Research On Reducing Sugar Production From Sweet Sorghum

Energy consumption has increased steadily, there is a great interest in exploringalternative energy sources. Alcohol can substitute gasoline. At present, the crops straw stalkis the out put rich and the giant textile cellulose straw material, and it has been considered thefuel alcohol for the following resource. For complication of natural plant fiber，how todegenerated them into fermentable sugar is the key problem in biotransformation.Goodpretreatment would decrease impedient function of lignin，and increase the output ofhydrolysis product.In this paper，Filter paper activity（FPA）method was selected to determine the cellulaseactivity of these seven Trichoderma viride and semi-cellulose the activity of methods formeasuring the activity of xylanase. Screening out enzyme activity was higher strains—L21Trichoderma viride. The cellulose and xylanase activity were0.36U/mL and46.27U/mL.The optimal solid state fermentation of sweet sorghum was: ammonium sulfate as nitrogensource, ratio of solid to liquid2:3, water content of media400%, concentrate of surface activeagent0.5%, culture time120h, culture temperature28℃. Ability of enzyme productionwould reach the peak when cells produce a great deal of spores. Enzyme was abstracted andpurified from L21under the optimal condition. The hydrolysis rate was4.58%when treatedthe sweet sorghum in24h,50℃by this enzyme. Effect of particle size of materials,substrate concentration, usage of cellulase and reaction time in enzymatic hydrolysis of sweetsorghum straw was studied in this paper. The enzymatic hydrolysis rate was the highest undercondition as follow:40mesh sweet sorghum straw, ratio of solid to liquid1:30, cellulase200U/g and reaction time24h. The hydrolysis rate was6.94%.The optimal hydrolysis condition of acid-assisted pretreatment was1%diluted sulfuricacid, ratio of solid to liquid1:20,120℃, reaction time5h. The hydrolysis rate was23.77%.The optimal hydrolysis condition of alkali-assisted pretreatment was2%diluted sodiumhydroxide, ratio of solid to liquid1:20, room temperature, reaction time36h. The hydrolysisrate was10.36%. Effect of ultrasonic-assisted, acid-assisted and alkali-assisted pretreatment in enzymatic hydrolysis of sweet sorghum straw was studied in this paper. The resultindicated that the optimal pretreatment technology was the power of ultrasonic120W, theevery treatment time of ultrasonic1s, the quiescent interval of ultrasonic4s and the totaloperation time20min. The research showed that ultrasonic-assisted pretreatment canenhance the enzymatic hydrolysis rates obviously. The hydrolysis rates were20.8%,58.35%,73.22%when ultrasound was combined with acid, alkali, acid-alkali respectively. It showedthat acid-alkali method was the best way to pretreat fiber materials.