Effect Of Polyethylene Glycol On Enzymatic Hydrolysis Of Lignocellulose

Natural lignocellulosic is a kind of abundant renewable resource,which can be used as raw material for bioconversion to produce chemicals,and has great potential to replace traditional fossil fuels as clean energy.Using lignocellulosic as raw material to obtain high value-added chemical or energy products through bioconversion technology is one of the effective ways to solve the existing problems of resource shortage and environmental pollution.However,there are still some limiting factors in its industrial production.In lignocellulosic materials,cellulose,as the main substrate for biological transformation,is wrapped by lignin and hemicellulose.Cellulase cannot be effectively bound to the substrate,resulting in low catalytic efficiency of enzyme,large amount of enzyme loading.Thus,the cost is increased,and the substrate has not been fully transformed.Existing methods mechanical treatment and steam blasting have higher energy consumption.Acid hydrolysis may produce toxic by-products,and ionic liquid is expensive.Looking for environmentally friendly,low energy consumption,low price and effectively improving cellulase hydrolysis method,is conducive to the green development of industrial production.In this paper,the effects of polyethylene glycol on the enzymatic hydrolysis of lignocellulose were studied using rice straw,partially delignificated rice straw and pure cellulose filter paper as experimental materials.Polyethylene glycol(PEG)can be used as additive in the enzymatic hydrolysis of lignocellulose to improve the enzymatic hydrolysis efficiency.The enzyme activity was characterized by reducing the glucose concentration in the supernatant,and the enzyme hydrolysis efficiency was quantified by the method of 3,5-dinitrosalicylic acid.Compared with the improvement of lignocellulosic enzymatic hydrolysis efficiency of polyethylene glycol with molecular weight of 1000,2000,3350 and 4000 respectively,among which,polyethylene glycol with molecular weight of 4000 increased the enzymatic hydrolysis glucose yield of partial delignificated rice straw by 16.0%,and the enzymatic hydrolysis glucose yield of filter paper by 72.3%,which was better than that of polyethylene glycol with other three molecular weights.Compared with 0.5%,1%,2% polyethylene glycol concentration of lignocellulosic enzymatic hydrolysis process of the promotion effect,1%concentration is relatively higher,increased by 9.3%.After the enzymatic hydrolysis system was expanded,the enzymatic hydrolysis efficiency of partial delignificated rice straw was increased by 12.8%,and that of partial delignificated corn straw by 26.0%.In the two experimental groups of adding polyethylene glycol(PEG)and cellulose enzyme synchronously,or adding polyethylene glycol to treat the substrates,and adding cellulase after washing,the efficiency of enzymatic hydrolysis was increased in both groups.In addition to affecting the binding of cellulase to the substrate and impacting on cellulase,polyethylene glycol can improve the hydrolysis efficiency by influencing the cellulose substrate.The effect of polyethylene glycol on the enzymatic hydrolysis of rice straw and filter paper was observed by inverted microscope.It can be seen that the degradation degree of the edge of rice straw slices increased,and the epidermal peeling of filter paper fiber bundle was obvious.The substrate residue structure after enzymatic hydrolysis was observed by scanning electron microscopy,and polyethylene glycol was added to increase the surface crack of fiber substrate.Rice straw,partially delignificated rice straw and filter paper were treated with polyethylene glycol and analyzed by fourier transform infrared spectrometer.The results showed no chemical bond cleavage and functional group change.The accessibility of cellulase to substrate is also one of the limiting factors of industrial production.Polyethylene glycol promotes the physical structure of lignocellulose to become loose,and the increase of epidermal peel,that makes it easier for cellulase to effectively combine with cellulose.Therefore,the efficiency of enzymatic hydrolysis of lignocellulose was improved.This may be a new idea to optimize the process of lignocellulase hydrolysis.