scholarly journals A biological source of marine sedimentary iron oxides

2017 ◽  
Author(s):  
Jacob P. Beam ◽  
Jarrod J. Scott ◽  
Sean M. McAllister ◽  
Clara S. Chan ◽  
James McManus ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Coastal Sediments ◽  
Iron Cycling ◽  
Sedimentary Environments ◽  
Biological Source ◽  
Iron Oxidizing Bacteria ◽  
Numerical Abundance ◽  
Oxidative Processes ◽  
Numerous Element ◽  
Annual Flux

AbstractThe biogeochemical cycle of iron is intricately linked to numerous element cycles. Although reductive biological processes that bridge the iron cycle to other element cycles are established, little is known about microbial oxidative processes on iron cycling in sedimentary environments—resulting in the formation of iron oxides. Here, we show that a major source of sedimentary iron oxides originates from the metabolic activity of iron-oxidizing bacteria from the class Zetaproteobacteria, stimulated by burrowing animals in coastal sediments. Zetaproteobacteria were estimated to be a global total of 1026 cells in coastal, bioturbated sediments and would equate to an annual production of approximately 7.9 x 1015 grams of sedimentary iron oxides—twenty-five times larger than the annual flux of iron oxides by rivers. These data suggest that iron-oxidizing Zetaproteobacteria are keystone organisms in marine sedimentary environments given their low numerical abundance; yet exert a profound impact via the production of iron oxides.

scholarly journals Antarctic ice sheet fertilises the Southern Ocean

2014 ◽  
Vol 11 (10) ◽  
pp. 2635-2643 ◽  
Author(s):  
R. Death ◽  
J. L. Wadham ◽  
F. Monteiro ◽  
A. M. Le Brocq ◽  
M. Tranter ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Ice Sheet ◽  
Ocean Model ◽  
Coastal Sediments ◽  
Global Ocean ◽  
Iron Cycling ◽  
Antarctic Ice Sheet ◽  
Significant Control ◽  
Subglacial Meltwater ◽  
The Impact

Abstract. Southern Ocean (SO) marine primary productivity (PP) is strongly influenced by the availability of iron in surface waters, which is thought to exert a significant control upon atmospheric CO2 concentrations on glacial/interglacial timescales. The zone bordering the Antarctic Ice Sheet exhibits high PP and seasonal plankton blooms in response to light and variations in iron availability. The sources of iron stimulating elevated SO PP are in debate. Established contributors include dust, coastal sediments/upwelling, icebergs and sea ice. Subglacial meltwater exported at the ice margin is a more recent suggestion, arising from intense iron cycling beneath the ice sheet. Icebergs and subglacial meltwater may supply a large amount of bioavailable iron to the SO, estimated in this study at 0.07–0.2 Tg yr−1. Here we apply the MIT global ocean model (Follows et al., 2007) to determine the potential impact of this level of iron export from the ice sheet upon SO PP. The export of iron from the ice sheet raises modelled SO PP by up to 40%, and provides one plausible explanation for seasonally very high in situ measurements of PP in the near-coastal zone. The impact on SO PP is greatest in coastal regions, which are also areas of high measured marine PP. These results suggest that the export of Antarctic runoff and icebergs may have an important impact on SO PP and should be included in future biogeochemical modelling.

scholarly journals Antarctic Ice Sheet fertilises the Southern Ocean

2013 ◽  
Vol 10 (7) ◽  
pp. 12551-12570 ◽  
Author(s):  
R. Death ◽  
J. L. Wadham ◽  
F. Monteiro ◽  
A. M. Le Brocq ◽  
M. Tranter ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Ice Sheet ◽  
Ocean Model ◽  
Coastal Sediments ◽  
Global Ocean ◽  
Iron Cycling ◽  
Antarctic Ice Sheet ◽  
Significant Control ◽  
Subglacial Meltwater ◽  
The Impact

Abstract. Southern Ocean (SO) marine primary productivity (PP) is strongly influenced by the availability of iron in surface waters, which is thought to exert a significant control upon atmospheric CO2 concentrations on glacial/interglacial timescales. The zone bordering the Antarctic Ice Sheet exhibits high PP and seasonal plankton blooms in response to light and variations in iron availability. The sources of iron stimulating elevated SO PP are in debate. Established contributors include dust, coastal sediments/upwelling, icebergs and sea ice. Subglacial meltwater exported at the ice margin is a more recent suggestion, arising from intense iron cycling beneath the ice sheet. Icebergs and subglacial meltwater may supply a large amount of bioavailable iron to the SO, estimated in this study at 0.07–1.0 Tg yr−1. Here we apply the MIT global ocean model (Follows et al., 2007) to determine the potential impact of this level of iron export from the ice sheet upon SO PP. The export of iron from the ice sheet raises modelled SO PP by up to 40%, and provides one plausible explanation for very high seasonally observed PP in the near-coastal zone. The impact on SO PP is greatest in coastal regions, which are also areas of high observed marine PP. These results suggest that the export of Antarctic runoff and icebergs may have an important impact on SO PP and should be included in future biogeochemical modelling.

