omega 7 and saturated C-18:0 and C-16:0. The intact polar lipids of the strain were dominated by diacylglyceride and sphingolipid core lipid structures with monoglycosidic, mixed phosphomonoglycosidic and fatty-acid-modified monoglycosidic polar head groups. The G+C content of the genomic DNA was 52.4 mol%. Based on the comparative 165 rRNA gene sequence analysis, strain MO-CFX1(T) was affiliated with the class Anaerolineae within the phylum Chloroflexi and was most closely related to Leptolinea tardivitalis YMTK-2(T) (sequence identity of 91.0%). Based on phenotypic and genetic properties of the novel isolate, we propose a novel species representing a new genus Pelolinea submarina gen. nov., sp. nov., for strain MO-CFX1(T) (=JCM 17238(T),=KCTC 5975(T)). This is the first formal description, to our knowledge, of an isolate of the phylum Chloroflexi from the deep-sea sedimentary environment.