Study On Screening And Identification Of Saccharomyces Cerevisiae And Stress Resistance

Saccharomyces cerevisiae is the primary yeast in brewing and winemaking. Quality wine producing need fine wine yeast strains, which can bring special characters and styles to the wine. Ningxia and Gansu provinces are the premium wine producing areas with rich wine-related yeast resources that were never discovered. Study on the resources of wine- related yeast is the basic for screening and breeding of fine wine yeast strains. Saccharomyces cerevisiae strains were screened from the yeast isolates from Ningxia and Gansu, and the Saccharomyces cerevisiae strains screened were identified by the method of morphology, physiological and molecule methods. Then, the stress resistance of the Saccharomyces cerevisiae strains to high-concentration ethanol, high osmotic pressure, high temperature, nutrient starvation were studied in this paper. The main result are as follow:Wine equipment surfaces, the grape surfaces and the spontaneous fermention must were used as isolated source. WL Nutrient Medium culture, Lysine Medium and Morphologic were performed for the screening of Saccharomyces cerevisiae. Physiological observation, physiological analysis and 26SrRNA D1/D2 domain sequencing of indentification indicated these yeasts stains belong to Saccharomyces cerevisiae.Combination WL medium with morphologic observation is efficiency and accurale.The result showed that the stress resistances among the screened Saccharomyces cerevisiae strains were obviously diferent.All the wild Saccharomyces cerevisiae strains studied can resist 10%(v/v)ethanol, N5238, C157, C242, C372, CY, G2257, T224 can resist 14%(v/v) ethanol, while N5254, N5262 , C190 and C720 can not resist 12%(v/v) ethanol. All the yeast strains can not resist 16%(v/v)ethanol and above. Wild Saccharomyces cerevisiae strains can resist 1. 8mol/L KCL, N5262, C242, C693, G2257 can resist 2.2 mol/L, C242 can resist 2. 4 mol/L, while, N5254, N6254, C157, C372, CY can not resist 2. 0 mol/L KCL. All the strains studied can grow after10 days' nutrient starvation. Wild Saccharomyces cerevisiae can grow on 50% glucose, but they can not survive on 60% glucose. Wild Saccharomyces cerevisiae stains can not grow in pH 1.5, they can grow in pH 2.0~4.5 and grow better in pH 4. 0. All the strains but N5254 and C190 can not grow at 37℃, while only C242, C720 can grow at 42℃, others can not survive at and above 42℃.