Abstract:In order to investigate safe and efficient novel inhibitors of Aspergillus flavus (A. flavus), the compounds of the antifungal volatile organic compounds (VOCs) produced by Bacillus subtilis PW2 were identified by headspace solid-phase microextraction gas chromatography-mass spectrometer (HS-SPME-GC-MS) technique. The target compounds with strong antifungal activity were screened from the identified components by double petri dish method. The minimum inhibitory concentration (MIC) of the target compound against A. flavus was determined by double petri dish method and 96-well plate gradient dilution method. The inhibitory effect of the target compound on aflatoxin B1(AFB1) production by A. flavus was analyzed using an AFB1 enzyme-linked immunosorbent assay(ELISA) kit. The morphological changes of the tested A. flavus spores were observed using scanning electron microscope (SEM), and the ergosterol relative content in the tested A. flavus cell membrane was analyzed using spectrophotometry method to explore the antifungal mechanisms. As a result, a total of 41 components were identified from the VOCs produced by PW2, and among them, 2-ethyl-1-hexanol was selected as the target compound. The MIC values of 2-ethyl-1-hexanol against A. flavus determined by the double petri dish method and 96-well plate gradient dilution method were 0.169 μL/mL and 6.25 μL/mL, respectively. The AFB1 were effectively inhibited by 2-ethyl-1-hexanol at the volume fractions of 3.13, 6.25, and 12.50 μL/mL in PDB medium, and the inhibition effect was enhanced as the volume fraction of 2-ethyl-1-hexanol increased. Treatment with 2-ethyl-1-hexanol resulted in surface depression and the rupture of A. flavus spores, as well as alteration in the relative content of ergosterol in the cell membrane, leading to cell membrane damage. This study can provide a theoretical reference for the development of aflatoxin inhibitors with 2-ethyl-1-hexanol as a functional component.
