Phocaeicola faecalis sp. nov., a strictly anaerobic bacterial strain adapted to the human gut ecosystem.

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A novel strictly anaerobic, Gram-negative bacterium, designated as strain FXJYN30E22T, was isolated from the feces of a healthy woman in Yining county, Xinjiang province, China. This strain was non-spore-forming, bile-resistant, non-motile and rod-shaped. It was found to belong to a single separate group in the Phocaeicola genus based on its 16S ribosomal RNA (rRNA) gene sequence. Alignments of 16S rRNA gene sequences showed only a low sequence identity (≤ 95.5 %) between strain FXJYN30E22T and all other Phocaeicola strains in public data bases. The genome (43.0% GC) of strain FXJYN30E22T was sequenced, and used for phylogenetic analysis which showed that strain FXJYN30E22T was most closely related to the type strain Phocaeicola massiliensis JCM 13223T. The average nucleotide identity (ANI) value and digital DNA-DNA hybridization (dDDH) between FXJYN30E22T and P. massiliensis JCM 13223T were 90.4 and 41.9 %, which were lower than the generally accepted species boundaries (94.0 and 70 %, respectively). The major cellular fatty acids and polar lipids were anteiso-branched C15:0 and phosphatidylethanolamine, respectively. The result of genome annotation and KEGG analysis showed that strain FXJYN30E22T contains a number of genes in polysaccharide and fatty acid synthesis that indicated adaptation to the human gut system. Furthermore, a pbpE (penicillin-binding protein) gene was found in the genome of strain FXJYN30E22T but in no other Phocaeicola species, which suggested this gene might be contribute to the adaptive capacity of strain FXJYN30E22T. Based on our data, strain FXJYN30E22T (= CGMCC1.17870T/KCTC25195T) was classified as a novel Phocaeicola species, and the name Phocaeicola faecalis sp. nov., was proposed.