| A thermophil bacterial strain was isolated, in order to gain thermostable cellulase that can convert cellulose, the most abundant renewable source in the world, into glucose and soluble sugars. Physiological and biochemical characteristics of the strain and characteristics of the cellulase were studied. The diluted samples selected from hot compost were cultured on the hemi-restrictive culture medium. The cellulase activities of different strains were measured and compared by the method of DNS. Besides, the cellulase activity of the ferment liquid with bacterium and that of clear liquid without bacterium were compared to determine if the cellulase was extracellular. Physiological and biochemical characteristics of the strain were studied. The results of tests show that the target strain is Bacillus stearothermophilus. Cellulase was purified from ferment liquid by salt out and gel-filteration. The purified cellulase was resolved into at least 8 subunits by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. But, PAGE without SDS didn't resolve it. The characteristics of the cellulase were studied. These characteristics include optimum temperature, optimum pH, and effect of various factors and the value of Km. The results show that the optimum temperature of cellulase reaction process rangs from 60℃~70℃ and the optimum pH is 7.0. The cellulase product and standard samples were compared by thin layer chromatography (TLC) to determine what the product was. The results show that the cellulase product is mainly glucose. |
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