Nocardioides mangrovi sp. nov., a novel endophytic actinobacterium isolated from root of Kandelia candel

A novel species of endophytic actinobacterium, designated strain GBK3GQG-3(T), was isolated from surface-sterilized root of Kandelia candel collected from Beilun Estuary, Guangxi Zhuang Autonomous Region, PR China. Cells of strain GBK3GQG-3(T) were Gram-stain-positive, aerobic, non-spore-forming and rod-shaped. Growth of GBK3QG-3(T) was observed at 10-40 degrees C (optimum, 30 degrees C), pH 5.0-9.0 (optimum, pH 7.0) and in the presence of 0-3% (w/v) NaCl (optimum, 0%). The G+C content of genomic DNA was determined to be 72.2mol%. On the basis of 16S rRNA gene sequence analysis, strain GBK3QG-3(T) was most related to the type strain of Nocardioides agrisoli CCTCC AB 2017058(T) (97.7% 16S rRNA gene sequence similarity), followed by Nocardioides ginkgobilobae SYP-A7303(T) (97.0%) and Nocardioides aquiterrae GW-9(T) (96.9%). Average nucleotide identity and digital DNA-DNA hybridization values between strain GBK3QG-3(T) and some strains of the genus Nocardioides with publicly available genomes were below 84.3 and 30.0%, respectively. The cell-wall peptidoglycan contained LL-diaminopimelic acid. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol. phosphatidylinositol. an unknown phospholipid and an unknown lipid. The major menaquinone was identified as MK-8(H-4), and the major fatty acids were identified as iso-C-16:0, iso-(17:0) and anteiso-C-17:0. Based on evidence collected from the phenotypic, genotypic and phylogenetic analyses, we propose a novel species named Nocardioides mangrovi sp. nov. The type strain is GBK3QG-3(T) (=CGMCC 4.7708(T) =JCM 34553(T)).