Optimization Of Laccase Production In Pleurotus Ostreatus In Solid State Fermentation And Its Enzymatic Properties

The expression regulation of laccase is affected by various conditions,including carbon sources,nitrogen sources,metal ions,aromatic compounds,and lignin debris compounds,which can affect the production of laccase,but the effect of various conditions on strains of different species have big different.Different culture methods(solid,liquid)and culture conditions also affect the synthesis of laccase.In this paper,the laccase activity in the substrate of P.ostreatus strain P7 during the cultivation process was studied.It was attempted to produce laccase by solid state fermentation using several agricultural wastes as the basic culture medium,and the medium for the production of laccase by solid fermentation was explored.The composition and fermentation conditions were optimized;and the enzymatic properties of laccase produced by solid fermentation of P7 strain were analyzed;the following main conclusions were obtained:(1)In the different growth stages of Pleurotus ostreatus,the activity of laccase in the matrix was measured.It was found that the laccase activity peaked when the fruiting body grew out,reaching 8.98(10.59)U/g;the zymogram of laccase is similar to that of liquid culture mycelia,and two isoenzymes can be detected.(2)Using rice straw powder,corn stover meal and sawdust powder as the basic culture medium,the growth of P7 strain and the production of laccase were determined.It was found that P7 could use corn stover flour to grow and synthesize laccase.Based on the corn straw powder as the basic matrix,the composition of suitable solid medium was optimized to obtain better enyme production.The optimized conditions are:corn stover 20%,initial media moisture content 80%,glucose 2%,yeast extract powder 0.03%;Cu2+concentration 0.1%;syringic acid 0.1%;cultivated at 28 ? for 32d,the highest laccase activity reached 83.39(±8.05)U/g in the optimal culture conditions,which was 44%higher than that of in the original medium.(3)The enzymatic properties of laccase produced by solid state fermentation of Pleurotus ostreatus P7 were studied.The optimal reaction temperature of the enzyme was 50?,the optimum pH was 5.0,and in the range was 50?-60? and pH4.0-5.0,the activities were relatively stable;DTT,B-mercaptoethanol,L-cysteine inhibited the laccase activity produced by the P.ostreatus strain P7.