Micromonospora azadirachtae sp. nov., isolated from roots of Azadirachta indica A. Juss. var. siamensis Valeton
A Gram-stain positive actinomycete, strain AZ1-19T, 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 AZ1-19T 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(H6), MK-10(H6) and MK-10(H8), and the major cellular fatty acids were identified as iso-C16:0, iso-C15:0, anteiso-C15:0 and anteiso-C17:0. Comparative analysis of 16S rRNA gene sequences revealed that strain AZ1-19T is closely related to Micromonospora costi CS1-12T (98.75% similarity), Micromonospora avicenniae 268506T (98.75%), Micromonospora haikouensis 232617T (98.68%) and Micromonospora siamensis TT2-4T (98.61%), whilst the corresponding phylogenetic analysis based on partial gyrase subunit B (gyrB) gene sequences indicated that strain AZ1-19T forms a clade with M. avicenniae 268506T 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 AZ1-19T represents a novel Micromonospora species for which the name Micromonospora azadirachtae sp. nov. is proposed. The type strain is AZ1-19T (= KCTC 39941T = NBRC 112784T = JCM 32148T = TISTR 2559T).
KeywordsMicromonospora azadirachtae Micromonosporaceae Azadirachta indica Endophytic actinomycetes Plant root
We would like to thank Dr A. Matsumoto and Prof Dr Y. Takahashi, Department of Drug Discovery, Kitasato University for the isoprenoid quinone analysis by LC-MS, and appreciate Assoc Prof Dr C. Thawai, Department of Biology, Faculty of Science, King’s Mongkut Institute of Technology Ladkrabang, for providing M. costi CS1-12T. We also thank the 2015 Royal Golden Jubilee Ph. D. Programme scholarship to N. K. for financial support under the Thailand Research Fund.
We declare that the present study was performed by the authors named in this article. N. Kuncharoen, S. Tanasupawat designed the study; N. Kuncharoen, S. Tanasupawat, and T. Kudo performed experiments on isolation, identification, analysis, and interpretation; M. Ohkuma gave technical support and conceptual advice. All authors read and approved the final manuscript.
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Conflicts of interest
The authors declare that there are no conflicts of interest.
This article does not contain any studies with human participants and/or animals performed by any of the authors. The formal consent is not required in this study.
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