Study On Lignin Peroxidase Of White-Rot Fungus

Basidiomycetes white-rot fungi which can secrete several extracellular enzymes, in which LiP plays a dominant role in lignin degradation. Researching and optimizing fermentative conditions of LiP and degrading rice straw by LiP is the main purpose of this dissertation.Under static culture condition, the results showed that the optimum culture conditions contained the following(L-1): Glucose 2g, ammonium tartrate 24mmol, veratryl alcohol 3mmol, Tween 80 1g, acetate buffer (pH4.5) 10mmol, KH2PO4 4g, MgSO4.7H2O 0.2g, CaCl2.2HO2 0.4g, VB1 1mg and trace elements 70ml. The highest lignin peroxidase activity appears in the sixth day after incubation in the above culture at 37℃. Under the condition of shaking culture, the results showed that the optimum culture conditions contained the following (L-1): Glucose 10, ammonium tartrate 2mmol, veratryl alcohol 3mmol, Tween 80 1 g, acetate buffer (pH4.5) lOmmol, KH2PO43g, MgSO4-7HO2 1g, 0.05g CaCl2.2H2O, VB, 1mg and trace elements 70ml. The highest lignin peroxidase activity appears in the eighth day after incubation in the above culture at 37℃,160r/min.We analysized synthesis of LiP under different culture conditions through SDS-PAGE, the quantity of protein in gel is corresponding to LiP activity. This showed the increase in quantity of LiP isoenzyme made total LiP activity correspondingly improved when the culture condition was changed.Having crude enzyme of LiP from static culture to degrade rice straw, the degrading rate of lignin is 8.7% at the 4th day. Through IR spectrum analysis of extractive products of degraded and undegraded rice straw by crude enzyme of LiP from static culture , it is found main reaction was oxidative reaction in lignin biodegrading process.