Antifungal activity of volatile organic compounds produced by Weizmannia coagulans CGMCC 9951 on Ceratocystis fimbriata in postharvest sweet potatoes and its potential biocontrol

Volatile organic compounds (VOCs) produced by microorganisms are regarded as potential eco-friendly fumigants for managing black spot disease in postharvest sweet potatoes. This study aimed to assess the efficacy of Weizmannia coagulans CGMCC 9951 VOCs in inhibiting Ceratocystis fimbriata. The findings indicated that C. fimbriata was effectively inhibited both in vitro and in vivo. The GC–MS analysis revealed that the VOCs primarily consist of Benzyl alcohol, Eugenol, Isoamyl acetate, Linalool, and Benzothiazole. Among these, Linalool and Benzothiazole exhibited the most significant inhibitory effects against C. fimbriata. Sweet potatoes treated with VOCs exhibited a significant decrease in the size and depth of black spots. Transcriptome analysis and fluorescence microscopy demonstrated that VOCs could substantially down-regulate the expression of genes associated with spore germination, cell wall integrity, DNA replication and repair, and pathogenicity. These results suggest that W. coagulans CGMCC 9951 VOCs effectively inhibit C. fimbriata and protect postharvest sweet potatoes.