Romboutsia hominis sp. nov., the first human gut-derived representative of the genus Romboutsia, isolated from ileostoma effluent

A Gram-stain-positive, motile, rod-shaped, obligately anaerobic bacterium, designated FRIFI T , was isolated from human ileostoma effluent and characterized. On the basis of 16S rRNA gene sequence similarity, strain FRIFI T was most closely related to the species Romboutsia ilealis CRIB T (97.7 %), Romboutsia lituseburensis DSM 797 T (97.6 %) and Romboutsia sedimentorum LAM201 T (96.6 %). The level of DNA-DNA relatedness between strain FRIFI T and R. ilealis CRIB T was 13.9±3.3 % based on DNA-DNA hybridization. Whole genome sequence-based average nucleotide identity between strain FRIFI T and closely related Romboutsia strains ranged from 78.4-79.1 %. The genomic DNA G+C content of strain FRIFI T was 27.8 mol%. The major cellular fatty acids of strain FRIFI T were saturated and unsaturated straight-chain C12-C19 fatty acids as well as cyclopropane fatty acids, with C16 : 0 being the predominant fatty acid. The polar lipid profile comprised five phospholipids and six glycolipids. These results, together with differences in phenotypic features, support the proposal that strain FRIFI T represents a novel species within the genus Romboutsia, for which the name Romboutsiahominis sp. nov. is proposed. The type strain is FRIFI T (=DSM 28814 T =KCTC 15553 T ).