Abiotic reduction of nitro aromatic pesticides in anaerobic laboratory systems

Tratnyek, Paul G.; Macalady, Donald L.

doi:10.1021/jf00085a058

Cited by 101 publications

(107 citation statements)

References 11 publications

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“…Because the reaction of 1,2-NQ with amines or other nucleophiles is rather unspecific, it may be expected that several other compounds with mediator activity are also formed in the system studied here. Similar reactions may also be relevant for other biological systems, because aromatic 1,2-dihydroxy compounds are formed as intermediates during the bacterial degradation of almost all aromatic compounds and hydroquinones have been shown to be able to reduce a wide range of natural and man-made substances, such as nitroaromatic compounds and ferric iron (13,16,32,33,44,49,55).…”

Section: Discussionmentioning

confidence: 99%

Identification of Quinoide Redox Mediators That Are Formed during the Degradation of Naphthalene-2-Sulfonate by Sphingomonas xenophaga BN6

Keck

Rau

Reemtsma

et al. 2002

Appl Environ Microbiol

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During aerobic degradation of naphthalene-2-sulfonate (2NS), Sphingomonas xenophaga strain BN6 produces redox mediators which significantly increase the ability of the strain to reduce azo dyes under anaerobic conditions. It was previously suggested that 1,2-dihydroxynaphthalene (1,2-DHN), which is an intermediate in the degradative pathway of 2NS, is the precursor of these redox mediators. In order to analyze the importance of the formation of 1,2-DHN, the dihydroxynaphthalene dioxygenase gene (nsaC) was disrupted by gene replacement. The resulting strain, strain AKE1, did not degrade 2NS to salicylate. After aerobic preincubation with 2NS, strain AKE1 exhibited much higher reduction capacities for azo dyes under anaerobic conditions than the wild-type strain exhibited. Several compounds were present in the culture supernatants which enhanced the ability of S. xenophaga BN6 to reduce azo dyes under anaerobic conditions. Two major redox mediators were purified from the culture supernatants, and they were identified by high-performance liquid chromatography-mass spectrometry and comparison with chemically synthesized standards as 4-amino-1,2-naphthoquinone and 4-ethanolamino-1,2-naphthoquinone.Wastewaters from textile industries are often highly colored due to residual dyestuff from the dyeing processes. It has been estimated that up to 60% of the total dyestuff used in the dyeing processes may be found in the wastewaters (3). Only small amounts of these dyes are removed by conventional aerobic biological wastewater treatment systems (37, 46). On the other hand, it is well known that azo dyes are reduced anaerobically by different microorganisms, which usually results in the generation of colorless aromatic amines (2,5,7,12,14,51,56). These amines are in most cases recalcitrant under anaerobic conditions (6). Therefore, it has been repeatedly suggested that two-stage anaerobic-aerobic treatment systems should be used to reduce the azo dyes anaerobically and to mineralize the amines formed in a subsequent aerobic stage (1,36,38,45,51,54). The first successful example of mineralization of a sulfonated azo dye by an anaerobic-aerobic treatment process involved a 6-aminonaphthalene-2-sulfonate-degrading mixed bacterial culture. This culture consisted of the naphthalenesulfonate-degrading strain Sphingomonas xenophaga BN6 in a mutualistic coculture with other bacterial strains (21,34,50). Recently, it was found that strain BN6 uses a new mechanism for conversion of azo dyes. During aerobic degradation of naphthalene-2-sulfonate (2NS), redox mediators are released, which mediate the reduction of azo dyes under anaerobic conditions (27). It was proposed that these redox mediators shuttle electrons from the cells to the azo dyes, which results in purely chemical, extremely nonspecific, extracellular reductive cleavage of the azo bond. Aerobic preincubation of strain BN6 with 2NS increased subsequent anaerobic reduction of the azo dyes almost 20-fold. It was suggested that 1,2-dihydroxynaphthalene (1,2-DHN), which is the ...

