scholarly journals A novel authigenic magnetite source for sedimentary magnetization

Geology ◽  
2020 ◽  
Author(s):  
Zhiyong Lin ◽  
Xiaoming Sun ◽  
Andrew P. Roberts ◽  
Harald Strauss ◽  
Yang Lu ◽  
...  
Keyword(s):  
Iron Reduction ◽  
Methane Seep ◽  
Iron Sulfides ◽  
Magnetic Minerals ◽  
Iron Reducing Bacteria ◽  
Reactive Iron ◽  
Methane Seepage ◽  
Biogenic Magnetite ◽  
Microbial Iron Reduction ◽  
Reducing Bacteria

We report a novel authigenic nanoscale magnetite source in marine methane seep sediments. The magnetite occurs in large concentrations in multiple horizons in a 230 m sediment core with gas hydrate–bearing intervals. In contrast to typical biogenic magnetite produced by magnetotactic bacteria and dissimilatory iron-reducing bacteria, most particles have sizes of 200–800 nm and many are aligned in distinctive structures that resemble microbial precipitates. The magnetite is interpreted to be a byproduct of microbial iron reduction within methanic sediments with rapidly changing redox conditions. Iron sulfides that accumulated at a shallow sulfate-methane transition zone were oxidized after methane seepage intensity decreased. The alteration process produced secondary iron (oxyhydr)oxides that then became a reactive iron source for magnetite authigenesis when methane seepage increased again. This interpretation is consistent with 13C depletion in coexisting carbonate nodules. The authigenic magnetite will record younger paleomagnetic signals than surrounding sediments, which is important for paleomagnetic interpretations in seep systems. The microbial and possibly abiotic processes that caused these magnetic minerals to form at moderate burial depths remain to be determined.

scholarly journals Can Primary Ferroan Dolomite and Ankerite Be Precipitated? Its Implications for Formation of Submarine Methane-Derived Authigenic Carbonate (MDAC) Chimney

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 413 ◽  
Author(s):  
Fan Xu ◽  
Xuelian You ◽  
Qing Li ◽  
Yi Liu
Keyword(s):  
Iron Reduction ◽  
Extracellular Polymeric Substances ◽  
Microbial Culture ◽  
Reduction Zone ◽  
Secondary Products ◽  
Iron Reducing Bacteria ◽  
Sulfate Reducing ◽  
Dolomite Problem ◽  
Reducing Bacteria ◽  
Ferroan Dolomite

Microbes can mediate the precipitation of primary dolomite under surface conditions. Meanwhile, primary dolomite mediated by microbes often contains more Fe2+ than standard dolomite in modern microbial culture experiments. Ferroan dolomite and ankerite have been regarded as secondary products. This paper reviews the process and possible mechanisms of microbial mediated precipitation of primary ferroan dolomite and/or ankerite. In the microbial geochemical Fe cycle, many dissimilatory iron-reducing bacteria (DIRB), sulfate-reducing bacteria (SRB), and methanogens can reduce Fe3+ to Fe2+, while SRB and methanogens can also promote the precipitation of primary dolomite. There are an oxygen respiration zone (ORZ), an iron reduction zone (IRZ), a sulfate reduction zone (SRZ), and a methanogenesis zone (MZ) from top to bottom in the muddy sediment diagenesis zone. DIRB in IRZ provide the lower section with Fe2+, which composes many enzymes and proteins to participate in metabolic processes of SRB and methanogens. Lastly, heterogeneous nucleation of ferroan dolomite on extracellular polymeric substances (EPS) and cell surfaces is mediated by SRB and methanogens. Exploring the origin of microbial ferroan dolomite may help to solve the “dolomite problem”.

scholarly journals Effect of Sub-Stoichiometric Fe(III) Amounts on LCFA Degradation by Methanogenic Communities

