Study On Laccase Production Under Solid-state Fermentation And Laccase Application

The laccase production by Coriolus versicolor was studied under solid-state fermentation. Cornhusk was found to be a good carbon source for laccase production and the optimal ratio of cornhusk and wheat bran was 6:4. The optimum moisture content of substrate, inoculation dosage, and culture temperature were 65%, 10% and 30°C, respectively. High laccase activity (75432.5U/g) was obtained by solid-state fermentation after 10 days.The characterization of laccase from Coriolus versicolor was studied. The laccase had the highest activity at 55℃ and pH4.5. It was stable under 40℃ and at pH5-6. The Km value was 0.013 mmol/L with ABTS as a substrate. lmmol/L Cu²⁺ could stimulate the enzyme. The half-lives of liquid laccase at constant temperature and 4℃ were 30d and 66d, respectively. Addition of 4%-8% Na₂SO₄ could improve the storage stability of liquid laccase. Laccase powder was more stable than liquid enzyme.Laccase from Coriolus versicolor was immobilized by the method of being adsorbed first on activated carbon, and then entrapped into calcium alginate gels. The dechlorination of 2, 4-dichlorophenol in wastewater was performed by the immobilized laccase in a columnar reactor. The optimal temperature and pH value for the reaction were 40℃ and 4.5, respectively. Compared with free laccase, the immobilized laccase had a better thermostability, and also had a broader range of pH value and temperature in which the enzymatic catalysis displayed. The removal efficiencies of 2, 4-dichlorophenol (1 mmol/L) were all above 99.5% with the concentration of 0.5mmol/L chloride ions released during repeated 8 batch reactions. The research results had shown a good prospect of application in the biochemical treatment of polluted wastewater.The backstaining caused by indigo blue was always a big problem in the process of biofinishing blue jeans using cellulase from Trichoderma reesei. Laccase could hydrolyze indigo blue and reduce the backstaining. With the laccase dosage of 0.50% (o.w.f), the backstaining extent on white cotton fabric decreased 83% by 60min. The results of scale-up experiments showed that synergistic effect of laccase and cellulase not only reduced 82.2% of indigo blue in biofinishing effluent, but also weakened 83% of backstaining on blue jeans.