Studies on mutation breeding of straw degradation strains and its fermentation conditions

To improve cellulase activity and obtain strong degradating strains,the Trichoderma viride(T.viride) was treated by compound mutagenic way of ethyl sulfate and ultraviolet radiation,and high producing cellulase strains were screened by plates of Congo red dying,which then were transfered to PDA culture-medium cultured for 10 generation successively and further screened by liquid fermentation.Liquid fermentation condition was optimized using straw as only carbon source.The results showed that: six T.viride mutant strains with high producing cellulase were breeded,and CMCase,FPase and β-Gase enzyme activity of h157 were increased by 72.53%,42.18% and 69.29% respectively compared with wild strain.The highest level of cellulase activity for h157 was obtained by the compound carbon sources of rice stalk and maize straw,and their optimal ration was 6∶ 1.The optimal organic and inorganic nitrogen source were bean cake powders and ammonium sulfate,and their optimal ration was 1∶ 1.The optimal ratio of C∶ N was 7∶ 1,and the optimal mass concentration was 3.3%.The optimal conditions for producing enzyme were pH 5.2,28 ℃ and 4 d.