Oxygen Dependency of Neutrophilic Fe(II) Oxidation by<i>Leptothrix</i>Differs from Abiotic Reaction

Vollrath, S.; Behrends, Thilo; Cappellen, Philippe Van

doi:10.1080/01490451.2011.594147

Cited by 42 publications

(57 citation statements)

References 55 publications

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“…However, cell growth was not detected with more rapid agitations (180 rpm rotary and 140 rpm reciprocal) probably due to excessive oxygenation of the medium. This result was expected because low oxygen has been reported to favor growth and Fe(II) oxidation of aerobic Leptothrix [2,15,[18][19][20], consistent with their good growth at the natural air-water interface [17]. The present study confirmed that use of a proper amount of Fe powders in the medium did not adversely affect the cell growth under favorable shaking modes.…”

Section: Influence Of Fe Powders and Culture-shaking Modes On Exponensupporting

confidence: 78%

Use of Iron Powder to Obtain High Yields of Leptothrix Sheaths in Culture

et al. 2015

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Abstract:The Leptothrix species, Fe-oxidizing bacteria, produce an extracellular, microtubular sheath with a complicated organic-inorganic hybrid nature. We have discovered diverse industrial functions for this material, e.g., electrode material for Li-ion batteries, catalyst enhancers, pigments, plant growth promoters, and plant protectants. To consistently obtain material with the qualitative and quantitative stability needed for industrial applications, we focused on developing an optimum culture system for sheath synthesis by the Leptothrix sp. strain OUMS1. Although we have used Fe plates as an Fe source in the liquid silicon-glucose-peptone medium (SGP), the plates do not yield a consistent quality or precise mass, and formation of Fe-encrusted sheath is restricted to a surface of the plates, which limits harvest yield. In this study, to obtain a high yield of sheaths, we cultured OUMS1 in SGP supplemented with Fe powders. The addition of Fe powders to the medium (up to 14.0 g/L) did not adversely influence growth of OUMS1. The final yield of sheaths was about 10-fold greater than in the Fe plate culture. The sheaths also maintained a microtubular form and crystalline texture similar to those produced on Fe plates

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Section: Influence Of Fe Powders and Culture-shaking Modes On Exponensupporting

confidence: 78%

Use of Iron Powder to Obtain High Yields of Leptothrix Sheaths in Culture

et al. 2015

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“…Although it was found that they carry the genes for nitrate reduction (75,103), there is so far no evidence from growth experiments that they can actually live by that type of metabolism. Other microaerophilic Fe(II) oxidizers, e.g., different Leptothrix spp., are known to grow either by solely oxidizing organic carbon or by cometabolizing organic carbon and Fe(II) coupled with O 2 reduction (104,105). Therefore, it is particularly interesting to investigate the physiology of newly isolated strains of Zetaproteobacteria, and we expect that the microaerophilic Fe(II) oxidizers are the most important group of microbial Fe(II) oxidizers in Aarhus Bay sediments.…”

Section: Coexistence Of Different Physiological Types Of Fe(ii) Oxidimentioning

confidence: 99%

Coexistence of Microaerophilic, Nitrate-Reducing, and Phototrophic Fe(II) Oxidizers and Fe(III) Reducers in Coastal Marine Sediment

Laufer

Nordhoff

Røy

et al. 2016

Appl Environ Microbiol

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Iron is abundant in sediments, where it can be biogeochemically cycled between its divalent and trivalent redox states. The neutrophilic microbiological Fe cycle involves Fe(III)-reducing and three different physiological groups of Fe(II)-oxidizing microorganisms, i.e., microaerophilic, anoxygenic phototrophic, and nitrate-reducing Fe(II) oxidizers. However, it is unknown whether all three groups coexist in one habitat and how they are spatially distributed in relation to gradients of O 2 , light, nitrate, and Fe(II). We examined two coastal marine sediments in Aarhus Bay, Denmark, by cultivation and most probable number ( Fe(III)-reducing microorganisms were discovered in the late 1980s (6). Many of the better-known Fe(III)-reducing bacteria of the genera Shewanella, Geobacter, and Geothrix are found mainly in freshwater and more rarely in marine sediments (7,8). Still, Fe(III) reduction can account for a large fraction of organic-matter mineralization in coastal marine sediments (up to 50%) (9).Fe(II)-oxidizing bacteria were first described in 1836 by Ehrenberg (10) as so-called "iron bacteria." It took more than a century before the first microbes belonging to this group could be grown in the laboratory (11) and even longer until it was demonstrated that they grow autotrophically by oxidizing Fe(II) with O 2 (12). These bacteria face the problem that, at neutral pH, the abiotic reaction of oxygen and Fe(II) is fast. Therefore, bacterial Fe(II) oxidation with O 2 at neutral pH is limited to micro-oxic ([O 2 ] Ͻ 50 M) conditions, where microbial iron oxidation can compete favorably with the [O 2 ]-limited abiotic reaction (13,14). Favorable conditions for the growth of microaerophilic Fe(II) oxidizers are found in opposing gradients of Fe(II) and O 2 , e.g., in the oxicanoxic transition zone in sediments or groundwater seeps (15). Today, there are at least four known groups of exclusively microaerophilic Fe(II) oxidizers, i.e., Gallionella (11, 12), Sideroxydans (3), Leptothrix (16,17), and Mariprofundus (18). Furthermore, certain bacteria belonging to the genera Marinobacter and Hyphomonas are also described as growing under micro-oxic conditions by Fe(II) oxidation (19,20).The photoferrotrophs (5) are not only of interest for modern habitats, but may also be responsible for the formation of banded iron formations (BIFs) in the Precambrian (21,22). Until now, only a few pure cultures have been known, and there is no known monophylogenetic group that specializes solely in anoxygenic phototrophic Fe(II) oxidation. Known strains are metabolically flexible and belong to various physiological groups of anoxygenic phototrophs, i.e., the purple sulfur, purple nonsulfur, and green anoxygenic phototrophic bacteria (5,(23)(24)(25).For the nitrate-reducing Fe(II) oxidizers, most known strains cannot be maintained in culture over several transfers with nitrate

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“…Incorporation of water molecules or anions other than hydroxide in freshly formed Fe oxyhydroxides results in stoichiometric ratios between H + production and Fe(II) oxidation lower than 2 (Fox, 1988;Bonneville et al, 2004;Vollrath et al, 2012). Hence, the stoichiometric ratio between produced H + and oxidised Fe(II) is expected to be lower when Fe hydroxyphosphates form during Fe(II) oxidation compared to formation of pure Fe oxyhydroxides.…”

Section: Reaction Stoichiometrymentioning

confidence: 87%

“…Hence, initial aqueous P/Fe ratios ((P/Fe) ini ) were varied between 0 and %0.9 (Table 1). The experimental setup was similar to that used by Vollrath et al (2012). The experiments were carried out in a 1 litre glass reactor with an electrically powered stirrer (Applikon Stirrer Controller P100) and a dissolved oxygen sensor (Applisens DO2 sensor, low drift).…”

Section: Batch Experiments With Synthetic Solutionsmentioning

confidence: 99%