Study On Secondary Metabolites Of Two Microbial Strains

Microbial secondary metabolite products are one of the most important natural treasures for human beings.Microbial secondary metabolites have diverse structures such as polyketone natural products,oligopeptide natural products,terpenoids,nucleoside natural products,etc.They have a wide range of biological activities such as anti-bacterial,anti-fungal,anti-tumor,immunosuppressive,etc.,are also widely used in food,health care products,cosmetics and other industries,bringing great convenience to people’s production and life.Polyketone natural products are the largest family of secondary metabolites of microorganisms and are an important source of new drug development and research.In this thesis,a large number of streptomyces and fungi were fermented and screened with different media,and through the analysis of the fermentation metabolites of these strains,a fungus NF666 and an actinomycete NA6319 were selected for the secondary metabolites’separation and structure identification.First in this thesis,the secondary metabolites of the insect endophytic fungus NF666 were studied.Through the fermentation on rice culture medium,the compounds1-11 were obtained through extraction,forward silica gel,ODS reverse phase column,gel column,HPLC,etc.,and there are nine new compounds in them.Through the analysis of high-resolution mass spectrometry（LC-MS）and nuclear magnetic resonance spectra(¹H NMR,¹³C NMR,¹H-¹H COSY,DEPT,HSQC,HMBC,NOESY),the planar structure of compound 1-11 was finally determined.Among them,compounds 1-7 are natural polyketone products,and compounds 8-11 are siderophores.Then in this thesis,the secondary metabolites of soil actinomycetes NA6319 were studied.Compounds 12-18 were obtained through liquid culture fermentation,extraction,ODS reverse column,gel column,HPLC,etc.Through the analysis of high-resolution mass spectrometry（LC-MS）and nuclear magnetic resonance spectra(¹H NMR,¹³C NMR,¹H-¹H COSY,DEPT,HSQC,HMBC,NOESY),the planar structure of compound 12-18 was finally determined.Compounds 12-18 all belong to the manumycin family of polyketides.Finally,compounds 1-18 were tested for antibacterial activity.The results show that polyketides（6）and（7）have good antibacterial activities against Pseudomonas aeruginosa,Staphylococcus aureus,Escherichia coli,Pectobacterium carotovorum subsp.Carotovorum.The structure and biological activity of polyketides derived from microorganisms is reviewed.