Reduction of Copper(II) by Iron(II)

Matocha, Christopher J.; Karathanasis, A. D.; Rakshit, Sudipta; Wagner, Katharina

doi:10.2134/jeq2005.0002

Cited by 55 publications

(32 citation statements)

References 43 publications

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“…Fe(II) has been shown to reduce Cu(II) under environmentally relevant conditions (35). Our own experiments showed that in our growth medium, Fe(II) could quickly reduce a significant amount of Cu(II) to Cu(I) abiotically (see Fig.…”

Section: Discussionmentioning

confidence: 50%

Iron and Copper Act Synergistically To Delay Anaerobic Growth of Bacteria

Bird

Coleman

Newman

2013

Appl Environ Microbiol

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bTransition metals are known to cause toxic effects through their interaction with oxygen, but toxicity under anoxic conditions is poorly understood. Here we investigated the effects of iron (Fe) and copper (Cu) on the anaerobic growth and gene expression of the purple phototrophic bacterium Rhodopseudomonas palustris TIE-1. We found that Fe(II) and Cu(II) act synergistically to delay anaerobic growth at environmentally relevant metal concentrations. Cu(I) and Cu(II) had similar effects both alone and in the presence of ascorbate, a Cu(II) reductant, indicating that reduction of Cu(II) to Cu(I) by Fe(II) is not sufficient to explain the growth inhibition. Addition of Cu(II) increased the toxicity of Co(II) and Ni(II); in contrast, Ni(II) toxicity was diminished in the presence of Fe(II). The synergistic anaerobic toxicity of Fe(II) and Cu(II) was also observed for Escherichia coli MG1655, Shewanella oneidensis MR-1, and Rhodobacter capsulatus SB1003. Gene expression analyses for R. palustris identified three regulatory genes that respond to Cu(II) and not to Fe(II): homologs of cueR and cusR, two known proteobacterial copper homeostasis regulators, and csoR, a copper regulator recently identified in Mycobacterium tuberculosis. Two P-type ATPase efflux pumps, along with an F o F 1 ATP synthase, were also upregulated by Cu(II) but not by Fe(II). An Escherichia coli mutant deficient in copA, cus, and cueO showed a smaller synergistic effect, indicating that iron might interfere with one or more of the copper homeostasis systems. Our results suggest that interactive effects of transition metals on microbial physiology may be widespread under anoxic conditions, although the molecular mechanisms remain to be more fully elucidated.

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Section: Discussionmentioning

confidence: 50%

Iron and Copper Act Synergistically To Delay Anaerobic Growth of Bacteria

Bird

Coleman

Newman

2013

Appl Environ Microbiol

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“…This may be due to the decreasing Cu solubility with increasing pH, as generally observed in acidic soils under reducing conditions. Moreover, recent studies by Biasioli et al, 12 Fulda et al 37 and Matocha et al 38 have shown that, under anoxic conditions, Cu(II) can be reduced to Cu(I) or Cu(0) and subsequently stabilized as insoluble Cu(I)-humic acids complexes or precipitated as Cu2O. Huang et al 18 presented similar results for OM-amended paddy soils.…”

Section: Column Experimentsmentioning

confidence: 78%

Leaching potential of metallic elements from contaminated soils under anoxia

Balint

Nechifor

Ajmone-Marsan

2014

Environ. Sci.: Processes Impacts

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Environmental ImpactThe higher frequency and intensity of extreme rainfall events, as well as the variations in precipitation patterns and intensities as a result of climate change may cause important shifts in soil hydrological regime. This could expose contaminated soils to significant variations in redox potentials possibly influencing metallic element behaviour and their potential transfer to other environmental compartments. This study shows that alternating soil redox conditions may enhance the release and redistribution of metals in more labile fractions. In particular, the presence of redox-sensitive minerals, such as chalcopyrite, in soils affected by mine tailings, could release significant amounts of Cu due to the alternating redox conditions and therefore have important environmental implications. Graphical abstractThe alternation of redox cycles may play a higher role in the release, leaching and redistribution of metallic elements from contaminated soils with respect to oxidizing and reducing conditions alone. AbstractUnderstanding metallic element (ME) behaviour in soils subjected to alternating redox conditions is of significant environmental importance, particularly for contaminated soils. Although variations in the hydrological status of soils may lead to the release of ME, redox-driven changes in ME dynamics are still not sufficiently understood. We studied the effects of alternating redox cycles 2 on the release, leaching and redistribution of Zn, Cu and Pb in metal mine-contaminated and noncontaminated soils by means of a column experiment. Although the release of Zn was promoted by the onset of reductive conditions, successive redox cycles favoured metal partitioning in less labile fractions limiting its further mobilization. The release of Cu in soil porewaters and redistribution in the solid phase towards more labile pools were strongly dependent on the alternation between oxidizing and reducing conditions. In contaminated soils, the presence of chalcopyrite could have determined the release of Cu under oxic conditions and its relative immobilization under subsequent anoxic conditions. The behaviour of Pb did not seem to be influence by redox status, although higher concentrations in the column leachates with respect to soil porewaters suggested that alternating redox conditions could nonetheless result in substantial mobilization. This study provides evidence that the alternation of soil redox conditions may play a more important role in determining the release and leaching of metallic elements from soils with respect to reducing or oxidizing conditions considered separately.

