Screening And Establishment Of Lignocellulose Synergy Hydrolysis System With White-rot Fungi Extracellular Broth

White-rot fungi which have complete lignocellulose-degrading system have an advantage for the degradation of lignocellulose in natural state. Thus, it was possible to construct a complex enzyme hydrolysis system with the enzymes of white-rot fungi extracellular broth and commercial cellulases. This work evaluated the effect of extracellular broth from 9 strains white-rot fungi and 1 strain brown-rot fungus on enzymatic hydrolysis of different kinds of lignocellulose, constructed the composite enzyme system with extracellular proteins from Echinodontium taxodii 2538 and cellulase. Further, the effects of temperature and ratio of composite enzyme system on enzymatic hydrolysis were also investigated, and then optimised the system.This work first evaluated the activity of lignocellulose-degrade enzymes in the extracellular broth of 9 white-rot fungi strains and 1 brown-rot fungus strain, and evaluated the hydrolysis efficiency of extracellular broth of these strains. Then the effect of extracellular broth and extracellular proteins of these strains on enzymatic hydrolysis of different kinds of lingocellulose which came from different species was evaluatede. The results showed that the extracellular proteins from Ganodermae sp. EN2, Echinodontium taxodii 2538 and Irpex lacteus 254 could increase the initial hydrolysis rate remarkably, and reducing sugar yeild of enzymatic hydrolysis on alkali treated com stalks, alkali treated bamboo and alkali treated hard-wood were improved by 10.60%,15.82%,12.60%; 22.85%,36.77%,21.39%and 1.95%,34.75%,23.26% after hydrolyzed 6h. The coposite systems were constructed preliminarily, and the synergistic action between extracellular broth and cellulase was found in them.To make further explorations of the mechanism of synergistic action in the hydrolysis system, HPLC was used to analysis the monosaccharide yeild of hydrolysis of lignocellulose pretreated by different meansures(original corn stalks, alkali treated corn stalks and acid treated corn stalks). The results showed that xylose yeild was increased by adding extracellular proteins from Ganodermae sp. EN2 leading to the increase of reducing sugar yeild. Extracellular proteins from I. lacteus 254 significantly increased the initial rate of hydrolysis of cellulose. After lh hydrolysis of original corn stalks, alkali treated corn stalks and acid treated corn stalksfor, the glucose yeild in the composite system were 57.50%、36.78%、67.98% higher than control. The synergy effect of cellulose hydrolysis between commercial cellulase and extracellular proteins from E. taxodii 2538 was observed significantly, the glucose yeild of hydrolysis of original corn stalks by the composite system at 1h,6h,24h was 87.25%,15.96%,9.45% higher than control; the glucose yeild of hydrolysis of alkali pretreated corn stalks by the composite system at 1h,6h, 24h was 87.25%,15.96%,9.45% higher than control; the glucose yeild of hydrolysis of acid pretreated corn stalks by the composite system at 1h,6h,24h was 87.25%,15.96%,9.45% higher than control. In summary, the extracellular proteins from I. lacteus 254 and E. taxodii 2538 could remarkably increase the hydrolysis rate of cellulose in lignocellulose feedstocks, and extracellular proteins could also improve the final glucose yeild in composite system.Mild pretreat processes and low enzyme loading are required in the field of lignocellulose hydrolysis in industrial applications. Therefore, the effects of enzyme loading and degree of pretreatment on composite hydrolysis system contrasted with commercial cellulase and E. taxodii 2538 extracellular proteins were detected. And this system was opitimized by detection the effects of different ratio and different temperature on the composite system. The results showed that the glucose yeild of all 3 kinds of hydrolysis system was reduced while the enzyme loading was reduced by 50%, but the reduce dgrees of composite system contructed with I. lacteus 254 extracellular proteins and with E. taxodii 2538 extracellular proteins were lower than control, showing that to some extent the white-rot fungi extracellular protein could reduce the demand of enzyme loading. Then the composite system contructed with E. taxodii 2538 extracellular proteins and commercial cellulase was opitimized, and the optimal ratio of fungus proteins and commercial cellulase is 1:3, and the optimal temperature is 48℃, with the glucose yeild of 624.52 mg/g feedstock in 48 h.Through the evaluation, screening and optimization, coposite system which was constructed with E. taxodii 2538 extracellular proteins and commercial cellulase was obtained. This system can increace the glucose yeild of lignocellulose hydrolysis with the dosage of commercial cellulase beng reduced, which has application prospect.