Study On Decolorization Of Acid Blue 45 By MnP Peroxidase Of Phanerochaete Chrysosporium

By producing enzymes such as peroxidase(LiP),manganese peroxidase(MnP)and Laccase(Lac),Phanerochaete chrysosporium has great effect on different dyes waste water.However,the unstability of the enzyme system and bacterias keep off its industrious application.In order to solve these problems,documents were consulted extensively,and Phanerochaete chrysosporium is applied to treat with blue acid 45 under exterior regulations in the type and concentration of nutrition.The production medium was modified on the basis of the Tien and Kirk medium,containing 20 mmol/L acetate buffer (pH 4.4) instead of dimethyl succinate buffer.Several sets of shaking flask experiments under free and immobilized conditons were conducted. The knotted cotton carriers used in immobilized condition was invented by Doctor Zhou Cheng from Tsinghua University.Cuture conditions and the content of carriers influenced the change of MnP activity and stability,and the system with 370g/L carriers ranked first with 1469U/L MnP. So here we can conclude safely flasks with carriers produce more enzymes and 370g/L was the optimum carrier content.In order to direct the design of fermentation process,a kinetics model was built for the batch culture of Phanerochaete chrysosporium.The parameters in the model were calibrated based on the experimental data from free and immobilized culture separately.The diference between each variable's values calculated based on kinetics model and experimental data was within 15%.The influence of dye concentrations on decolorization and degradation was studied under optimum condition with 370g/L carrier. The experiments showed when the concentrations was lower than 600mg/L,the system had better duplicity,and the decolorization and degradation of acid blue 45 was excellent, since both of them exceeded 90%.On consideration of the high cost in the sterile treatment of reactor,culture medium and wastewater,influence of different injecting time of dyes on decolorizing acid blue 45 with white rot fungi under non-sterile conditions were investigated.The results showed that the decolorization under non-sterile condition was similar with sterile condition,after it was incubated for 1 to 4 days under sterile condition;however,the efficiency was 55% at 2 days if white rot fungus had been incubated for 0.5day under sterile condition.The reason of that decrease was because the growth of white rot fungus was suppressed by acid blue 45 and the reaction system was contaminated by yeast fungus.So,in decolorizing acid blue 45 ,if only white rot fungus is predominated strain in reaction system,the incubating time under sterile condition could be shortened to 1day or more.The study results would provide guidance to the scaled production of MnP and lower the cost of waste water treatment. And the outcomes also have theorical value and practical function in the study of decoloration mechanism by white rot fungi.