Screening Of Wine-related Yeast With High Tolerance And The Study On Fermentation Performance In Hexi Corridor Region

Yeast strains have a significant effect on wine color, aroma, sensory quality and style,however, yeasts that used in the production of wine are mostly from imports in Gansuprovince, appearing a "homogenization" tendency. At the same time, the use of importedactive dry yeast can reduce the importance of yeast diversity and the role of indigenous yeast,therefore, a need of research and conservation for local wild yeast resources of the wineindustrial base in Hexi region is carried out urgently. In this experiment, ripe grape berries asobject of study, the use of YEPD medium for isolation of wine-related yeast strains from thespontaneous fermentation grape juice, WL nutrient medium, morphological, physiological andbiochemical tests were used initially for isolation and identification, from which the strongtolerance performance strains were screened as germplasm resources and conserved.Meanwhile some strains were identified by26S rDNA D1/D2region sequencing, and then thestrains with better tolerance were used to compare the capability of producing aroma. Theresults were as follows:1. Based on the colony differences on WL nutrient medium,10yeast genetic clusteringgroups were obtained preliminaryly: Rhodotorula, Metschnikowia, Zygosaccharomyces,Saccharomyces, Saccharomycodes ludwigii, Pichia, Candida, Hansenula and other two kindsof yeasts.2. Tolerance test results showed that strains WLFE, WLFEC-3, WLFM-6, ZXFS,MGFEC-1, MGFEH-3, MGFM-7can withstand a ethanol concentration of18%; strainsWLFE, WLFEC-3, WLFM-6, QLFS-4, MGFEC-1, MGFEH-3, MGFM-7can withstand theglucose concentration of50%; strains WLFE, WLFM-6, MGFEH-3, MGFM-7can withstand18%NaCl; strains WLFE, WLFEC-3, ZXFS, MGFM-7can withstand the acidic environmentof pH2.5; WLFE, WLFEC-3, WLFM-6, ZXFS-6, QLFS-4, MGFEC-1, MGFEH-3, MGFM-7can withstand low temperature of12℃; strains WLFE, WLFEC-3, MGFM-7can tolerate250mg/L of SO2.3. Strains tested by26S rDNA gene sequencing results showed that belong to6speciesof5genera, respectively: Metschnikowia aff belonging to Metschnikowia, Rhodotorula slooffiae belonging to Rhodotorula, Saccharomyces cerevisiae belonging to Saccharomyces.The strains that not be able to be identified by WL nutrient medium were identified by26SrDNA gene sequencing: Sporobolomyces roseus belonging to Sporobolomyces,Cryptococcus flavescens and Cryptococcus magnus belonging to Cryptococcus.The analysis of aroma components from4wine samples showed that the wine sample which inoculated MGFM-7strain was found27kinds of aroma compounds, WLFEC-3strain11kinds, and the samples inoculated strains ZXFS and WLFE had eight kinds of aroma compounds, respectively. So strain MGFM-7can produce more kinds of aroma compounds and helpenrich the taste of wine. But the yeast fermentation characteristics and its values in use of thisregion need to do further research.