Experimental Study On Hydrolysis Efficiency And Enzyme Recycling During The Hydrolysis Of Netural Bagasse Sulfite Pulp

Aim to reduce the dose of cellulase during the hydrolysis process, the paper focused on thecomparision of cellulase-recycling methods and tried to develop a new process to reusecellulase during the hydrolysis of neutral bagasse sulfite pulp.As a potential lignin cellulosic material, bagasse sulfite pulp (BSP), contains69.54%cellulose,18.76%hemicellulose and13.41%lignin. Enzymatic hydrolysis of BSP wasperformed at the cellulose concentration of80g/L, pH4.8and50oC.15FPIU cellulase and15CBU β-glucosidase per gram cellulose were added in the reaction system. After48h ofhydrolysis, cellobiose, glucose and xylose could reach4.88g/L,58.00g/L and11.76g/L,respectively. Hydrolysis yield, glucose yield and xylose yield were71.02%,65.26%and51.05%. By the end, the supernatant contained about17.14%cellulase,67.19%β-glucosidaseand30.97%total protein.In order to get a higher cellulase recovery, the adsorption-desorption relationship betweencellulase and substrate were further investigated. When15FPIU/g of cellulase was mixed withfresh BSP at0-4℃,100r/min, pH5.2. After2h of adsorption, more than75%protein and55%filter paper activity were adsorbed on BSP. On the other hand, desorption profile studieson hydrolysis residues showed that the optimum desorption condition was at pH4.8,40℃,100r/min and2h. When the hydrolysis residue was directly put into the2round hydrolysis of40g/L cellulose with supplement of7.5CBU/g β-glycosidase, the three yields were64.67%,59.41%and43.66%at48h.The total mixed supernatant from two rounds of hydrolysis was used to ferment L-lacticacid by Bacillus coagulans CC-17. Glucose was completely consumed within24h, and thetotal conversion ratio of sugar to acid was82.82%. Material balance analysis showed that usingSSF and recycling methods,66.96g L-lactic acid was produced from163.66g dry BSP. Duringthe whole process, total of1043.1FPIU cellulase and1374.3CBU β-glucosidase were used.