INFLUENCE OF 2,4,6-TRINITROTOLUENE (TNT) CONCENTRATION ON THE DEGRADATION OF TNT IN EXPLOSIVE-CONTAMINATED SOILS BY THE WHITE ROT FUNGUS PHANEROCHAETE-CHRYSOSPORIUM

The ability of Phanerochaete chrysosporium to bioremediate TNT (2,4,6-trinitrotoluene) in a soil containing 12,000 ppm of TNT and the explosives RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine; 3,000 ppm) and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine; 300 ppm) was investigated. The fungus did not grow in malt extract broth containing more than 0.02% (wt/vol; 24 ppm of TNT) soil. Pure TNT or explosives extracted from the soil were degraded by P. chrysosporium spore-inoculated cultures at TNT concentrations of up to 20 ppm. Mycelium-inoculated cultures degraded 100 ppm of TNT, but further growth was inhibited above 20 ppm. In malt extract broth, spore-inoculated cultures mineralized 10% of added [C-14]TNT (5 ppm) in 27 days at 37-degrees-C. No mineralization occurred during [C-14]TNT biotransformation by mycelium-inoculated cultures, although the TNT was transformed.