Ruthenibacterium lactatiformans gen. nov., sp. nov., an anaerobic, lactate-producing member of the family Ruminococcaceae isolated from human faeces

Two novel strains of Gram-stain-negative, rod-shaped, obligately anaerobic, non-spore-forming, non-motile bacteria were isolated from the faeces of healthy human subjects. The strains, designated as 585-1^T and 668, were characterized by mesophilic fermentative metabolism, production of D-lactic acid, succinic acid and acetic acid as end products of D-glucose fermentation, prevalence of C_18:1ω9, C_18:1ω9 aldehyde, C_16:0 and C_16:1ω7c fatty acids, presence of glycine, glutamic acid, lysine, alanine and aspartic acid in the petidoglycan peptide moiety and lack of respiratory quinones. Whole genome sequencing revealed the DNA G+C content was 56.4-56.6 mol%. The complete 16S rRNA gene sequences of the two strains shared 91.7/91.6% similarity with Anaerofilum pentosovorans Fae^T, 91.3/91.2% with Gemmiger formicilis ATCC 27749^T and 88.9/88.8% with Faecalibacterium prausnitzii ATCC 27768^T. On the basis of chemotaxonomic and genomic properties it was concluded that the strains represent a novel species in a new genus within the family Ruminococcaceae, for which the name Ruthenibacterium lactatiformans gen. nov., sp. nov. is proposed. The type strain of Ruthenibacterium lactatiformans is 585-1^T (=DSM 100348^T=VKM B-2901^T).