Rhodococcus huquni sp. nov., Rhodococcus quanlei sp. nov. and Rhodococcus ruitaii sp. nov., three novel species of Rhodococcus from wild mammal faeces in China

Six Gram-stain-positive, coccobacilli, non-motile, oxidase-negative, catalase-positive strains, designated HY-051 T , HY049, HY190 T , HY1757, HY647 T and HY359, were isolated from the faeces of Tibetan wild asses ( Equus kiang ) in Tibet, China, and from fruit bat ( Rousettus leschenaultii ) faeces in Yunnan, China. All strains are strictly aerobic. Optimal growth for all strains occurred at 28.0 °C, pH 7.0 and with 1.0% (w/v) NaCl. While 16S rRNA gene analysis confirmed their placement within the genus Rhodococcus , phylogenomic analyses revealed that strains HY-051 T /HY049, HY190 T /HY1757 and HY647 T /HY359 represent distinct lineages. Notably, the digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values between these strains and their closest relatives were well below the species delineation thresholds (70% dDDH and 95–96% ANI). Chemotaxonomically, all three groups differ from their closest phylogenetic neighbours by the absence of C 15 : 0 and C 16 : 1 fatty acids and the presence of Summed Feature 3. Additionally, distinct whole-cell sugar patterns (ribose/arabinose or glucose/galactose), differential menaquinone profiles and API ZYM and 50CH biochemical profiles (e.g. aesculin hydrolysis and carbohydrate utilization) further distinguish them from known species. Based on polyphasic taxonomic analyses, strains HY-051 T and HY049 constitute a novel species of the genus Rhodococcus , for which the name Rhodococcus huquni sp. nov. is proposed, with strain HY-051 T (=JCM 34841 T =CGMCC 1.19145 T ) as the type strain; strains HY190 T and HY1757 constitute a novel species of the genus Rhodococcus , for which the name Rhodococcus quanlei sp. nov. is proposed, with strain HY190 T (=JCM 34842 T =CGMCC 1.19375 T ) as the type strain; and strains HY647 T and HY359 constitute a novel species of the genus Rhodococcus , for which the name Rhodococcus ruitaii sp. nov. is proposed, with strain HY647 T (=JCM 34787 T =CGMCC 1.19150 T ) as the type strain.