Micromonospora azadirachtae sp. nov., isolated from roots of Azadirachta indica A. Juss. var. siamensis Valeton

Abstract

A Gram-stain positive actinomycete, strain AZ1-19 T , isolated from roots of Azadirachta indica A. Juss. var. siamensis Valeton, collected from Chachoengsao province, Thailand, was characterised taxonomically by using a polyphasic approach. Strain AZ1-19 T was found to have characteristics consistent with those of members of the genus Micromonospora. The cell wall peptidoglycan of the strain was found to contain meso-diaminopimelic acid. The predominant phospholipids were identified as diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol. The characteristic whole-cell sugars were identified as glucose, xylose, galactose and mannose. The major menaquinones were found to be MK-9(H 6 ), MK-10(H 6 ) and MK-10(H 8 ), and the major cellular fatty acids were identified as iso-C 16:0 , iso-C 15:0 , anteiso-C 15:0 and anteiso-C 17:0 . Comparative analysis of 16S rRNA gene sequences revealed that strain AZ1-19 T is closely related to Micromonospora costi CS1-12 T (98.75% similarity), Micromonospora avicenniae 268506 T (98.75%), Micromonospora haikouensis 232617 T (98.68%) and Micromonospora siamensis TT2-4 T (98.61%), whilst the corresponding phylogenetic analysis based on partial gyrase subunit B (gyrB) gene sequences indicated that strain AZ1-19 T forms a clade with M. avicenniae 268506 T with a high bootstrap value. The DNA G + C content was determined to be 69.8 mol%. Moreover, a combination of DNA–DNA relatedness values and some phenotypic and chemotaxonomic properties indicated that the strain could be distinguished from closely related species. Therefore, it is considered that strain AZ1-19 T represents a novel Micromonospora species for which the name Micromonospora azadirachtae sp. nov. is proposed. The type strain is AZ1-19 T (= KCTC 39941 T = NBRC 112784 T = JCM 32148 T = TISTR 2559 T ).