Research On Isolation,Identification And Metabolites Of Actinomycetes Associated With Coral In Wenchang Hainan

Coral symbiotic actinomycetes are an important part of marine microorganisms,with novel species and rich secondary metabolites.They are important resources for the discovery of new species of actinomycetes and leading compounds with antimicrobial activity.Hainan Island is surrounded by the sea and has a wide variety of corals,which provides abundant materials for studying coral-associated actinomycetes.We haveanalyzed the diversity of symbiotic actinomycetes isolated from coral samplescollected from Wenchang sea,Hainan,havescreened antibacterial strains and haveidentified their active metabolites.The main research results are as follows:Extract the genomes of 6 coral samples and perform high-throughput sequencing analysis after PCR amplification using actinomycete-specific primers,the result revealed that there are abundant actinomycete groups in corals,including 6 classes,19 orders,33 families and 50 genera under the phylum Actinobacteriota.Arthrobacter and Propionibacterium as well as many unknown groups were found in each coral sample,there are differences in the community structure of symbiotic actinomycetes between coral species and between corals of the same species.A total of 77 marine actinomycetes were isolated from 6 coral samples,which were preliminarily identified as 8 genus of actinomycetes by 16 S r RNA sequencing analysis,namely: Streptomyces,Salinispora,Micromonospora,Saccharopolyspora,Gordoni,Nocardiopsis,Tsukamurella and Rhodococcus.Using polyphasic analysis,strain HNM0947,strain HNM0983 and strain HNM0986 were identified as new species of marine actinomycetes.They are named: Nocardiopsis coralli sp.nov,Saccharopolyspora montiporae sp.nov and Saccharopolyspora galaxeae sp.nov.The 77 marine actinomyceteisolates were screened for the agar diffusion method,and there are 8 actinomycetes that had antibacterial activity and were fermented on a small scale,and the activity of the fermentation crude extracts was tested.It was found that the fermentation crude extracts of 6 strains of actinomycetes showed antibacterial activity.According to the results of the screening of the agar diffusion method and the screening of the antibacterial activity of the crude fermentation extract,the strain HNM0925 of the genus Salinispora and the strain HNM0560 of the genus Streptomyces were selected to isolate and identify their active metabolites through large-scale fermentation.Compound H5 was isolated from strain HNM0925,and its structure was identified as rifamycin S;Compound H6 was isolated from strain HNM0560,and its structure was identified as actinomycin D.Compounds H5 and H6 showed strong antibacterial activity against MRSA,Escherichia coli,Staphylococcus aureus,Streptococcus agalactiae and Bacillus subtilis.Based on the research results of this paper,it clearly shows that the corals from the coast of Wenchang,Hainan contain rich and novel actinomycetes resources,which are worthy of further research and utilization.