Isolation, Main Characteristics And Breeding Of Wine Yeast In Helan Mountain Wine-producing Regions

Saccharomyces cerevisiae can directly affect the wine quality in the wine brewing process, and play a dominant role in the formation of the characteristics and style of wine.Yeast which could toally show the variety of personality and regional characteristics can be screened from grape vineyard. The east area of Helan Mountain in Ningxia is one of the ten main producing areas of wine in China. Therefore, it is very important to breed wine yeasts suitable for the characteristics of the local grape and optimize its production performance.In this paper, 117 strains were isolated from the surface of mature wine grape and its rhizosphere soil in the east wine area of Helan Mountain in Ningxia. The colony morphology of the strains were observed by WL medium. Combined with colony morphology, these yeasts were initially divided into 6 types, including 9 strains of S. cerevisiae.Tolerance experiment was carried out in 9 strains of S. cerevisiae, tolerance of alcohol, SO2, glucose, low pH and NaCl, the resistance of HBN05 was relatively good, and it could be used as the following excellent strains breeding.The activity of the β-glucosidase of 9 strains of S. cerevisiae was respectively determined, the results showed that β-glucosidase in S. cerevisiae was mainly distributed in vitro, the β-glucosidase activity of strain SLZ02 was the highest, which could be used in the following protoplast fusion breeding.The rates of fructose utilization of 9 strains of S. cerevisiae were determined, and the mechanism of the rate of fructose utilization of S.cerevisiae were preliminary studied. Through analysing the realation between these key enzymes activities of fructose metabolism（PFK and HK） and the rates of fructose utilisation,indicated that the enzyme activities of these two enzymes made no effect on the rates of fructose utilization of yeast. The highest rate of fructose utilization was the strain MLZ11,which could be used as the parent strain of protoplast fusion breeding.Brewing yeasts were used as the original strains separated from the preliminary tests, based on mutation breeding technology and protoplast fusion technology for the screening of strains, the strain R17 with better relatively performance was obtained, which the ethanol tolerance was 12%（v/v）, the tolerance value of SO2 was 250 mg/L, the glucose tolerance was 30%, the pH tolerance was low to 3.5, the tolerance value of NaCl was 100 g/L, the extracellular β-glucosidase activity was 130.90 μmol pNP·g^-1·h^-1, and the fructose utilization was 88.92%.