Study On Biodegradation Of Nitrogenous Heterocyclic Compounds By Laccase Mediator System

Nitrogenous heterocyclic compounds are quite toxic to the environment and human health,which are widely existing in coking plants, medical wastewater, printing and dyeing plants andso on. Therefore, it is very important to research on the water restoration of nitrogen heterocycliccompounds. Laccase exists widely in fungi, which is characterized by the substrate diversity. Bycontrast, pure laccase enzyme preparation is characterized by effectiveness and specificity. Purelaccase enzyme preparation and small molecular mediator combine to form laccase mediatorsystem, which has significant effect on pulping and papermaking, dyeing and decolourization,detoxification of wastewater, soil remediation and so on. The main research results of this paperinclude:The fermentation medium which mainly contains bagasse was optimized by using responsesurface methodology to get maximum laccase activity. According to the result, laccase activitymaximum was96480U/L, when the best addition was bran8.14g/L, cottonseed meal0.6g/L,bagasse50g/L, Tween-800.42mL/L, KH₂PO₄1g/L, MgSO₄1.5g/L, CuSO₄0.04g/L,ZnSO₄7H₂O0.2g/L, yeast extract2.83g/L, respectively.The article researched on enzymatic properties of laccase enzyme preparation Pleurotusostreatus. The best temperature and pH value were50oC and4.0. Catalytic reaction of thelaccase enzyme preparation was complied with Michaelis-Menten kinetic rules.Laccase/ABTS mediator system could degrade low concentration indole and pyridineefficiently, but quinoline could not. The optimal conditions were obtained for indole as follows:pH value3.0, ABTS concentration0.5mmol/L, laccase addition1U/mL, and the new substancesmaybe oxindole and isatin.The co-effect of indole mixed with pyridine showed a contradictory effect, while theco-effect of indole mixed with quinoline showed a cooperative effect, and indole degradationwas enhanced when the co-effect of pyridine and quinoline mixed with indole.