Study On The Biosynthesis Pathway Of Natural Products Of Fungi Based On The Activation Of Silent Gene Clusters

Fungal secondary metabolites are a class of small molecular compounds with diverse structure types,which have a variety of physiological and pharmacological activities and have a wide variety of applications in medicine and agriculture.Therefore,it is significant for human society to develop and utilize these fungal secondary metabolites.Genome sequencing has revealed that fungi has far greater potential metabolites biosynthesis gene clusters(BGCs),however,in the fact,many of the them are often silenced and not expressed in laboratory cultures.To activate silent biosynthetic gene clusters and to obtain lots of bioactive secondary metabolites many methods can be used,such as heterologous expression,manipulating transcriptional regulatory factor and global regulatory factor and so on.After Aspergillus ochraceus sequencing,the only non-reducing polyketidesynthase gene 8632 was selected for heterologous expression.The High Performance Liquid Chromatography showed that four new peaks appeared at 8-12 min.A large number of fermentation 8632 heterogenously expressed strains were successfully isolated and identified as 8-dihydroxy-3-hydroxymethyl-1h-2-benzopyran-1-one,6-hydroxymellein,C12-pyrone,and orthospori.Compounds orthospori and c12-pyrone have certain reducing activity.Our group knocked out a histone deacetylase gene xb-4305 from Aspergillus ochraceus,The High Performance Liquid Chromatography showed that the mutant strain of xb-4305 increased most compounds production and accumulate a new compound.The compound was isolated and identified as benzoisofuranone derivative.The Δxb-4305 mutant strain transcriptome sequencing results showed that expression of levels of four polyketide synthase genes 7176,2050,5827 and 9908 were significantly increased,some 2050,5827 and 9908 was selected for heterologous expression,2050 and 5827 genes are not found new peak on The High Performance Liquid Chromatography,genes 9908 too long to complete build plasmid.Through genome sequencing and bioinformatics analysis of a Penicilliumaethiopicum.There was a gene cluster contig310 which has a core polyketide synthase–nonribosomal peptide synthetase(PKS–NRPS)hybrids gene,also contained oxido-reductases enzyme genes and transcriptional activator genes and so on.Through overexpressing the transcriptional regulatory factor a new compound named Penamycin was isolated and purified.In order to determine the biosynthesis pathway of the compound,knock out PKS–NRPS gene Penamycin disappeared.After combined the PKS–NRPS gene,Noribosomal peptide synthetasea(NRPS)gene,P450 oxidase gene,FAD oxidase gene and reductase ER gene to heterologousexpression a new compound has obtained.a series of 18 structurally different tryptophan cyclodipeptides were evaluated for plant growth regulation using the Echinochloa crusgalli(L.)Beauv and Arabidopsis thaliana seedling growth bioassay methods,Among these compounds tested,Cyclo(L-Asp-L-Trp)can inhibit Echinochloa crusgalli(L.)Beauv shoot and root elongation,other compounds also have effects on the growth of the shoot and root elongation of Echinochloa crusgalli(L.)Beauv and Arabidopsis thaliana.