Cutibacterium equinum sp. nov., isolated from horse faeces

Strain CBA3108T is a Gram-positive, non-spore-forming, obligately anaerobic bacterium isolated from horse faecal samples obtained in Jeju Island, Republic of Korea. The cells of CBA3108T are non-motile short rods that have been assessed as catalase-positive and oxidase-negative. Growth of the strain occurs under the following conditions: 25-45 degrees C (optimum, 35 degrees C); pH 6-9 (optimum, pH 6); and in the presence of 0-6% (w/v) NaCl (optimum, 2%). Major fatty acids in the strain include C-15:0 iso and C-15:0 iso DMA, while major polar lipids include phosphatidylglycerol, diphosphatidylglycerol and phosphatidylcholine. Based on phylogenetic analysis using 16S rRNA gene sequences, strain CBA3108(T) forms a phyletic lineage distinct from other closely related species within the genus Cutibacterium. It was found to be most closely related to Cutibacterium avidum ATCC 25577(T) (98.27 % 16S rRNA gene sequence similarity) and other strains within the genus (<= 98.0 %). The genomic DNA G+C content of strain CBA3108(T) was 63.2 mol%. The in silico DNA-DNA hybridization values of strain CBA3108(T) with C. avidum ATCC 25577(T), C. porci WCA-380-WT-3A(T) and C. acnes subsp. acnes DSM 1897(T) were 33.6, 21.7 and 22.7 %, respectively. Its phenotypic, chemotaxonomic and molecular properties support the hypothesis that strain CBA3108(T) represents a novel species in the genus Cutibacterium, for which we propose the name Cutibacterium equinum sp. nov. The type strain is CBA3108(T) (=KACC 22889(T)=JCM 35966(T)).