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Protoplast UV mutagenesis of this thesis by starting to alcohol yeast strains FY- 23 ( provided by the Company Culture Collection ), and further screening , purification , bred a high temperature characteristics of the yeast strain FY - 23 - 9. From the study of the physiological characteristics of the original strain , alcohol yeast protoplast the best formation rate and the condition of the best regeneration rate , including bacterial pre- incubation time , enzyme concentration and time of the enzyme , protoplast formation and regeneration : snail enzyme with 1.5 % , the reaction time was 25min . Protoplast formation rate of 99.54% , the regeneration rate of 5.1% . And studied the mortality rate curve of the ultraviolet irradiation of the protoplasts , and determining the TTC screening irradiated 10s, 15s, 20s after the regeneration plates . After through the TTC tablet screening , get nine the color deepest yeast strain , its Durham tube the two sieve and fermentation shake flask rescreening , pick out a comprehensive performance best strain FY -23 -9 , for the most good fermentation process conditions of . DE value , including raw corn liquefied solution saccharification liquid DE value , the ratio of water , fermented optimum temperature fermentation initial pH and inoculum size ; certain conditions and orthogonal experiment to determine the best process conditions : the most suitable material to water ratio is 1:2 , liquefied liquid DE value control in about 20% saccharification liquid the DE value control more than 95% , fermentation temperature of 38 ° C , fermentation initial pH 5.0 , inoculum size of 10%. Last verification test on a 50L fermentor , 72h Alcohol 11.33 % ( v / v ) , 0.47% residual sugar , the conversion rate of 43.21% , with the original strain FY-23 under the optimum conditions quite . With the value of industrial production .
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