Screening high temperature tolerant yeast strains and technological optimization of ethanol fermentation of energy beet.

It has been an interesting topic using energy beet to ferment ethanol. Because temperature would affect ethanol fermentation of energy beet greatly,in order to explore the adaptability to high temperature of the different strains and to screen better yeast to ferment in the high temperature,in this study,at first,by the single factor,temperature,the yeast HADY was screened to be tolerant to high temperature,such that when the fermentation temperature was 45℃,the translation rate of ethanol was 81.68%. However,the translation rate of ethanol of ADY was the highest at 31°C. Secondly,three main factors were screened out from nine factors related to fermentation by Plackett-Burman design and response surface methodology,including substrate concentration,ratio of solvent to material,added HADY amount,nutrient salts,phosphorus addition amount,pH value,rotational speed,fermentation temperature and fermentation time. The three main factors are substrate concentration,fermentation temperature and phosphorus addition amount. The optimized technological parameters of HADY are as follows:substrate concentration (mass fraction) 12%,mass ratio of solvent to material 1:1,added HADY 15%,nutrient salts 0.5,added phosphorus 0.9%,pH 5.0,rotation speed 130r/min,fermentation temperature 37℃ and fermentation time 44 hours. It is shown that the translation rate of ethanol is 89.43%.