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Applied and Environmental Microbiology, December 2001, p. 5460-5466, Vol. 67, No. 12
Air Force Research Laboratory, Tyndall Air
Force Base, Florida,1 and Department of
Civil and Environmental Engineering, University of Connecticut,
Storrs, Connecticut2
Received 7 May 2001/Accepted 11 September 2001
The electron-withdrawing nitro substituents of
2,4,6-trinitrotoluene (TNT) make the aromatic ring highly resistant to
oxidative transformation. The typical biological transformation of TNT
involves reduction of one or more of the nitro groups of the ring to
produce the corresponding amine. Reduction of a single nitro
substituent of TNT to an amino substituent increases the electron
density of the aromatic nucleus considerably. The comparatively
electron-dense nuclei of the aminodinitrotoluene (ADNT) isomers would
be expected to be more susceptible to oxygenase attack than TNT. The
hypothesis was tested by evaluating three nitroarene dioxygenases for
the ability to hydroxylate the ADNT isomers. The predominant reaction was dioxygenation of the ring to yield nitrite and the corresponding aminomethylnitrocatechol. A secondary reaction was benzylic
monooxygenation to form aminodinitrobenzyl alcohol. The substrate
preferences and catalytic specificities of the three enzymes differed
considerably. The discovery that the ADNT isomers are substrates for
the nitroarene dioxygenases reveals the potential for extensive
bacterial transformation of TNT under aerobic conditions.
0099-2240/01/$04.00+0 DOI: 10.1128/AEM.67.12.5460-5466.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Oxidative Transformation of Aminodinitrotoluene
Isomers by Multicomponent Dioxygenases
*
Corresponding author. Mailing address: AFRL/MLQL, 139 Barnes Dr.-Suite 2, Tyndall AFB, FL 32403. Phone: (850) 283-6058. Fax: (850) 283-6223. E-mail: jim.spain{at}tyndall.af.mil.
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