| Cellulose is the most abundant organic substance on the earth. It is an important regenerating resource and energy. Cellulose is hard to be ultilized, because of the complicated molecule structure. Due to friendly enviro nment, ethanol is considered as a good substitute to fossil fuel. Although, the themal value of ethanol is lower than gasoline.Simultaneous saccharification and fermentation (SSF) is diffecult to be used extensively, because of discrepancy of optimal temperature between cellulases and yeast. In this study, we want to obtain suitable cellulase and thermotolerant yeast strain,the optimal temperature of which fall in same temperature range.One cellulase producing strain Neurospora intermedia was isolated with optimal growing temperature and pH of 28℃and 5.0. Optimal cellulase active temperature and pH of secreted cellulase were 42℃and 5.0. Meanwhile, a thermotolerant yeast strain Candida krusei was isolated with highest growing temperature of 50℃and ethanol yield of 5.8% at 42℃. It also can grow in sugar free organic mediam.When SSF was performed by only using these two isolated, growth of the yeast was arrested. The growth of yeast can be observed whenβ-glucosidase was added in SSF solution. And ethanol product by yeast also can be detected. To solve this problem, the gene of theβ-glucosidase must be introduced in yeast to hydrolyze cellubiose to glucose. Two shuttle plasmids were construced, pYESKB and pPIRPKT, with G418 selection mark. pYESKB is an episomal plasmid and pPIRPKT is an integrative plasmid.In this study, SSF was completed by two isolated andβ-glucosidase. Altoμgh the yield of ethanol was low, but it provides feasible method for SSF...
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