Purification Identification And Mutation Breeding Of Cellulose-degrading Microbial Flora

The paper include three parts to research on the strains which can degradate fibrin: isolate and screen of strains with cellusase activity, mutation of single strain and optimization design of culture condition.Frist, isolate and screen of strains with cellulase activity. Four strains with cellulase activity of bacterial Fl, F2, F3and F4was isolated from a flora called5which saved by laboratory. By morphological observation and16SrDNA sequence analysis,identified F1, F2, F3and F4was Bacillus thuringiensis, Cellulosimicrobium sp., Alcaligenes faecalis and Bacillus cereus.Second, mutation of single strain. The strain F2is mutated by UV mutation and UV-LiCl mutation. After mutation, about7280strains was grew. Though gram’s iodine screen154strains were retained. After cellulase activity screen8strains were retained. Last, one high-effective mutation strain called the UV-LiCl69th strain, was retained after analysis of enetic stability.The mutatent enzyme activity value is0.31mg/ml,1.4times than the original strain.Last, optimization design of culture condition.The best culture conditions of69th mutatent strain was confirmed, by determined the best nitrogen source,content of carbon and nitrogen source. Design orthogonal experiment of the carbon source, nitrogen source and temperature. Optimal result of the orthogonal experiment is the69th culture medium. That is3.0gNa2HPO4,0.5g MgSO4-7H2O,0.5g CaCl2,7.5mgFeSO7H20,2.5mg MnSO4H2O,2.0ZnSO4mg,1000mL distilled water,2%80mesh straw,1%(NH4)2SO4,natural pH. Rotate at150r/min and35℃.The enzyme activity of the69th is0.081mg/mL,3.7times than the original strain.