scholarly journals Enrichment of novel Verrucomicrobia, Bacteroidetes and Krumholzibacteria in an oxygen-limited, methane- and iron-fed bioreactor inoculated with Bothnian Sea sediments

2020 ◽  
Author(s):  
Paula Dalcin Martins ◽  
Anniek de Jong ◽  
Wytze K. Lenstra ◽  
Niels A. G. M. van Helmond ◽  
Caroline P. Slomp ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Coastal Sediments ◽  
Ecosystem Functions ◽  
Marker Genes ◽  
Iron Cycling ◽  
Low Oxygen ◽  
Coastal Marine ◽  
Metabolic Versatility ◽  
Comprehensive Knowledge ◽  
Bothnian Sea

AbstractMicrobial methane oxidation is a major biofilter preventing larger emissions of this powerful greenhouse gas from marine coastal areas into the atmosphere. In these zones, various electron acceptors such as sulfate, metal oxides, nitrate or oxygen can be utilized. However, the key microbial players and mechanisms of methane oxidation are poorly understood. In this study, we inoculated a bioreactor with methane- and iron-rich sediments from the Bothnian Sea in order to investigate microbial methane and iron cycling under low oxygen concentrations. Using metagenomics, we observed shifts in the microbial community over approximately 2.5 years of bioreactor operation. Marker genes for methane and iron cycling, as well as respiratory and fermentative metabolism, were investigated. Metagenome-assembled genomes representing novel Verrucomicrobia, Bacteroidetes and Krumholzibacteria were recovered and revealed potential for methane oxidation, organic matter degradation, and iron cycling, respectively. This work brings new insights into the identity and metabolic versatility of microorganisms that may be members of such functional guilds in coastal marine sediments and highlights that the methane biofilter in these sediments may be more diverse than previously appreciated.ImportanceDespite the essential role of microorganisms in preventing most methane in the ocean floor to reach the atmosphere, comprehensive knowledge on the identity and the mechanisms employed by these microorganisms is still lacking. This is problematic because such information is needed to understand how the ecosystem functions in the present and how microorganisms may respond to climate change in the future. Here, we enriched and identified novel taxa potentially involved in methane and iron cycling in an oxygen-limited bioreactor inoculated with methane- and iron-rich coastal sediments. Metagenomic analyses provided hypotheses about the mechanisms they may employ, such as the use of oxygen at very low concentrations. The implication of our results is that in more shallow sediments, where oxygen-limited conditions are present, the methane biofilter is potentially composed of novel, metabolically versatile Verrucomicrobia that could contribute to mitigating methane emissions from coastal marine zones.

scholarly journals Mud, microbes, and macrofauna: seasonal dynamics of the iron biogeochemical cycle in an intertidal mudflat

2020 ◽  
Author(s):  
Jacob P. Beam ◽  
Sarabeth George ◽  
Nicholas R. Record ◽  
Peter D. Countway ◽  
David T. Johnston ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Community ◽  
Seasonal Dynamics ◽  
Solid Phase ◽  
Nutrient Release ◽  
Coastal Sediments ◽  
Biogeochemical Cycle ◽  
Intertidal Mudflat ◽  
Iron Cycling ◽  
Natural Ecosystems

AbstractMicroorganisms and burrowing animals exert a pronounced impact on the cycling of redox sensitive metals in coastal sediments. Sedimentary metal cycling is likely controlled by seasonal processes including changes in temperature, animal feeding behavior due to food availability, and availability of organic matter in sediments. We hypothesized that the iron biogeochemical cycle and associated sedimentary microbial community will respond to seasonal changes in a bioturbated intertidal mudflat. In this study, we monitored the spatiotemporal dynamics of porewater and highly reactive solid phase iron with the corresponding prokaryotic and eukaryotic sedimentary microbial communities over one annual cycle from November 2015 to November 2016. Continuous and seasonally variable pools of both porewater Fe(II) and highly reactive iron (FeHR) were observed throughout the season with significant increases of Fe(II) and FeHR in response to increased sediment temperature in summer months. Maximum concentrations of Fe(II) and FeHR were predominantly confined to the upper 5 cm of sediment throughout the season. Iron-oxidizing and -reducing microorganisms were present and stable throughout the season, and exhibited strong depth-dependent stratification likely due to availability of Fe(II) and FeHR pools, respectively. Otherwise, the community was dominated by Deltaproteobacteria, which are involved in sulfur and potentially iron cycling, as well as Gammaproteobacteria and Bacteroidetes. The microbial community was relatively stable throughout the seasonal cycle, but showed strong separation with depth, probably driven by changes in oxygen availability and organic matter. The relative abundance of diatoms revealed a noticeable seasonal signature, which we attribute to spring and fall blooms recorded in the sediments. Macro-, meio, and microfauna were detected throughout the season with some seasonal variations that may influence sedimentary iron transformations by active microbial grazing. The seasonal dynamics of the sedimentary iron cycle are controlled by numerous, interdependent processes, with macrobiota-microbiota relationships and depth stratification comprising primary components. Deciphering these processes in natural ecosystems is essential to understand how they might respond to future environmental perturbations, such as anthropogenic nutrient release to coastal systems.

