纤维素降解菌的筛选与诱变育种

Screening and breeding by induced mutation of cellulose-degrading strains

采用羧甲基纤维素(CMC)平板初筛和50℃培养,筛选到一株纤维素酶活力较高的耐高温霉菌MY菌株,其CMC培养基最适pH为6.0,培养温度为40℃,最佳产酶时间为5d.以MY菌株为出发菌株,分别采用紫外线和硫酸二乙酯诱变,以透明圈直径与菌落直径的比值(HC值)提高30%以上或菌落形态发生明显变异为筛选指标,共筛选到97株突变株;通过测定粗酶液CMC酶活力,从中筛选出29株CMC酶活力提高30%以上的菌株;结合突变菌株的传代稳定性实验,最后筛选得到1株性能优良的霉菌MY004突变株,其CMC酶活力比原始菌株MY提高了80.6%.

A mold strain MY with high cellulase activity and temperature-resistance was screened by cultured on carboxymethyl cellulose（CMC）plate and at 50℃.The optimal conditions for MY strain producing cellulase were as follow：pH of CMC medium 6.0,cultivating temperature 40℃,cellulase producing time 5d.Ultraviolet ray（UV）and diethyl sulfate were applied to mutate MY strain,respectively.30% increasing of HC value（ratio of diameters of clearing zone to colony）and colony morphology with obvious variation were used as screening indexes,and 97 mutants were selected.Subsequently,carboxymethyl cellulase（CMCase）activity of each mutant was determined and 29 strains with 30% increasing of CMCase activity were screened.Finally,MY004 mutant was obtained for its CMCase activity increasing by 80.6% after inoculated 12 generations.