Preliminary Research On Synergies Of Laccase And Cellobiose Dehydrogenase In Lignin Biodegradation

In the paper,laccase secreted by white rot fungus Trametes trogii YDHSD was purified.Also,whether different white rot fungi produce cellobiose dehydrogenase was examined.Finally,the synergy mechanism of laccase and cellobiose dehydrogenase involved in the appearing of fading ring was researched.The fermenting condition in which white rot fungus Trametes trogii YDHSD is able to produce laccase was examined.It turned out that the activity of laccase reached the maximum after the fungus was growing for six days.The costs of wheat bran extract media was low and the activity of laccase was high.Also,the laccase produced by white rot fungus Trametes trogii YDHSD was purified.After freezing and thawing,ultrafiltration,ammonium sulfate precipitation,DEAE Sepharose FF anionic exchange chromatography and Sephacryl S-200 size exclusion chromatography,purified laccase was gotten and the molecular weight was about 90 kDa.Whether different white rot fungi produce cellobiose dehydrogenase(CDH) was examined.The activity of CDH produced by Trametes trogii YDHSD,Irpex lacteus dft-1,Trametes versicolor Sdu-4,Trametes hirsuta Lg-9,Schizophyllum commune was very low and almost zero.The production of CDH was not influenced by media component,carbon source and nitrogen source,the way to assay the activity and Sodium Azide(NaN3).The appearing of fading ring was examined.The ability of different organic solvents that extract guaiacol its degrading products was compared.It turned out that acetonitrile and ethyl acetate possessed higher ability.In addition,the activity of laccase and CDH in different areas was assayed,and the substances existing in different areas were analyzed by UV-visible spectrograph.Moreover,the appearing of fading ring was proved by laccase secreted by Trametes trogii YDHSD and dithiothreitol(DTT).It is concluded that in the red area guaiacol was oxidized by laccase by white rot fungus,and in the fading area the red substance was reduced by CDH.The appearing of fading ring is an oxidation-reduction process.Laccase and CDH not only play an important role in the appearing of fading ring in the plate,but also are the essential enzymes in the degrading of lignin.It turned out that the synergies of laccase and CDH is that CDH can reduce the product that was oxidized by laccase.