A comparison of Fe(III) reduction rates between fresh and aged biogenic iron oxides (BIOS) by Shewanella putrefaciens CN32

Najem, Tarek; Langley, Sean; Fortin, Danielle

doi:10.1016/j.chemgeo.2016.06.006

Cited by 13 publications

(7 citation statements)

References 81 publications

(226 reference statements)

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“…This indicates that encrustation is potentially negligible in environments that do not have elevated Fe(II) concentrations. In environments with elevated Fe(II) concentrations, bacteria encrusted in Fe minerals have been found (19,20,(55)(56)(57). In anoxic environments, the abiotic oxidation of Fe(II) by metabolic products of denitrifying bacteria or by O 2 under microoxic conditions can potentially contribute to encrustation of microbial cells.…”

Section: Discussionmentioning

confidence: 99%

“…The spectra were recorded at 77 K in transmission geometry using a constant acceleration drive system (WissEL). A 57 Co source embedded in a rhodium matrix was used as a gamma radiation source. The sample spectra were calibrated against a 7-m-thick ␣- 57 Fe foil at room temperature (RT).…”

Section: Methodsmentioning

confidence: 99%

“…A 57 Co source embedded in a rhodium matrix was used as a gamma radiation source. The sample spectra were calibrated against a 7-m-thick ␣- 57 Fe foil at room temperature (RT). The RECOIL software suite (University of Ottawa, Canada) was used for the calibration and the modeling of the spectra.…”

Section: Methodsmentioning

confidence: 99%

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Insights into Nitrate-Reducing Fe(II) Oxidation Mechanisms through Analysis of Cell-Mineral Associations, Cell Encrustation, and Mineralogy in the Chemolithoautotrophic Enrichment Culture KS

Nordhoff

Tominski

Halama

et al. 2017

Appl Environ Microbiol

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Most described nitrate-reducing Fe(II)-oxidizing bacteria (NRFeOB) are mixotrophic and depend on organic cosubstrates for growth. Encrustation of cells in Fe(III) minerals has been observed for mixotrophic NRFeOB but not for autotrophic phototrophic and microaerophilic Fe(II) oxidizers. So far, little is known about cellmineral associations in the few existing autotrophic NRFeOB. Here, we investigate whether the designated autotrophic Fe(II)-oxidizing strain (closely related to Gallionella and Sideroxydans) or the heterotrophic nitrate reducers that are present in the autotrophic nitrate-reducing Fe(II)-oxidizing enrichment culture KS form mineral crusts during Fe(II) oxidation under autotrophic and mixotrophic conditions. In the mixed culture, we found no significant encrustation of any of the cells both during autotrophic oxidation of 8 to 10 mM Fe(II) coupled to nitrate reduction and during cultivation under mixotrophic conditions with 8 to 10 mM Fe(II), 5 mM acetate, and 4 mM nitrate, where higher numbers of heterotrophic nitrate reducers were present. Two pure cultures of heterotrophic nitrate reducers (Nocardioides and Rhodanobacter) isolated from culture KS were analyzed under mixotrophic growth conditions. We found green rust formation, no cell encrustation, and only a few mineral particles on some cell surfaces with 5 mM Fe(II) and some encrustation with 10 mM Fe(II). Our findings suggest that enzymatic, autotrophic Fe(II) oxidation coupled to nitrate reduction forms poorly crystalline Fe(III) oxyhydroxides and proceeds without cellular encrustation while indirect Fe(II) oxidation via heterotrophic nitrate-reductionderived nitrite can lead to green rust as an intermediate mineral and significant cell encrustation. The extent of encrustation caused by indirect Fe(II) oxidation by reactive nitrogen species depends on Fe(II) concentrations and is probably negligible under environmental conditions in most habitats.IMPORTANCE Most described nitrate-reducing Fe(II)-oxidizing bacteria (NRFeOB) are mixotrophic (their growth depends on organic cosubstrates) and can become encrusted in Fe(III) minerals. Encrustation is expected to be harmful and poses a threat to cells if it also occurs under environmentally relevant conditions. Nitrite produced during heterotrophic denitrification reacts with Fe(II) abiotically and is probably the reason for encrustation in mixotrophic NRFeOB. Little is known about cell-mineral associations in autotrophic NRFeOB such as the enrichment culture KS. Here, we show that no encrustation occurs in culture KS under autotrophic and mixotrophic conditions while heterotrophic nitrate-reducing isolates from culture KS become en-

