Screening Of Cellulase Highly Producing Trichoderma Strains And Their Degradation Efficiency Of Crop Straw

Straw cellulose is one of the most abundant renewable carbohydrate resources inthe world,it is not easy degraded by animal for its complicated structure. Cellulaseproduced by microorganisms can improve the digestibility of animal feed on straw. Thisstudy included:Strain with high cellulase activity were screened based on the existingTrichoderma viride strains.The optimization of media and culture conditions forTrichoderma viride; Preparation of crude enzyme solution, and the crude enzyme extract;The degradation effect of cellulose on Crop Straw;The main results were as follows:1. Based on six Trichoderma viride strains, two fungi strains with relatively higherenzyme activity were selected by the preliminary screening of Filter Paper culturemedium and final screening of cellulase production, that is Trichoderma viride X-57andTrichoderma viride BS.2. The main medium of submerged fermentation was optimized by single factor andorthogonal test,then the culture conditions was optimized by single factor test based onthe optimum substrate component. The optimal medium of X-57was determined: Theconcentration of stalk power and bran(the ratio was4:3) was2%,the concentration ofNH4NO3was0.4%,the concentration of tween-80was0.05%,added0.5%KH2PO4to thesubstrate;The optimal culture conditions of X-57was determined:The inoculum was6%,the rotation rate was175r/min,the cultivate time was4d,at this condition the CMCaseand filter paper activity were1677.53U/mL and282.69U/mL respectively.The optimalmedium of BS was determined: The concentration of stalk power and bran(the ratio was4:3) was2%,the concentration of NH4NO3was0.4%,the concentration of tween-80was0.1%,added1%KH2PO4to the substrate; The optimal culture conditions of BS wasdetermined:The inculum was5%,the rotation rate was175r/min,the cultivate time was3d,at this condition CMCase and filter paper activity were1523.38U/mL and203.41U/mLrespectively.3.The staged-control process of fermentation for cellulase in the5L fermentor wasstudied. The CMCase of triangular flask for X-57is higher than the fermentation intriangular flask and the natural fermentation, respectively removed to36.3%、24.3%. The CMCase of triangular flask for BS removed to21.4%、14.9%.In this Paper,westudied the extracting condition of enzyme.The results showed that the CMCase of X-57and BS reached the maximum when the rotate speed of centrifuge was4000r/min andcentrifuge time was15min.The cellulase activity of X-57and BS were higher whenusing buffer as extractant than pure water in the vitality test of cellulase.The X-57cellulase activity were higher extracted by70%alcohol than extracted by ammoniumsulfate and the BS cellulase activity were higher extracted by70%ammonium sulfatethan extracted by alcohol.4.The study shows that the rice straw cellulose degradation rate can reach31.79%and hemicellulose degradation rate reached27.31%by the aerobic fermentation of X-57;Cellulose degradation rate can reach25.47%and hemicellulose degradation rate reached18.46%by the aerobic fermentation of x-57.The protein content of rice straw increasedby79.4%through the aerobic fermentation of X-57crude enzyme solution;The proteincontent of rice straw increased by58.1%through the aerobic fermentation of BS crudeenzyme solution.