Ferrous iron oxidation and rusticyanin in halotolerant, acidophilic ‘Thiobacillus prosperus’

Nicolle, James Le C.; Simmons, Susan J.; Bathe, Stephan; Norris, Paul R.

doi:10.1099/mic.0.023192-0

Cited by 44 publications

(30 citation statements)

References 29 publications

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“…prosperus V6 (DSM 14174) that has similarity to the rus operon of At. ferrooxidans T (Nicolle et al, 2009) and it is hypothesized that expression of the rusticyanin gene is actively involved in Fe oxidation, presumably in a similar way to that described for At. ferrooxidans T .…”

Section: Resultsmentioning

confidence: 86%

“…ferrooxidans T is inhibited by low concentrations of chloride (Blake et al, 1991; Harahuc et al, 2000), whereas chloride is required for expression of rusticyanin in Ac. prosperus V6 (Nicolle et al, 2009) and maximum iron oxidation in Ac. prosperus T was seen at 20 g/L NaCl.…”

Section: Resultsmentioning

confidence: 99%

“…The Ac. prosperus type strain was isolated from a volcanic marine environment and is halotolerant, being able to grow in chloride concentrations from 0.04 to 0.6 M (2.3–35 g L −1 ; Nicolle et al, 2009). The underlying mechanisms for Ac.…”

Section: Introductionmentioning

confidence: 99%

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Multiple Osmotic Stress Responses in Acidihalobacter prosperus Result in Tolerance to Chloride Ions

et al. 2017

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Extremely acidophilic microorganisms (pH optima for growth of ≤3) are utilized for the extraction of metals from sulfide minerals in the industrial biotechnology of “biomining.” A long term goal for biomining has been development of microbial consortia able to withstand increased chloride concentrations for use in regions where freshwater is scarce. However, when challenged by elevated salt, acidophiles experience both osmotic stress and an acidification of the cytoplasm due to a collapse of the inside positive membrane potential, leading to an influx of protons. In this study, we tested the ability of the halotolerant acidophile Acidihalobacter prosperus to grow and catalyze sulfide mineral dissolution in elevated concentrations of salt and identified chloride tolerance mechanisms in Ac. prosperus as well as the chloride susceptible species, Acidithiobacillus ferrooxidans. Ac. prosperus had optimum iron oxidation at 20 g L−1 NaCl while At. ferrooxidans iron oxidation was inhibited in the presence of 6 g L−1 NaCl. The tolerance to chloride in Ac. prosperus was consistent with electron microscopy, determination of cell viability, and bioleaching capability. The Ac. prosperus proteomic response to elevated chloride concentrations included the production of osmotic stress regulators that potentially induced production of the compatible solute, ectoine uptake protein, and increased iron oxidation resulting in heightened electron flow to drive proton export by the F0F1 ATPase. In contrast, At. ferrooxidans responded to low levels of Cl− with a generalized stress response, decreased iron oxidation, and an increase in central carbon metabolism. One potential adaptation to high chloride in the Ac. prosperus Rus protein involved in ferrous iron oxidation was an increase in the negativity of the surface potential of Rus Form I (and Form II) that could help explain how it can be active under elevated chloride concentrations. These data have been used to create a model of chloride tolerance in the salt tolerant and susceptible species Ac. prosperus and At. ferrooxidans, respectively.

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Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 99%

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Multiple Osmotic Stress Responses in Acidihalobacter prosperus Result in Tolerance to Chloride Ions

et al. 2017

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“…('Thiobacillus prosperus') still awaits resolution. The main distinguishing feature of this acidophile is its tolerance to salt, being able to grow in up to 3.5 % (0.6 M) sodium chloride, whereas most iron-oxidizing acidithiobacilli are inhibited by 1 % salt (Nicolle et al, 2009). Both the original strain and a novel strain (V6) have been shown to grow optimally in the presence of 1-2 % sodium chloride and also, like Af.…”

Section: Acidophilic Aerobic Iron-oxidizing Proteobacteriamentioning

confidence: 99%

“…thiooxydans, require reduced sulfur (e.g. tetrathionate) for rapid oxidation of ferrous iron in liquid media (Nicolle et al, 2009). …”

Section: Acidophilic Aerobic Iron-oxidizing Proteobacteriamentioning

confidence: 99%

The iron-oxidizing proteobacteria

2011

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The ‘iron bacteria’ are a collection of morphologically and phylogenetically heterogeneous prokaryotes. They include some of the first micro-organisms to be observed and described, and continue to be the subject of a considerable body of fundamental and applied microbiological research. While species of iron-oxidizing bacteria can be found in many different phyla, most are affiliated with the Proteobacteria. The latter can be subdivided into four main physiological groups: (i) acidophilic, aerobic iron oxidizers; (ii) neutrophilic, aerobic iron oxidizers; (iii) neutrophilic, anaerobic (nitrate-dependent) iron oxidizers; and (iv) anaerobic photosynthetic iron oxidizers. Some species (mostly acidophiles) can reduce ferric iron as well as oxidize ferrous iron, depending on prevailing environmental conditions. This review describes what is currently known about the phylogenetic and physiological diversity of the iron-oxidizing proteobacteria, their significance in the environment (on the global and micro scales), and their increasing importance in biotechnology.

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Effect of chloride on ferrous iron oxidation by a Leptospirillum ferriphilum‐dominated chemostat culture

Gahan

Sundkvist

Dopson

et al. 2010

Biotech & Bioengineering

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Biomining is the use of microorganisms to catalyze metal extraction from sulfide ores. However, the available water in some biomining environments has high chloride concentrations and therefore, chloride toxicity to ferrous oxidizing microorganisms has been investigated. Batch biooxidation of Fe(2+) by a Leptospirillum ferriphilum-dominated culture was completely inhibited by 12 g L(-1) chloride. In addition, the effects of chloride on oxidation kinetics in a Fe(2+) limited chemostat were studied. Results from the chemostat modeling suggest that the chloride toxicity was attributed to affects on the Fe(2+) oxidation system, pH homeostasis, and lowering of the proton motive force. Modeling showed a decrease in the maximum specific growth rate (micro(max)) and an increase in the substrate constant (K(s)) with increasing chloride concentrations, indicating an effect on the Fe(2+) oxidation system. The model proposes a lowered maintenance activity when the media was fed with 2-3 g L(-1) chloride with a concomitant drastic decrease in the true yield (Y(true)). This model helps to understand the influence of chloride on Fe(2+) biooxidation kinetics.

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Ferrous iron oxidation and rusticyanin in halotolerant, acidophilic ‘Thiobacillus prosperus’

Cited by 44 publications

References 29 publications

Multiple Osmotic Stress Responses in Acidihalobacter prosperus Result in Tolerance to Chloride Ions

Multiple Osmotic Stress Responses in Acidihalobacter prosperus Result in Tolerance to Chloride Ions

The iron-oxidizing proteobacteria

Effect of chloride on ferrous iron oxidation by a Leptospirillum ferriphilum‐dominated chemostat culture

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