Vanadate reducing bacteria and archaea may use different mechanisms to reduce vanadate in vanadium contaminated riverine ecosystems as revealed by the combination of DNA-SIP and metagenomic-binning

Yan, Geng; Sun, Xiaoxu; Dong, Yiran; Gao, Wenlong; Gao, Pin; Li, Baoqin; Yan, Wangwang; Zhang, Haihan; Soleimani, Mohsen; Yan, Bei; Häggblom, Max M.; Sun, Weimin

doi:10.1016/j.watres.2022.119247

Cited by 13 publications

(6 citation statements)

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“…Iron-reducing bacteria are important members of Hg-methylating communities in natural environments (Bravo et al, 2018;Leclerc et al, 2021) and one common bacterium used to study mechanisms of MeHg formation in laboratory settings is Geobacter sulfurreducens (Kerin et al, 2006;Schaefer and Morel, 2009;Schaefer et al, 2014;Lin et al, 2015;Si et al, 2015;Qian et al, 2016;Thomas et al, 2020). Geobacter species generally play an important role in the biogeochemistry of many environments due to their capacity to grow on abundant minerals containing iron or manganese, and interact with other trace metals such as uranium or vanadium (Cologgi et al, 2014;Yan et al, 2022). The use of G. sulfurreducens enables relatively good control of Hg speciation and its availability for cellular uptake, because it is incapable of sulfate reduction, thus, minimizing the formation of sulfides during the assay (Schaefer and Morel, 2009).…”

Section: Introductionmentioning

confidence: 99%

Methylmercury formation in biofilms of Geobacter sulfurreducens

et al. 2023

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IntroductionMercury (Hg) is a major environmental pollutant that accumulates in biota predominantly in the form of methylmercury (MeHg). Surface-associated microbial communities (biofilms) represent an important source of MeHg in natural aquatic systems. In this work, we report MeHg formation in biofilms of the iron-reducing bacterium Geobacter sulfurreducens.MethodsBiofilms were prepared in media with varied nutrient load for 3, 5, or 7 days, and their structural properties were characterized using confocal laser scanning microscopy, cryo-scanning electron microscopy and Fourier-transform infrared spectroscopy.ResultsBiofilms cultivated for 3 days with vitamins in the medium had the highest surface coverage, and they also contained abundant extracellular matrix. Using 3 and 7-days-old biofilms, we demonstrate that G. sulfurreducens biofilms prepared in media with various nutrient load produce MeHg, of which a significant portion is released to the surrounding medium. The Hg methylation rate constant determined in 6-h assays in a low-nutrient assay medium with 3-days-old biofilms was 3.9 ± 2.0 ∙ 10−14 L ∙ cell−1 ∙ h−1, which is three to five times lower than the rates found in assays with planktonic cultures of G. sulfurreducens in this and previous studies. The fraction of MeHg of total Hg within the biofilms was, however, remarkably high (close to 50%), and medium/biofilm partitioning of inorganic Hg (Hg(II)) indicated low accumulation of Hg(II) in biofilms.DiscussionThese findings suggest a high Hg(II) methylation capacity of G. sulfurreducens biofilms and that Hg(II) transfer to the biofilm is the rate-limiting step for MeHg formation in this systems.

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Section: Introductionmentioning

confidence: 99%

Methylmercury formation in biofilms of Geobacter sulfurreducens

et al. 2023

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“…The LCF results for V K -edge data of the 1.5-week deployed V-bearing Lpc gel (Table , Figure ) show that V was reduced from V V to V IV in areas that correspond to the ferruginous zone of the sediment, indicating that V was likely reduced by the access of porewater Fe 2+ . There are, however, also reports of vanadate reduction to V IV by bacteria and archaea, ,− which we cannot ruled out as occurring here. The biotic V reduction is further discussed in Section .…”

