Phycicoccus mangrovi sp. nov., a novel endophytic actinobacterium isolated from bark of Sonneratia apetala.

Two novel strains KQZ13P-1 and MAQZ13P-2 were isolated from bark of Sonneratia apetala collected from Maowei sea Mangrove Nature Reserve in Guangxi Zhuang Autonomous Region, China. Two strains were Gram-positive, aerobic, non-spore-forming, no diffusion pigment actinobacterial strains and investigated by a polyphasic approach to determine their taxonomic position. The average nucleotide identity (ANI) value and the digital DNA-DNA hybridization (dDDH) value between the two strains were 99.9% and 99.7%, respectively, suggesting that they belonged to the same species. The ANI and dDDH values between strain KQZ13P-1 and five Phycicoccus species were 74.4-95.3% and 20.1-61.5%, respectively. Phylogenetic analyses based on 16S rRNA gene sequences showed that the two strains were member of the genus Phycicoccus and were closely related to P. jejuensis NRRL B-24460 (99.2% sequence similarity), followed by P. ginsengisoli DCY87 (97.5-97.6%). Moreover, based on 88 core genes, the phylogenomic tree indicated that the two strains clustered with P. jejuensis NRRL B-24460. The cell-wall peptidoglycan of both strains contained meso-diaminopimelic acid. The major fatty acids in two strains were Cω8c, iso-C and iso-C. The major polar lipids included diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE) and phosphatidylinositol (PI). Based on phylogenetic, phenotypic and chemotaxonomic analysis, strains KQZ13P-1 and MAQZ13P-2 represent a novel species of the genus Phycicoccus, for which the name Phycicoccus mangrovi sp. nov. is proposed. The type strain is KQZ13P-1 (=CGMCC 1.18973 = JCM 34556).