Study On Screening Of Biocontrol Aspergillus Flavus In Ecological Economic Crop Peanut And Soil

The aim of this study was to isolate fungi from soil and peanuts, and Aspergillusflavus strains were identified by traditional methods. Applied ultraviolet fluorescencemethod and High-Performance Liquid Chromatography（HPLC） to screen aflatoxicoge-nic strains from above Aspergillus flavus. There were5biocontrol characters ofaflatoxin-nonproducing isolates（including growth, amount of sporulation, confrontation,survive ability in rhizospher, pot experiment） to screen isolates with strong biocontrolpotential capability, then we studied mechanism of aflatoxin-nonproducing at the level ofgene.The specific results were as fellows:68strains of Aspergillus flavus were isolatedand identified from soil and peanuts, including52strains in soil and16strains inpeanuts.27strains produced of aflatoxin, and40strains did not produce aflatoxin. Threeisolates of A.flavus T5-14, T5-8and T3-2produced higher amount of aflatoxin. Then weevaluatied three different fluid medium of SDA, YES and CYA, the results showed that,YES fluid medium is the best media for aflatoxin production by A.flavus. Strains ofAspergillus flavus T5-1having strong biocontrol potential was screened, which caninhibit the growth of Aflatoxin producing A.flavus. Strain T5-1was identified asAspergillus flavus based on5.8S rDNA-ITS sequences. GenBank blast showed that5.8SrDNA sequence shared99%homology with that of Aspergillus flavus. Strain T5-1losedaflatoxin biosynthetic gene aflF, aflU, aflT, aflC and aflD. The genes aflF, aflC andaflD were the key genes in the biosynthesis pathway of aflatoxin. So the strain could notsynthesize aflatoxin.