Study On Secondary Metabolites Of A Marine Actinomycete In Two Different Culture Conditions

Marine organisms exist in the ocean companied with high salinity,high pressure,low temperature and low nutrients,which create their unique metabolic and defensive systems.The main secondary metabolites of actinomycetes including antibacterial,antitumor,cytotoxic compounds,and immunosuppressant,the actinomycetes in unknown,undeveloped environment or even in the marine environment that lack of developing become the primary source to discover novel secondary metabolites.Microorganisms produce a variety of secondary metabolisms in different culture conditions.To obtain more significant compounds,one strain many compounds(OSMAC)strategy is generated by changing the external conditions gradually,and then promoting the expression of the silent gene in the macroscopic level.Therefore,it’s necessary to change the growth conditions of the microorganisms on the macro level but without molecular biotechnology.The technique possesses a low threshold of use and simple operation steps.The compounds could be gained more quickly and accurately when combined traditional separation methods with instruments such as high-performance liquid chromatography.In this study,a novel strain,Amycolatopsis sp.WP1,isolated from deep-sea marine sediments collected from Indian Ocean,was applied to study the strains in two different species by using OSMAC strategies,to study secondary metabolites in culture conditions and then find novel or biologically active compounds.First,the strain WP1 was shaker cultivate with AM2 medium and 9 compounds were isolated.Compounds were identified by comparing their NMR,MS data and specific rotation with those reported in the literature,compounds were authenticated as 1-9,Prunetina(4’,5-diidroxi-7-metoxiisoflavona)(1),6-methoxymethyleugenin(2),AI-77-C(3).WH-80332(4),4’,7-Diidzein(5),4’,5,7-Genistein(6),Daidzein(4’,7-hydroxyisoflavone-7-O-β-D-glucopyranoside)(7),6″-O-acetylgenistin(8),and Glycitin(9).After that,strain WP1 was cultured in a modified ISP4 medium fermenter cultivate,and we obtained two compounds.Compounds were identified as Cyclo(L-trans(4-hydroxyprolinyl)Lphenylalanine)(10),Brevianamide F(11).For the first time,compound 4 has its absolute configuration determined by CD spectra.11 compounds were first isolated from Amycolatopsis sp.WP1.These compounds were evaluated for their antimicrobial activities against four human pathogenic strains,but only compound 3 showed weak antimicrobial activities with MIC value of 62.5 μg/mL,This is the first time discovered compound 3 possess antibacterial activity.Other compounds had no well antimicrobial activities(MIC value of > 100 μg/mL).