Section: Resultsmentioning

confidence: 60%

“…In general, V reduction occurred in the reducing zones of the sediment and increased with increasing sediment depth with the lowest average V oxidation state of +3.79 (21% V III at a depth of ∼15 cm, based on LCF fits: Table and Figure ). The increasing reduction of V with sediment depth is consistent with the redox potential tending to decrease with sediment depth and V reduction driven by both dissolved ferrous iron and hydrogen sulfide. ,,,, We cannot, however, exclude the potential role of microbial V reduction. − Based on the calculated Gibbs free energy of V V reduction to V IV (Section S4) compared to Fe III and SO 4 2– reduction, it may be energetically favorable for bacteria to couple V reduction with organic C mineralization. However, the calculated Gibbs free energy of reactions under standard conditions may drastically vary from in situ energies, and therefore, the microbial influence of V reduction in natural marine sediments requires further investigation.…”

Section: Resultsmentioning

confidence: 62%

“…8,13,17,84,91 We cannot, however, exclude the potential role of microbial V reduction. 86−89 Based on the calculated Gibbs free energy of V V reduction 86 to V IV (Section S4) compared to Fe III and SO 4 2− reduction, 68 it may be energetically favorable for bacteria to couple V reduction with organic C mineralization. However, the calculated Gibbs free energy of reactions under standard conditions may drastically vary from in situ energies, 28 and therefore, the microbial influence of V reduction in natural marine sediments requires further investigation.…”

Section: Implications For the Early Diagenesis Of Vanadium In Marinementioning

confidence: 99%

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The Fate of Vanadium-Bearing Iron Oxyhydroxides in Marine Sediments: Integrating Gel-Based In Situ Mineral Probes with Synchrotron X-ray Fluorescence Microspectroscopy

Haase,

Sekine,

Doriean

et al. 2024

ACS Earth Space Chem.

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Vanadium (V) is a redox-sensitive trace metal often used as a paleoredox proxy in ancient marine sediments. However, our understanding of the early diagenesis of V is limited to laboratory-based simulations and bulk geochemical measurements of natural sediments. Microscale measurements are essential to exploring V geochemistry in organic-rich coastal sediments, where redox zonation changes over small spatial scales. Here, we describe an innovative in situ two-dimensional (2D) imaging approach to study redox-driven changes of V-bearing iron oxyhydroxides (lepidocrocite and ferrihydrite) in intertidal mudflat sediments of an Australian lagoon lake (Coombabah Lake, Queensland). Vanadium-bearing iron oxyhydroxides were suspended in a polyurethane-based hydrogel matrix, loaded on laser-cut acrylic probes, and exposed to mudflat sediments for up to 6 weeks. Changes in V speciation and Fe mineralogy were examined using synchrotron-based X-ray fluorescence (XRF) microspectroscopy for high-resolution chemical imaging of elemental (V, S, Fe) distributions combined with micro-X-ray absorption near-edge structure (μXANES) spectroscopy at the V and Fe K-edges for speciation analysis. Linear combination fitting of μXANES data revealed that solid-phase V V was reduced to V IV in the ferruginous zone of sediments and to a mixture of mainly V IV and some V III (up to 10−20%) in the sulfidic zone, where the reduction correlated with the degree of sulfidation and conversion of the iron oxyhydroxides to FeS (up to 96%). The combination of gel-based mineral probes with synchrotron-based μXRF tools can unravel small-scale geochemical relationships and provide new insights into the early diagenesis of trace elements in marine sediments.

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“…5,9,10 Nitrate reductase (Nap) and nitrite reductase (NIR) have been reported to contribute to the reduction process of pentavalent vanadium during denitrification, implying that nitrate and pentavalent vanadium may compete for electrons in the same electron pool. [26][27][28] The removal performance of nitrate in the reactor with and without V(V) was compared. In the process of nitrate-N removal, sodium acetate showed a superior performance, where 100 mg N per L nitrate was degraded to less than 1.5 mg N per L within 12 hours, followed by ethanol and glucose, and the nitrate concentration of 100 mg N per L was degraded to less than 1.5 mg N per L at the 24th hour of the reaction.…”

Section: Variation Of Nitrate and By-products And V(v)mentioning

confidence: 99%