| Aspergillus flavus could lead human and animal diseases,such as aspergillosis and liver cancer.Aflatoxins were known as grade ? carcinogen by FAO and WHO.The regulation mechanism of aflatoxins biosynthesis was not very clear.It was found that trichostatin A(TSA)could suppress aflatoxins production.This research aimed at studying the regulation mechanism of aflatoxins production by TSA.Aspergillus flavus was treated by different concentrations of TSA,and it was found that the inhibition rate is proportional to the concentration of TSA.Meanwhile,TSA also leaded growth delay,spore production increase.To further study function of TSA,5 ?M TSA which got nearly 50%of inhibition rate was selected.Aspergillus flavus was treated at different time under that concentration,and toxins were detected by TLC and quantified by HPLC precisely.It was drew a conclusion that the inhibition effect by TSA arised at early point,and kept a long time stablely.At the same time,the transcription of aflatoxins biosynthsis genes were analyzed by qPCR,and it was found that the expression level of structural genes aflC,aflK,aflO,aflQ were all down-regulation,but the global transcription factors AflR was not very distinctly different.Histone deacetylase gene hdaA in Aspergillus flavus was cloned and knocked out successfully.The strain of hdaA knock out(?hdcA)had no effect on growth,but decreased aflatoxins and increased spore production.So,it was concluded that HdaA was involved in regulation of aflatoxins biosynthesis and spore producing.After TSA treatment,the aflatoxins produced by ? hdaA was more than that by wild tpye,but still decreased when compared to DMSO treatment.Through analysis of inhibition rate,it was found that the ?hdaA strain had a weak response to TSA.The results from this study provided theoretical support for looking for anti-aflatoxins drugs.It had important theoretical significance on preventing aflatoxins contamination,protecting the environment and improving the food production. |
PDF Full Text Request