Study On The Screening Of Cellulolytic Strains Degradation Characteristic Of Cellulose

The microbe degradation would be most potential and ideal way for application of cellulase. Because the degradation activity of microbe is finite, mechanism of cellulose biodegradation is focus on the single and model microbe, so far application of cellulose is relatively deferrable. In order to solving of present environmental and energy crisis, the high degradation activity microbe screened and research of mechanism of cellulose biodegradation would have important theory and practice value.A new strain of cellulolytic fungus is isolated from soil, when grown on cellulose double plate, the velocity of growth is rapid and the result of degradation of cellulose is good. The morphological and physiological properties of this strain are studied. According to these, the strain is identified as Penicilliun terrestre Jensen. In this base, the medium components of the optimal liquid state fermentation, the physiological properties of the crude cellulase and the purification of cellulase from this strain are studied. The results are illustrated as follows:A new strain of cellulolytic fungus is isolated from soil by cellulose double plate, the result of degradation of cellulose powder CF-11 is good. To see the characterization of the colonies, the mycelia and conidia, this strain is inoculated on the Czapek medium after isolation. According to Manual of Determinative Fungus and related bibliography, the strain is identified as Penicillium terrestre ,we named it Penicilliunm.DS-811.Penicilliun sp.DS-811 is inoculated in 6 different liquid state culture mediums. CMCase, FPase in each medium and the time of cultivation are compared so that the optimal original liquid state fermentation medium is decided. In the base of the original fermentation medium, the optimum culture conditions are studied. The culture conditions include carbon source, nitrogen source, initial pH of medium, inoculation amount and velocity of shaker. The results show that the optimum conditions of producing cellulase are as follows: The temperature is 30℃,the initial pH is 7.0, the shaking speed is 140r/min,the inoculation amount is 12.5% facilitates cellulase production. The highest cellulase activities are obtained by using 2%CMC-Na as carbon sources and 1%NaNO3 as nitrogen source. Under the conditions mentioned above, the activities of CMCase and Fpase in the cultivation broth after growing 144h are 103.31U/mL and 53.34U/mL, respectively.The crude cellulase was purified by ammonium sulfate fractionation and freeze-drying. The anlysis shows that the optimum temperature of CMCase activity was 40-60℃,the optimum pH of CMCase activity was 4.0.The optimum pH of CMCase was 4.0. When the temperature was 30℃-50℃and the pH was 5.0, CMCase and were stabilified. The purified cellulose assayed by SDS-PAGE shows one protein band which shows that the purified cellulase is haplo-component. Meanwhile, this shows molecular weights of this enzyme about 77,000Da.