The Mutagenesis of Bacillus subtilis Protoplast for Screening Highly Producing Cellulase Strains

The Bacillus subtilis B6 isolated from environment was used for protoplast Ultraviolet(UV) mutagenesis,diethyl sulfate(DES) mutagenesis and combination mutagenesis to screen high cellulase activity mutant strains. The results showed that the cellulase production of 10 excellent mutant strains chosen from 342 mutants was significant higher than B6 through fermentation culture in shaking flasks. The cellulase activities of Z12 from UV mutagenesis,H1 from DES mutagenesis and F12 from combination mutagenesis were 448. 3 ,450. 9 and 491. 8 U /mL respectively, which were more than 70% than that of original strain,further more the mutants producing cellulase abilities had no change over 5 generations. The experimental results showed that the producing cellulase ability of Bacillus Subtilis could be increased through protoplast mutagenesis and combination mutagenesis could improve the mutagenic effect.