Process Biochemistry, Vol.98, 202-210, 2020
Effects of harvest dates on microbial communities of ice grape skins from Xinjiang of China
Ice wine is a sweet dessert wine made from pressing grapes naturally frozen on the vines. The structure and metabolic characteristics of native microbial community dominated by organics and nutrients transformation in fermenting process of ice wine on the grape skin are likely to change due to climate events. Our objective was to evaluate the influence of harvest time on structure and metabolic characteristics of bacterial and fungal communities on Vidal ice grape surface. Vidal grape samples were picked between October and December in 2018; Harvest 1 (VG1): 14 October; Harvest 2 (VG2): 16 November; Harvest 3 (VG3): 18 December. Vishniacozyma, Alternaria, Cladosporium, Stenotrophomonas, unidentified Cyanobacteria and Sphingomonas existed in all harvest dates and were the main genera widespread in most grape samples from the three harvest periods. Saprotrophic fungi and bacteria involved in metabolism were also dominant. For fungi, wood saprotrophs and unidentified saprotrophs were detected comprising Phoma, Didymella, Filobasidium and Clavaria. Delayed harvest of ice grapes has a distinct advantage for pathogen reduction compared with that of normally harvested grapes. Among bacteria, the most frequently occurring types in the metabolism category were energy metabolism, carbohydrate metabolism and lipid metabolism. In short, the harvest period can positively regulate the function of Vidal ice grape epidermal microorganisms.
Keywords:Ice grape surface;Harvest period;Microbial community structures;FUNGuild and PICRUSt;Functional prediction