Diversity Of Secondary Metabolites From Two Marine Streptomyces

In this paper,the diversity of secondary metabolites from two marine Streptomyces strains was studied by changing the culture method,adding chemical elicitors and analyzing the gene clusters of secondary metabolites.The strains were identified by 16 S r DNA as Streptomyces sp.FJNU027 and Streptomyces sp.FJNU028.The silencing gene clusters in the strain Streptomyces sp.FJNU027 were activated to increase the diversity of secondary metabolites through the strategy of adding chemical elicitors.In the process of Streptomyces sp.FJNU027 culture,a chemical epigenetic modifier was added,and it was found that the color of fermentation broth changed.TLC,HPLC and LC-MS analysis showed that the diversity of secondary metabolites increased under the action of chemical epigenetic reagent SAHA.Biosynthesis gene clusters in the strain Streptomyces sp.FJNU027 were analyzed through the web of antiSMASH.A total of 25 potential secondary metabolites gene clusters were found.These clusters were predicted to biosynthesis these secondary metabolites,including five terpenes,three PKS,two ectoines,two NRPS,two siderophores,one lanthipeptide,one phenazine,two bacteriocins,one butyrolactone,and six others.Most of them are unknown gene cluster or secondary metabolites with extremely low similarity known secondary metabolites gene cluster.Therefore Streptomyces sp.FJNU027 showed the potential to produce novel secondary metabolites.Five new compounds isolated from the strain were compared with gene clusters.The correspondence between the new secondary metabolites and gene clusters was determined.The silencing gene clusters in Streptomyces sp.FJNU028 were activated by changing culture conditions and strategies to increase the diversity of secondary metabolites.A medium with short fermentation cycle,abundant secondary metabolites and good inhibition of Saccharomyces cerevisiae activity was selected from 28 kinds of medium: 20% YPD medium.The optimal fermentation cycle was determined to be 4 days by inhibiting the activity of S.cerevisiae.With the inhibition of S.cerevisiae activity as the index,the optimal liquid content of 500 m L triangle bottle was determined to be 450 m L.The optimal culture method was used to ferment FJNU028 150 L,from which 9.3g organic crude extract with good inhibition of S.cerevisiae activity was obtained.The silencing gene clusters in Streptomyces sp.FJNU028 were activated to increase the diversity of secondary metabolites through the addition of chemical epigenetic modifier strategy.TLC and HPLC were used to analyze the diversity of FJNU028 secondary metabolites.It was found that the strain was insensitive to chemical elicitors and no new secondary metabolites were found.Biosynthesis gene clusters in the strain Streptomyces sp.FJNU028 were analyzed through the web of antiSMASH.A total of 24 potential secondary metabolite gene clusters were found.These clusters were predicted to biosynthesis these secondary metabolites,including five terpenes,four PKS,five NRPS,three bacteriocins,two siderophores,one NRPS-like,one lanthipeptide,four ectoines,and two others.Most of them are unknown gene cluster or secondary metabolites with extremely low similarity known secondary metabolites gene cluster.Therefore,Streptomyces sp.FJNU028 showed greater potential novel structure of secondary metabolites synthesis.In this paper,the secondary metabolites of Streptomyces sp.FJNU027 and FJNU028 were increased by activating silencing gene clusters through changing fermentation methods and adding chemical elicitors.Through the web of antiSMASH,the biosynthesis gene clusters in two strains Streptomyces sp.FJNU027 and FJNU028 were analyzed and their secondary metabolites were predicted.Five new compounds isolated from Streptomyces sp.FJNU027 were compared with their gene clusters.The study in this paper showed that the strategy of changing fermentation mode and adding chemical elicitors were effective methods to increase the diversity of secondary metabolites and laid a basis for making full use of marine actinomycete resources.