秸秆降解菌株的诱变选育及发酵条件的研究

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

摘要:

为提高纤维素酶活性,获得降解秸秆能力强的菌株,采用硫酸二乙酯和紫外线复合诱变方法处理绿色木霉(Trichoderma viride)菌株,通过刚果红培养基初筛并进行10代PDA斜面继代培养和液体发酵复筛,选择纤维素酶活性高的菌株,以秸秆为底物进行液体发酵条件优化.结果表明:选育出6株稳定高产纤维素酶的绿色木霉(T.viride)突变株,其中h157菌株CMCase比出发菌株提高72.53%,FPase提高42.18%,βGase提高85.15%.h157菌株以稻草和玉米秆为碳源可大幅度提高纤维素酶活,稻草和玉米秆的最佳比例为6∶1,最佳无机氮源和有机氮源为(NH4)2SO4和豆饼粉,最佳比例为1∶1,碳氮比为7∶1,碳氮质量分数为3.3%,最适产酶pH为5.2,最佳产酶温度为28℃,最佳产酶时间为第4天.

Abstract:

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.