| Laccase(E.C. 1.10.3.2)is copper-containing oxidase that catalyse the oxidation of aromatic compounds. It is widely used in biological, chemical, medical and environmental fields. In this thesis, the submerged fermentation and solid-state fermentation of Coriolus versicolor laccase, the enzymatic characterization, and the application of laccase in indigo and gold orange Ⅱ decolorization was investigated. The major results were as follows:The laccase production by Coriolus versicolor was performed in submerged fermentation, using corn husk as carbon source and carbamide, ammonium sulfate as nitrogen source. It was found that the suitable C/N, temperature and pH value was 20, 30℃ and 4.5, respectively. The laccase activity reached 4570.8 IU/mL at 6 d in an Erlenmeyer flask. The laccase production in a 3.7 L fermentor showed that the appropriate aeration and agitation speed were 0.75 vvm and 300 r/min, respectively. Under optimized conditions, the laccase activity could reach 4948.4 IU/mL at 144 h.Laccase production by Coriolus versicolor using lignin residue, recovered from the alkali extracting liquor of corn stover, as culture medium in submerged fermentation was investigated. Results showed that the laccase activity could be significantly improved by lignin residue. When 6 g/L lignin residue was added to culture medium in an 250 mL Erlenmeyer flask, the laccase activity reached 7005.6 IU/ml which was 5.0 times as high as that of the control whose activity was 1390.1 IU/ml. Suitalbe content of glucose could enhance the Laccase production, and the laccase activity was increased to 7283.6 IU/ml when 10 g/L glucose was added to the culture medium. Furthermore, adding method of glucose into medium was investigated, it showed that the laccase yield by adding in-batch (initial concentration 5g /L and adding to 10 g/L 3 d later) was 20% higher than by adding once for all. Laccase activity could reach 7506.2 IU/mL in a fermentor.The laccase production by Coriolus versicolor was studied under solid-state fermentation. Results showed that cornhusk was a good carbon source for laccase production and the optimum ratio of cornhusk and wheat bran was 6:4. The optimumwater content of substrate and inoculation dosage were 65% and 10%, respectively. When 0.5% glucose was added to culture medium, the laccase activity reached 75549.5 IU/g. On the optimum medium, the activity of laccase could reach 75432.5 IU/g after 10 d, which was much higher than that of the literature reported.The laccase storage stability was investigated. Result showed that laccase powder was more stable than liquid enzyme. At room temperature, the half-lives of liquid laccase and laccase powder were 30 d and 60 d, respectively. At 4℃, the half-lives of liquid laccase was 66 d, and the residual activity of laccase powder was 83.0% after conserved for 6 months.The characterization of laccase from Coriolus versicolor was investigated. The optimum temperature and pH value of laccase were 55℃ and 4.5, using ABTS as substrate. It was stable under 40℃ and at pH 5～6. The laccase was used to decolorize two general commercial dyes, indigo and gold orange Ⅱ. In the decolorization of indigo, the suitable pH value, temperature and the content of HBT was 4.5, 30℃, 2%. When the laccase concentration in indigo dyeing Wastewater was 3.75 IU/mL, the decolorization rate of indigo reached 93% in 420 min. While in the decolorization of gold orange Ⅱ, the suitable pH value and the content of HBT was 4.5 and 2%. When the laccase concentration in gold orange Ⅱ dyeing Wastewater was 14.0 IU/mL, the decolorization rate of gold orange Ⅱ reached 90% in 540min. The results were of great value both in environment protection and in treatment of dyeing Wastewater.
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