The Degradation Of Aromatic Leather Chemicals By White-rot Fungi

White-rot fungus is a genetic term of mycelial fungus which can cause white rot to the wood.They can not only degrade the lignin but also degrade aromatic compounds.And because of this,they have great prospect of application in eliminating aromatic compounds.The degradation of aromatic compounds mainly depending on the lignin degradation enzyme system,which can be divided into two types: peroxidase?MnP,LiP?and laccase.In this paper,effects of six dyes and five phenols on the secretion of lignin degradation enzymes by phanerochaete chrysosporium was studied.The results indicated that dyes play different roles in the secretion of lignin peroxidase at different degradation stage,and the introduction of sulfo group in the dye molecule can minimize the inhibiting effect on the secretion of both lignin peroxidase and manganese peroxidase.On the other hand,the phenols which hydroxys located in meta position have less inhibitory action on the secretion of manganese peroxidase then that the hydroxys located in ortho position,and the more number of hydroxys on benzene ring,the less inhibition effect on the secretion of lignin peroxidase.Compared to free cells,the immobilized phanerochaete chrysosporium cells are more stable in the secretion of the enzymes,and the phenols used in the experiment become inducer of manganese peroxidase.However,the secretion of the enzymes is still affected by the metabolism and the inducer,which lead to the unstable of the bioreactor.So we co-immobilized the white-rot fungi cells and their lignin degradation enzymes through Ca-alginate gel particles in this paper.First,we obtained the lignin degradation enzymes from Trametes versicolor,and then the cross-linked lignin degradation enzyme aggregates?CLLDEAs?were prepared The under the cross-linking of glutaraldehyde,The activity yields of obtained cross-linked enzyme aggregates were 42.7% for lignin peroxidases?LiP?,31.4% for manganese peroxidases?MnP?and 40.4% for laccase?Lac?,respectively.And their specific activities were 30.2 U/g as CLLDEAs-Li Ps,9.5 U/g as CLLDEAs-MnPs and 28.4 U/g as CLLDEAs-Lac.Further,the presentof the CLLDEAs in the particles extremely improved their ability to degrade the dyes.Compared to the immobilized Ph.chrysosporium without the CLLDEAs,the co-immobilized particles enhanced the decolorized rate of Acid Violet 7?from 45.2% to 93.4%?and Basic Fuchsin?from 12.1% to 67.9%?.In addition,the addition of the combi-CLEAs improved the adaptability of the white-rot fungal particles to adverse environmental conditions.Because of the high degradation ability and stable of the co-immobilization,this paper also use microcapsule as carrier to fulfill the co-immobilization of the cell and the enzymes.The results indicated that the microcapsule have higher color removal rate than the gel particle to Acid Scarlet GR(0.312555 day-1 and 0.13399days^-1)and Basic Fuchsin(0.0573days^-1 and 0.0467days^-1).What's more,the microcapsule has higher stability than the gel particle in the degradation of Acid Scarlet GR under the existence of trivalent chromium?the degradation rate was 95.0±3.6% and 10.3±4.6% respectively?.