2020 ◽  
Vol 8 (9) ◽  
pp. 1375
Author(s):  
Ana J. Cavaleiro ◽  
Ana P. Guedes ◽  
Sérgio A. Silva ◽  
Ana L. Arantes ◽  
João C. Sequeira ◽  
...  
Keyword(s):  
Iron Reduction ◽  
Anaerobic Bacteria ◽  
Granular Sludge ◽  
Microbial Interactions ◽  
Methanogenic Activity ◽  
Iron Reducing Bacteria ◽  
Hydrogenotrophic Methanogenesis ◽  
Degrading Bacteria ◽  
Acetoclastic Methanogenesis ◽  
Reducing Bacteria

Long-chain fatty acids (LCFA) are common contaminants in municipal and industrial wastewater that can be converted anaerobically to methane. A low hydrogen partial pressure is required for LCFA degradation by anaerobic bacteria, requiring the establishment of syntrophic relationships with hydrogenotrophic methanogens. However, high LCFA loads can inhibit methanogens, hindering biodegradation. Because it has been suggested that anaerobic degradation of these compounds may be enhanced by the presence of alternative electron acceptors, such as iron, we investigated the effect of sub-stoichiometric amounts of Fe(III) on oleate (C18:1 LCFA) degradation by suspended and granular methanogenic sludge. Fe(III) accelerated oleate biodegradation and hydrogenotrophic methanogenesis in the assays with suspended sludge, with H2-consuming methanogens coexisting with iron-reducing bacteria. On the other hand, acetoclastic methanogenesis was delayed by Fe(III). These effects were less evident with granular sludge, possibly due to its higher initial methanogenic activity relative to suspended sludge. Enrichments with close-to-stoichiometric amounts of Fe(III) resulted in a microbial community mainly composed of Geobacter, Syntrophomonas, and Methanobacterium genera, with relative abundances of 83–89%, 3–6%, and 0.2–10%, respectively. In these enrichments, oleate was biodegraded to acetate and coupled to iron-reduction and methane production, revealing novel microbial interactions between syntrophic LCFA-degrading bacteria, iron-reducing bacteria, and methanogens.

scholarly journals Functional diversity of microbial communities in pristine aquifers inferred by PLFA – and sequencing – based approaches

2016 ◽  
Author(s):  
Valerie F. Schwab ◽  
Martina Hermann ◽  
Vanessa-Nina Roth ◽  
Gerd Gleixner ◽  
Robert Lehmann ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Functional Diversity ◽  
Iron Reduction ◽  
Rrna Genes ◽  
Anammox Bacteria ◽  
Iron Reducing Bacteria ◽  
Nitrite Oxidizing Bacteria ◽  
Relative Abundances ◽  
Reducing Bacteria ◽  
Nitrospira Moscoviensis

Abstract. Microorganisms in groundwater play an important role in aquifer biogeochemical cycles and water quality. However, the mechanisms linking the functional diversity of microbial populations and the groundwater physicochemistry are still not well understood due to the complexity of interactions between surface and subsurface. Here, we used phospholipid fatty acids (PLFAs) relative abundances to link specific biochemical markers within the microbial communities to the spatio-temporal changes of the groundwater physicochemistry. PLFAs were isolated from groundwater of two physicochemically distinct aquifer assemblages in central Germany (Thuringia). The functional diversities of the microbial communities were mainly correlated with groundwater chemistry, including dissolved O2, Fet and NH4+ concentrations. Abundances of PLFAs derived from eukaryotes and potential nitrite oxidizing bacteria (11MeC16:0 as biomarker for Nitrospira moscoviensis) were high at sites with elevated O2 concentration where groundwater recharge supplies both bioavailable organic substrates and NH4+ needed to sustain heterotrophic growth and nitrification processes. In anoxic groundwaters more rich in Fet, PLFAs abundant in sulphate reducing bacteria (SRB), iron-reducing bacteria and fungi increased with Fet and HCO3− concentrations suggesting the occurrence of active iron-reduction and the possible role of fungi in meditating iron solubilisation and transport in those aquifer domains. In NH4+ richer anoxic groundwaters, anammox bacteria and SRB- derived PLFAs increased with NH4+ concentration further evidencing the dependence of the anammox process on ammonium concentration and potential links between SRB and anammox bacteria. Additional support of the PLFA-based bacterial communities was found in DNA and RNA-based Illumina MiSeq amplicon sequencing of bacterial 16S rRNA genes, which evidenced high predominance of nitrite-oxidizing bacteria Nitrospira e.g. Nitrospira moscoviensis in oxic zones of the aquifers and of anammox bacteria in NH4+ richer anoxic groundwater. Higher relative abundances of sequence reads in the RNA-based data sets affiliated with iron-reducing bacteria in Fet richer groundwater supported the occurrence of active dissimilatory iron-reduction. The functional diversity of the microbial communities in these biogeochemically distinct groundwater assemblages can be largely attributed to the redox conditions linked to changes in bioavailable substrates and input of substrates with the seepage. Our results demonstrate the power of complementary information derived from PLFA-based and sequencing-based approaches.

