Biotransformation and photolysis of 2,4-dinitroanisole, 3-nitro-1,2,4-triazol-5-one, and nitroguanidine

Park

et al. 2021

Environ. Sci. Technol.

The nitroheterocyclic 3-nitro-1,2,4-triazol-5-one (NTO) is an ingredient of insensitive explosives increasingly used by the military, becoming an emergent environmental pollutant. Cometabolic biotransformation of NTO occurs in mixed microbial cultures in soils and sludges with excess electron-donating substrates. Herein, we present the unusual energy-yielding metabolic process of NTO respiration, in which the NTO reduction to 3-amino-1,2,4-triazol-5-one (ATO) is linked to the anoxic acetate oxidation to CO2 by a culture enriched from municipal anaerobic digester sludge. Cell growth was observed simultaneously with NTO reduction, whereas the culture was unable to grow in the presence of acetate only. Extremely low concentrations (0.06 mg L–1) of the uncoupler carbonyl cyanide m-chlorophenyl hydrazone inhibited NTO reduction, indicating that the process was linked to respiration. The ultimate evidence of NTO respiration was adenosine triphosphate production due to simultaneous exposure to NTO and acetate. Metagenome sequencing revealed that the main microorganisms (and relative abundances) were Geobacter anodireducens (89.3%) and Thauera sp. (5.5%). This study is the first description of a nitroheterocyclic compound being reduced by anaerobic respiration, shedding light on creative microbial processes that enable bacteria to make a living reducing NTO.

Section: Introductionmentioning

confidence: 99%

Bacteria Make a Living Breathing the Nitroheterocyclic Insensitive Munitions Compound 3-Nitro-1,2,4-triazol-5-one (NTO)

Madeira

Park

et al. 2021

Environ. Sci. Technol.

“…Finally, the waste stream from a DNAN manufacturing process in China contained 2,4‐dinitrochlorobenzene in addition to the constituents mentioned above (Shen et al, 2013). In contrast, because they perform industrial processes distinct from the manufacturing plants, load/assemble/pack facilities produce waste streams containing mixtures of IMCs, such as DNAN, NTO, and nitroguanidine (NQ; Schroer, 2019).…”

Section: Introductionmentioning

confidence: 99%

Designing bacterial consortia for the complete biodegradation of insensitive munitions compounds in waste streams

Biotech & Bioengineering

Owens

Rios-Valenciana

et al. 2022

Insensitive munitions compounds (IMCs), such as 2,4‐dinitroanisole (DNAN) and 3‐nitro‐1,2,4‐triazol‐5‐one (NTO), are replacing conventional explosives in munitions formulations. Manufacture and use of IMCs generate waste streams in manufacturing plants and load/assemble/pack facilities. There is a lack of practical experience in executing biodegradation strategies to treat IMCs waste streams. This study establishes a proof‐of‐concept that bacterial consortia can be designed to mineralize IMCs and co‐occurring nitroaromatics in waste streams. First, DNAN, 4‐nitroanisole (4‐NA), and 4‐chloronitrobenzene (4‐CNB) in a synthetic DNAN‐manufacturing waste stream were biodegraded using an aerobic fluidized‐bed reactor (FBR) inoculated with Nocardioides sp. JS 1661 (DNAN degrader), Rhodococcus sp. JS 3073 (4‐NA degrader), and Comamonadaceae sp. LW1 (4‐CNB degrader). No biodegradation was detected when the FBR was operated under anoxic conditions. Second, DNAN and NTO were biodegraded in a synthetic load/assemble/pack waste stream during a sequential treatment comprising: (i) aerobic DNAN biodegradation in the FBR; (ii) anaerobic NTO biotransformation to 3‐amino‐1,2,4‐triazol‐5‐one (ATO) by an NTO‐respiring enrichment; and (iii) aerobic ATO mineralization by an ATO‐oxidizing enrichment. Complete biodegradation relied on switching redox conditions. The results provide the basis for designing consortia to treat mixtures of IMCs and related waste products by incorporating microbes with the required catabolic capabilities.

Selecting the best electron donor and operational temperature for the rapid biotransformation of the insensitive munitions compound 2,4-dinitroanisole (DNAN) by anaerobic sludge

Melo

Water Science and Technology

Paraiso

et al. 2021

2,4-Dinitroanisole (DNAN) is a toxic compound increasingly used by the military that can be released into the environment on the soil of training fields and in the wastewater of manufacturing plants. DNAN's nitro groups are anaerobically reduced to amino groups by microorganisms when electron donors are available. Using anaerobic sludge as the inoculum, we tested different electron donors for DNAN bioreduction at 20 and 30 °C: acetate, ethanol, pyruvate, hydrogen, and hydrogen + pyruvate. Biotic controls without external electron donors and abiotic controls with heat-killed sludge were also assayed. No DNAN conversion was observed in the abiotic controls. In all biotic treatments, DNAN was reduced to 2-methoxy-5-nitroaniline (MENA), which was further reduced to 2,4-diaminoanisole (DAAN). Ethanol or acetate did not increase DNAN reduction rate compared to the endogenous control. The electron donors that caused the fastest DNAN reductions were (rates at 30 °C): H2 and pyruvate combined (311.28 ± 10.02 μM·d−1·gSSV−1), followed by H2 only (207.19 ± 5.95 μM·d−1·gSSV−1), and pyruvate only (36.35 ± 2.95 μM·d−1·gSSV−1). Raising the temperature to 30 °C improved DNAN reduction rates when pyruvate, H2, or H2 + pyruvate were used as electrons donors. Our results can be applied to optimize the anaerobic treatment of DNAN-containing wastewater.