Screening Of Anti-tumor Symbiotic Microorganisms Of Enteromorpha Prolifera And Study On The Active Substance Isolated From Them

Historically,natural products have been,and continue to be,an invaluable source for the discovery of various therapeutic agents.In recent years,more and more novel antitumor compounds from marine bacteria,marine fungi and marine actinomycetes were found,and many of them have entered clinical phase.Marine microorganisms have attracted the attention of scientists as new sources of antitumor agents.Many studies have shown that the unique ecological environment of the ocean can produce a series of natural products with anti-cancer,antibacterial and anti-inflammatory properties.Enteromorpha prolifera is a rich resource in our country,but the overall utilization rate is not high that causes the huge waste issues.And it is rare to report on the screening of anti-tumor active substances from Enteromorpha in China and abroad,especially the research and utilization of its symbiotic microorganism.Therefore,the separation and cultivation of algae symbiotic microorganisms may be a shortcut to discover new natural drugs,and it is expected to bring new research prospect for potential drug application.In this study,there were 10 symbiotic bacterial strains isolated from Enteromorpha prolifera collected from different sites in the sea waters of Qingdao China,and showed potent cytotoxicity on humman liver cancer cells.Two strains,Y15-8 and HT15-8,have the best cytotoxicity,were identified,respectively,belong to genus Bacillus and Raoultella,respectively.The metabolite of Bacillus sp.Y15-8 was purified by using ultrafiltration,ammonium sulfate precipitation and anion exchange liquid chromatography.Eventually,an active protein,named PBY15-8,molecular weight 24.3k Da was obtained,and it belongs to a catalase.MTT assay indicated that PBY15-8 was cytotoxicity towards BEL-7402 human hepatocellular carcinoma cell lines,A549 human lung carcinoma cell lines and NCI-H460 human lung carcinoma cell lines.The IC50 of BEL-7402,A549 and NCI-H460 were 7 ?g/m L,11 ?g/m L,and 21 ?g/m L,respectively.Furthermore,the metabolites of Raoultella sp.HT15-8 were separated by different methods,and a small molecule compound,named HTP with cytotoxicity was obtained,and further experimental verification was needed for its structural identification.These results suggest that the purified PBY15-8 and HTP both have a significant value for developing antitumor candidant drugs.The studies lay a foundation for the developmentof algae microbial resources,and also provide scientific theoretical basis for the research of anti-tumor drug lead compounds.