Phototrophic Fe(II) Oxidation Promotes Organic Carbon Acquisition by
            <i>Rhodobacter capsulatus</i>
            SB1003

Caiazza, Nicky C.; Lies, Douglas P.; Newman, Dianne K.

doi:10.1128/aem.02830-06

Cited by 24 publications

(28 citation statements)

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“…While most of the organisms we and others have studied can grow by coupling Fe(II) oxidation to CO 2 fixation (15,23,46), not all strains that oxidize Fe(II) can use it as an electron donor to support growth. An example of this is Rhodobacter capsulatus, which can benefit from Fe(II) oxidation only via an indirect pathway: it grows photoheterotrophically on low-molecular-weight organic compounds that form due to a photochemical reaction between biogenic Fe(III) and organic compounds that it cannot otherwise use (citrate and nitrilotriacetate [NTA]) (4). This observation led us to hypothesize that microbial Fe(II) oxidation might be more broadly useful to microorganisms by making refractory organic compounds, such as humic substances, more bioavailable through photochemical degradation (4).…”

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confidence: 99%

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Rhodobacter capsulatus Catalyzes Light-Dependent Fe(II) Oxidation under Anaerobic Conditions as a Potential Detoxification Mechanism

Poulain

Newman

2009

Appl Environ Microbiol

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Diverse bacteria are known to oxidize millimolar concentrations of ferrous iron [Fe(II)] under anaerobic conditions, both phototrophically and chemotrophically. Yet whether they can do this under conditions that are relevant to natural systems is understood less well. In this study, we tested how light, Fe(II) speciation, pH, and salinity affected the rate of Fe(II) oxidation by Rhodobacter capsulatus SB1003. Although R. capsulatus cannot grow photoautotrophically on Fe(II), it oxidizes Fe(II) at rates comparable to those of bacteria that do grow photoautotrophically on Fe(II) as soon as it is exposed to light, provided it has a functional photosystem. Chelation of Fe(II) by diverse organic ligands promotes Fe(II) oxidation, and as the pH increases, so does the oxidation rate, except in the presence of nitrilotriacetate; nonchelated forms of Fe(II) are also more rapidly oxidized at higher pH. Salt concentrations typical of marine environments inhibit Fe(II) oxidation. When growing photoheterotrophically on humic substances, R. capsulatus is highly sensitive to low concentrations of Fe(II); it is inhibited in the presence of concentrations as low as 5 M. The product of Fe(II) oxidation, ferric iron, does not hamper growth under these conditions. When other parameters, such as pH or the presence of chelators, are adjusted to promote Fe(II) oxidation, the growth inhibition effect of Fe(II) is alleviated. Together, these results suggest that Fe(II) is toxic to R. capsulatus growing under strictly anaerobic conditions and that Fe(II) oxidation alleviates this toxicity.

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“…Fe(III) reduction was measured in the dark and in the presence of various ligands at different pHs. Fe(II) concentrations were measured as a function of time using the ferrozine assay (36) as previously described (4,12,23).…”

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Rhodobacter capsulatus Catalyzes Light-Dependent Fe(II) Oxidation under Anaerobic Conditions as a Potential Detoxification Mechanism

Poulain

Newman

2009

Appl Environ Microbiol

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“…We made vectors with the pBBR1 replicon and kanamycin (pMQ131) or gentamicin (pMQ132) resistance markers, capable of use for yeast recombination. These vectors have been used successfully for complementation of mutations in S. marcescens (Shanks, et al, 2007) (Kalivoda, et al, 2008), in Rhodobacter capsulatus (Caiazza, et al, 2007) and pMQ132 has been used in P. aeruginosa strain PA14 (Shanks, unpublished).…”

Section: Resultsmentioning

confidence: 99%

New yeast recombineering tools for bacteria

Shanks¹,

Kadouri²,

MacEachran³

et al. 2009

Plasmid

116

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Recombineering with Saccharomyces cerevisiae is a powerful methodology that can be used to clone multiple unmarked pieces of DNA to generate complex constructs with high efficiency. Here we introduce two new tools that utilize the native recombination enzymes of S. cerevisiae to facilitate the construction of a variety of useful tools for bacteria. First, yeast recombineering was used to make directed nested deletions in a bacterial-yeast shuttle plasmid using only one or two single stranded oligomers, thus obviating the need for a PCR step. Second, we have generated several new shuttle vectors for yeast recombineering capable of replication in a wide variety of bacterial genera. As a demonstration of utility, some of the approaches and vectors generated in this study were used to make a pigP deletion mutation in the opportunistic pathogen Serratia marcescens.

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“…They have an extremely versatile metabolism that utilizes iron in ways that allows growth under multiple environmental conditions. The use of iron by purple nonsulfur bacteria can be exemplified by such processes as: i) Aerobic respiration where terminal cytochrome oxidase cbb 3 and b 260 use heme as a cofactor; ii) Respiratory and photosynthesis electron transport where heme containing cytochromes c y , c 2 and bc 1 shuttle electrons to photosystem reaction centers as well as to respiratory terminal oxidases; iii) Enzymes such as coproporphyrinogen III oxidase that contains a Fe-S cluster involved in synthesis of heme; iv) Enzymes involved in bacteriochlorophyll synthesis that utilize iron-sulfur clusters (Sirijovski et al, 2007; Sarma et al, 2008); v) Purple nonsulfur bacteria are also capable of anaerobic oxidation of ferrous iron to facilitate phototrophic growth (Widdel et al, 1993; Ehrenreich and Widdel, 1994; Croal et al, 2007; Caiazza et al, 2007; Poulain and Newman, 2009). These are just a few representative examples of the many processes used by this group of bacteria that rely on the use of iron as a cofactor, and that illustrate their heavy need for this metal.…”

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confidence: 99%

Iron homeostasis in the Rhodobacter genus

Zappa¹,

Bauer²

2013

Advances in Botanical Research

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Metals are utilized for a variety of critical cellular functions and are essential for survival. However cells are faced with the conundrum of needing metals coupled with e fact that some metals, iron in particular are toxic if present in excess. Maintaining metal homeostasis is therefore of critical importance to cells. In this review we have systematically analyzed sequenced genomes of three members of the Rhodobacter genus, R. capsulatus SB1003, R. sphaeroides 2.4.1 and R. ferroxidans SW2 to determine how these species undertake iron homeostasis. We focused our analysis on elemental ferrous and ferric iron uptake genes as well as genes involved in the utilization of iron from heme. We also discuss how Rhodobacter species manage iron toxicity through export and sequestration of iron. Finally we discuss the various putative strategies set up by these Rhodobacter species to regulate iron homeostasis and the potential novel means of regulation. Overall, this genomic analysis highlights surprisingly diverse features involved in iron homeostasis in the Rhodobacter genus.

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Phototrophic Fe(II) Oxidation Promotes Organic Carbon Acquisition by Rhodobacter capsulatus SB1003

Cited by 24 publications

References 40 publications

Rhodobacter capsulatus Catalyzes Light-Dependent Fe(II) Oxidation under Anaerobic Conditions as a Potential Detoxification Mechanism

Rhodobacter capsulatus Catalyzes Light-Dependent Fe(II) Oxidation under Anaerobic Conditions as a Potential Detoxification Mechanism

New yeast recombineering tools for bacteria

Iron homeostasis in the Rhodobacter genus

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