Antifungal effect of o‐vanillin on mitochondria of Aspergillus flavus: ultrastructure and TCA cycle are destroyed

Abstract Aspergillus flavus ( A. flavus ) is a conditioned pathogen that severely endangers food safety. This study is aimed to determine the mode of action of o ‐vanillin against A. flavus mitochondria. First, o ‐vanillin hindered respiration. Furthermore, the mitochondrial ultrastructures were damaged with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterisation. The activities of the tricarboxylic acid (TCA) cycle‐related enzymes were regulated significantly ( P < 0.05), and the most significant reduction and promotion was citrate synthase (CS) and malic dehydrogenase (MDH), respectively, at 100 μg mL −1 of o ‐vanillin. Consistent with the above phenotypic results, real‐time quantitative reverse transcription polymerase chain reaction (PCR) (QRT‐PCR) results showed that the relative expressions of genes encoding the TCA‐related enzymes were regulated remarkably ( P < 0.05), especially for CIT1 gene (downregulated) and MDH gene (upregulated). This study demonstrated the damage of o ‐vanillin on mitochondria and shed light on the antifungal mechanism of o ‐vanillin against A. flavus .