F. Fant et al. / Environmental Pollution 111 (2001) 503±507
507
that some bacteria can reduce the aromatic ring of dinitro-
and trinitro-compounds by the addition of a hydride ion
to form a hydride±Meisenheimer complex, which subse-
quently re-aromatizes with the elimination of nitrite
(Spain, 1995; Haidour and Ramos, 1996). Recently, Rie-
ger et al. (1999) reported the evidence for the formation of
a hydride±Meisenheimer complex of picric acid (2,4,6-tri-
nitrophenol) and its protonated form under physiological
conditions using Rhodococcus erythropolis HLPM-1. It
was also proved that these complexes are key inter-
mediates of denitration and productive microbial degra-
dation of picric acid (Rieger et al., 1999).
Haidour, A., Ramos, J.L., 1996. Identi®cation of products resulting
from the biological reduction of 2,4,6-trinitrotoluene, 2,4-dini-
trotoluene, and 2,6-dinitrotoluene by Pseudomonas sp. Environ-
mental Science and Technology 30, 2365±2370.
Hao, O.J., Phull, K.K., Davis, A.P., Chen, J.M., Maloney, S.W., 1993.
Wet air oxidation of trinitrotoluene manufacturing red water. Water
Environmental Research 65, 213±220.
Hartter, D.R., 1985. The use and importance of nitroaromatic chemi-
cals in the chemical industry. In: Rickert, D.E. (Ed.), Toxicity of
Nitroaromatic Compounds. Chemical Industry Institute of Tox-
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Held, T., Draude, G., Schmidt, F.R.J., Brokamp, A., Reis, K.H.,
1997. Enhanced humi®cation as an in-situ bioremediation technique
for 2,4,6-trinitrotoluene (TNT) contaminated soils. Environmental
Technology 18, 479±487.
Hundal, L.S., Shea, P.J., Comfort, S.D., Powers, W.L., Singh, J.,
1997. Long-term TNT sorption and bound residue formation in
soil. Journal of Environmental Quality 26, 896±904.
4. Conclusions
Jenkins, T.F., 1990. U.S. Army Cold Regions Research and Engi-
neering Laboratory, Special report, pp. 90±98.
This work showed that in a H2O/d6-acetone mixture,
TNT forms a Meisenheimer complex with cysteine and
aniline. When an overdose of cysteine is present, the
equilibrium moves entirely to the Meisenheimer com-
plex. After exposure to daylight, the formation of the
complex is more enhanced. The addition of cysteine,
aniline or crude protein extracts to water and soils pol-
luted with TNT or any other nitroaromatic compound
could be used as a simple and rapid process for binding
the pollutant and initiating further biological remediation
(Verstraete and Devlieghere, 1997).
Olah, G.A., Mayr, H.J., 1976. Carbone-13 nuclear magnetic resonance
study of Meisenheimer complexes and their charge distribution
pattern. Organic Chemistry 41, 3448±3451.
Price, C.B., Brannon, J.M., Hayes, C.A., 1997. Eect of redox poten-
tial and pH on TNT transformation in soil±water slurries. Journal
of Environmental Engineering ASCE 123, 988±992.
Rieger, P.G., Knackmuss, H.-J., 1995. Basic knowledge and perspec-
tives on biodegradation of 2,4,6-trinitrotoluene and related
nitroaromatic compounds in contaminated soil. In: Spain (Ed.),
Biodegradation of Nitroaromatic Compounds. Plenum Press, New
York, pp. 1±18.
Rieger, P.G., Sinnwell, V., Preuû, A, Francke, W., Knackmuss, H.-J.,
1999. Hydride±Meisenheimer complex formation and protonation
as key reactions of 2,4,6-trinitrophenol biodegradation by Rhodo-
coccus erythropolis. Journal of Bacteriology 181, 1189±1195.
Schmelling, D.C., Gray, K.A., Kamat, P.V., 1998. Radiation-induced
reactions of 2,4,6-trinitrotoluene in aqueous solution. Environ-
mental Science and Technology 32, 971±974.
Acknowledgements
Financial support was received from SOILS ltd. and
VLAR ltd. (Belgium). We thank B. Meyns for his kind
advice.
Spain, J.C., 1995. Biodegradation of nitroaromatic compounds.
Annual Review of Microbiology 49, 523±555.
VanBeelen, P., Burris, D.R., 1995. Reduction of the explosive 2,4,6-
trinitrotoluene by enzymes from aquatic sediments. Environmental
Toxicology and Chemistry 14, 2115±2123.
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