Aerobic biotransformation of 2,4-dinitroanisole in soil and soil Bacillus sp.

Abstract

2,4-Dinitroanisole (DNAN) is a low sensitive melt-cast chemical being tested by the Military Industry as a replacement for 2,4,6-trinitrotoluene (TNT) in explosive formulations. Little is known about the fate of DNAN and its transformation products in the natural environment. Here we report aerobic biotransformation of DNAN in artificially contaminated soil microcosms. DNAN was completely transformed in 8 days in soil slurries supplemented with carbon and nitrogen sources. DNAN was completely transformed in 34 days in slurries supplemented with carbons alone and persisted in unamended microcosms. A strain of Bacillus (named 13G) that transformed DNAN by co-metabolism was isolated from the soil. HPLC and LC-MS analyses of cell-free and resting cell assays of Bacillus 13G with DNAN showed the formation of 2-amino-4-nitroanisole as the major end-product via the intermediary formation of the arylnitroso (ArNO) and arylhydroxylamino (ArNHOH) derivatives, indicating regioselective reduction of the ortho-nitro group. A series of secondary reactions involving ArNO and ArNHOH gave the corresponding azoxy-and azodimers. Acetylated and demethylated products were identified. Overall, this paper provides the evidence of fast DNAN transformation by the indigenous microbial populations of an amended soil with no history of contamination with explosives and a first insight into the aerobic metabolism of DNAN by the soil isolate Bacillus 13G.

Biodegradation of IMX-101 explosive formulation constituents: 2,4-Dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine

“…The broad diversity of microorganisms reported in the literature to degrade the individual IMX-101 compounds [15][16][17][19][20][21]23] along with rapid acclimation of most cultures (digester sludge, compost) observed in this study, suggest IMX-101 biodegradation may readily occur in engineered treatments systems and potentially in natural systems. Our findings that the compounds in IMX-101 are likely used a nitrogen source are in keeping with results previously reported for NQ.…”

“…Aerobic degradation of DNAN has also been shown by Bacillus sp. strain (13G) in soil slurries augmented with both carbon and nitrogen sources [20]. Recently, a mixed aerobic consortium including Pseudomonas sp.…”

Aerobic Biodegradation of 2,4-Dinitroanisole by Nocardioides sp. Strain JS1661

“…The initial reaction in the biotransformation of DNAN by bacteria and in abiotic transformation with zero valent iron is the reduction of the nitro group in the ortho position to yield 2-amino-4-nitroanisole (3)(4)(5). Under anoxic conditions, DNAN is biotransformed to toxic metabolites such as diaminoanisole (3,(5)(6)(7)(8).…”

“…Under anoxic conditions, DNAN is biotransformed to toxic metabolites such as diaminoanisole (3,(5)(6)(7)(8). A Bacillus strain was reported to transform DNAN slowly under aerobic conditions to 2-amino-4-nitroanisole as a predominant dead-end product (4). A recent investigation revealed substantial aerobic biodegradation of DNAN by enrichment cultures derived from activated sludge, but the responsible bacteria were not isolated (9).…”

Environmental Fate of 14C Radiolabeled 2,4-Dinitroanisole in Soil Microcosms

“…6, 7 Besides adsorption, DNAN is readily (bio)transformed in anaerobic conditions by indigenous soil microorganisms as well as by abiotic processes. 6, 8 The main transformation route is nitro-group reduction to aromatic amines, stimulated by electron donating amendments 9 , as well as anaerobic conditions. 6 During nitroreduction, the initially formed nitroso reactive intermediates, can condense with the secondarily formed amino groups to form azo-dimers.…”