Abstract
A novel endophytic actinomycete strain AZ1-13(T) was isolated from roots of Azadirachta indica, and its taxonomic position was investigated using a polyphasic approach. Pairwise 16S rRNA gene sequence similarities of strain AZ1-13(T) and its closest species, Jishegella zingiberis PLAI1-1(T) and Micromonospora endophytica 202201(T), were 99.7 and 99.2 %, respectively. Phylogenetic analyses of the family Micromonosporaceae based on 16S rRNA gene sequences indicated strains AZ1-13(T) and J. zingiberis PLAI1-1(T) are located within the genus Micromonospora. The approximate genome size of the strain was 5.96 Mb with 71.9 mol% of G+C content. The strain AZ1-13(T) exhibited ANIb values of 87.4% with J. zingiberis PLAI1-1(T) and 85.1% with M. endophytica 202201(T). Chemotaxonomic characteristics of strain AZ1-13(T) were consistent within the genus Micromonospora: cell-wall peptidoglycan of the strain contained meso-diaminopimelic acid; glucose, mannose, ribose and xylose are presented as the whole-cell sugars; the predominant menaquinones were MK-9(H-4) and MK-9(H-6); major cellular fatty acids were iso-C-15 : 0, 10-methyl C-17 : 0, C-17 : 0, anteiso-C-17 : 0 and iso-C-17 : 1 omega 8c; diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol were detected as distinguished phospholipids. Based on phenotypic properties, phylogeny and genomic data, the strain AZ1-13(T) could be distinguished from its closest neighbours, representing a novel species of the genus Micromonospora, for which the name Micromonospora radicis sp. nov. is proposed. The type strain is AZ1-13(T) (=KCTC 39786(T)=NBRC 112324(T)=JCM 32147(T)=TISTR 2404(T)). This study also proposed that J. zingiberis is transferred to the genus Micromonospora as Micromonospora zingiberis comb. nov. (type strain PLAI1-1(T)=TBRC 7644(T)=NBRC 113144(T)=JCM 32592(T)).
