Biogeography Of Streptomycetes In Different Mangrove Locations And The Identification Of Two Novel Streptomyces

The biogeography of microorganisms has received a lot of attention over the past decade, and has become a new area of ecological research. In this study we chose Streptomyces as the research object and discovered its distribution in mangrove soil from four different locations (Sanya and Wenchang in Hainan, Shenzhen in Guangdong, and Xiamen in Fujian). The isolated streptomycetes were investigated from three respects: the physical and chemical properties of the soil samples,16S rRNA gene sequence similarities and bioactivities; PRIMER statistical analysis was employed to understand the correlation among geography environmental variaties、16S rRNA gene clades and the distribution of bioactive strains; two novel Streptomyces species:WC172205 and SZ172115 discovered from the 16S rRNA gene sequences analysis were identified.From the results obtained, Wenchang mangrove soil was unique in environmental varieties, at the same time, the isolates from Wenchang mangrove soil exhibited evident difference in 16S rRNA gene sequence similarity and the distribution of bioactivity compared with those isolated from other three locations. Environmental parameters (organic matter OM, total nitrogen N, total phosphorus P2O5, available potassium K, pH, Salinity) had a significant correlation with the distribution of streptomycetes’16S rRNA gene sequence clades and the distribution of bioactive strains.The isolate 172205T was obtained from mangrove soil collected at Qinglan Harbour, Wenchang, Hainan, China. Strain 172205T possessed strong activity against the human immortalised myelogenous leukaemia K562 cell line. Comparison of 16S rRNA gene sequences indicated that the strain represents a novel member of the genus Streptomyces, exhibiting the highest 16S rRNA gene sequence similarities (≤98.29%) to members of the genus Streptomyces. The DNA relatedness values between strain 172205T and S. flocculus NBRC 13041T, S. ferralitis SFOp68T and S. haliclonae DSM 41970T were 50.28±4%,49.15±11%,37.56±11%, respectively, all of which are below the 70% threshold value for distinguishing genomic species. The G+C content of the genomic DNA of strain 172205 is 70.33 mol%. The results of DNA-DNA hybridization, physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain 172205T from phylogenetically related type strains. Therefore, strain 172205T represents a new species, for which the name Streptomyces qinglanensis sp. nov. is proposed (=CGMCC 4.6825T=DSM 42035T).An actinomycete strain, which was designated 172115T, was isolated from mangrove soil in Shenzhen, China. The strain was determined to belong to the genus Streptomyces, based on its phenotypic and phylogenetic characteristics. The cell wall contained Gly, LL- and meso-diaminopimelic acids (DAP) and the whole-cell hydrolysates consisted of rhamnose, ribose, galactose and glucose. The predominant menaquinones were MK-9(H6), MK-9(H8). The major components of fatty acids included iso-C14:0 (10.65%), iso-C15:0 (10.64%), anteiso-C15:0 (12.19%), iso-C16:0 (33.14%). The major polar lipids were phosphatidylinositol (PI), phosphatidylethanolamine (PE), and diphosphatidyl glycerol (DPG). DNA-DNA hybridization and comparison of phenotypical characteristics suggested that strain 172115T is a novel Streptomyces species, for which, the name Streptomyces shenzhenensis sp. nov. is proposed for strain 172115T (=CCTCCAA 2011001T=DSM 42034T).