Oxidation of Fe(II)–Organic Matter Complexes in the Presence of the Mixotrophic Nitrate-Reducing Fe(II)-Oxidizing Bacterium <i>Acidovorax</i> sp. BoFeN1

Peng, Chao; Sundman, Anneli; Bryce, Casey; Catrouillet, Charlotte; Borch, Thomas; Kappler, Andreas

doi:10.1021/acs.est.8b00953

Cited by 58 publications

(51 citation statements)

References 90 publications

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“…Fe 2+ and nitrite production rates. Also, Fe-organic matter complexes, as they potentially occur in nature, will influence the reaction kinetics and the fate of Fe and N species 59 . In addition to that, in nature other processes, such as anammox, DNRA, and nitrate reduction by sulfur oxidation will impact the N 2 O emission rate 60,61 .…”

Section: Discussionmentioning

confidence: 99%

N2O formation by nitrite-induced (chemo)denitrification in coastal marine sediment

Otte

Blackwell

Ruser

et al. 2019

Sci Rep

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Nitrous oxide (N 2 O) is a potent greenhouse gas that also contributes to stratospheric ozone depletion. Besides microbial denitrification, abiotic nitrite reduction by Fe(II) (chemodenitrification) has the potential to be an important source of N 2 O. Here, using microcosms, we quantified N 2 O formation in coastal marine sediments under typical summer temperatures. Comparison between gamma-radiated and microbially-active microcosm experiments revealed that at least 15–25% of total N 2 O formation was caused by chemodenitrification, whereas 75–85% of total N 2 O was potentially produced by microbial N-transformation processes. An increase in (chemo)denitrification-based N 2 O formation and associated Fe(II) oxidation caused an upregulation of N 2 O reductase (typical nosZ ) genes and a distinct community shift to potential Fe(III)-reducers ( Arcobacter ), Fe(II)-oxidizers ( Sulfurimonas ), and nitrate/nitrite-reducing microorganisms ( Marinobacter ). Our study suggests that chemodenitrification contributes substantially to N 2 O formation from marine sediments and significantly influences the N- and Fe-cycling microbial community.

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Section: Discussionmentioning

confidence: 99%

N2O formation by nitrite-induced (chemo)denitrification in coastal marine sediment

Otte

Blackwell

Ruser

et al. 2019

Sci Rep

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“…In total, three different types of medium were prepared. First, for the nongrowth cell suspension experiment, an anoxic PIPES-buffered medium (pH 7) with Fe(II)-OM complexes was prepared following a slightly modified method published previously (67). To guarantee complexation of most of the Fe(II) present by the different sources of OM tested, the final concentrations of Fe(II), citrate, EDTA, PPHA, and SRFA were 0.1 mM, 0.2 mM, 0.12 mM, 0.2 mg/ml, and 0.2 mg/ml, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Samples were taken in an anoxic glove box (100% N 2 , UNIlab Plus; MBraun, Germany) every 3 to 4 days for the growth experiment or every 1 to 2 h for cell suspension and abiotic photochemical Fe(III) reduction experiments. Fe(II) concentrations were determined anoxically using the ferrozine assay (69) modified as in Peng et al (67). The quantification of Fe(II) in samples without PPHA and SRFA was performed using 1 M anoxic HCl and anoxic ferrozine solution (0.1% [wt/vol]) dissolved in ammonium acetate (C 2 H 7 NO 2 , 50% [wt/vol]).…”

Section: Methodsmentioning

confidence: 99%

Cryptic Cycling of Complexes Containing Fe(III) and Organic Matter by Phototrophic Fe(II)-Oxidizing Bacteria

