Aerobic degradation of dinitrotoluenes and pathway for bacterial degradation of 2,6-dinitrotoluene.
An oxidative pathway for the mineralization of 2,4-dinitrotoluene (2, 4-DNT) by Burkholderia sp. strain DNT has been reported previously. We report here the isolation of additional strains with the ability to mineralize 2,4-DNT by the same pathway and the isolation and characterization of bacterial strains that mineralize 2, 6-dinitrotoluene (2,6-DNT) by a different pathway. Burkholderia cepacia strain JS850 and Hydrogenophaga palleronii strain JS863 grew on 2,6-DNT as the sole source of carbon and nitrogen. The initial steps in the pathway for degradation of 2,6-DNT were determined by simultaneous induction, enzyme assays, and identification of metabolites through mass spectroscopy and nuclear magnetic resonance. 2,6-DNT was converted to 3-methyl-4-nitrocatechol by a dioxygenation reaction accompanied by the release of nitrite. 3-Methyl-4-nitrocatechol was the substrate for extradiol ring cleavage yielding 2-hydroxy-5-nitro-6-oxohepta-2,4-dienoic acid, which was converted to 2-hydroxy-5-nitropenta-2,4-dienoic acid. 2, 4-DNT-degrading strains also converted 2,6-DNT to 3-methyl-4-nitrocatechol but did not metabolize the 3-methyl-4-nitrocatechol. Although 2,6-DNT prevented the degradation of 2,4-DNT by 2,4-DNT-degrading strains, the effect was not the result of inhibition of 2,4-DNT dioxygenase by 2,6-DNT or of 4-methyl-5-nitrocatechol monooxygenase by 3-methyl-4-nitrocatechol.
Nishino
S F
SF
Air Force Research Laboratory, Tyndall Air Force Base, Florida 32403-5323, USA.
Paoli
G C
GC
Spain
J C
JC
D000332:Aerobiosis; D000395:Air Pollutants, Occupational; D000421:Alcaligenes / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D001420:Bacteria, Aerobic / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019117:Burkholderia / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D004136:Dinitrobenzenes / Q000378:metabolism*; D007700:Kinetics; D010101:Oxygen Consumption; D012722:Sewage / Q000382:microbiology; D012988:Soil Microbiology; D014871:Water Microbiology
D000395:Air Pollutants, Occupational; D004136:Dinitrobenzenes; D012722:Sewage; C023514:2,6-dinitrotoluene