Study On The Fermentation Of Lignin Peroxidase Of Penicillium Sp.P6

The degradation of lignin is the critical process and step of utilizing plant cellulose materials effectively. There are three kinds of lignin-catalyzing enzymes produced by fungi: Lignin peroxidase (LiP), Manganese peroxidase (MnP) and Laccase. LiP is the key enzyme of degradation of lignin; it can also degrade polycyclic aromatic hydrocarbons (PAH).Penicillium sp.P6 selected and cultured by our laboratory is an effective lignin-degrading fungus, it can produce extracellular LiP and a little MnP. In this research the production of LiP and MnP was studied, and the fermentative parameters of LiP production were optimized.First the effects of rice bran, maize bran, wheat bran, GMY media were investigated, the results showed in all of four kinds of media MnP activity was more lower, LiP was higher, and wheat bran was the optimal substrate for LiP production. The effects of adding benzyl alcohol and MnSO₄ to wheat bran medium on LiP activity were subsequently studied, the result showed MnSO₄ had a good effect. In addition medium volume, initial pH and culture temperature were assayed, the result showed the optimal values were pH 4.8, medium volume 100mL/500mL and 28 ℃. Furthermore the orthogonal experiments on MnSO4 content, wheat bran and medium pH were carried out. The results revealed that wheat bran and pH had significant effect, but MnSO4 content was not, and the maximum activity of LiP reached 2.69 U/mL. On the basis of the above the single and double factors methods confirmed the optimal content of wheat bran and MnSO4 were 5% and 5.66mM respectively. So far, under the inoculums of 1.1 × 106 spores/ mL the suitable conditions of fermentation were determined as follows:, fermentation time 8d, pH 4.8, medium volume 100mL to 500 mL triangular flask; wheat bran content 5%, and MnSO₄ 5.66mM.Under the optimal parameters, an experiment was done in 10L fermenter. During 4d's fermentation, LiP activity showed a process of ascending first, then descending, and there was a max of 3.03U/mL of LiP activity at 76.5 h and pH 6.0.