Biocontrol of postharvest blue mold in pear fruit by Hanseniaspora uvarum Y22: Antifungal mechanisms involving mycoparasitism and volatile organic compounds.

Pear fruit is susceptible to Penicillium expansum infection after harvest, leading to blue mold disease, which causes significant economic and safety concerns. This study evaluated the biocontrol potential of Hanseniaspora uvarum Y22, an antagonistic yeast isolated from organic farm soil, against blue mold in pear fruit via in vitro and in vivo experiments. The results showed a significant reduction in both blue mold incidence and lesion diameter following inoculation of 1 × 108 cells/mL H. uvarum Y22 in pear wounds. H. uvarum Y22 effectively prevented the germination of spores and the elongation of germ tubes in P. expansum. Further studies showed that H. uvarum Y22 could secrete extracellular β-1,3-glucanase and chitinase, as well as adhered to and mycoparasitize pathogenic fungal hyphae. Its non-volatile organic compounds (NVOCs) exhibited no significant antifungal activity. Notably, volatile organic compounds (VOCs) generated by H. uvarum Y22 showed strong antifungal effects in vitro and in fruit fumigation experiments. The main VOC components identified by GC-MS were phenethyl acetate (45.90%), phenethyl alcohol (17.71%), and isopentyl acetate (14.60%), all of which displayed significant inhibitory efficacy against pathogen. These findings indicate that H. uvarum Y22 controls blue mold through preventing spore germination and the elongation of germ tubes, engaging in hyperparasitism, and emitting antifungal VOCs. This study establishes a theoretical foundation for developing of eco-friendly postharvest preservation methods for pear fruit, utilizing antagonistic yeast and its active volatile compounds.