Study On Optimization Of Laccase Production Conditions By White Rot Fungi And Degradation Of Bisphenol A By Laccase

In this thesis,Laccase production conditions by Coriolus versicolor were explored and the degradation of bisphenol A by using laccase crude enzyme was studied.In order to investigate the role of laccase in the process of degradation,laccase from Coriolus versicolor was used to degrade bisphenol A.The possible product structure was detected by GC-MS and the reaction mechanism was speculated.The degradation of bisphenol E by laccase and the impact of mediator on the degradation rate investigated.The major research achievements were as follows:1.The optimal conditions for the production of laccase by Coriolus versicolor were as follows: initial pH was 4.5,culture temperature was 30 ℃,inoculation rate was 10%,and the activity of laccase activity could reach 804.17 U / L.2.The effect of degradation by Laccase from Coriolus versicolor is obvious: the degradation rate can reach 91.39% when bisphenol A was degraded at 35 ℃,pH 3.6,enzyme dosage 3 mL and initial concentration 10 mg / L.3.Laccase from Coriolus versicolor can effectively degrade bisphenol A in the absence of mediators,especially for bisphenol A of low concentrations,which can almost be degraded totally.The degradation rate can be effected by the initial concentration of bisphenol A,the degradation temperature,the pH of the degradation system,the concentration of the mediator and the amount of enzyme.This laccase is more sensitive to pH and the degradation rate of bisphenol A is higher under acidic conditions.1-Hydroxybenzotriazol(HBT)can promote the degradation rate.4.It is presumed that the intermediate product of Bisphenol A degraded by laccase from Coriolus versicolor include: 1-methyl-4-isopropenyl-2-cyclohexenol,benzene,ethylbenzene,2,4-bis(1,1-Dimethylethyl)-6-methylphenol and so on,the possible reaction mechanisms were deduced.5.Laccase from Coriolus versicolor can degrade bisphenol E.The degradation rate can reach to 53.16% after 7 hours degradation,when the initial concentration of bisphenol E is about 10 mg/L.When the concentration of bisphenol E was 20 mg/L,the degradation rate could reach to 33.72%.The degradation rate can reach to 99% and beyond when HBT(0.5 mmol/L)is used as a mediator.