Screening High-quality Yeast Of Fermentation Characteristics Of Koumiss In Xilingolo

120 stains yeast screened out from 5 koumiss in Xinlingol,Inner Mongolia,which was used the WL medium to separate preliminarily for these yeast.Then screening 1 high-quality yeast by TTC,gas formation,morphology identification,physiology and biochemistry and Fermentation Characteristics.This yeast treated as compound mutation and experiment of high-sugar-tolerant,1 mutant stain yeast were selected.Making sure the performance of heredity was stable by experiment of alcoholic fermentation.Finally making the teast of DNA for 1 high-quality mutant stain yeast.120 stains yeast was used the WL medium to separate preliminarily,and selected 8 genera yeast.They are Hansenlaspora uvarum,Hansenula anomala,Torulaspora delbrueckii,Saccharomyccs cerevisiae,Saccharomycodes ludwigii,Schizasaccharomyces pombe,and 2 genera yeast not sure.By some way of screen,A9 is high-quality yeast.It can grow in pH>1.5,the suger concentration(w/w)54%,SO2 concentration 400mg/L,alcohol(v/v)<18%and temperature is 43?.It has a well tolerated compare with others.The optimal parameter of UV mutation was confirmed by the principle of fatality rate range 75-80%.Under the 30W UV lamp,distance from UV lamp 30cm,shining 75s,the fatality rate of UV mutation was 78.9%;To make sure the optimal parameter,the bacterium suspension of 1%DES was shocked in the thermostatic water-bath shocking box at the temperature of 35? for 15min,and fatality rate of DES mutation was 76.1%.By three continuous times UV-DES compound mutations,four mutant stains were selected.Four mutant stains were selected to make experiment of high-sugar-tolerant with original strain A9,concluding that the best of high-sugar-tolerant mutation yeast was A9-2.By experiment of alcoholic fermentation,in the fermentation broth of the third generation of A9-2,the weight loss of CO2 was 13.86g,the residual sugar was 13.7°Be,the alcoholic strength was 5.4(v/v).The different indicators were similar to that of the tenth generation fermentation broth,made sure the performance of heredity was stable and the fermentation performance was higher than that of the original strain A9 obviously.Finally on strain A9-2 26S rDNA D1/D2 sequence analysis,result show A9-2 is Kluyveromyces marxianus.