Microencapsulated Saccharomyces cerevisiae NX2320 via fluidized bed drying suppresses Botrytis cinerea in grapes: Cell membrane disruption and oxidative stress as key antifungal mechanisms.

Grapes are highly susceptible to pathogenic fungal infections both in the field and during storage. The use of microorganisms to inhibit pathogens and preserve fruits and vegetables has garnered significant research attention. However, the application of free microorganisms is limited due to challenges in transportation and preservation, as well as their short survival time, which restricts their practical use in the food industry. In this study, Saccharomyces cerevisiae NX2320 demonstrated effective inhibition of Botrytis cinerea growth in Potato Dextrose Agar (PDA) media. To enhance its stability and antifungal efficacy, S. cerevisiae NX2320 was microencapsulated using two distinct methods: (1) sodium alginate and chitosan combined with vacuum freeze-drying (VFD), and (2) sorbitol anhydride monostearate with fluidized bed drying (FBD). Comparative analysis revealed that S. cerevisiae NX2320 microcapsules prepared via FBD exhibited superior antifungal activity and stability compared to those produced using VFD. The FBD microcapsules were successfully applied to grapes both in the field and during storage. Treatment with S. cerevisiae NX2320 microcapsules significantly reduced the disease index and decay percentage while improving the overall quality of the grapes compared to untreated controls. Transcriptome analysis and biochemical validation identified cell membrane disruption and oxidative stress as the primary antifungal mechanisms of S. cerevisiae NX2320 microcapsules against B. cinerea. Additionally, volatile organic compounds (VOCs) were identified as the key antifungal substances produced by the microcapsules. These findings highlight the potential of S. cerevisiae NX2320 microcapsules as an effective biocontrol agent for grape preservation in both field and storage conditions.