Screening Of Cellulase-producing Fungus And Its Cellulase Charateristics

Cellulose is one of the most abundant compounds on earth, and it is a naturalresource that is almost inexhaustible and renewable. Cellulase can degradate celluloseinto glucose. So Screening fungi that can produce cellulase is meaningful forenvironment protect, food, industrial production, and so on.A fungal strain was isolated that solid sampled Jiangxi Yin Tan which canproduce cellulose with high activity, so we have studied the strain and the cellulasesproduce by this strain. After identify the strain by morphology and molecular, thestrain was belong to Mucor amphibiorum.The fermention conditions of M. amphibiorum was optimized, which was beensure that the optimal medium compositions is: CMC-Na13g, NH₄N_O30.8g,KH₂PO₄2g, MgSO₄1g, Soybean cake meal1g, yeast extract1g, Tween-801mL,H2O1L, pH6.0; and the optimal cultivation conditions for M. amphibiorum is:250mL conical flask contain50mL fermentation liqor,30°C incubating temperature andshaking cultivation at180r/min for6days.The characteristics of the cellulase which secreted by M. amphibiorum wasstudied, and the result is: CMC enzyme can be induced by D-xylose, and all CMCenzyme、C₁enzyme、BG enzyme have two optimum pH, the optimum fermentationtime is6day, the cellulose have the highest activity; and the30°C is the optimumfermentation temperature for produce cellulose; the optimum fermentation pH is6.0.The enzyme activity is slightly activated by Zn2+、Ca²⁺、Fe²⁺、Mn²⁺, whereas Hg+、Al3+can inhibited the enzyme activity.The crude enzyme of β-glucosidase was obtained from M. amphibiorumfermentation broth by ammonium sulfate fractional precipitation. The crude enzymewas used to purify β-glucosidase by DEAE-Sepharose FF ion exchangechromatography. SDS-PAGE electrophoresis showed that the molecular weight ofβ-glucosidase is about72kD. After Kinetic analysis for β-glucosidase, the β-glucosidase binding capacity withglucose is stronger than D-fructose.