Epidermidibacterium keratini gen. nov., sp. nov., a member of the family Sporichthyaceae, isolated from keratin epidermis.

Abstract

A novel actinobacterial strain, designated EPI-7T, was isolated on R2A agar from human skin (keratinocytes) and subjected to a taxonomic study using a polyphasic approach. Strain EPI-7T showed a Gram-positive reaction, was non-motile, non-spore-forming, and cells had a rod-shape. Colonies were round, convex and pale yellow. Phylogenetic analysis based on 16S rRNA gene sequences showed that the novel isolate formed a cluster with several uncultured bacterial clones and with cultured members of the genera Modestobacter and Sporichthya. The 16S rRNA gene sequence similarities with respect to the type strains of recognized species from the above genera and other phylogenetic neighbours ranged from 92.6 to 93.4 %. The G+C content of the genomic DNA was 68.9 mol%. The only isoprenoid quinone was MK-9(H4), and the major fatty acids detected were C17 : 1ω8c, C16 : 0, iso-C15 : 0 and summed feature 3. The major polar lipids were found to be phosphatidylethanolamine, phosphatidylinositol, three unidentified phospholipids, phosphatidylglycerol, phosphatidylcholine, two unidentified amino lipids and three unidentified lipids. The cell-wall peptidoglycan contained meso-diaminopimelic acid, glutamic acid and alanine. Whole-cell sugars present included rhamnose, glucose and galactose. The combination of the genotypic and phenotypic data allowed differentiation of strain EPI-7T from its closest phylogenetic neighbours and provided evidence that strain EPI-7T represents a novel genus and species in the family Sporichthyaceae. The name Epidermidibacterium keratini gen. nov., sp. nov. is proposed with the type strain being EPI-7T (=KCCM 90264T=JCM 31644T).