Effect of volatile compounds produced by Weissella cibaria BWL4 on Botrytis cinerea infection in fruit and complete genome sequence analysis of BWL4

Botrytis cinerea, one of the most harmful pathogenic fungi, causes significant postharvest decay in fruit. In this study, the effects of Weissella cibaria BWL4 on B. cinerea and the gray mold in grape and kiwifruit were evaluated. Additionally, the genome of an antagonistic bacterium BWL4 was sequenced. Results showed that the application of BWL4 inhibited B. cinerea infection in grape and kiwifruit. BWL4 produced antifungal volatile substances against B. cinerea. A gas chromatography–mass spectrometry of solid phase microextraction samples (SPME-GC-MS) analysis showed that BWL4 produced 54 volatiles. Among these volatiles, furfural, 2,6-dimethyl-pyrazine, dimethyl trisulfide, 2-pentyl furan, 2-ethyl hexanol, hexamethyl-cyclotrisiloxane, dodecamethyl-cyclohexasiloxane, 2,4-di-tert-butylphenol, and butylated hydroxytoluene, exhibited antifungal activity against B. cinerea, with MICs of 0.8 g L−1, 0.2 g L−1, 0.9 g L−1, 5 g L−1, 0.4 g L−1, 8 g L−1, 8 g L−1, 80 mg L−1, and 2 g L−1, respectively. In vivo assay showed that these compounds inhibited the disease development in kiwifruit. These compounds except dimethyl trisulfide can also inhibit gray mold in grape. The genome of W. cibaria BWL4 consists of a circular chromosome of 2.42 Mb and 6 plasmids. The genome size is 2.53 Mb, encoding 2327 putative genes. Several genes involved in the biosynthesis of some antifungal volatiles and 17 genes associated with biocontrol were identified. These results suggested that W. cibaria BWL4 can be considered as an effective biological control agent for the postharvest management of B. cinerea infection.