Peptoniphilus equinus sp. nov., a novel Gram-stain-positive anaerobic coccus isolated from the faeces of a thoroughbred racehorse

A novel, anaerobic, Gram-stain-positive coccoid strain, CBA3646 T , was isolated from the faeces of a thoroughbred racehorse. Phylogenetic analysis based on 16S rRNA gene sequencing yielded results indicative of CBA3646 T representing a member of the genus Peptoniphilus , with the species most closely related to it being Peptoniphilus asaccharolyticus DSM 20463 T , with a similarity of 94.79 %. DNA–DNA relatedness and average nucleotide identity values between CBA3646 T and P. asaccharolyticus DSM 20463 T were 21.4 and 67.6 %, respectively. CBA3646 T has a circular chromosomal genome of 1 709 189 bp (45.5 mol% DNA G+C content), containing 1652 genes in total, 1584 predicted protein-coding genes, 3 complete rRNA loci and 47 tRNA genes. The cells were non-motile diplococci, catalase-positive and oxidase-negative. Growth of CBA3646 T was observed at 20–40 °C (optimal temperature, 35 °C) and in the presence of 0–4 % (w/v) NaCl (optimum concentration, 1 %). The major fatty acids (>10 %) of CBA3646 T were C 16 : 0 , C 18 : 1 ω9 c and C 18 : 1 ω9 c dimethyl acetal, with its major polar lipids being diphosphatidylglycerol and phosphatidylglycerol. The elucidated phylogenetic, physiological, chemotaxonomic and molecular properties are indicative of strain CBA3646 T representing a novel species of the genus Peptoniphilus , or which the name Peptoniphilus equinus sp. nov. is proposed. The type strain is CBA3646 T (= KACC 22890 T = JCM 35845 T ).