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Insights into Nitrate-Reducing Fe(II) Oxidation Mechanisms through Analysis of Cell-Mineral Associations, Cell Encrustation, and Mineralogy in the Chemolithoautotrophic Enrichment Culture KS

Nordhoff

Tominski

Halama

et al. 2017

Appl Environ Microbiol

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“…Barcellos et al [ 68 ] found that shorter intervals of oxic and anoxic conditions lead to higher Fe 3+ reduction rates compared to longer intervals if the total incubation time is identical, although the Fe 3+ reduction rates at the start are the same. Our model is able to reproduce this finding after the inclusion of one simple rule of aged iron minerals being less prone to reduction than fresh iron minerals [ 69 ], which could be due to secondary mineral formation. If not interrupted by Fe 3+ reduction, crystallization processes can lead to the transformation of oxides in minerals which are harder to reduce for the bacteria [ 70 , 71 ].…”

Section: Resultsmentioning

confidence: 86%

“…Experimental studies focus on isolated aspects of the system, such as reduction rates [ 29 , 68 , 69 , 72 ] or the percentage of attached FeRB [ 31 , 73 , 74 ]. Those studies are used for the parametrization of our model and can therefore not be re-used for validation.…”

Section: Resultsmentioning

confidence: 99%

Agent-based modelling of iron cycling bacteria provides a framework for testing alternative environmental conditions and modes of action

Then¹,

Ewald²,

Söllner³

et al. 2022

R. Soc. open sci.

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Iron-reducing and iron-oxidizing bacteria are of interest in a variety of environmental and industrial applications. Such bacteria often co-occur at oxic-anoxic gradients in aquatic and terrestrial habitats. In this paper, we present the first computational agent-based model of microbial iron cycling, between the anaerobic ferric iron (Fe 3+ )-reducing bacteria Shewanella spp. and the microaerophilic ferrous iron (Fe 2+ )-oxidizing bacteria Sideroxydans spp. By including the key processes of reduction/oxidation, movement, adhesion, Fe 2+ -equilibration and nanoparticle formation, we derive a core model which enables hypothesis testing and prediction for different environmental conditions including temporal cycles of oxic and anoxic conditions. We compared (i) combinations of different Fe 3+ -reducing/Fe 2+ -oxidizing modes of action of the bacteria and (ii) system behaviour for different pH values. We predicted that the beneficial effect of a high number of iron-nanoparticles on the total Fe 3+ reduction rate of the system is not only due to the faster reduction of these iron-nanoparticles, but also to the nanoparticles’ additional capacity to bind Fe 2+ on their surfaces. Efficient iron-nanoparticle reduction is confined to pH around 6, being twice as high than at pH 7, whereas at pH 5 negligible reduction takes place. Furthermore, in accordance with experimental evidence our model showed that shorter oxic/anoxic periods exhibit a faster increase of total Fe 3+ reduction rate than longer periods.

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A critical review of abiotic and microbially-mediated chemical reduction rates of Fe(III) (oxyhydr)oxides using a reactivity model

Xiu

Yuan

Polya

et al. 2021

Applied Geochemistry

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A comparison of Fe(III) reduction rates between fresh and aged biogenic iron oxides (BIOS) by Shewanella putrefaciens CN32

Cited by 13 publications

References 81 publications

Insights into Nitrate-Reducing Fe(II) Oxidation Mechanisms through Analysis of Cell-Mineral Associations, Cell Encrustation, and Mineralogy in the Chemolithoautotrophic Enrichment Culture KS

Insights into Nitrate-Reducing Fe(II) Oxidation Mechanisms through Analysis of Cell-Mineral Associations, Cell Encrustation, and Mineralogy in the Chemolithoautotrophic Enrichment Culture KS

Agent-based modelling of iron cycling bacteria provides a framework for testing alternative environmental conditions and modes of action

A critical review of abiotic and microbially-mediated chemical reduction rates of Fe(III) (oxyhydr)oxides using a reactivity model

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