Transcriptomic and biochemical analyses reveal the antifungal mechanism of cell-free supernatant from Aspergillus luchuensis YZ-1 against Aspergillus flavus

Aspergillus flavus (A. flavus) and its metabolites, aflatoxins, are widespread in crops and foods, threatening public health. Using chemical fungicides to control A. flavus can pose safety hazards and cause environmental pollution. Therefore, there is an urgent need for safe and effective antifungal agents to control A. flavus. In this study, we isolated Aspergillus luchuensisYZ-1 cell-free supernatant (CFS), volatiles, and mycelial extracts to investigate their inhibitory effects on A. flavus. Results indicate that the CFS exhibited greater efficacy in impeding the growth and synthesis of aflatoxin B1 (AFB1) in A. flavus. Transcriptomic analysis revealed a significant downregulation of lipid metabolism, biosynthesis of other secondary metabolites, and glycan metabolism in A. flavus treated with CFS. Approximately 94% of the genes in the aflatoxin synthesis pathway were significantly downregulated. Furthermore, the CFS treatment significantly increased reactive oxygen species (ROS) production in A. flavus, affected its energy metabolism, and upregulated methane metabolism and the pentose phosphate pathway. We then investigated the inhibitory mechanism of YZ-1 against A. flavus by biochemical analysis. It was further confirmed that CFS had destructive effects in the cell wall and cell membrane of A. flavus, as indicated by leakage of nucleic acids, proteins, alkaline phosphatase (AKP), as well as decreased chitin and ergosterol content. In summary, this study provides novel insights into the mechanisms of CFS against A. flavus, suggesting its potential as a biocontrol agent in food and agriculture.