Description of Anaerostipes faecalis sp. nov., a new segmented filamentous bacterium isolated from swine faeces.

A novel, strictly anaerobic, gram-negative, segmented filamentous bacterium strain AGMB03513, was isolated from the faeces of a 5-month-old pig. Phylogenetic analysis based on the 16S rRNA gene indicated that the isolate was a member of the family Lachnospiraceae, and the closest strain was Anaerostipes butyraticus. Strain AGMB03513 formed a lineage within the genus Anaerostipes and was closely related to A. butyraticus DSM 22094 (= KCTC 15125, 95.8%), Anaerostipes hadrus DSM 3319 (= KCTC 15606, 95.5%), Anaerostipes caccae DSM 14662 (= KCTC 15019, 94.0%), and Anaerostipes rhamnosivorans DSM 26241 (= KCTC 15316, 93.4%). Strain AGMB03513 grew at temperatures between 30 and 45 °C, within a pH range of 7.0-9.0, and in medium containing up to 1.5% NaCl. Cells were found to utilise D-glucose, D-mannitol, D-lactose, D-saccharose, D-maltose, D-xylose, L-arabinose, D-mannose, and D-sorbitol, and acetate was identified as the major end product of metabolism. The major components of the cellular fatty acids were C, C, and C. In addition, the bacterium contained meso-diaminopimelic acid in the cell wall. According to the comparative analysis of the whole genome sequence, the DNA G + C content of strain AGMB03513 was 37.0 mol%. In addition, Average nucleotide identity (ANI), average amino acid identity (AAI), and digital DNA-DNA hybridisation (dDDH) values were obtained in comparisons of strain AGMB03513 with reference strains of species in the genus Anaerostipes. ANI values were found to be between 71.0 and 75.7%, AAI values between 66.6 and 73.2%, and dDDH values between 19.5 and 21.4%. All the data were below the threshold range for species determination. Based on phenotypic, phylogenetic, biochemical, chemotaxonomic, and genomic characteristics, we considered it reasonable to assign a novel species status to strain AGMB03513, for which we propose the name Anaerostipes faecalis sp. nov. The type strain is AGMB03513 (= KCTC 25020 = NBRC 114896).