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Section: Discussionmentioning

confidence: 99%

Identification of Quinoide Redox Mediators That Are Formed during the Degradation of Naphthalene-2-Sulfonate by Sphingomonas xenophaga BN6

Keck

Rau

Reemtsma

et al. 2002

Appl Environ Microbiol

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“…analogue, 2,6-anthrahydroquinone disulfonate (AQDS) (Tratnyek and Macalady, 1989) greatly enhanced photoproduction of Fe(II) under both oxic and anoxic conditions. UV irradiation of AQDS in the presence of Fe(III) for 21.5 h produced substantial amounts of Fe(II) under oxic (2140 -60 lM, n = 3) and anoxic (2200 -30 lM, n = 3) conditions, and little to no Fe(III) reduction was observed in identical treatments wrapped in aluminum foil prior to light exposure (Table 1) , approximately 72 mM Fe(II)], a significant portion of which is converted to Fe(III) during cultivation.…”

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confidence: 99%

Natural Organic Matter as Global Antennae for Primary Production

2013

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Humic substances (HS) are high-molecular-weight complex refractory organics that are ubiquitous in terrestrial and aquatic environments. While resistant to microbial degradation, these compounds nevertheless support microbial metabolism via oxidation or reduction of their (hydro)quinone moieties. As such, they are known to be important electron sinks for respiratory and fermentative bacteria and electron sources for denitrifying and perchlorate-reducing bacteria. HS also strongly promote abiotic reduction of Fe(III) when irradiated with light. Here, we show that HS-enhanced Fe(III) photoreduction can also drive chemolithotrophic microbial respiration by producing Fe(II), which functions as a respiratory electron donor. Due to their molecular complexity, HS absorb most of the electromagnetic spectrum and can act as broad-spectrum antennae converting radiant energy into bioavailable chemical energy. The finding that chemolithotrophic organisms can utilize this energy has important implications for terrestrial, and possibly extraterrestrial, microbial processes and offers an alternative mechanism of radiation-driven primary productivity to that of phototrophy.

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“…Since previous studies have shown that Shewanella oneidensis strain MR-1 (19,38) is able both to respire humic acids and to produce electron-shuttling molecules (22; M. Dubiel and D. K. Newman, unpublished results), we performed a small genetic screening of 500 transposon-generated mutants to explore the mechanistic basis of the reduction of the humic acid analog anthraquinone-2,6-disulfonate (AQDS) (35). Transposon mutagenesis was performed as previously described (22), and isolates were screened to identify mutants that were apparently unable to use AQDS as an electron acceptor during anaerobic growth on lactate.…”

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confidence: 99%

Protective Role of tolC in Efflux of the Electron Shuttle Anthraquinone-2,6-Disulfonate

2002

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Extracellular electron transfer can play an important role in microbial respiration on insoluble minerals. The humic acid analog anthraquinone-2,6-disulfonate (AQDS) is commonly used as an electron shuttle during studies of extracellular electron transfer. Here we provide genetic evidence that AQDS enters Shewanella oneidensis strain MR-1 and causes cell death if it accumulates past a critical concentration. A tolC homolog protects the cell from toxicity by mediating the efflux of AQDS. Electron transfer to AQDS appears to be independent of the tolC pathway, however, and requires the outer membrane protein encoded by mtrB. We suggest that there may be structural and functional relationships between quinone-containing electron shuttles and antibiotics.

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Abiotic reduction of nitro aromatic pesticides in anaerobic laboratory systems

Cited by 101 publications

References 11 publications

Identification of Quinoide Redox Mediators That Are Formed during the Degradation of Naphthalene-2-Sulfonate by Sphingomonas xenophaga BN6

Identification of Quinoide Redox Mediators That Are Formed during the Degradation of Naphthalene-2-Sulfonate by Sphingomonas xenophaga BN6

Natural Organic Matter as Global Antennae for Primary Production

Protective Role of tolC in Efflux of the Electron Shuttle Anthraquinone-2,6-Disulfonate

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