Study On The Fermentation Of Cellulase And The Hydrolyzation Of Straw By Cellulase

Because of the eruption of energy crisis, the research of using the plant fiber to produce fuel alcohol has been paid moe attention. The key point of this area is how to hydrolyze the plant fiber by cellulase. This research focuses on the fermentation of cellulase by Trichoderma reesei, the treatment of broth and the pretreatment of fiber.The fermentation o f cel lulase b y Trichoderma reesei was s tudied. Firstly, th e main medium was optimized by statistic software-SAS, and the optimal medium was determined(g/L): corn steep liquior 28.0, glucose 26.2, microcrystalline cellulose 34.7, citric acid 1.17. The filter paper activity(FPA) was 20U/mL, which is close to the intending activity 20.1U/mL. Secondly, the process of fermentation of cellulase in the 5L fermentor was studied, including batch fermentation and fed-batch fermentation. The FPA of cellulase was 54.1U/mL in batch fermentation, and it was 65.6 U/mL in fed-batch fermentation. Thirdly, we researched the dynamics in batch fermentation, and c alculated m odel p arameters. The m odel c an reflect the c ell gr owth, p roduct synthesis and substrate consumption well.The treatment of the broth was studied. Firstly, the cellulase in the broth was extracted by ammonium s ulfate. Then t he cellulase was purified by ion e xchange chromatography with resin DEAE-PHEMA. Relative activity was 0.391U/mg, and cellulase was purified to 1.74 fold after ammonium sulfate precipitation method. After ion exchange chromatography, relative activity was 0.619U/mg, and cellulase was purified to 2.75 fold.The plant fiber was treated by some methods such as, dilute acid pretreatment, dilute sodium hydroxide pretreatment, and ammonia pretreatment. The lignose can not be removed by dilute acid pretreatment, and the rate of enzyme hydrolysis was 25% after treatment of dilute acid. Sodium hydroxide pretreatment can remove most lignose, and the rate of enzyme hydrolysis was more than 70%. The plant fiber can also be easyly hydrolyzed by enzyme after ammonia pretreatment, and the ammonia pretreatment is temperate. The best pretreatment is sodium hydroxide pretreatment.