scholarly journals Iron oxide deposits associated with the ectosymbiotic bacteria in the hydrothermal vent shrimp Rimicaris exoculata

2008 ◽  
Vol 5 (2) ◽  
pp. 1825-1865 ◽  
Author(s):  
L. Corbari ◽  
M.-A. Cambon-Bonavita ◽  
G. J. Long ◽  
F. Grandjean ◽  
M. Zbinden ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Iron Oxides ◽  
Environmental Scanning ◽  
Rimicaris Exoculata ◽  
Transmission Electron ◽  
Iron Oxidizing Bacteria ◽  
Scanning Transmission ◽  
Mid Atlantic Ridge ◽  
Chemoautotrophic Bacteria ◽  
Hydrothermal Ecosystems

Abstract. The Rimicaris exoculata shrimp is considered a primary consumer that dominates the fauna of most Mid-Atlantic Ridge (MAR) hydrothermal ecosystems. These shrimps harbour in their gill chambers an important ectosymbiotic community of chemoautotrophic bacteria associated with iron oxide deposits. The structure and elemental composition of the minerals associated with these bacteria have been investigated by using X-ray microanalyses, light microscopy, and transmission, environmental scanning and scanning transmission electron microscopy. The nature of the iron oxides in shrimps obtained from the Rainbow vent field at 36°14.0' N, has also been determined by Mössbauer spectroscopy. This multidisciplinary approach has revealed that the three step-levels of mineral crust found in the Rimicaris exoculata shrimps consist of heavy concretions formed by nanoparticles of two-line ferrihydrite intermixed with minor inorganic SiO2, (Ca,Mg)SO4, and (Ca,Mg)3(PO4)2 minerals that may stabilise the ferrihydrite form of iron oxides. Morphological observations on the bacteria have revealed their close interactions with these minerals and, thus, indicate the biogenic origin of the iron oxide deposits. The evolution of the bacterial density in the three mineral crust levels is related to the amount of the iron deposits and it is proposed that the lower crust level is the most likely region for the location of the iron-oxidizing bacteria.

Biogenic iron oxides produced by neutrophilic iron-oxidizing bacteria under laboratory conditions

2013 ◽  
Vol 24 ◽  
pp. S108-S109 ◽  
Author(s):  
Ralitza Angelova ◽  
Lyubomir Slavov ◽  
Mihail Iliev ◽  
Blagoi Blagoev ◽  
Daniela Kovacheva ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Laboratory Conditions ◽  
Iron Oxidizing Bacteria ◽  
Biogenic Iron Oxides ◽  
Biogenic Iron

Deferrization of Kaolinic Sand by Iron Oxidizing and Iron Reducing Bacteria

2007 ◽  
Vol 20-21 ◽  
pp. 130-133 ◽  
Author(s):  
Daniel Kupka ◽  
Michal Lovás ◽  
Vladimir Šepelák
Keyword(s):  
Iron Oxides ◽  
Pure Culture ◽  
Ionic Species ◽  
Raw Material ◽  
Bacterial Leaching ◽  
Iron Extraction ◽  
Iron Reducing Bacteria ◽  
Iron Oxidizing Bacteria ◽  
Reducing Bacteria ◽  
Iron Bearing

Iron oxidizing bacteria Acidithiobacillus ferrooxidans, iron reducing bacteria Acidiphilium spp. and their mixture were applied for leaching of iron impurities from quartz sand. The bacterial leaching was carried out in order to decrease the amount of colouring iron oxides and to improve the technological properties of the raw material. Mineralogical analysis confirmed the presence of siderite, iron-bearing muscovite and various amorphous and crystalline forms of iron oxides occurring both free and coating siderite and quartz particles. Mössbauer spectroscopy revealed various oxidation and magnetic states of iron ions, with the prevalence of reduced ionic species. Highest extraction of iron was achieved with pure culture of iron-reducing bacteria with ferrous iron as dominant species in the leaching liquor. Surprisingly, iron oxidizing bacteria caused passivation of the surface of iron-bearing minerals, resulting in the depression of iron leaching in comparison with abiotic control. Ferric iron was major species in the leaching solution containing the mixed culture of iron-oxidizing and iron-reducing bacteria. The mixture was far less efficient in iron extraction than pure culture of iron-reducing bacteria.

