Exploitation of the biocontrol potential of a marine-derived Bacillus velezensis and its application on postharvest strawberry

Fresh strawberry fruit have a significant postharvest diseases incidence and economical losses. To explore more effective postharvest management instruments, a strain of Bacillus velezensis 12Y with excellent antagonistic activity was isolated from the Nanhai Sea. Its whole genome and activity against fruit fungal pathogens was studied. The genomic sequencing revealed that 12Y contains an abundance of functional gene related to biocontrol and biosynthetic gene clusters of secondary metabolites with potential antimicrobial properties. In the strawberry preservation experiment, YFB 12Y fermentation broth (YFB) could effectively reduce the natural decay and extend shelf life of strawberry by delaying the decline of total soluble solids and titratable acid with no adverse effects on weight loss and hardness. Moreover, YFB could enhance the activity of key enzymes in phenylpropanoid metabolism pathway, induce the accumulation of anthocyanin and total phenols, delay the decrease of antioxidant capacity, and reduce the peroxidation of strawberry cell membranes. This study demonstrated the potential of B. velezensis 12Y as an excellent biocontrol bacteria and a promising preservation agent for strawberry.