title: Metabolism of 2,4-dinitrotoluene (2,4-DNT) by Alcaligenes sp. JS867 under oxygen limited conditions.
abstract: Transformation of 2,4-dinitrotoluene (2,4-DNT) by Alcaligenes JS867 under varying degrees of oxygen limitation was examined. Complete 2,4-DNT removal was observed under oxygen excess with near stoichiometric release (83%) of nitrite. Average kinetic parameters were estimated based on a dual-Monod biokinetic model with 2,4-DNT and O2 as growth limiting substrates. The negative impact of nitrite accumulation on the reaction rate was adequately described by inclusion of a noncompetitive inhibition term for NO2-. Under aerobic conditions, mumax, KsDNT, and KiNO were 0.058 (0.004)hr(-1), 3.3(+/-1.3) mg 2,4-DNT/L, and 1.2(+/-0.2)hr(-1), respectively. At increasing oxygen limitation, rates of 2,4-DNT disappearance and nitrite production decreased and incomplete removal of 2,4-DNT commenced. JS867 was able to use NO2- as a terminal electron acceptor when grown on glucose or succinate under anaerobic conditions. However, during growth on 2,4-DNT and under O2-limited conditions, JS867 did not use released nitrite as electron acceptor. The nearly constant molar ratios of DNT removed over NO2- released under various degrees of oxygen limitation suggested that oxygenolytic denitration pathways continued. No evidence of nitroreduction was obtained under the examined oligotrophic conditions. JS867 displayed a high affinity for oxygen consumption with K(SO2) value of 0.285(+/-0.198) mg O2/L. Our results indicate that under oligotrophic conditions with 2,4-DNT as dominant carbon source, oxygen availability and nitrite accumulation may limit 2,4-DNT biomineralization, but the accumulation of reduced 2,4-DNT transformation products will be small.
authors.affiliation: Department of Civil and Environmental Engineering, University of Connecticut, Storrs 06269-2037, USA. barth.smets@uconn.edu
authors.forename: B F
authors.initials: BF
authors.lastname: Smets
authors.forename: R J
authors.initials: RJ
authors.lastname: Mueller
mesh_terms: D000421:Alcaligenes / Q000187:drug effects / Q000378:metabolism*; D000465:Algorithms; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D002273:Carcinogens / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004136:Dinitrobenzenes / Q000378:metabolism*; D004579:Electron Transport; D007700:Kinetics; D009566:Nitrates / Q000494:pharmacology; D009573:Nitrites / Q000737:chemistry / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002273:Carcinogens; D004136:Dinitrobenzenes; D009566:Nitrates; D009573:Nitrites; C016403:2,4-dinitrotoluene; D009584:Nitrogen; D010100:Oxygen