|Other Abstract||Objective: Yeast plays a major role during wine fermentation, which can directly affect wine quality and aroma. However, with the widespread application of commercial yeast, the phenomenon of homogenization of wine products has become increasingly serious, lacking regional characteristics. The climate and geographical environment of China's wine-producing regions are complex and changeable, which makes the yeasts also diverse. The development and application of local yeasts have important value for brewing wines with unique style and regional characteristics. In addition, the potential for biological control of antagonistic yeasts for harvesting fruits and vegetables is huge, and is of great significance for protecting the environment and improving food safety.
Methods: In this study, the Cabernet Sauvignon and Chardonnay grape berries, leaves and soil were used as experimental materials. The representative strains were identified by combining the morphological and sequence analysis. According to the tolerance of yeast to alcohol, glucose, pH and SO2, the wild yeasts with excellent resistance were screened out. The selected novel strains were used to explore the antagonistic properties of Aspergillus carbonarius, Botrytis cinerea and Penicillium expansum.
Results: (1) A total of 791 wild yeast strains were isolated and screened, identified as 9 genera and 14 species, including Hanseniaspora uvarum, Hanseniaspora lachancei, Hanseniaspora osmophila, Rhodotorula graminis, Candida railenensis, Candida oleophila, Candida zeylanoides, Candida californica, Papiliotrema flavescens, Pichia fermentans, Pichia kluyveri, Wickerhamomyces anomalus, Solicoccozyma aeria and Kluyveromyces hubeiensis, showing the diversity of wild yeast in the Deqin wine regions of yunnan. (2) The isolates are mainly non-Saccharomyces cerviae, most of them were able to grow in the environment of 18% alcohol content, 60% glucose, pH 2.5 and 360mg/L SO2. Among them, Hanseniaspora uvarum was superior to other yeasts in the ability of the above resistance, but it could not grow well in the environment of pH 7.0. Based on the results of all the stress resistance tests, a total of 62 excellent strains were screened. (3) The study screened out 73 strains of yeasts that could slow down or inhibit the growth of A. carbonarius, B. cinerea and P. expansum. And the bacteriostatic ability increases with the increasing of yeast cell concentration. In addition, the strains that produced volatile compounds and have strong film-forming capacity against mold are also superior to other strains. The change in the concentration of Fe3+ will affect the size of the inhibition zone produced by yeast against B. cinerea, but the effect was not obvious.
Conclusion: The diversity of wild yeasts in Deqin wine region of Yunnan province was rich, with 14 species belonging to 9 genera. According to the stress resistance test, 62 excellent yeast strains were selected, mainly Hanseniaspora Uvarum. Seventy-three yeast strains were selected to slow down or inhibit the growth of A. carbonarius, B. cinerea and P. expansum. And the bacteriostatic ability increases with the increasing of yeast cell concentration. In addition, the strains with strong volatile compounds and membrane forming ability had better inhibitory effect on mold than other strains.|