Changes in the lipid composition of Antarctic sea-ice diatom communities during a spring bloom: an indication of community physiological status

1989 ◽  
Vol 1 (2) ◽  
pp. 133-140 ◽  
Author(s):  
Peter D. Nichols ◽  
Anna C. Palmisano ◽  
Mark S. Rayner ◽  
Glen A. Smith ◽  
David C. White
Keyword(s):  
Sea Ice ◽  
Lipid Composition ◽  
Spring Bloom ◽  
Natural Populations ◽  
Coastal Sediments ◽  
Physiological Status ◽  
Austral Spring ◽  
Biological Source ◽  
Antarctic Sea Ice ◽  
Algal Groups

The lipid composition of natural populations of diatoms in the sea ice at McMurdo Sound was determined during the austral spring bloom of 1985, using and Iatroscan TLC–FID system. The major lipid classes in all samples were polar lipids (including phospholipid, glycolipid and chlorophyll) and triacylglycerol, with lesser proportions of free fatty acids. Total lipid increased through November and early December, reaching a maximum (3300 mg m−2 at Cape Armitage and 1800 mg m−2 at Erebus Ice Tongue) c. one week after the chlorophyll a maxima. This increase was largely attributable to a corresponding increase in triacylglycerol. At the lipid maxima, triacylglycerol/polar lipid ratios in the range 1.0 to 2.5 were observed. The dynamic variations in lipid class abundances indicate that profound changes in the physiology of sea-ice diatoms are occurring throughout the spring bloom. A range of sterols (C26–C30) were detected; 24-methylenecholesterol, brassicasterol and 24-ethylcholesterol were the major sterols at the Cape Armitage and Erebus sites. The similarity of the sterol profiles to those of Antarctic freshwater algal communities strongly indicates diatoms as a more probable source of C29 sterols in the freshwater lakes than cyanobacteria or other algal groups. The hydrocarbons isolated from sea-ice diatoms at all sites were dominated by two unsaturated components, n−C21:6 and a diunsaturated isoprenoid C25 alkene. Until this study, no biological source had been validated for the isoprenoid C25:2 diene, even though it has been detected in many estuarine and coastal sediments.

scholarly journals Reduction of Soluble Iron and Reductive Dissolution of Ferric Iron-Containing Minerals by Moderately Thermophilic Iron-Oxidizing Bacteria

1998 ◽  
Vol 64 (6) ◽  
pp. 2181-2186 ◽  
Author(s):  
Toni A. M. Bridge ◽  
D. Barrie Johnson
Keyword(s):  
Iron Reduction ◽  
Ferric Iron ◽  
Bacterial Species ◽  
Ferric Hydroxide ◽  
Single Species ◽  
Reductive Dissolution ◽  
Iron Cycling ◽  
Moderately Thermophilic ◽  
Iron Oxidizing Bacteria ◽  
Moderate Thermophiles

ABSTRACT Five moderately thermophilic iron-oxidizing bacteria, including representative strains of the three classified species (Sulfobacillus thermosulfidooxidans, Sulfobacillus acidophilus, and Acidimicrobium ferrooxidans), were shown to be capable of reducing ferric iron to ferrous iron when they were grown under oxygen limitation conditions. Iron reduction was most readily observed when the isolates were grown as mixotrophs or heterotrophs with glycerol as an electron donor; in addition, some strains were able to couple the oxidation of tetrathionate to the reduction of ferric iron. Cycling of iron between the ferrous and ferric states was observed during batch culture growth in unshaken flasks incubated under aerobic conditions, although the patterns of oxidoreduction of iron varied in different species of iron-oxidizing moderate thermophiles and in strains of a single species (S. acidophilus). All three bacterial species were able to grow anaerobically with ferric iron as a sole electron acceptor; the growth yields correlated with the amount of ferric iron reduced when the isolates were grown in the absence of oxygen. One of the moderate thermophiles (identified as a strain of S. acidophilus) was able to bring about the reductive dissolution of three ferric iron-containing minerals (ferric hydroxide, jarosite, and goethite) when it was grown under restricted aeration conditions with glycerol as a carbon and energy source. The significance of iron reduction by moderately thermophilic iron oxidizers in both environmental and applied contexts is discussed.

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