Impact of DDT Stress on Laccase Production and Isozyme Patterns of Ectomycorrhizal Fungus Xerocomus chrysenteron

摘要

Four oxidative enzymes,which were considered as key enzymes in DDT biodegradation of fungi,were tested 15 days after cultivation in the solid culture.Three of these enzymes,laccase,polyphenol oxidase and peroxidase were observed in all the cultures.X.chrysenteron showed very strong laccase activity in both control and DDT treated cultures.The laccase activity increased along with raised DDT concentration,this result indicates laccase as a potential key enzyme during DDT biodegradation by X.chrysenteron.To study DDT's impact on laccase production,different amounts of DDT were added to the liquid culture media on the lOth day.After 20-day exposure,the laccase activity was significantly higher than control.Native-PAGE staining with ABTS illustrated the laccase isozyme patterns after 20-day exposure to DDT.It showed two laccases isoformed in both control and DDT treated cultures,while DDT-treated cultures also showed a third isoform.This result indicated the impact of DDT or its metabolites on laccase production and that laccase might be an important enzyme in DDT's biodegradation by X.chrysenteron.