Study On The Mechanism Of Synergistic Action Of Cellulase Produced By Trichoderma Viride And Its Application

Straw is an abundant and sustainable renewable energy resource.The cellulose in the straw is the main component for bio-energy products.And the efficient saccharification of cellulose to produce reducing sugars is a prerequisite for reducing the cost of bio-ethanol production.Three components of cellulases:endoglucanase,exoglucanase and?-glucosidase involves into cellulose saccharification.It is the key to improve the saccharification ability of cellulase to adjust the proper ratio of the three components.In this dessertation,the fermentation media components and condition for cellulase production by Trichoderma viride AS3.3711 was first optimized under the liquid fermentation.Then the principal component analysis and non-linear regression analysis were applied to explore the most suitable proportional relationship of the three cellulase components synergistic effect.Finally,the inner law of simultaneous saccharification and mixed fungi fermentation for ethanol was studied.The study laid the foundation for bio-ethanol.The main conclusions are as follows:?1?The effect of various carbon sources,nitrogen sources,inorganic salts,and nutritional factors on cellulase synthesis was compared using mono-factor-at-a-time.The orthogonal design was applied to optimize the medium composition for the synthesis of CMCase and FPase by T.viride.The optimum medium for CMCase products included?g/L?fructose 0.235,xylose 0.5295,corn steep liquor 2.3688,CaCl₂ 0.061,FeSO₄ 0.0111,ZnSO₄ 0.0528.The maximum enzymatic activity was8.268 IU/mL.The optimum medium for FPase products included?g/L?fructose 6,corn syrup 9.546,soybean meal 3.564,CaCl₂ 0.326,FeSO₄ 0.08,ZnSO₄ 0.08.The maximum FPase activity was 4.9242 IU/mL.?2?The principal component analysis was applied to construct the comprehensive hydrolysis index?CHI?including a single action and interactions of endoglucanase,exoglucanase,and?-glucosidase.Using the yield of total reduce sugar(Y_trs)as the dependent variable and CHI as the independent variable,the nonlinear regression confirmed a positive correlation between CHI and Y_trsrs under the test conditions.Using Y_trsrs as the response value,the activities of endoglucanase,exoglucanase,and?-glucosidase were used as independent variables,the regression analysis showed the most suitable proportional relationship for the synergistic action for the three enzymes components was 13.6:3.8:1.Under this condition,the optimum saccharification action of straw was obtained,and the maximum Y_trsrs is 48.43%.?3?The action of each factor on the ethanol production in the process of the simultaneous saccharification and fungi fermentation mixed Saccharomyces cerevisiae period with xylose yeast confirmed by orthogonal design was listed as following:fermentation cycle>initial pH>fermentation temperature>yeast inoculum.The optimum conditions for fermentation with mixed strains are as follows:yeast inoculation ratio was xylose yeast:S.cerevisiae as 1:3,fermentation temperature 32°C,inoculation amount 12%,fermentation period 144h,initial pH 5.Under the condition,the yield of ethanol was 10.924 g/L using the T.viride broth as cellulase solution.Under the similar condition,the yield of ethanol was increased 22%us the cellulase with the optimum proportional components.The rules of cell growth,substrate consumption and product synthesis in the process of the alcohol fermentation were studied.The various kinetic equations were obtained by origin software.