title: Aerobic denitration of 2,4,6-trinitrotoluene in the presence of phenazine compounds and reduced pyridine nucleotides.
abstract: Phenazine-containing spent culture supernatants of Pseudomonas aeruginosa concentrated with a C18 solid-phase extraction cartridge initiate NAD(P)H-dependent denitration of 2,4,6-trinitrotoluene (TNT). In this study, TNT denitration was investigated under aerobic conditions using two phenazine secondary metabolites excreted by P. aeruginosa, pyocyanin (Py) and its precursor phenazine-1- carboxylic acid (PCA), and two chemically synthesized pyocyanin analogs, phenazine methosulfate (PMS+) and phenazine ethosulfate (PES+). The biomimetic Py/NAD(P)H/O2 system was characterized and found to extensively denitrate TNT in unbuffered aqueous solution with minor production of toxic amino aromatic derivatives. To a much lesser extent, TNT denitration was also observed with PMS+ and PES+ in the presence of NAD(P)H. No TNT denitration was detected with the biomimetic PCA/NAD(P)H/O2 system. Electron paramagnetic resonance (EPR) spectroscopy analysis of the biomimetic Py/NAD(P)H/O2 system revealed the generation of superoxide radical anions (O2 •−). In vitro TNT degradation experiments in the presence of specific inhibitors of reactive oxygen species suggest a nucleophilic attack of superoxide radical anion followed by TNT denitration through an as yet unknown mechanism. The results of this research confirm the high functional versatility of the redox-active metabolite pyocyanin and the susceptibility of aromatic compounds bearing electron withdrawing substituents, such as nitro groups, to superoxide-driven nucleophilic attack.
authors.affiliation: Earth and Life Institute, Laboratory of Bioengineering, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Ben
authors.initials: B
authors.lastname: Stenuit
authors.forename: Guillaume
authors.initials: G
authors.lastname: Lamblin
authors.forename: Pierre
authors.initials: P
authors.lastname: Cornelis
authors.forename: Spiros N
authors.initials: SN
authors.lastname: Agathos
mesh_terms: D000332:Aerobiosis; D002384:Catalysis; D003470:Culture Media; D004578:Electron Spin Resonance Spectroscopy; D008773:Methylphenazonium Methosulfate / Q000737:chemistry / Q000378:metabolism; D009249:NADP / Q000737:chemistry / Q000378:metabolism*; D010619:Phenazines / Q000737:chemistry / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000737:chemistry / Q000378:metabolism*; D011710:Pyocyanine / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D052616:Solid Phase Extraction; D013481:Superoxides / Q000378:metabolism; D014303:Trinitrotoluene / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D003470:Culture Media; D010619:Phenazines; D017382:Reactive Oxygen Species; C028122:5-ethylphenazine; D013481:Superoxides; D014303:Trinitrotoluene; C037165:1-phenazinecarboxylic acid; D008773:Methylphenazonium Methosulfate; D009249:NADP; D011710:Pyocyanine