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“…Reduction of Cu 2ϩ to Cu ϩ can be driven by metallic iron or Fe 2ϩ serving as reductants. This process has been thermodynamically analyzed in detail by Matocha et al (21). Cu ϩ can then form insoluble cuprite (Cu 2 O), even under anaerobic conditions (21).…”

Section: Discussionmentioning

confidence: 99%

Copper Reduction and Contact Killing of Bacteria by Iron Surfaces

Mathews

Kumar

Solioz

2015

Appl Environ Microbiol

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Federation bThe well-established killing of bacteria by copper surfaces, also called contact killing, is currently believed to be a combined effect of bacterial contact with the copper surface and the dissolution of copper, resulting in lethal bacterial damage. Iron can similarly be released in ionic form from iron surfaces and would thus be expected to also exhibit contact killing, although essentially no contact killing is observed by iron surfaces. However, we show here that the exposure of bacteria to iron surfaces in the presence of copper ions results in efficient contact killing. The process involves reduction of Cu 2؉ to Cu ؉ by iron; Cu ؉ has been shown to be considerably more toxic to cells than Cu 2؉ . The specific Cu ؉ chelator, bicinchoninic acid, suppresses contact killing by chelating the Cu ؉ ions. These findings underline the importance of Cu ؉ ions in the contact killing process and infer that ironbased alloys containing copper could provide novel antimicrobial materials.T he killing of bacteria by metallic copper surfaces, so-called "contact killing," is now well established and has explicitly been shown for many species (1). Bacteria are killed within minutes on surfaces of copper or copper alloys containing at least 60% copper. In contrast, cells can survive for days on surfaces of stainless steel, glass, or plastics. Copper and copper alloys have attracted attention as a means of creating self-sanitizing surfaces in the light of increasing nosocomial infections in Western hospitals. In a number of hospital trials, rooms have been fitted with copper alloy table tops, bedrails, door handles, light switches, bathroom fixtures, etc., in an effort to curb nosocomial infections (2-5; K. Laitinen et al., unpublished data). These copper surfaces resulted in a 2-to 3-log reduction of the microbial burden on a continuous basis. However, further data are needed to convincingly demonstrate that these measures also lead to a lasting reduction of nosocomial infections. Nevertheless, it appears clear that copper-containing materials can contribute to hospital hygiene and lower the bacterial burden also in other facilities where clean or aseptic working procedures are required (6).The mechanism of contact killing of bacteria by coppercontaining materials is of interest not only in connection to its use in hospitals but also from a purely scientific point of view. Laboratory studies have shown that bacteria on copper surfaces suffer rapid membrane damage and DNA degradation, in addition to other less well-defined cellular damage (7-12). The importance and the order of the different processes leading to cell death may depend on the type of microorganism (9). One key element required for contact killing is the release of copper ions from the metal surface. Bacterial copper resistance systems appear unable to cope with the released copper (13-15). The second important requirement for contact killing is bacterial contact with the metal surface (16). Recently, we showed that bacteria are also killed effectively ...

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Reduction of Copper(II) by Iron(II)

Cited by 55 publications

References 43 publications

Iron and Copper Act Synergistically To Delay Anaerobic Growth of Bacteria

Iron and Copper Act Synergistically To Delay Anaerobic Growth of Bacteria

Leaching potential of metallic elements from contaminated soils under anoxia

Copper Reduction and Contact Killing of Bacteria by Iron Surfaces

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