Screening And Pilot Conditions Of High-yield Xylanase Mutagenized Strains Of Trichoderma Viride

Hemicellulose is an important substance in the cellulosic raw material,which is second only to cellulose,accounting for 15%to 35%of the dry weight of plants.In the current energy shortage,making full use of cellulosic raw materials to produce fuel ethanol has become an energy source.An important way of thinking.In the process of hemicellulose utilization,xylanase plays a vital role in reducing the cost of hemicellulose utilization by increasing the activity of xylanase,thereby reducing the production cost of whole fiber ethanol.The necessary means.In this study,100 strains of mutagenized strains of Trichoderma viride were stored in the laboratory as the starting strains.The mutagenic effects of Trichoderma viride were highly produced by screening,optimization of enzyme fermentation conditions and enzymatic hydrolysis experiments.After conducting research,the experimental results are as follows:1.10 strains of mutagenized strains with higher enzyme activity than 10%of the original strain were obtained by rescreening;10 strains were rescreened,and each mutagenized strain was made into three groups of parallels,and finally obtained A24 and A75 strains with good parallel activity;the genetic stability of A75 and A24 showed that the genetic stability of A75 was more advantageous than that of A24,and A75 was used as the experimental strain for subsequent research.2.The enzyme production conditions of A75 shake flask fermentation were studied by single factor test and orthogonal test.The results showed that the culture formula of A75 was 4.0%,MgSO₄,7H₂O 1%,?NH₄?₂SO₄ 1%,KH₂PO₄ 0.1%,CaCl₂ 0.05%,trace element solution 0.1%,Tween 80 0.04%;culture conditions are pH 5.0,30?,150 rpm/min,144¹68 h,the xylanase activity reached 7715.64 IU/mL is about 28%higher than before optimization.3.The results of 50 L Chinese fermentation of A75 showed that the amount of lactose was 15%¹8%,and the reducing sugar concentration was reduced to 0.6%.The dissolved oxygen value of the fermenter was controlled at 20%^Between 30%,the tank pressure was set to 0.04 kPa,and the rotation speed did not exceed 400 rpm/min.Under this condition,the final xylanase activity reached 40216 IU/mL,which was 18%higher than that of the original strain.4.The results of enzyme characterization of A75-producing xylanase showed that the enzymes produced by A75 were mainly xylanase,and also contained a certain amount of cellulase,and?-glucosidase was almost free.The xylanase is an acidic xylanase with poor heat resistance,an optimum temperature of 50?,and an optimum pH of 5.0.5.Using the steam explosion corn stalks as the enzymatic hydrolysis raw material,combined with cellulase and?-glucosidase,the enzymatic hydrolysis effect of the enzyme produced by A75 was tested.The results showed that the enzymatic hydrolysis effect was the best when the addition amount was 25 IU/mL,1200 IU/mL and 20 IU/mL per gram of dry material.