Discovery Of Secondary Metabolites From Streptomyces Sp. CPCC 202372 And Study On Biosynthesis Of Polyketomycin

Objectives: With the development of society,various diseases emerge endlessly,and the resistance of traditional antibiotics and side effects become increasingly prominent.Therefore,it is urgent to find new antibiotics for the clinical treatment of acute and chronic diseases.Streptomyces can produce natural secondary metabolites with diverse chemical structures and rich physiological activities,which is an important source of innovative microbial drugs.Hence,the secondary metabolites of Streptomyces sp.CPCC202372 were isolated and identified,and the obtained compound polyketomycin was studied for biosynthesis,hoping to obtain active compounds with novel structures,providing lead compounds for microbial drug research and making contributions to human health.Methods: Streptomyces sp.CPCC 202372 was isolated from the soil of Yunnan Province.Chemical studies were conducted on its secondary metabolites produced,and the metabolic spectrum analysis showed that the secondary metabolites were abundant.We used preparative liquid chromatography and gel column chromatography to isolate and purify the fermentation products,and obtained compounds.The structures of compounds were analyzed by means of LC-MS,HRMS and NMR techniques.Based on the results of genome sequencing,the genetic manipulation of the strain was carried out,and the key genes of polyketomycin were inactivated to explore the biosynthesis mechanism of polyketomycin.Results: The secondary metabolites from Streptomyces sp.CPCC 202372 were isolated and identified.It was found that the strain could produce polyketomycin and its related products,as well as peptides containing pyrazine ring.Compounds 4,6 and 7 were new compounds.In the course of exploring the biosynthesis of polyketomycin,some important genes related to polyketomycin were found.Among of them,orf778,orf794,orf796 and orf805 were the core genes.Orf769 and orf812 were regulatory genes,which played a negative regulartory role.And orf788 and orf811 were post-modified genes.These results laid the foundation for the study of biosynthesis mechanism of polyketomycin.Conclusion: Seven compounds were obtained from the secondary metabolites of Streptomyces sp.CPCC 202372,which classified into three classes by structure,comprising two polyketide compounds,two salicylate compounds,and three peptide compounds containing a pyrazine ring.Three of them are new compounds.By exploring the structure-activity relationship of polyketide compounds,it was found that the dimethylsalicylyl group was the active group of polyketomycin.Furthermore,we studied the biosynthetic pathway of polyketomycin,gene inactivation experiments were performed on some key genes,and the biosynthetic pathway of polyketonomycin was preliminarily inferred.