Aranciamycin K (1) and isotirandamycin B (2) were isolated from a marine-derived Streptomyces sp. SCSIO 41399, along with the previously reported four anthracycline derivatives (3–6), and two known tirandamycin derivatives (7 and 8). Their structures including absolute configurations were determined by extensive analysis of their spectroscopic analysis and ECD calculation method. Most of the isolated compounds were tested for their cytotoxic, antibacterial, and antifungal activities. Compounds 2, 7 and 8 displayed potent bacteriostatic effects against Streptococcus agalactiae with MIC values of 11.5, 5.9 and 5.7 μM, respectively. Besides, compounds 3, 5 and 6 exhibited moderate in vitro cytotoxic activities against the K562 cell lines with IC₅₀ values of 22.0 ± 0.20, 1.80 ± 0.01 and 12.1 ± 0.07 μM, respectively.

A novel streptomycete (strain HNM0141T) was isolated from tropical forest soil collected from Bawangling mountain of Hainan island, PR China and its taxonomic position was established in a polyphasic study. The organism had chemical and morphological properties consistent with its classification as a member of the Streptomyces violaceusniger clade. On the basis of the results of 16S rRNA gene sequence analysis, HNM0141T showed highest similarity to Streptomyces malaysiensis CGMCC4.1900T (99.4 %), Streptomyces samsunensis DSM 42010T (98.9 %), Streptomyces yatensis NBRC 101000T (98.3 %), Streptomyces rhizosphaericus NBRC 100778T (98.0 %) and Streptomyces sporoclivatus NBRC 100767T (97.9 %). The strain formed a well-delineated subclade with S. malaysiensis CGMCC4.1900T and S. samsunensis DSM 42010T. The levels of DNA–DNA relatedness between HNM0141T and S. malaysiensis CGMCC4.1900T and S. samsunensis DSM 42010T were 62 and 44 %, respectively. On the basis of phenotypic and genotypic characteristics, HNM0141T represents a novel species in the S. violaceusniger clade for which the name Streptomyces solisilvae sp. nov. is proposed. The type strain is HNM0141 T (=CCTCC AA 2016045T=KCTC 39905T).

Strain HNM0947^T, representing a novel actinobacterium, was isolated from the coral Galaxea astreata collected from the coast of Wenchang, Hainan, China. The strain was found to have morphological and chemotaxonomic characteristics consistent with the genus Nocardiopsis . The organism formed abundant fragmented substrate mycelia and aerial mycelia which differentiated into non-motile, rod-shaped spores. Whole-cell hydrolysates contained meso-diaminopimelic acid and no diagnostic sugars. The major menaquinones were MK-10(H₈), MK-10(H₆) and MK-10(H₄). The major phospholipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides. The major fatty acids were iso-C_16:0, anteiso-C_17:0, C_18:0, C_18:0 10-methyl (TBSA) and anteiso-C_15:0. The G+C content was 71.3 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain HNM0947^T belonged to the genus Nocardiopsis and shared highest sequence similarity to Nocardiopsis salina YIM 90010^T (98.8%), Nocardiopsis xinjiangensis YIM 90004^T(98.5%) and Nocardiopsis kunsanensis DSM 44524^T (98.3%). The strain HNM0947^T was distinguished from its closest type strain by low average nucleotide identity (90.8%) and dDDH values (60.4%) respectively. Based on genotypic, chemotaxonomic and phenotypic characteristics, it was concluded that strain HNM0947^T represents a novel species of the genus Nocardiopsis whose name was proposed as Nocardiopsis coralli sp. nov. The type strain was HNM0947^T (=CCTCC AA 2020015 ^T=KCTC 49525 ^T).

Oil tea camellia (Camellia spp.) is an important woody oil crop with a high nutritional and economic value. Whole-genome resequencing (WGR) technology can provide an in-depth understanding of the genetic background of this plant as well as a reference for breeding research, germplasm resource conservation, and genetic modification. In this study, we analyzed SNP and InDel variations in 49 individual oil tea camellia germplasm samples collected from five populations located in three provinces of China: Hainan, Guangdong and Guangxi. The samples were analyzed through WGR after the ploidy of the samples was determined through flow cytometry. A total of 239,441,603 high-quality single nucleotide polymorphisms (SNPs) and 23,510,374 high-quality insertion/deletion variation sites (InDels) were obtained. The distribution of SNPs and InDels in different functional regions differed significantly, with a high density of variations in non-coding regions, such as intergenic regions and introns, and a relatively low density of variations in coding regions. Transition was the main type of SNP variation. A population genetic diversity analysis revealed that the sampled oil tea camellia populations exhibited a high genetic diversity and extensive genetic variation. The genetic diversity of the oil tea camellia populations in the Hainan region was higher than inland regions. This study also determined the genetic diversity of and variations between octoploid and decaploid oil tea camellia in the tropics and between Hainan-based and inland oil tea camellia. Such findings provide a reference for the conservation of germplasm resources and the genetic modification of oil tea camellia.