Study On Immobilization Of Cellulase With Mesoporous Molecular Sieves

Cellulose is the most important natural renewable resources. If fully utilized, our production and life will greatly changed. Degradation of cellulose by cellulase has the advantages of high efficiency and less pollution. But free cellulase was unstable, difficult to recycle. These drawbacks, severely limits the cellulase applied in the industry. The immobilized enzyme can overcome these shortcomings, has a very broad application prospects.Cellulase immobilized on the mesoporous molecular sieve was studied in this paper. Firstly, amino-functionalized SBA-15molecular sieve was prepared by the co-condensation method, then characterized by XRD, nitrogen adsorption desorption, elemental analysis. The immobilization of cellulase was carried out using glutaraldehyde as crosslink agent, using the mesoporous molecular sieves as carrier. Some factors that affect immobilization, such as concentration of glutaraldehyde, enzyme load, pH, immobilization time were investigated. The immobilized optimum condition was glutaraldehyde concentration1%, the amount of enzyme30mg/g, pH=4, fixed time8h. Under the optimum conditions, immobilized enzyme was prepared. The enzymatic properties of the immobilized enzyme in a buffer solution system was studied. Compared with the free enzyme, the optimal temperature of immobilized enzyme is60℃, which is10℃higer than that of free enzyme, the optimal pH is4, one unit moved to left, Km=3.6mg/mL, affinity with Substrate slightly declined. The immobilized cellulase was markedly improved in thermal stability, operational stability and storage stability. Next, three ionic liquids,[Bmim]Cl,[Bmim]OAc,[Mmim]DMP was synthesized, characterized by FT-IR,1H NMR,13C NMR,31P NMR to confirm the structure. Then the enzymatic properties of the immobilized enzyme in three kinds of ionic liquid, including the optimum temperature, operational stability, thermal stability was studied. The results showed that the [Bmim]Cl ionic liquid is not conducive to the immobilized cellulase enzymatic hydrolysis of cellulose, because chloride ions play an inhibitory effect on cellulase. Both [Emim]OAc and [Mmim]DMP ionic liquids were conducive to the degradation of cellulose by immobilized cellulase, especially in the [Emim]OAc ionic liquid system, immobilized enzyme has a higher activity.