Optimization Of Condition For Producing Lacease By White-rot Fungus And Application On Rice Straw Degradation

Crop straw is an important biomass energy.The reasonable use of crop straw can effectively alleviate the decrease of fossil fuel and dwindle the environmental pollution of combustion of fossil fuel. It becomes the main research that white-rot fungus producing laccase play role in pretreatment of straw.At present most of the studies of white-rot fungus processing straw were focused on the white-rot fungus growing on the straw medium, using laccase secreteing by white-rot fungus growth on straw. Neither of the growth of white-rot fungus or secretion of laccase is in the best state. In my article the process of white rot fungus growing and laccase production conditions was optimized. Laccase acativity of Pleurotus ostreatus is using at the pretreatment of straw. Analysis of laccase for degradation rate of straw lignin was studied. At the same time, the enz-yme properties of laccase was discussed.There were two means to increase the production of laccase by white rot fungus:firstly, adding natural substances in the laccase production medium, on which basis the optimal culture conditions were explored; Secondly, on the basis of the first method, adding small size porous material namely zeolite powder,by which way new training mode about white-rot fungus producing laccase were explored, and feasibility analysis of the mode of white-rot fungus to produce laccase continuous culture conditions was done. When laccase got high activity, parts of enzymology characteristics of laccase was analyzed, and research of laccase’s effect on the degradation of straw was studied also.The main conclusions include:(1) Adding potato lixivium200g/L, as natural ingredients medium, can effectively improve laccase production, the optimum culture conditions for28℃, and150r/min shaking culture, under this condition the laccase activity could reach112U/mL, and it is significantly higher than the conventional culture39U/mL. Adding0.05g/bottle of zeolite powder, the laccase activity could reach175U/mL;(2)The laccase was able to provide3times in the cultivation of the35d cycle enzyme bacteria liquid, within50%of the original strain of screening and supplementing the same amount of fresh sterile culture after taking out the laccase liquid, and was higher than one-time cultivation way around45d to realize continuous culture,(3)The laccase of Pleurotus ostreatus were analyzed. The best preservation conditions for laccase is of30℃during preservation after centrifuged, optimum reaction temperature of40℃, the optimum reaction pH of5. (4)It was founded that the laccase activity of Pleurotus ostreatus of170U/mL or more has the best ratio of solid-liquid ratio1:5, at the degradation of straw, namely the laccase liquid dosage is5mL/g straw powder. Through80mesh sieve of straw lignin degradation rate was significantly higher than that through40mesh. While straw powder of80mesh sieving, degradated by laccase which was more than170U/mL, the best temperature of40℃, and the best pH of5. Under this condition of the use of laccase treatment15d straw powder, straw lignin degradation rate could reach18%.