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

Abstract

A novel, anaerobic filamentous bacterium, strain MO-CFX1T, 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 µm and 130–150 nm in width. Growth of the strain was observed at 10–37 °C (optimum 25–30 °C), at pH 5.5–8.5 (optimum pH 7.0) and in 0–50 g NaCl l−1 (optimum 15 g NaCl l−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 C18 : 1ω9, C16 : 1ω7 and saturated C18 : 0 and C16 : 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 16S rRNA gene sequence analysis, strain MO-CFX1T was affiliated with the class Anaerolineae within the phylum Chloroflexi and was most closely related to Leptolinea tardivitalis YMTK-2T (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-CFX1T ( = JCM 17238T, = KCTC 5975T). This is the first formal description, to our knowledge, of an isolate of the phylum Chloroflexi from the deep-sea sedimentary environment.