Identification Of Yeast Strains From Chateau Rongzi Of Shanxi And Screening Of Saccharomyces Cerevisiae Strains

In wine production.the main biochemical process is alcoholic fermentation in which yeasts play an essential role.The vinification characteristics of the yeasts contribute to the sensory characters of wine significantly.In this study,1280 yeast strains were isolated from spontaneous fermentation of five main grape varieties(Chardonnay,Merlot,Cabernet Sauvignon.Marselan.Cabernet Franc)in Rongzi vineyard,Shanxi,2011.These strains were clasffied through different cultural features on WLN nutrient medium.Then strains were identified with 26S rDNA D1/D2 domain sequence analysis.Sequences were analyzed using the BLAST at NCBI.to construct phylogenetic tree.Strains of Saccharomyces cerevisiae were distinguished by interdelta fingerprinting and 2-3 strains were chosen from each pattern for basic physiological property(the tolerance capacity,flocculation capacity,autolytic capacity.and killer capacity)study in order to screen out more superior S.cerevisie strains.The main results were as following:1.The result showed that the selected yeast stains belonged to 8 species of 7 genera.namely,Saccharomvces cerevisiae,Hanseniaspora uvarum,Hanseniaspora occidentalis.Pichia kluyver,Metschnikowia pulcherrima,Candida zemplinina,Issatchen kiaterricola.Aureobasidium pullulans with proportion of 38.36%,48.98%,0.86%,2.58%,1.72%,3.13%,2.81%and 1.56%respectively。2.Ninety-two S.cerevisiae strains were isolated from Marselan spontaneous fermentation.and three commercial yeasts(RC212,BM45 and CY3079)were distinguished by Interdelta fingerprinting.The result showed that they could be classified into 6 genetypes with the ratio of 21.74%,1.09%,1.09%.42.38%,4.35%,29.3 5%,respectively.3.Eleven S.cerevisiae strains were used for physiological performance,and the commercial wine veast RC212.BM45 and CY3079 were used as control.All strains exhibit higher flocculation capacity and fine autolytic capacity.These S.cerevisiae strains could grow well on the YEPD medium containing 500 mg/L of SO2.RMaa-3-16,RMab-2-25,RMaa-3-14,RMab-2-30,RMaa-3-11,RMaa-3-29,RMaa-3-34,RMab-3-38 and RMab-3-40 could tolerant 14%of alcohol.RMab-2-25,RMab-2-30,RMaa-3-11 and RMaa-3-34 showed strong killer capacity,while RMaa-3-16,RMaa-3-14,RMaa-3-31.RMaa-3-32 and RMab-3-40 exhibited faint killer capacity.4.The flocculation capacity and autolytic capacity analysis showed no significant difference within the same genotype group distinguished by Interdelta fingerprinting.Two physiological characteristics of genotype Ⅱ showed significantly difference compared with other genotypes.Only the autolysis capacity of Genotype I showed significant differences compared with other genotypes,and with no obvious advantage in flocculation capacity.Results from tolerance and killer capacity revealed that the same genotype did not show a strong relevance.5、According to results of each physiological characterization,strains of RMab-2-25 and RMab-2-30(Genotype Ⅰ),RMaa-3-11(Genotype Ⅱ)and RMaa-3-34(Genotype Ⅴ)were better than other strains and the three commercial strains in terms of tolerance.flocculation.autolysis and killer capacity.Strains of RMaa-3-16,RMab-2-25,RMab-2-30,RMaa-3-11,RMaa-3-14,RMaa-3-31,RMaa-3-32,RMaa-3-34,RMab-3-40 and RMab-3-40 were similar to three commercial strains.