Screening Of A High Yield Yeast Strain And Optimization Of Its Process

Yeast strain ZX-19, which is kept by the strain conserve center of BBCA, was studied as the initial strain in aspects of growth curve; then, on the base of these data, in the logarithm stage, yeasts were treated with heat-shock and ultraviolet, further more, they were screened by TTC plate, selected by cultivated in Duse tube, again in shaking flasks. At last, a high-yield strain ZX-19-509 with stable genetic character was obtained.This research studied the alcohol patience and high-concentration sugar patience characters .The result is, strain ZX-19-509 performs a little higher alcohol patience and could grow in 25g/100ml saccharification solution well. Such indexes of optimum growth temperature, optimum growth pH, seed stages and inoculation ratio , DE value of liquefacient sugar solution, fermentation temperature, and initial pH value , concentration of inorganic ion and DE value of saccharification solution.The optimal result is, the optimum growth temperature is 30℃and the optimum pH is 5.5, the best seed stage and inoculation ratio are 22h and 10% respectively, the top-well DE value of liquefacient suger solution is 20%, the optimum fermentation temperature is 32℃and the fittest initial pH is 5.5, the DE value of saccharification solution be 96%. Each adding quantity of the four concentration of inorganic ion also determined.We took a test on 500l fermentor in large by using the obtained strain and optimized techniques. 60h later, the average alcohol yield is up to 12.7%(v/v), and the transform ratio is 45.1%, which increased 0.7 points in alcohol output compared to the initial strain and 2.4 points in transform ration compared to that of 42.7%.