BIOREMEDIATION OF DIOXIN-CONTAMINATED SOILS BY DIFFERENT TYPES OF BACTERIA

摘要

Methods for bioaugmentation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/PCDFs or Cl_XDDs/Cl_XDFs, x=l-8) by gram-positive and gram-negative bacteria have developed. A dibenzofuran (DF)-utilizing bacterium Terrabacter sp. strain DBF63 and a carbazole (CAR)-utilizing bacterium Pseudomonas sp. strain CA10 were used as inocula. In biotransformation experiments of PCDDs and PCDFs, both the DF-grown DBF63 cells and the CAR-grown CA10 cells could degrade the tested mono- to trichlorinated DDs and DFs, and some mono- and dichlorinated DDs and DFs were converted to corresponding chlorosalicylic acid and chlorocatechols. 2,8-Cl_2DF degradation by DBF63 cells and 2,3-Cl_2DD degradation by CA10 cells were also investigated in model soil samples, showing that 90% of 2,8-Cl_2DF was degraded by augmented strain DBF63 after 3 days and that 80% of 2,3-Cl_2DD was degraded by augmented strain CA10 after 5 days. Finally, using both dioxin-degraders, we tried remediation of the actual dioxin-contaminated soil. It was revealed that both strains had potential to degrade tetra- to hexachlorinated congeners including most toxic compound, 2,3,7,8-Cl_4DD.