Study On Isolation,transformation And Secondary Metabolites Of Antagonistic Activity Streptomyces Endus NF-1222

At present,new diseases and insect pests of animals and plants are constantly occurring and various drug-resistant bacteria keep emerging,so the development of new drugs and new antibiotics is urgent.Searching for actinomycetes with biologically active and studying their secondary metabolites are helpful to enrich the drug screening resources,which is of great significance to the discovery of new antibiotics.In this study,17 strains of actinomyces were isolated and screened from the soil collected from diverse habitats in Jiujiang,Jiangxi province and Yongzhou,Hunan province.One strain with the best antagonistic activity,NF-1222,was selected for physiological,biochemical and 16 S rDNA molecular identification,and named Streptomyces endus NF-1222.The strain was fermented and secondary metabolites were isolated and extracted to obtain four compounds.The chemical structures of the four compounds were identified by IR,MS and NMR.They are Hygromycin A(NF1222-1),3-(N-ethyl acetamide)-indole(NF1222-2),Ring(L-leucyl-L-valine)(NF1222-3)and Ring(L-prolyl-L-leucyl)(NF1222-4).The active component of the actinomycete product is Hygromycin A.In order to further explore the metabolic potential of Streptomyces endus NF-1222,the gene adpA with global positive regulatory function,was overexpressed in this actinomycetes to activate the silencing gene and obtain new secondary metabolites.We constructed adpA gene-integrated overexpressed plasmid pQH17,performed conjugation and transfer,and selected conjugates to obtain 60 recombinant strains.The recombinant strains were fermented and metabolized by HPLC.A strain that can produce new liquid peaks(compared to the original strain)was obtained,named Streptomyces endus NF-1222 A.The Streptomyces endus NF-1222 A was fermented and the new liquid-phase peak-corresponding compound(NF1222A-1)which was identified as a new O-cinnamoyl threonine derivative was extracted.In addition,a known compound was isolated.It is D-neo-Inositol,5-deoxy-5-[[(2E)-3-(3,4-dihydroxyphenyl)-2-methyl-1-oxo-2-propen-1-yl]amino]-1,2-O-methylene(NF1222A-10).The antibacterial,antitumor,insecticidal and acaricidal activities of the new compound were further studied,and it was found that the new compound had acaricidal activity.This study shows that overexpression of global positive regulatory gene adpA in actinomycetes can activate unconventional or silent secondary metabolic pathways,enabling mutated strains to produce new secondary metabolites,which is conducive to further excavation of existing resources of actinomycetes.