| lignocellulose that plants produced through photosynthesis is the most and the cheapest regeneration resource. Plants produces as much as 150 billion tons biomass every year, more than half of which is cellulose and semicellulose. China as a agricultural country, the agriculture is so development that the productivity of corn straw in our country is more than 200 million tons for one year. Most of the corn straw is used to burn or directly discard, very few is been used, which causes environmetal pollution and resources waste. The cellulase produced by microorganisms can be used to degrading native cellulose to sugar, it is of great significance to reduce the environmental pollution and the energy crisis.This research used the soils from the corn straw piles as sample. 88 High-yield cellulase strains have been screened from 1283 cellulase production strains, bond with Congo red but oligosaccharide in medium prepared by sodium carboxymethycellulose as unique carbon source. After the determination of FPA and CMC activity, we get a wild cellulase production strain, which is named sw-75. Sw-75 has been identified as Penicillium.UV-LiCl mutagenesis of sw-75 is prescreened by LiCl-swollen cellulose medium, 88 High-yield cellulase strains have been separated from 963 strains. Subsequent with the determination of FPA and CMC activity, also stability analysis, we get a mutant strain ysw-30, which FPA and CMC activity are increased 50%,27% than the initial strain, respectively.In the last part, we optimize the fermentation conditions of the mutant ysw-30. After single factor experiment and central composite experiment, we get the optimized medium, which contains 3.360% corn straw, 1.677% soybean oil meal, 0.484% urea, 0.258% (NH4)2SO4, 0.010% Tween-80 and MgSO4,CaCO3.Optimal fermentation process is in the 250ml flask, added materials 80ml, init-pH 6, inoculum size 10%, incubation temperature 32℃, rotation speed 180rpm, fermentation time 4 days, the final FPA of cellulase is 1.850IU/ml·min.
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