Peng

Bryce

Sundman

et al. 2019

Appl Environ Microbiol

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Fe-organic matter (Fe-OM) complexes are abundant in the environment and, due to their mobility, reactivity, and bioavailability, play a significant role in the biogeochemical Fe cycle. In photic zones of aquatic environments, Fe-OM complexes can potentially be reduced and oxidized, and thus cycled, by light-dependent processes, including abiotic photoreduction of Fe(III)-OM complexes and microbial oxidation of Fe(II)-OM complexes, by anoxygenic phototrophic bacteria. This could lead to a cryptic iron cycle in which continuous oxidation and rereduction of Fe could result in a low and steady-state Fe(II) concentration despite rapid Fe turnover. However, the coupling of these processes has never been demonstrated experimentally. In this study, we grew a model anoxygenic phototrophic Fe(II) oxidizer,Rhodobacter ferrooxidansSW2, with either citrate, Fe(II)-citrate, or Fe(III)-citrate. We found that strain SW2 was capable of reoxidizing Fe(II)-citrate produced by photochemical reduction of Fe(III)-citrate, which kept the dissolved Fe(II)-citrate concentration at low (<10 μM) and stable concentrations, with a concomitant increase in cell numbers. Cell suspension incubations with strain SW2 showed that it can also oxidize Fe(II)-EDTA, Fe(II)-humic acid, and Fe(II)-fulvic acid complexes. This work demonstrates the potential for active cryptic Fe cycling in the photic zone of anoxic aquatic environments, despite low measurable Fe(II) concentrations which are controlled by the rate of microbial Fe(II) oxidation and the identity of the Fe-OM complexes.IMPORTANCEIron cycling, including reduction of Fe(III) and oxidation of Fe(II), involves the formation, transformation, and dissolution of minerals and dissolved iron-organic matter compounds. It has been shown previously that Fe can be cycled so rapidly that no measurable changes in Fe(II) and Fe(III) concentrations occur, leading to a so-called cryptic cycle. Cryptic Fe cycles have been shown to be driven either abiotically by a combination of photochemical reduction of Fe(III)-OM complexes and reoxidation of Fe(II) by O2, or microbially by a combination of Fe(III)-reducing and Fe(II)-oxidizing bacteria. Our study demonstrates a new type of light-driven cryptic Fe cycle that is relevant for the photic zone of aquatic habitats involving abiotic photochemical reduction of Fe(III)-OM complexes and microbial phototrophic Fe(II) oxidation. This new type of cryptic Fe cycle has important implications for biogeochemical cycling of iron, carbon, nutrients, and heavy metals and can also influence the composition and activity of microbial communities.

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“…Acidovorax sp. BoFeN1 is able to promote oxidation of Fe(II)-citrate, Fe(II)-EDTA, Fe(II)-humic-acid, and Fe(II)-fulvic-acid, but only in the presence of aqueous Fe(II) (Peng et al, 2018). Potential toxicity of ligands may also be a controlling factor in these processes.…”

Section: Mechanisms Of Oxidationmentioning

confidence: 99%

Microbial anaerobic Fe(II) oxidation – Ecology, mechanisms and environmental implications

Bryce

Blackwell

Schmidt

et al. 2018

Environmental Microbiology

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Iron is the most abundant redox-active metal in the Earth's crust. The one electron transfer between the two most common redox states, Fe(II) and Fe(III), plays a role in a huge range of environmental processes from mineral formation and dissolution to contaminant remediation and global biogeochemical cycling. It has been appreciated for more than a century that microorganisms can harness the energy of this Fe redox transformation for their metabolic benefit. However, this is most widely understood for anaerobic Fe(III)-reducing or aerobic and microaerophilic Fe(II)-oxidizing bacteria. Only in the past few decades have we come to appreciate that bacteria also play a role in the anaerobic oxidation of ferrous iron, Fe(II), and thus can act to form Fe(III) minerals in anoxic settings. Since this discovery, our understanding of the ecology of these organisms, their mechanisms of Fe(II) oxidation and their role in environmental processes has been increasing rapidly. In this article, we bring these new discoveries together to review the current knowledge on these environmentally important bacteria, and reveal knowledge gaps for future research.

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Oxidation of Fe(II)–Organic Matter Complexes in the Presence of the Mixotrophic Nitrate-Reducing Fe(II)-Oxidizing Bacterium Acidovorax sp. BoFeN1

Cited by 58 publications

References 90 publications

N2O formation by nitrite-induced (chemo)denitrification in coastal marine sediment

N2O formation by nitrite-induced (chemo)denitrification in coastal marine sediment

Cryptic Cycling of Complexes Containing Fe(III) and Organic Matter by Phototrophic Fe(II)-Oxidizing Bacteria

Microbial anaerobic Fe(II) oxidation – Ecology, mechanisms and environmental implications

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