Studies On Identification Or The Pendophyte From Salicornia Bigelovii Torr.Based On Pks Type Ⅰ Functional Gene And Its Secondary Metabolites

Polyketide synthase type I is a key enzyme which regulates polyketides from microbial secondary metabolites. It can catalyze and synthesize many compounds with bacteriostatic, anti-viral, anti-tumor biological activity and other biological activities. Therefore, it has become a new strategy that type I PKS gene could predict the chemical structure types of compounds on studying the secondary metabolites of endophytic fungi. Based on the corresponding relations of "Gene-Enzyme-Compound", it can be directly targeted to the gene synthesized compounds, and then greatly increasing the probability of polyketide compounds.In this study, halophytic Salicornia bigelovii was a raw material and the endophytic fungi was isolated and purified by surface sterilization and the PDA plate. Four isolates, codes Salicornl, Salicorn2, Salicorn3 and Salicorn4, containing type I polyketide synthase gene were obtained by PCR amplification. These isolates have the potential to produce polyketide compounds by phylogenetic tree analysis.These four endophytic fungi were identified as Alternaria alternate, Aspergillus flavus, Penicillium cyclopium and Aspergillus versicolor by using molecular biotechnology method and morphological observation, respectively.Four strains were fermented by static fermentation respectively. Their fermentation products were mixed and four pure compounds from fermentation products were isolated by solvent extraction, concentration and column chromatography. The compounds’ structures were determined to be 1,5,9-trihydroxy-3,7-dimethylanthracen-10-(9H)-one (1), (3β,5a,8a,22E)-5,8-epidioxyergosta-6,9,22-trien-3-ol(2), ditryptophenaline (3), Cerebroside C (4) by nuclear magnetic resonance(1H NMR,13C NMR, HMBC, HMQC,1H-1H COSY), mass spectrometry and other modern spectroscopic techniques.