Screening And Optimization Of Yeast Strains High-yield Ethanol By Fermenting Sweet Sorghum Stalks

On the basis of the summary of actual state about energy and the advantages of sweet sorghum stalk fermented to product ethanol in the Inner Mongolia region, the low energy N+ beam bio-engineering technology to mutate yeast strains and to choose the high yield mutation in order to lay the foundation for further industrialization of ethanol production with sweet sorghum stalk.Main results were as follows:Firstly, physical parameters of implanted N+ion including energy and doses were studied. The survival rate curve of yeasts implanted was in accord with the classic "saddle" curve.When energy was 10keV and dose was 70,90×2.6×1013N+/cm2, the survival rate and mutagentic rate of yeasts was higher, about 20 percent and 50 %, respectively. By constantly implanting and filtrating,two stabilizing and high yield yeast strains,12#-70-11,12#-90-A1,were gained.the increase of ethanol was 0.60 % and 2.92%, respectively. And the mutant strains of fermentation rate was faster than the original strain.Secondly,with L1634orthogonal designing,the optimum fermentation conditions of the mutant strains 12#-70-11,12#-90-A1 and the original strain 12# were obtained, which was as follows: the fermentation temperature was 30℃,pH value was 4.5, the inoculator was 7%, the ethanol was 5.13%,5.02% and 5.10%,the residual sugar content was 0.32%,0.32% and 0.08 %.Thirdly,the results of the liquid and solid fermentation showed that: at the end of fermentation, the broth (Matrix) ethanol content of mutant strains was increased to a certain extent compared to the original strain, this showed that N+ion implantation technology was effective in breeding yeast for fermenting sweet sorghum stalks in Inner Mongolia region.