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BIOREMEDIATION OF TNT WASTES BY HIGHER PLANTS
W.F. Mueller 1 , G.W. Bedell 1 , S. Shojaee1 and P.J. Jackson2 , 1 New Mexico State University, Department of Chemistry and Biochemistry, Las Cruces, NM 88003 and 2 Los Alamos National Laboratories, Life Sciences Division, Los Alamos, NM 87545
ABSTRACTThe uptake and biotransformation of TNT was studied in cell suspension cultures and in wholeplants of Datura innoxia and Lycopersicon peruvianum. In cell culture, TNT was rapidly removed from the growth medium and recovered from the cell extract in the form of a variety of biotransformation products resulting from nitroreduction, deamination, N- acetylation and side chain oxidation to aldehyde and carboxylic acid metabolites. Whole plants of the same species grew well in soils contaminatedwith TNT up to 750 ppm; at 1000 ppm TNT the Datura plants showed some signs of phytotoxicity, while the Lycopersicon plants were severely affected. Both species removed TNT from soil and stored its metabolites at levels up to thirty times higher than the TNT soil concentrations. After a two week growth period, only 4 to 9.2% of the applied TNT was found in the soils.KEY WORDSbioremediation,2,4,6-trinitrotoluene (TNT), soil, explosives, plants |

INTRODUCTION
Soil contamination with 2,4,6-trinitrotoluene (TNT) and related explosives is a problema at many military installations and at some sites operated by the Department of Energy. Explosives residues in soil can be mobilized by surface runoff and by leaching into ground water, resulting in contamination of streams and aquifers. TNT isclassified as a possible human carcinogen, with a Drinking Water Equivalent Level (DWEL) of 20 µg/L and a lifetime health advisory of 2 µg/L [1].
In view of the high toxicity, cleanup of contaminated sites is mandatory to prevent surface water and aquifer contamination. Incineration of TNT-contaminated soil is a radical cleanup method that produces a rather undesirable sterile soil residue.Bioremediation approaches have been studied by several research groups [2, 3] using adapted cultures of bacteria or fungi. Composting of TNT-contaminated soils is in the demonstration phase and reportedly works well to reduce TNT levels from several thousand ppm to 20-30 ppm. Plants can absorb xenobiotics from soil and ground water, biotransform toxic contaminants to less toxic or non-toxicmetabolites, and immobilize them by sequestration into vacuoles or incorporation into cell walls.
Other benefits of plant growth in contaminated soils are upward movement of wáter by root uptake and evapotranspiration, counteracting of the downward movement of contaminants towards the water table, and increased microbial activity in the soil, as roots provide oxygen and organic carbon in form ofexudates. Rhizobial and mycorrhizal communities are established in which the metabolic activities of bacteria, fungi, microfauna and plants form complementary systems capable of detoxifying and mineralizing xenobiotic contaminants.

BIORREMEDIACIÓN DE RESIDUOS TNT POR LAS PLANTAS SUPERIORES
W.F. Mueller 1, G.W. Bedell 1, S. Shojaee 1 y PJ Jackson2, Universidad Estatal de Nuevo México, Departamento deQuímica y Bioquímica, Las Cruces, NM 88003 2 y Laboratorios Nacionales Los Alamos, División de Ciencias de la Vida, Los Alamos, NM 87545
RESUMENLa absorción y la biotransformación de TNT se ha estudiado en suspensiones celulares y en plantas enteras de innoxia Datura y Lycopersicon peruvianum. En cultivos celulares, el TNT se retiró rápidamente del medio de cultivo y se recuperó de la célula deextraer en forma de una variedad de productos resultantes de la biotransformación, nitroreducción, desaminación, N-acetilación y oxidación de la cadena lateral de metabolitos del ácido aldehído y carboxílicos. Las plantas enteras de la misma especie creció bien en suelos contaminados con TNT hasta 750 ppm; a 1000 ppm de TNT, las plantas Datura mostraron algunos signos de fitotoxicidad, mientras...