Effect Of Protein Additives On Enzymatic Hydrolysis Of Lignocellulose And Its Mechanism

The conversion of renewable lignocellulose into liquid fuels and chemicals is one of the effective ways to solve the shortage of fossil resources such as petroleum and coal.Among them,the use of cellulase to hydrolyze lignocellulose into fermentable monosaccharides is a key step in the biotransformation of lignocellulose.But because of the highly complex crystalline structure of lignocellulose and the presence of lignin,it will lead to the non-productive and irreversible adsorption of lignin by enzyme,which will reduce the efficiency of enzyme hydrolysis and increase the production cost.Adding non-enzymatic protein during the enzymatic hydrolysis of lignocellulosic material is a better choice to reduce the nonproductive adsorption of cellulase.In order to study the mechanism of such proteins in the enzymatic hydrolysis of lignocellulose and find more economical and effective non-enzymatic protein,three proteins(Collagen,BSA and Casein)which increased hydrophobicity in turn,were selected as additives in this paper.The effect of protein hydrophobicity on enzymatic hydrolysis of sugar from bagasse was studied,as well as the possible mechanism of action and the optimization of conditions for alkali degradation with cellulase pretreatment of bagasse.The main experimental results were as follows:First of all,three non-hydrolyzed proteins Collagen,BSA and Casein with sequentially increased hydrophobicity were obtained through online prediction and actual measurement.It was found that Casein with the strongest hydrophobicity had the best enzymolysis effect on Bagasse,the synergistic effect was 32.1%,BSA was next,the synergistic effect was 20.3%,the least hydrophobic Collagen was the worst,the synergistic effect was 5.9%.At the same time,it was compared that the protein additives and surfactants had the same promoting effect on the enzymatic hydrolysis of bagasse.Secondly,the possible mechanism of the protein additive was analyzed.The thermal stability experiments show that protein additives can improve the thermal stability of cellulase.The adsorption behavior of different hydrophobic proteins on Lignin and the adsorption of cellulase on Lignin treated with different protein auxiliaries were analyzed,the results showed that protein additives could reduce the non-productive adsorption of cellulase on Lignin,and the more hydrophobic the protein was,the easier it was to bind to Lignin,and the less the non-productive adsorption of Lignin on cellulase was.The same results were obtained by using SDSPAGE to study the effect of protein additives on lignin adsorption of cellulase components.Then,Casein was selected as an additive to synergistically degrade alkaline pretreatment bagasse,and the conditions of enzymatic hydrolysis were optimized.When the temperature was 50 ° C,the p H was 5.0,and the casein addition amount was 50 mg/g substrate,the enzymolysis efficiency was the highest at 66.4%.When using batch feed enzymolysis 20% of high solid content substrate(adding 5%,4% and 3% bagasse at 8 h,12 h and 16 h respectively),the enzymolysis efficiency was increased by 9% compared with the one-time feeding.By studying the effect of protein hydrophobicity on lignocellulosic enzymatic hydrolysis and its mechanism and the optimization of the conditions for the synergistic degradation of alkali pretreatment of bagasse with cellulase,this paper aims to find a more economical and effective protein additive to serve the enzymatic hydrolysis of lignocellulosic and provide a reference for the commercialization of bioethanol.