| Production of chitosanase by Trichoderma viride was studied. The optimal compositions of the medium were as follows (g·L-1): solved chitosan 9.0, glucosamine 5, peptone 8.5, K2HPO4 1.6, CaCl2·2H2O 0.55, MgSO4·7H2O 0.3, FeSO4·6H2O 0.07, MnSO4·H2O 0.016, ZnSO4·7H2O 0.014, CoCl2·6H2O 0.037. The optimal culture conditions were as follows: the initial pH 5.5, temperature 28℃, inoculum size 6%, 75 ml medium in 250 ml shaken flask. In optimized conditions, the activity of chitosanase reached 291 u·L-1 after 40 h, 29.9% higher than original conditions.The immobilization of Trichoderma viride 867 was also studied. The optimal immobilized conditions were as follows(flasks): inoculum size was 107/mL, support weight was 0.6 g/50 mL medium, stay time was 2 h, culure time was 48 h.Chitosanase was simply purified by salting out, dialysis, ultrafiltration. The optimal concentration of ammonium sulfate was 60%, After purification, the specific activity of chitosanse was 1.3 times higher than the original one, and the recovery of chitosanase was 74.4%. Experiments showed that the optimal reaction temperature and pH of chitosanase were 55℃and 5.0, respectively. The enzyme was stable between 30-60℃and pH 4.5-6.0. The optimal substrate was chitosan. Cu2+, Fe2+, Zn2+, Mn2+, and urea had inhibition effect, while K+, Ca2+ had activation effect. In addition, Mg2+, EDTA had little effect on chitosanse.Degradation of chitoan using chitosanse produced by immobilized Trichoderma viride in convoluted fibrous bed bioreactor was studied. Experiments showed that the optimal immobilized conditions was glucose 100g/L, inoculum size 107/mL, aeration rate 2.0 vvm, rotate speed 300r/min. Usiong 1% chitosan as the only carbon and nitrogen source, The degradation rate was very stable in eight batch. The mean degradation rate of these eight batch was 80%. On the condition of adding 10 L culture medium per day, the degradation rate was stable and reached 70% during 7 days.
|
PDF Full Text Request