Microlunatus nigridraconis sp. nov., an actinobacterium from rhizosphere soil

An actinobacterium, designated strain CPCC 203993T, was isolated from a rhizosphere soil sample collected from Heilongjiang Province, northeast China, and was characterized using a polyphasic taxonomy approach. Cells of the strain were Gram-stain-positive, non-motile and non-endospore-forming cocci. The 16S rRNA gene sequence comparison of strain CPCC 203993T with members of the genus Microlunatus yielded 93.9 % to 97.8 % similarities. In the phylogenetic tree based on 16S rRNA gene sequences, strain CPCC 203993T was affiliated to the clade of the genus Microlunatus next to Microlunatus parietis DSM 22083T, while the DNA-DNA hybridization value of 31.5 % (±1.8 %) between strain CPCC 203993T and Microlunatus. parietis DSM 22083T was far below 70 %. This result indicated that strain CPCC 203993T represented a different genomic species from M. parietis. Chemotaxonomically, the strain contained ll-2,6-diaminopimelic acid as the diagnostic diamino acid, MK-9(H4) as the only menaquinone, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, three unidentified glycolipids and one unidentified phospholipid in the polar lipids extracts, and anteiso-C15 : 0, iso-C15 : 0 and iso-C16 : 0 as the major cellular fatty acids, without mycolic acids. The genomic DNA G+C content was 64.04 mol%. The above evidence from the polyphasic study merit the recognition of strain CPCC 203993T as a representative of a novel species of the genus Microlunatus, for which Microlunatus nigridraconis sp. nov. is proposed. The type strain is CPCC 203993T (=DSM 29529T=NBRC 110715T=KCTC 29689T).