Cellobiase Production under Submerged Fermentation and Its Application on Lignocellulosic Material Hydrolysis
|Keywords||cellobiase submerged fermentation corn stover cellulase enzymatic hydrolysis|
Cellobiase plays a pivotal role in the process of lignocellulosic material degradation. The common Trichoderma reesei enzyme system has insufficient cellobiase activity which decreases the saccharification efficiency of cellulose by cellulase seriously. According to the above question, cellobiase production under submerged fermentation and synergetic hydrolysis of alkali-pretreated corn stover by cellobiase have been mainly studied.Cellobiase production by Aspergillus niger ZU-04was carried out under submerged fermentation. Cellobiase activity could reach5.93IU/mL after5d at30℃and6.23IU/mL after4d under variable temperature when the concentrations of glucose, corn steep powder and wheat bran were2.0%,0.3%and1.0%, respectively.Effect of different inducing conditions on cellobiase production by recombinant Trichoderma reesei-2was investigated. The results showed that induction effect of lactose was the best with the maximum enzymatic activity15.76IU/mL which is78.8-fold that of host strain. The induction effects of glucose/avicel or lactose/avicel were poorer than that of lactose with the maximum enzymatic activity11.45IU/mL,12.37IU/mL, respectively. The enzyme activity was less than2IU/mL when glucose or avicel was used as the carbon soure.Enhancing the proportion of cellobiase in available Trichoderma reesei enzyme system had an important effect on the overall catalytic activity of cellulase and synergetic degradation. It was found that endoglucanase activity was kept more or less constant, exoglucanase activity and filter paper activity were increased by47.5%and24.6%, respectively by adding cellobiase into Trichoderma reesei cellulase.Enzymatic hydrolysis of alkali-pretreated corn stover was investigated. Study showed that the hydrolysis yield could reach65.7%after48h when the dosage of cellulase was20FPIU/g substrate.Supplementing cellobiase greatly reduced the inhibition effect caused by cellobiose accumulation and helped to increase the hydrolysis yield to80.9%when CBIU/FPIU was0.51.The hydrolysis yield was not significantly improved when CBIU/FPIU was further raised. The results had broad application prospects on bioconversion and utilization of cellulosic materials.