Screening And Breeding Of Strain Producing High Yield Cellulase And Xylanase Of Penicillium Decumbens

The protoplasts of Penicillium decumbens,the initial strain which produce high yield cellulase,were treated by UV at morality of 98%. A mutant with high xylanase activity was screened and named No.6.The xylanase and cellulase activity of the mutant kept stable after 10 generations.It’s easier using spores to prepare protoplasts than using hypha. When prepare the protoplasts, the spores were pretreated for 8-12h in bourgeon medium. The optimum condition is cellulase 7.5mg/ml, snailase 7.5mg/ml and lysozyme 2.5mg/ml, lytic time 2.5～3h at 30℃.The numbers of protoplasts reached up to 7.25×107 per milliliter, and the optimum condition of protoplasts regeneration is glucose-regeneration culture, the rate of regeneration reached up to 17.1%。We optimized the fermentation condition to get the highest level of the enzymes. The optimum medium follow:major carbon resource bran 4%, supplemented carbon resource glucose 0.1%.There is no other component added. Under this condition, the activity of the xylanase and cellulase was 215.4IU/ml and 19.7IU/ml.The enzymes of the mutant 6 and the parent A50 are characterized. The xylanase and cellulase of A50 have their maximal activity at 50℃and 60℃,respectively. But the two enzymes of the mutant were all optimally active at 50℃.The optimum pH of the xylanase produced by A50 and the mutant was pH 4.2, the optimum pH of the cellulases was pH4.2 and pH 3.8,respectively. The enzymes had better stability in the range pH 3.0-8.0,when incubated at various pHs at 30℃for 12h.The activities of the xylanases were stable when the temperature was below 40℃and the cellulase were stable when the temperature was below 50℃The SDS-PAGE and activity staining of the culture supernatant of the mutant and A50 revealed that extracellular cellulase and xylanase are different.The mutant contained a new xylanase.It show that why the mutant had higher xylanase activity than parent.The colonies of the mutant and the parent are different. They are all white but the mutant grow slowly than parent. The spores of the mutant are shorter and rounder than the parent.