Transcription Factor AP-1 Regulates Growth,Ochratoxin A Synthesis And Oxidative Tolerance In Aspergillus Niger

Aspergillus niger,an important industrial fermenting microorganism,is widely used in the production of food and enzyme preparations,but its production of fungal toxins has been a threat to human health.Yap1 is a transcription factor reported for the first time in Saccharomyces cerevisiae.It has multiple regulatory functions.The regulatory functions of its homologous genes ApyapA and Aoyap have also been reported in Aspergillus parasiticus and Aspergillus ochra.In these fungi,Yap1 homologous genes all play a common role in regulating oxidative stress.However,in addition to regulating oxidative stress,it is also related to pathogenicity and toxin biosynthesis.However,there is no report on the regulation of this homologous gene in Aspergillus niger.This paper proposes to investigate the role of AP-1,a regulator of oxidative stress in Aspergillus niger,on the biosynthesis of OTA,the growth and development of the fungus and the stress response under oxidative stress,as well as the ability to infest grapes.As an important industrial fermentation microorganism,Aspergillus niger is widely used in the production of food and enzyme preparations,but the mycotoxins it produces have always threatened human health.（1）An11g07980（AP-1）knockout strain and overexpression strain were successfully screened using Agrobacterium-mediated infestation of A.niger.The genetic stability of the two modified strains was verified by genetic stability passages,which laid the foundation for the subsequent studies.（2）In comparison with the phenotypic characteristics of A.niger CICC＿41702,it was found that the OE::AP-1 strain had reduced sporulation,short and loose mycelium,while theΔAP-1 strain had significantly more clumped and dense mycelium with more branching nodes.There were no significant differences in conidial morphology.（3）The AP-1 gene was found to negatively regulate OTA production in Aspergillus niger by studying the amount of OTA biosynthesis.（4）The regulation of oxidative stress in A.niger was investigated by exogenous addition of H₂O₂ and Menadione,and the results showed that the deletion of AP-1 gene caused the strain to be extremely sensitive to H₂O₂ and Menadione.（5）The AP-1 gene plays an important regulatory role in the detoxification of H₂O₂ as determined by intracellular ROS levels and related antioxidant enzyme activities.The CAT activity of the OE:AP-1 strain increased by 26.5%and the H₂O₂ content decreased by 60%compared to the wild type strain at the 5th day of growth.（6）The AP-1 gene plays an important role in the response of A.niger to the ROS produced by grapes during infestation,as shown by the fact that the diameter ofΔAP-1strains infested with grapes at 5th d of growth was reduced by approximately 1.97-fold compared to A.niger CICC＿41702 and the diameter of OE::AP-1 strains infested with grapes increased by 1.19-fold...