Pilosibacter rotomagensis sp. nov., a Butyrate-Producing Bacterium Isolated from Human Faeces

Isolating bacteria from the human gut microbiota and analyzing their phenotypes is essential for complementing the data obtained by metagenomics and for characterizing the functions of these microorganisms in human physiology. In this study, we isolated bacteria from the gut microbiota of healthy individuals and identified an uncharacterized bacterial strain that we designated HC1M1C21^T. Phylogenetic analyses based on 16S rRNA and whole genome sequences indicated that this strain belongs to the family Lachnospiraceae. The closest relative of strain HC1M1C21^T is Pilosibacter fragilis CSJ-4^T (97.0% 16S rRNA gene sequence identity). P. fragilis was initially classified in the family Clostridiaceae. Based on our phylogenetic analyses, we propose to transfer the genus Pilosibacter from the family Clostridiaceae to the family Lachnospiraceae. HC1M1C21^T has a DNA G + C content of 48.7%. This strain is anaerobic, Gram-stain-positive, non-motile and non-spore-forming. HC1M1C21^T cells appear as single rods or chained rods with tapered ends. Optimal growth was observed at 37°C, at pH between 5.7 and 7.0 and at salinity below 10 g/L. HC1M1C21^T is a potent butyrate producer. On the basis of these data, HC1M1C21^T represents a novel species from the genus Pilosibacter, for which the name Pilosibacter rotomagensis sp. nov. is proposed. The type strain of P. rotomagensis is HC1M1C21^T (= DSM 119410^T=LMG 33828^T).