Organohalide Respiration with Diclofenac by Dehalogenimonas

Abstract

Diclofenac (DCF) is a pharmaceutically active contaminant frequently found in aquatic ecosystems. The transformation pathways and microbiology involved in the biodegradation of DCF, particularly under anoxic conditions, remain poorly understood. Here, we demonstrated microbially mediated reductive dechlorination of DCF in anaerobic enrichment culture derived from contaminated river sediment. Over 90% of the initial 76.7 ± 3.6 μM DCF was dechlorinated at a maximum rate of 1.8 ± 0.3 μM day −1 during a 160 days' incubation. Mass spectrometric analysis confirmed that 2-(2-((2-chlorophenyl)amino)phenyl)acetic acid (2-CPA) and 2anilinophenylacetic acid (2-APA) were formed as the monochlorinated and nonchlorinated DCF transformation products, respectively. A survey of microbial composition and Sanger sequencing revealed the enrichment and dominance of a new Dehalogenimonas population, designated as Dehalogenimonas sp. strain DCF, in the DCFdechlorinating community. Following the stoichiometric conversion of DCF to 2-CPA (76.0 ± 2.1 μM) and 2-APA (3.7 ± 0.8 μM), strain DCF cell densities increased by 24.4 ± 4.4-fold with a growth yield of 9.0 ± 0.1 × 10 8 cells per μmol chloride released. Our findings expand the metabolic capability in the genus Dehalogenimonas and highlight the relevant roles of organohalide-respiring bacteria for the natural attenuation of halogenated contaminants of emerging concerns (e.g., DCF).

Thermodynamic and Kinetic Behaviors of Persulfate-Based Electron-Transfer Regime in Carbocatalysis

“…SMX and OG are the discrete points below the fitting line due to their smaller hydrophilic coefficients (log P SMX = 0.86, log P OG = 1.53) among the eight organics, resulting in the weaker hydrophobic interactions with the CNT surface. In contrast, DCF is the discrete point overtop the fitting line, due to its strongest hydrophobic interaction (log P DCF = 4.12) . Thus, the fitting equation exhibited a good linearity ( R 2 = 0.700) between ln k obs‑ad and log P (Figure b), suggesting that the hydrophobicity of organics is also one of the most crucial factors for organic adsorption.…”

“…In contrast, DCF is the discrete point overtop the fitting line, due to its strongest hydrophobic interaction (log P DCF = 4.12). 46 Thus, the fitting equation exhibited a good linearity (R 2 = 0.700) between ln k obs-ad and log P (Figure 3b), suggesting that the hydrophobicity of organics is also one of the most crucial factors for organic adsorption. Specifically, CNT has a graphitic layer mesh surface structure, leading to a strong adsorption effect with hydrophobic compound.…”

Dehalogenimonas etheniformans sp. nov., a formate-oxidizing, organohalide-respiring bacterium isolated from grape pomace

“…Uninoculated bottles spiked with the respective chlorinated compound were prepared as negative controls to account for abiotic losses and/or transformation. Chlorinated compounds and dechlorination products were analysed using a 7890B GC-FID system (Agilent Technologies) or an 1260 II HPLC system (Agilent Technologies) as described previously [37, 38]. To verify if growth of GP T was linked to reductive dechlorination, genomic DNA was extracted using the TIANamp Soil DNA Kit (TIANGEN) and quantitative real-time PCR (qPCR) specifically targeting the 16S rRNA gene of the genus Dehalogenimonas was performed using the primer set Dhgm478f and Dhgm536r and the TaqMan probe Dhgm500p as described previously [39].…”

Sequential Reductive Dechlorination of Triclosan by Sediment Microbiota Harboring Organohalide-Respiring Dehalococcoidia

“…26 Microbial reductive dechlorination is an essential process contributing to the natural attenuation of halogenated compounds in subsurface environments. 27,28 In this process, organohalide-respiring bacteria (OHRB) utilize halogenated compounds as electron acceptors for energy conservation and transform them into less toxic or less recalcitrant products. 27,29 Until recently, the reductive dechlorination of TCS was demonstrated in Dehalococcoides-containing microcosms de-rived from the activated sludges of a wastewater treatment plant.…”

“…27,28 In this process, organohalide-respiring bacteria (OHRB) utilize halogenated compounds as electron acceptors for energy conservation and transform them into less toxic or less recalcitrant products. 27,29 Until recently, the reductive dechlorination of TCS was demonstrated in Dehalococcoides-containing microcosms de-rived from the activated sludges of a wastewater treatment plant. 30 The involvement of OHRB in the anaerobic biotransformation of TCS was further investigated with several Dehalococcoides pure cultures, of which only strain CG1 exhibited TCS-dechlorinating activity and diclosan (5-chloro-2-(4-chlorophenoxy)phenol,4′,4-DCPP), a dichlorinated TCS derivative was formed as the dechlorination end product.…”