Knoellia sinensis gen. nov., sp nov and Knoellia subterranea sp nov., two novel actinobacteria isolated from a cave

Two novel strains of the class Actinobacteria were isolated from a cave in China. Cells of both strains were Gram-positive, non-motile, non-spore-forming and not acid-fast and exhibited a rod/coccus growth cycle. Both isolates grew well on complex organic media under aerobic conditions. Their cell wall peptidoglycan contained meso-diaminopimelic acid as diagnostic diamino acid. The acyl type of the glycan chain of peptidoglycan was acetyl. The major respiratory quinone was MK-8(H-4). The cellular fatty acid profile was characterized by the predominance of 13-methyltetradecanoic (i-C-15:0), 15-methylhexadecanoic (i-C-17:0), 14-methylpentadecanoic (i-C-16:0) and 14-methylhexadecanoic (ai-C-17:0) acids. The major polar lipids were phosphatidylethanolamine, phosphatidylinositol and diphosphatidylglycerol. Mycolic acids were absent. The DNA G+C composition was 68-69 mol%. 16S rDNA-based phylogenetic analysis revealed an intermediate phylogenetic position of the cave isolates between the genera Janibacter and Tetrasphaera, which did not permit their unambiguous affiliation to either genus. Differences in morphological, physiological and chemotaxonomic properties between the two isolates and their closest phylogenetic neighbours support the proposal of a new genus and two novel species, Knoellia sinensis gem. nov., sp. nov. and Knoellia subterranea sp. nov. The type and only strains of the species are respectively HKl 0119(T) (= DSM 12331(T) = CIP 106775(T)) and HKl 0120(T) (= DSM 12332(T) = CIP 106776(T)).