scholarly journals Humic Acid Reduction by Propionibacterium freudenreichii and Other Fermenting Bacteria

1998 ◽  
Vol 64 (11) ◽  
pp. 4507-4512 ◽  
Author(s):  
Marcus Benz ◽  
Bernhard Schink ◽  
Andreas Brune
Keyword(s):  
Molecular Weight ◽  
Humic Acids ◽  
Iron Reduction ◽  
Ferric Iron ◽  
Hydrogen Oxidation ◽  
Low Molecular Weight ◽  
Propionibacterium Freudenreichii ◽  
Iron Reducing Bacteria ◽  
Fermenting Bacteria ◽  
Reducing Bacteria

ABSTRACT Iron-reducing bacteria have been reported to reduce humic acids and low-molecular-weight quinones with electrons from acetate or hydrogen oxidation. Due to the rapid chemical reaction of amorphous ferric iron with the reduced reaction products, humic acids and low-molecular-weight redox mediators may play an important role in biological iron reduction. Since many anaerobic bacteria that are not able to reduce amorphous ferric iron directly are known to transfer electrons to other external acceptors, such as ferricyanide, 2,6-anthraquinone disulfonate (AQDS), or molecular oxygen, we tested several physiologically different species of fermenting bacteria to determine their abilities to reduce humic acids.Propionibacterium freudenreichii, Lactococcus lactis, and Enterococcus cecorum all shifted their fermentation patterns towards more oxidized products when humic acids were present; P. freudenreichii even oxidized propionate to acetate under these conditions. When amorphous ferric iron was added to reoxidize the electron acceptor, humic acids were found to be equally effective when they were added in substoichiometric amounts. These findings indicate that in addition to iron-reducing bacteria, fermenting bacteria are also capable of channeling electrons from anaerobic oxidations via humic acids towards iron reduction. This information needs to be considered in future studies of electron flow in soils and sediments.

Effects of Magnetic Minerals Exposure and Microbial Responses in Surface Sediment Across Bohai Sea

2021 ◽  
Author(s):  
Lei Chen ◽  
Mingpeng Wang ◽  
Yuntao Li ◽  
Weitao Shang ◽  
Jianhui Tang ◽  
...  
Keyword(s):  
Community Composition ◽  
Surface Sediment ◽  
Iron Reduction ◽  
Bohai Sea ◽  
Bacterial Community Composition ◽  
Microbial Community Composition ◽  
Magnetic Minerals ◽  
Iron Reducing Bacteria ◽  
Α Diversity ◽  
Microbial Responses

Abstract Extensive production and application of magnetic minerals produce significant amounts of magnetic wastes to the environment. These magnetic minerals exposure could affect microbial community composition and geographic distribution. Here, we reported magnetic susceptibility is involved in determining bacterial α-diversity and community composition in surface sediment across Bohai Sea. Environmental factors (explained 9.80%) played a larger role than spatial variables (explained 6.72%) in conditioning the bacterial community composition. Exposure of magnetite center may shape geographical distribution of five dissimilatory iron reducing bacteria (DIRB). Microbial iron reduction ability and electroactive activity in sediment close to magnetite center are stronger than those far away. Our study provides novel understanding for response of DIRB and electroactive bacteria to magnetic minerals exposure.

