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

A novel strictly anaerobic, Gram-negative bacterium, designated as strain FXJYN30E22^T, 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 16 S ribosomal RNA (rRNA) gene sequence. Alignments of 16 S rRNA gene sequences showed only a low sequence identity (≤  95.5 %) between strain FXJYN30E22^T and all other Phocaeicola strains in public data bases. The genome (43.0% GC) of strain FXJYN30E22^T was sequenced, and used for phylogenetic analysis which showed that strain FXJYN30E22^T was most closely related to the type strain Phocaeicola massiliensis JCM 13223^T. The average nucleotide identity (ANI) value and digital DNA-DNA hybridization (dDDH) between FXJYN30E22^T and P. massiliensis JCM 13223^T 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 C_15:0 and phosphatidylethanolamine, respectively. The result of genome annotation and KEGG analysis showed that strain FXJYN30E22^T 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 FXJYN30E22^T but in no other Phocaeicola species, which suggested this gene might be contribute to the adaptive capacity of strain FXJYN30E22^T. Based on our data, strain FXJYN30E22^T (= CGMCC1.17870^T/KCTC25195^T) was classified as a novel Phocaeicola species, and the name Phocaeicola faecalis sp. nov., was proposed.