EVALUATION OF CELLULASE PRODUCTION BY A NEW MUTANT STRAIN OF Penicillium decumbens ML-017

摘要

The parent strain L-06 was subjected to mutation involving treatment of Ethyl Methyl Sulfonate (EMS) followed by UV-irradiation. In the mutation experiment, 106 colonies were selected on the basis of hydrolytic zone on Congo Red medium, and these mutants were further assessed for the cellulase activity by DNS method. One of these mutants, ML-017 showed the highest filter paper activity (FPA) than others. So in this work, Response surface methodology (RSM) was used to evaluate the effects of fermentation parameters for cellulase production by Penicillium decumbens ML-017 in solid-state fermentation using rice bran as substrate. Initial pH, temperature and moisture content were optimized using filter paper activity (FPA) as response. After the optimization, The maximum activity of FPA in ML-017 were 5.76 IU/g. And their maximum FPA were observed in pH of 5.7, moisture content of 72%, and the temperature of 30°C. The FPA in ML-017 was increased by 44.12% compared to its original strain L-06. Transcription and Expression level ofendo-β-1,4-glucanases (EG) gene was determined by semi-quantitative RT-PCR and activity staining respectively. PCR products were cloned and sequenced and a consensus partial sequence for EGI and 18S rRNA gene was obtained. Combining the these results should provide a solid foundation that cellulase activity increased in ML-017 for understanding molecular control of cellulase production ofML-017 that cellulase molecular structure and types may not change but its yield ofcellulase are improved.