Screening Of β-Glucosidase Producing Yeast Strains From Hexi Corridor Wine Regions Of Gansu Province

β-glucosidase enzyme can hydrolyse glycosidic aroma precursors in wine, releasingvolatile aglycone and forming a full-bodied and rich wine aroma. In the winemaking process,as dominant microorganism during the alcoholic fermentation, yeasts have an importantimpact on the sensory quality of the wine, but also the main sources of β-glucosidase.Different yeasts have different capacity to produce β-glucosidase. Wine RegionsEnvironmental is the primary source wine related yeast strains. At present, there are fewresearches of wine-related wild yeast producing β-glucosidase. Studying and screening nativeand β-glucosidase producing yeast strains is important for making wines with regionalcharacteristics.The samples were collected from the vineyard of4different wine regions in HexiCorridor in this study, in order to obtain β-glucosidase producing yeast strains. Evaluationwas carried out for the fermentation performance, tolerance and β-glucosidase activity of theisolated yeast strains. The main findings are as follows:1Using p-NPG for screening and comparing with commercial yeast strains ICV foractivity,4β-glucosidase producing strains were obtained. β-glucosidase activity of strains wascarried out with quantitative determination, then MQFSC-3showed the highest activity of51.40±4.74U/mL, followed by GTFE, GTFE-4and MQFSM-3, their activity were50.43±3.36U/mL,45.42±4.15U/mL and43.07±2.54U/mL, respectively.2WL medium and lysine medium were used for4yeast strains to preliminary classify,combined with the results of26SrDNAD1/D2area sequence analysis, the results suggestedthat strains MQFSC-3, GTFE and MQFSM-3were Saccharomyces cerevisiae, GTFE-4wasMetschnikowia aff. Fructicola.3The4selected yeast strains were studied for their fermentation performance, and thecomprehensive comparison among alcohol tolerance, sulfur tolerance, tolerance to high-sugarand low pH tolerance of the strains showed that Saccharomyces cerevisia strains MQFSC-3and GTFE have the best overall performance, with potential application of wine productionwith regional specialties.4The influencing factors of enzyme producing of strains MQFSC-3and GTFE werestudied, the results showed that the strain MQFSC-3showed good characteristics for enzymeproduction in winemaking conditions, with greater potential for application in thefermentation.5Compared with spontaneous fermentation and commercial strain ICV, strain MQFSC-3 had a relatively good fermentation performance, and no significant effect on wine color. Thestrain increased the content of esters, higher alcohols, and promoted the hydrolysis of terpenes,in particular fermentation conditions, even better than commercial yeast, showed strongβ-glucosidase activity and excellent strain characteristics.