sp. nov., isolated from the rumen of cows.

The genus plays an important role in polysaccharide degradation and fermentation in the rumen. To further understand the function of the phylogenetically diverse genus , it is necessary to explore the individual characteristics at the species level. In this study, Gram-negative anaerobic bacterial strains isolated from the rumen of Holstein cows were identified. Strain R5019 was classified within the genus based on 16S rRNA gene sequence-based phylogenetic analysis. The values of 16S rRNA gene sequence similarity, average nucleotide identity and digital DNA-DNA hybridization between strain R5019 and its phylogenetically nearest species PPPA20 were 89.8, 82.6, and 29.3 %, respectively. The genome size of R5019 was estimated to be ca. 4.19 Mb with a genomic G+C content of 49.5 mol%. The major cellular fatty acids and menaquinones were C anteiso and C anteiso and MK-11 and MK-12, respectively. Succinate, lactate, malate, acetate and formate were produced as the fermentation end products using glucose. Based on phylogenetic, physiological, biochemical and genomic differences between 11 strains and other phylogenetically related species, a novel species, sp. nov., is proposed within the genus . The type strain is R5019 (=JCM 34664=DSM 112675).