Micromonospora radicis sp. nov., isolated from roots of Azadirachta indica var. siamensis Valenton, and reclassification of Jishengella zingiberis as Micromonospora zingiberis comb. nov.

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 ω8 c ; 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 ).