Study On Improving Saccharomyces Cerevisiae Inhibitor Tolerance And Xylose Using Ability

Cellulosic ethanol is a kind of clean energy,free from contaminating the environment.The production and utilization of cellulosic ethanol meet the national sustainable development strategy.In lignocellulose pretreatment process,a variety of toxic compounds was generated,which can severely affect the fermentation process.Besides,glucose and xylose are the two main sugars existing in lignocellulose hydrolysate.So,efficient conversion of both glucose and xylose is the point to the production of ethanol.Therefore,strengthen the Saccharomyces cerevisiae strains to inhibitor tolerance and xylose-fermenting capability are two challenges of cellulosic ethanol production.In this study,we combine the method of mutation and fusion.Hybrid Saccharomyces cerevisiae strains were obtained by mating the lab xylose-fermenting Saccharomyces cerevisiae E7 with the industrial Saccharomyces Cerevisiae Angle.The hybrid strains inherit xylose-fermenting capability together with inhibitor tolerance ability from their patent strains.In the presence of 30 %FAP,the hybrid strains E7-11 and E7-12 can achieve a ethanol yield 0.36 g/g and 0.39 g/g under high temperature 40℃.Hybrid strains are potential to be used in the SScF process.Then,xylulose kinase plays an important role in xylose utilization of Saccharomyces cerevisiae.Based on the docking analysis binding between enzyme and ligand,site-directed mutation of the 531 th amino acids of Scheffersomyces stipites was constructed.Whereas,compared with the original Saccharomyces cerevisiae strain,the mutants did not show significant difference in xylose fermentation process.Besides,the combination of the N-terminal and C-terminal of four sources of xylulose kinase,only Saccharomyces Cerevisiae PRS415-LX-XKSZH-1 showed xylose fermenting capbilty.The strategy of combination did not work.