Construction of Composite Microorganisms and Their Physiological Mechanisms of Postharvest Disease Control in Red Grapes.

Red grapes often suffer from postharvest diseases like blue mold and black mold caused by and . Biological control using beneficial yeasts and bacteria is an effective method to manage these diseases. sp. and sp. are effective microorganisms for the control of postharvest diseases of red grapes. This study combined two yeast strains ( and ) and two bacterial strains ( and ) to investigate their biological control effects on major postharvest diseases of red grapes and explore the underlying physiological mechanisms. Research showed that compound microorganism W3 outperformed the others; it reduced spore germination and germ tube growth of and , while its volatiles further inhibited pathogen growth. Additionally, the treatment enhanced the antioxidant capacity of grapes and increased resistance to pathogens by boosting peroxidase activities, superoxide dismutase, catalase and ascorbate peroxidase, phenylalanine ammonolyase, and polyphenol oxidase. Furthermore, the combined treatment increased the activity and accumulation of antifungal compounds such as total phenols and flavonoids, thereby improving disease resistance and reducing decay. Therefore, composite microorganisms combining various antagonistic strains may offer a viable substitute for tackling postharvest diseases in red grapes.