Microlunatus cavernae sp. nov., a novel actinobacterium isolated from Alu ancient cave, Yunnan, south-west China

A Gram-positive, coccoid, non-endospore-forming actinobacterium, designated YIM C01117T, was isolated from a soil sample collected from Alu ancient cave, Yunnan province, south-west China. Based on the 16S rRNA gene sequence analysis, strain YIM C01117T was shown to belong to the genus Microlunatus, with highest sequence similarity of 97.4 % to Microlunatus soli DSM 21800T. The whole genomic DNA relatedness as shown by the DNA–DNA hybridization study between YIM C01117T and M. soli DSM 21800T had a low value (47 ± 2 %). Strain YIM C01117T was determined to contain LL-diaminopimelic acid with Gly, Glu and Ala amino acids (A3γ′ type) in the cell wall. Whole-cell hydrolysates were found to contain glucose, galactose, mannose and ribose. The major polar lipids were determined to be phosphatidylglycerol and diphosphatidylglycerol. The predominant menaquinone system present is MK-9(H4), while the major fatty acids were identified to be anteiso-C15:0 (24.1 %), iso-C16:0 (22.3 %) and iso-C15:0 (11.4 %). The G+C content of the genomic DNA was determined to be 65.9 mol%. The chemotaxonomic and genotypic data support the affiliation of the strain YIM C01117T to the genus Microlunatus. The results of physiological and biochemical tests allow strain YIM C01117T to be differentiated phenotypically from recognized Microlunatus species. Strain YIM C01117T is therefore considered to represent a novel species of the genus Microlunatus, for which the name Microlunatuscavernae sp. nov. is proposed. The type strain is YIM C01117T (= DSM 26248T = JCM 18536T).