Screening And Characterization Of Decabromodiphenyl Ether Degrading Ectomycorrhizaes And Their Application On Assiting Phytoremediation Of Contaminated Soil

Polybrominated diphenyl ethers (PBDEs) are flame retardants that have been widely integrated into textiles, plastics and electric appliances for several decades. Once the electric appliances discarded, they will become electric wastes. The dismantling workshops had contaminated air, water and soil for its rough dismantling electric waste method. How to eliminate PBDEs in contaminated soil is just an urgent question. In this paper, Decabrominated diphenyl ethers (BDE-209) degrading ectomycorrhizas and degrading characteristic were studied. These results will serve as a significant reference for mycorrhizal-plant co-remediation in organic pollutant sites.Laccases of fungi attract considerable attention due to their possible involvement in the transformation of a wide variety of non-specific compounds including the polycyclic aromatic hydrocarbon polymeric lignin and humic substances. Laccase is an important element in environmental remediation. In this paper, Laccase producing strains were screened and the effects of laccase in BDE-209 degradation were also discussed. There were three ectomycorrhizal fungi which can produce laccase from nineteen ectomycorrhizal fungi inoculated in guaiacol medium, Cenococcum geophilum, Laccaria bicolor and Laccaria amethystina. In liquid condition, C. geophilum had produced the highest laccase activity for 11.7 U/L to the thirty day. When Cu concentrations were 30 umol/L and 50 umol/L C. geophilum get the highest laccase activity in the 25 day detection. These results exhibit that C. geophilum is a fine laccase producing strain. To test the deca-BDE tolerance of C. geophilum, C. geophilum inoculated contain different deca-BDE concentrations and measure the colony diameter at day 50. When the Deca-BDE concentrations were below 10 mg/L, deca-BDE will not affect the diameter of C. geophilum. Once the deca-BDE concentration was above 20 mg/L, it will inhibit the diameter of C. geophilum significantly. The C. geophilum was inoculated in liquid condition with lmg/L deca-BDE and there is no obvious degrading among 30 day inoculation and the fifty day the residue rate of deca-BDE was 35%. Laccase was parallelled detected, the laccase activity was around 0.5 U/L, so laccase may not affect BDE-209 degrading.Seventeen deca-BDE degrading ectomycorrhizal fungi were successfully screened from thirty ectomycorrhizal fungi. P. tinctorius and L. amethystina can degrade deca-BDE with ten day inoculation after optimized the inoculation time. The degrading rates were 54.1% and 45.8%. The dissolve promoter tween 80 retarded deca-BDE degrading of P. tinctorius, or inhibited it.Organic pollution usually accompanies with heavy metal pollution in e-waste dismantling area. The tolerance and the effects of heavy metal on degrading strain will affect in situ application. No significant growth of P. tinctorius was observed when Cu concentration over 300 mg/L on plate. However L. amethystina can grow at 400 mg/L Cu treatment. No significant growth of P. tinctorius was observed when Cd concentration was 50 mg/L on plate, however, L. amethystina can. The inhabitation rate of P. tinctorius was 82.3% and 44.2% for L.amethystina when the Cd concentration reached 50mg/L. In liquid condition, the inhabitation rate of P. tinctorius was 67.7% and 43.4% for L.amethystina when the Cu concentration reached 50 mg/L. In vitro experiment showed that L.amethystina was better than P. tinctorius for the tolerance of Cu and Cd.There is no significant difference for the degradation rates of P. tinctorius and L. amethystina at 0 to 50 mg/L Cu and 0-10 mg/L Cd. The degradation rates decreased when Cu and Cd concentrations increased. When the Cu concentration reached 200mg/L, the degradation rate of P. tinctorius and L. amethystina were 19.4% and 11.9% in ten day. The degradation rate of P. tinctorius and L. amethystina were 15.2% and 6.26% when the Cd concentration reached 50 mg/L. The degradation rate of P. tinctorius was better than L. amethystina at higher Cu and Cd concentration treatment.The degradation rate of P. tinctorius was better than L. amethystina at normal condition, the residue degradation rate may maintain certain degradation rate at higher Cu and Cd concentration treatment.Cytochrome P450 is a kind of intracellular enzyme which involved in a lot of xenobiotic compound transformed in fungi. The P450 inhibitor 1-ABT was investigated whither it will affect the deca-BDE degrading of P. tinctorius and L. amethystina.1-ABT will not affect deca-BDE degrading of P. tinctorius and L. amethystina will when the concentration was 50 μmol/L. The mechanisms of deca-BDE degrading pathway of P. tinctorius and L. amethystina need further investigation.The biomass of root, stem and needle of pine were significantly increased after inoculated with L. amethystina and C. geophilum. The accumulations of BDE-209 were also increased in root and needle by inoculated with L. amethystina and C. geophilum. Besides, the content of BDE-209 was the lowest around symbiosis plants. These results exhibited the degradation effects of L. amethystina mycelium was better than C. geophilum mycelium and non-mycorrhizal plants.