Authigenic nanoscale magnetite within methanic marine sediments

2021 ◽  
Author(s):  
Zhiyong Lin ◽  
Xiaoming Sun ◽  
Andrew Roberts ◽  
Harald Strauss ◽  
Benjamin Brunner ◽  
...  
Keyword(s):  
Marine Sediments ◽  
Iron Reduction ◽  
Iron Sulfide ◽  
Anaerobic Oxidation Of Methane ◽  
Magnetic Studies ◽  
Iron Reducing Bacteria ◽  
Fine Grained ◽  
Oxidation Of Methane ◽  
New Type ◽  
Reducing Bacteria

<p>Magnetic studies of methanic sediments focus mainly on magnetic iron sulfide (greigite, 3C pyrrhotite) formation and magnetic iron oxide (magnetite, titanomagnetite) dissolution, which mainly result from the release of hydrogen sulfide during sulfate-driven anaerobic oxidation of methane. In some instances, authigenic fine-grained magnetite within methanic environments is recognized from magnetic parameters, but the mechanisms for explaining its occurrence remain unclear. We report a novel authigenic nanoscale magnetite source in methanic marine sediments. The magnetite occurs in large concentrations in multiple horizons in a 230-m long sediment core with gas hydrate-bearing intervals. In contrast to typical biogenic magnetite produced by magnetotactic bacteria and dissimilatory iron-reducing bacteria, most particles have sizes of 200-800 nm and many are aligned in distinctive structures that resemble microbial precipitates. This new type of magnetite is interpreted to be a by-product of microbial iron reduction within methanic sediments. It will record younger paleomagnetic signals than surrounding sediments, which is important for paleomagnetic interpretations in methanic sediments.</p>

scholarly journals Functional diversity of microbial communities in pristine aquifers inferred by PLFA- and sequencing-based approaches

2017 ◽  
Vol 14 (10) ◽  
pp. 2697-2714 ◽  
Author(s):  
Valérie F. Schwab ◽  
Martina Herrmann ◽  
Vanessa-Nina Roth ◽  
Gerd Gleixner ◽  
Robert Lehmann ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Functional Diversity ◽  
Iron Reduction ◽  
Rrna Genes ◽  
Anammox Bacteria ◽  
Iron Reducing Bacteria ◽  
Nitrite Oxidizing Bacteria ◽  
Relative Abundances ◽  
Reducing Bacteria ◽  
Nitrospira Moscoviensis

Abstract. Microorganisms in groundwater play an important role in aquifer biogeochemical cycles and water quality. However, the mechanisms linking the functional diversity of microbial populations and the groundwater physico-chemistry are still not well understood due to the complexity of interactions between surface and subsurface. Within the framework of Hainich (north-western Thuringia, central Germany) Critical Zone Exploratory of the Collaborative Research Centre AquaDiva, we used the relative abundances of phospholipid-derived fatty acids (PLFAs) to link specific biochemical markers within the microbial communities to the spatio-temporal changes of the groundwater physico-chemistry. The functional diversities of the microbial communities were mainly correlated with groundwater chemistry, including dissolved O2, Fet and NH4+ concentrations. Abundances of PLFAs derived from eukaryotes and potential nitrite-oxidizing bacteria (11Me16:0 as biomarker for Nitrospira moscoviensis) were high at sites with elevated O2 concentration where groundwater recharge supplies bioavailable substrates. In anoxic groundwaters more rich in Fet, PLFAs abundant in sulfate-reducing bacteria (SRB), iron-reducing bacteria and fungi increased with Fet and HCO3− concentrations, suggesting the occurrence of active iron reduction and the possible role of fungi in meditating iron solubilization and transport in those aquifer domains. In more NH4+-rich anoxic groundwaters, anammox bacteria and SRB-derived PLFAs increased with NH4+ concentration, further evidencing the dependence of the anammox process on ammonium concentration and potential links between SRB and anammox bacteria. Additional support of the PLFA-based bacterial communities was found in DNA- and RNA-based Illumina MiSeq amplicon sequencing of bacterial 16S rRNA genes, which showed high predominance of nitrite-oxidizing bacteria Nitrospira, e.g. Nitrospira moscoviensis, in oxic aquifer zones and of anammox bacteria in more NH4+-rich anoxic groundwater. Higher relative abundances of sequence reads in the RNA-based datasets affiliated with iron-reducing bacteria in more Fet-rich groundwater supported the occurrence of active dissimilatory iron reduction. The functional diversity of the microbial communities in the biogeochemically distinct groundwater assemblages can be largely attributed to the redox conditions linked to changes in bioavailable substrates and input of substrates with the seepage. Our results demonstrate the power of complementary information derived from PLFA-based and sequencing-based approaches.

