UTILITY OF FOUR STRAINS OF WHITE-ROT FUNGI FOR THE DETOXIFICATION OF 2,4,6-TRINITROTOLUENE IN LIQUID CULTURE
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The purpose of this study was to investigate the potential of four different strains of white-rot fungi (Phanerochaete chrysosporuim, Phanerochaete sordida, Phlebia brevispora, and Cyathus stercoreus) to degrade 2,4,6-trinitrotoluene (TNT) in liquid medium. Loss of TNT from the culture medium was determined using high-performance liquid chromatography (HPLC), while the mutagenicity of the medium residues was evaluated using the Salmonella/microsome bioassay. The data indicate that within 21 dot incubation, all fungi were able to reduce the TNT concentration (from 90 mg/L.) in the liquid medium to below detection limits. In this study, P. sordida showed a relatively high growth rate and the fastest rate of TNT degradation. The fungal treatment also produced a significant reduction of TNT mutagenicity. Treatment with C. stercoreus, P. brevispora, P. sordida, and P. chrysosporium resulted in the elimination of 94%, 90%, 87%, and 67% of the initial TNT-amended medium mutagenicity, respectively. The data also demonstrate that during incubation, TNT was eliminated from the culture medium two to eight times faster than the reduction in mutagenic potential. These results suggest that TNT disappearance alone cannot be used as the sole criterion in TNT remediation. Chemical analysis revealed that the major metabolites in the initial transformation of TNT were the monoamino- dinitrotoluenes, which were also degraded by the selected white-rot fungi. The study demonstrated that the white-rot fungi are capable of metabolizing and detoxifying TNT under aerobic conditions in nonligninolytic liquid medium.
