纤维素酶高产菌株的复合交替诱变选育

Selecuion of high cellulase-yielding mutant by compound mutagenesis

以里氏木霉ZM-4为出发菌株,研究了紫外诱变、硫酸二乙酯诱变以及紫外与硫酸二乙酯复合交替诱变等不同诱变方法对其产纤维素酶能力的影响,力求得到高产纤维素酶突变株。结果表明,复合交替诱变的正突变率最高,达45.98%。其中,突变株ZM4-F3具有最高的产酶能力,其滤纸酶活值达11.71U,比出发菌株ZM-4提高了19.75%。对ZM4-F3产纤维素酶酶系进行了详细分析,发现其葡聚糖内切酶、葡聚糖外切酶及β-葡萄糖苷酶酶活均较出发菌株ZM-4有显著提高,其中以β-葡萄糖苷酶酶活增幅最大,达58.3%。利用ZM4-F3降解稻草96h,还原糖产量达2.231g/L,比出发菌株提高了21.7%;利用ZM4-F3降解稻草144h,纤维素分解率和稻草分解率分别达53.01%和68.32%,比出发菌株分别提高了20.2%和14.0%。在对ZM4-F3进行6代连续培养后,仍能保持较高及较稳定的产酶能力,可以应用于工业生产。

Using Trichoderma reesei ZM-4 as original strain, various mutagenesis including UV treatment, DES treatment and compound UV/DES alternate treatment were used to obtain high cellulase-yielding mutants. The results showed that compound alternate treatment exhibited the highest positive mutation rate, as high as 45.98%. The filter paper enzyme activity value of the most efficient mutant ZM4-F3 could achieve 11.71U, 19.75% higher than that of ZM-4. The composition of cellulase produced by ZM4-F3 was analyzed, which indicated that the values of endo-glucanase, exo-glucanase and 13-glucosidase of ZM4-F3 were all higher that that of ZM-4. The β-glucosidase of ZM4-F3 exhibited the highest increase, 58.3 % higher than that of ZM-4. Decomposing rice straw for 96 h by ZM4-F3, the production of reducing sugars could achieve 2. 231 g/L, 21.7% higher than that of ZM-4. Decomposing rice straw for 144 h by ZM4-F3, the cellulose decomposing rate and rice straw decomposing rate achieved 53.01% and 68.32% respectively, 20.2% and 14.0% higher than that of ZM-4 respectively. Cultivated for six continuous generations, ZM4-F3 could still keep a high stable capacity for rice straw decomposing, which could be served in cellulase industrial production.