scholarly journals Effects of Fe(III) Oxide Mineralogy and Phosphate on Fe(II) Secondary Mineral Formation during Microbial Iron Reduction

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 149
Author(s):  
Edward J. O’Loughlin ◽  
Maxim I. Boyanov ◽  
Christopher A. Gorski ◽  
Michelle M. Scherer ◽  
Kenneth M. Kemner
Keyword(s):  
Iron Reduction ◽  
Phosphate Concentration ◽  
Green Rust ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
X Ray Diffraction ◽  
Secondary Minerals ◽  
Iron Reducing Bacteria ◽  
Secondary Mineral Formation ◽  
Reducing Bacteria

The bioreduction of Fe(III) oxides by dissimilatory iron-reducing bacteria may result in the formation of a suite of Fe(II)-bearing secondary minerals, including magnetite (a mixed Fe(II)/Fe(III) oxide), siderite (Fe(II) carbonate), vivianite (Fe(II) phosphate), chukanovite (ferrous hydroxy carbonate), and green rusts (mixed Fe(II)/Fe(III) hydroxides). In an effort to better understand the factors controlling the formation of specific Fe(II)-bearing secondary minerals, we examined the effects of Fe(III) oxide mineralogy, phosphate concentration, and the availability of an electron shuttle (9,10-anthraquinone-2,6-disulfonate, AQDS) on the bioreduction of a series of Fe(III) oxides (akaganeite, feroxyhyte, ferric green rust, ferrihydrite, goethite, hematite, and lepidocrocite) by Shewanella putrefaciens CN32, and the resulting formation of secondary minerals, as determined by X-ray diffraction, Mössbauer spectroscopy, and scanning electron microscopy. The overall extent of Fe(II) production was highly dependent on the type of Fe(III) oxide provided. With the exception of hematite, AQDS enhanced the rate of Fe(II) production; however, the presence of AQDS did not always lead to an increase in the overall extent of Fe(II) production and did not affect the types of Fe(II)-bearing secondary minerals that formed. The effects of the presence of phosphate on the rate and extent of Fe(II) production were variable among the Fe(III) oxides, but in general, the highest loadings of phosphate resulted in decreased rates of Fe(II) production, but ultimately higher levels of Fe(II) than in the absence of phosphate. In addition, phosphate concentration had a pronounced effect on the types of secondary minerals that formed; magnetite and chukanovite formed at phosphate concentrations of ≤1 mM (ferrihydrite), <~100 µM (lepidocrocite), 500 µM (feroxyhyte and ferric green rust), while green rust, or green rust and vivianite, formed at phosphate concentrations of 10 mM (ferrihydrite), ≥100 µM (lepidocrocite), and 5 mM (feroxyhyte and ferric green rust). These results further demonstrate that the bioreduction of Fe(III) oxides, and accompanying Fe(II)-bearing secondary mineral formation, is controlled by a complex interplay of mineralogical, geochemical, and microbiological factors.

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