Faecalibaculum rodentium gen. nov., sp. nov., isolated from the faeces of a laboratory mouse

Abstract

A novel strictly anaerobic strain, ALO17T, was isolated from mouse faeces and found to produce lactic acid as a major metabolic end product. The isolate was observed to be Gram-stain positive, non-motile, non-spore forming small rods, oxidase and catalase negative, and to form cream-coloured colonies on DSM 104 agar plates. The NaCl range for growth was determined to be 0？2 % (w/v). The isolate was found to grow optimally at 37 °C, with 0.5 % (w/v) NaCl and at pH 7. The cell wall hydrolysates were found to contain ribose as a major sugar. The genomic DNA G+C content was determined to be 52.3 mol%. A phylogenetic analysis of the 16S rRNA gene sequence revealed that Holdemanella biformis DSM 3989T, Faecalicoccus pleomorphus ATCC 29734T, Faecalitalea cylindroides ATCC 27803T, and Allobaculumstercoricanis DSM 13633T are closely related to the isolate (87.4, 87.3, 86.9 and 86.9 % sequence similarity), respectively. The major cellular fatty acids (>10 %) of the isolate were identified as C18:1 cis 9 FAME (36.9 %), C16:0 FAME (33.7 %) and C18:0 FAME (13.2 %). In contrast to the tested reference strains, C20:0 FAME (4.0 %) was detected only in strain ALO17T whilst C16:0 DMA was absent. The isolate also differed in its substrate oxidation profiles from the reference strains by being positive for d-melibiose and stachyose but negative for N-acetyl-d-galactosamine and 3-methyl-d-glucose. On the basis of polyphasic taxonomic evidence from this study, the isolate is concluded to belong to a novel genus within the family Erysipelothricaceae. We propose the name Faecalibaculum rodentium gen. nov., sp. nov. to accommodate strain ALO17T (=KCTC 15484T = JCM 30274T) as the type strain.