Butyribacter intestini gen. nov., sp. nov., a butyric acid-producing bacterium of the family Lachnospiraceae isolated from human faeces, and reclassification of Acetivibrio ethanolgignens as Acetanaerobacter ethanolgignens gen. nov., comb. nov.

A novel, non-motile, Gram-stain-positive, non-spore-forming, obligate anaerobic bacterium, designated strain TF01-11T, was isolated from human faeces. The isolate was characterized by phylogenetic and phenotypic properties, as well as by determination of its whole genome sequence. The growth temperature and pH ranges were 30-42 °C and 6.0-8.5, respectively. The end products of glucose fermentation were butyric acid and a small amount of acetic acid. The genome was estimated to be 3.61 Mbp with G + C content of 36.8 mol%. Genes related to biosynthesis of diaminopimelic acid, polar lipids, polyamines, teichoic and lipoteichoic acids were present. The predominant fatty acids were C16:0 (37.9%), C14:0 (16.4%), C13:0 OH/iso-C15:1H (11.1%) and C18:1ω9c (10.6%). Phylogenetic analyses based on 16S rRNA gene sequences demonstrated that the isolate was a member of family Lachnospiraceae, with the highest sequence similarity to the type strain of Roseburia intestinalis DSM 14610T (92.2%), followed by Acetivibrio ethanolgignens ATCC 33324T (92.0%). The average nucleotide identity (ANI) and average amino acid identity (AAI) values between strain TF01-11T and these closest relatives were less than 70.5% and 52.3%. Based on results of phenotypic characteristics and genotypic properties presented in this study, strain TF01-11T represents a novel species in a new genus, for which the name Butyribacter intestini gen. nov., sp. nov. is proposed. The type strain of the type species is TF01-11T (CGMCC 1.5203T = DSM 105140T). In addition, Acetivibrio ethanolgignens is proposed to be reclassified as Acetanaerobacter ethanolgignens gen. nov., comb. nov.