Isolation And Identification Of Vineyard Yeast From The East Of Helan Mountain Of Ningxia And Analysis Their Stress Resistance

At present,the Saccharomyces cerevisiae strains from France and other countries are used to ferment fruit wine in China,but the pure Saccharomyces cerevisiae produces poor flavor of fruit wine for its poor ability to the local environment and increases the production cost of fruit wine.Therefore,it is very important to select yeast strains with regional characteristics.The east of Helan mountain of Ningxia has an abundant of yeast resources for its unique geographical loctation and special climatic condition.In this study,we chose the mature grapes,over ripe grapes,fresh leaves,dried leaves,soil and spontaneous fermented grape juice from 9 vineyards in the east of the Helan mountain of Ningxia to isolate the yeast,the yeast strains isolated were classified by the colonial morphology on WL medium and identified through sequence analysis of 26S r DNA D1/D2 domain.Additionally,the resistance of isolated yeast strains to glucose,ethanol and SO₂ was analyzed.The main results are following:A total of 1066 strains were isolated from different isolation sources.A total of 14species,including Hanseniaspora uvarum,Issatchenkia terricola,Wickerhamomyces anomalus,Metschnikowia pulcherrima,Saccharomyces cerevisiae,Pichia kudriavzevii,Saccharomycopsis vini,Cryptococcus uzbekistanensis,Cryptococcus albidus,Pichia guilliermondii,Rhodotorula mucilaginosa,Clavispora lusitaniae,Candida zemplinina and Hanseniaspora opuntiae(Hanseniaspora guilliermondii)were identified by morphological classification on WL medium and sequence analysis of 26S r DNA D1/D2 domain of yeast strains.There were often four kinds of yeast isolated in nine vineyards,they were S.cerevisiae,W.anomalus,M.pulcherrima and H.uvarum.Different vineyards had different yeast species except for the four kinds of yeast.Although no other yeast specie was isolated except for those four kinds of yeast from Luoshan,Yuma and Zhihui Yuanshi vineyards.Other yeast species were also isolated from other six vineyards,such as I.terricola and S.vini were isolated from Helan Qingxue vineyard.C.uzbekistanensis was isolated from Xixiawang vineyard.C.albidus and P.guilliermondii were isolated from Lanshan Yunhao vineyard.R.mucilaginosa and C.lusitaniae were isolated from Huahao vineyard.C.albidus was isolated from Lilan and Liushi vineyards.H.opuntiae(H.guilliermondii),C.zemplinina and P.kudriavzevii were isolated from spontaneous fermented grape juice.S.vini,C.lusitaniae,R.mucilaginosa and C.albidus were isolated from grape leaves.C.uzbekistanensis was isolated from grape.There were only two kinds of yeast isolated from soil,they were S.cerevisiae and W.anomalus.Different yeast strains had different tolerance ability to alcohol,sugar and SO₂,the grow speed of yeast decreased with the increasing of alcohol,sugar,and SO₂ concentrations.Alcohol had the greatest inhibitory effect on the isolated yeast,S.cerevisiae and the non-S.cerevisiae had the similar abibity of tolerance to alcohol,sugar and SO₂.The maximum alcohol tolerance abibity of Angel.S.cerevisiae and S.cerevisiae were 12%and 8%respectively.P.kudriavzevii had the greatest alcohol tolerance abibity(10%)among the non-S.cerevisiae,followed by H.opuntiae(or H.guilliermondii)with 8%alcohol.Alcohol tolerance of the most of non-Saccharomyces yeast strains were 6%.The maximum sugar tolerance ability for all the yeast were about 450 mg/L,when the sugar concentration was 500mg/L,Some non-S.cerevisiae strains could grow well.When the SO₂ concentration was 500mg/L,Angel.S.cerevisiae and S.cerevisiae could grow well.The maximum SO₂ tolerance of M.pulcherrima,P.kudriavzevii,P.guilliermondii and I.terricola were 500 mg/L.but C.albidus,C.uzbekistanensis,R.mucilaginosa and S.vini had poor tolerance to alcohol,sugar,and SO₂.Further research should be carried out.The results can provide the foundation for selecting yeast strain for fruit wine fermentation and provide the yeast strains for the research and development of wine with region characteristics of the east of Helan mountain of Ningxia.