Metal-phenolic networks improve biocontrol effect of Bacillus velezensis DM14 against pear anthracnose

Pear anthracnose is a serious postharvest disease that affects pear production. The use of antagonistic microorganisms for biological control provides a promising alternative to fungicides. Unfortunately, these microorganisms are susceptible to harsh environmental conditions, which limits their field application. To overcome this limitation, we investigate the biocontrol potential of Bacillus velezensis DM14, which was isolated from the surface of healthy pear fruits and exhibits significant inhibitory effects on Colletotrichum fructicola. Microscopic analysis revealed that C. fructicola cells exposed to secreted fermentation extract raw fermentation extract (RFE) of DM14 underwent significant morphological changes, including intracellular disruptions such as cytoplasmic disintegration and vacuolization, ultimately leading to cell death. While the fermentation extract of DM14 was effective in vitro, enhancing the survival of live DM14 cells is essential for practical application. Therefore, we use a one-step protection based on metal-phenolic network (MPN) encapsulation for DM14. This MPN-coated DM14 has shown a higher colonization rate under oxidative stress conditions in fruit wounds. Importantly, compared with uncoated DM14, the MPN-coated DM14 enhanced the prevention of pear anthracnose by approximately 37 %. Furthermore, the MPN coating strategy improved the tolerance to oxidative microenvironments in infected fruit wounds. Overall, this microbial encapsulation strategy is a promising way to protect fragile antagonistic microorganisms, providing attractive avenues in sustainable agriculture.