The biocontrol potential of endophyte <i>Bacillus velezensis</i> to reduce post-harvest tomato infection caused by <i>Rhizopus microsporus</i>

<i>Rhizopus microsporus</i> is a necrotrophic post-harvest pathogen that causes significant economic losses in the agricultural sector. To explore alternatives to conventional management strategies for the mitigation of post-harvest infections, we investigated the potential of two previously identified endophytic <i>Bacillus velezensis</i> strains as biological control agents. Through <i>in vitro</i> and <i>in vivo</i> experiments, we examined the mechanisms of biocontrol displayed by two <i>B. velezensis</i> strains (KV10 and KV15) against three <i>R. microsporus</i> strains (W2-50, W2-51, and W2-58). <i>In vitro</i> assays assessed co-cultivability and the inhibitory effects of <i>B. velezensis</i> against <i>R. microsporus</i>. The results demonstrated strain-specific antifungal activity with a reduction in fungal growth across treatments. Further analysis revealed that volatile organic compounds produced by <i>B. velezensis</i> contributed to its antifungal properties. To evaluate the biocontrol efficacy <i>in vivo</i>, tomato fruits were inoculated with <i>R. microsporus</i> and subsequently treated with <i>B. velezensis</i>. The results support the strain-specific reduction in tomato spoilage, yielding various spoilage rates observed across treatments. Our findings highlight the potential of <i>B. velezensis</i> as a promising biocontrol agent for the management of <i>R. microsporus</i> post-harvest infections in tomatoes. Further research is warranted to optimize the application <i>of B. velezensis</i> as a sustainable and environmentally friendly approach for controlling post-harvest diseases in tomatoes.IMPORTANCEOur study shows the significance of improving sustainable agriculture by offering an alternative to the use of chemical fungicides in post-harvest applications. Opportunistic fungal pathogens like <i>Rhizopus microsporus</i> can have detrimental effects on post-harvest commodities like tomatoes. Post-harvest fungal infections are mainly controlled by chemical fungicides that pose health risks to humans and the environment. Utilizing biocontrol agents provides an environmentally safe alternative. Understanding the mechanisms of biocontrol employed by beneficial bacteria like <i>Bacillus velezensis</i> on fungal pathogens gives insight into safer, more environmentally friendly alternatives to protect food crops. Our results suggest that targeted microbial solutions can mitigate post-harvest losses.