Rates of iron(III) reduction coupled to elemental sulfur or tetrathionate oxidation by acidophilic microorganisms and detection of sulfur intermediates

verfasst von: Anja Breuker, Axel Schippers
Abstract: Bioleaching processes and acid mine drainage (AMD) generation are mainly driven by aerobic microbial iron(II) and inorganic sulfur/compound oxidation. Dissimilatory iron(III) reduction coupled to sulfur/compound oxidation (DIRSO) by acidophilic microorganisms has been described for anaerobic cultures, but iron reduction was observed under aerobic conditions as well. Aim of this study was to explore reaction rates and mechanisms of this process. Cell-specific iron(III) reduction rates for different Acidithiobacillus (At.) strains during batch culture growth or stationary phase with iron(III) (∼40 mM) as electron acceptor and elemental sulfur or tetrathionate as electron donor (1% or 5 mM, respectively) were determined. The rates were highest under anaerobic conditions for the At. ferrooxidans type strain with 6.8 × 10⁶ and 1.1 × 10⁷ reduced iron(III) ions per second per cell for growth on elemental sulfur and tetrathionate, respectively. The iron(III) reduction rates were somehow lower for the anaerobically sulfur grown archaeon Ferroplasma acidiphilum, and lowest for the sulfur grown At. caldus type strain under aerobic conditions (1.7 × 10⁶ and 7.3 × 10⁴ reduced iron(III) ions per second per cell, respectively). The rates for five strains of At. thiooxidans (aerobe) were in between those for At. ferrooxidans (anaerobe) and At. caldus (aerobe). There was no pronounced pH dependence of iron(III) reduction rates in the range of pH 1.0–1.9 for the type strains of all species but rates increased with increasing pH for four other At. thiooxidans strains. Thiosulfate as sulfur intermediate was found for At. ferrooxidans during anaerobic growths on tetrathionate and iron(III) but not during anaerobic growths on elemental sulfur and iron(III), and a small concentration was measured during aerobic growths on tetrathionate without iron(III). For the At. thiooxidans type strain thiosulfate was found with tetrathionate grown cells under aerobic conditions in presence and absence of iron(III), but not with sulfur grown cells. Evidence for hydrogen sulfide production at low pH was found for the At. ferrooxidans as well as the At. thiooxidans type strains during microaerophilic growth on elemental sulfur and for At. ferrooxidans during anaerobic growths on tetrathionate and iron(III). The occurrence of sulfur compound intermediates supports the hypothesis that chemical reduction of iron(III) ions takes place by sulfur compounds released by the microbial cells.
Externe Organisation(en): Bundesanstalt für Geowissenschaften und Rohstoffe (BGR)
Typ: Artikel
Journal: Research in microbiology
Band: 175
ISSN: 0923-2508
Publikationsdatum: 01.2024
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Mikrobiologie, Molekularbiologie
Elektronische Version(en): https://doi.org/10.1016/j.resmic.2023.104110 (Zugang: Geschlossen)

BibTeX

@article{f3c15b3e638143f5ad966c00f19516eb,
title = "Rates of iron(III) reduction coupled to elemental sulfur or tetrathionate oxidation by acidophilic microorganisms and detection of sulfur intermediates",
abstract = "Bioleaching processes and acid mine drainage (AMD) generation are mainly driven by aerobic microbial iron(II) and inorganic sulfur/compound oxidation. Dissimilatory iron(III) reduction coupled to sulfur/compound oxidation (DIRSO) by acidophilic microorganisms has been described for anaerobic cultures, but iron reduction was observed under aerobic conditions as well. Aim of this study was to explore reaction rates and mechanisms of this process. Cell-specific iron(III) reduction rates for different Acidithiobacillus (At.) strains during batch culture growth or stationary phase with iron(III) (∼40 mM) as electron acceptor and elemental sulfur or tetrathionate as electron donor (1% or 5 mM, respectively) were determined. The rates were highest under anaerobic conditions for the At. ferrooxidans type strain with 6.8 × 106 and 1.1 × 107 reduced iron(III) ions per second per cell for growth on elemental sulfur and tetrathionate, respectively. The iron(III) reduction rates were somehow lower for the anaerobically sulfur grown archaeon Ferroplasma acidiphilum, and lowest for the sulfur grown At. caldus type strain under aerobic conditions (1.7 × 106 and 7.3 × 104 reduced iron(III) ions per second per cell, respectively). The rates for five strains of At. thiooxidans (aerobe) were in between those for At. ferrooxidans (anaerobe) and At. caldus (aerobe). There was no pronounced pH dependence of iron(III) reduction rates in the range of pH 1.0–1.9 for the type strains of all species but rates increased with increasing pH for four other At. thiooxidans strains. Thiosulfate as sulfur intermediate was found for At. ferrooxidans during anaerobic growths on tetrathionate and iron(III) but not during anaerobic growths on elemental sulfur and iron(III), and a small concentration was measured during aerobic growths on tetrathionate without iron(III). For the At. thiooxidans type strain thiosulfate was found with tetrathionate grown cells under aerobic conditions in presence and absence of iron(III), but not with sulfur grown cells. Evidence for hydrogen sulfide production at low pH was found for the At. ferrooxidans as well as the At. thiooxidans type strains during microaerophilic growth on elemental sulfur and for At. ferrooxidans during anaerobic growths on tetrathionate and iron(III). The occurrence of sulfur compound intermediates supports the hypothesis that chemical reduction of iron(III) ions takes place by sulfur compounds released by the microbial cells.",
keywords = "Acidithiobacillus, Acidophiles, DIRSO, Iron reduction, Reduction rates, Sulfur oxidation",
author = "Anja Breuker and Axel Schippers",
note = "Funding Information: This work was funded by the German Research Foundation ( DFG , grant SCHI 535/15–1) and is part of a joint NSFC- DFG funded project with Prof. Jinlan Xia, Central South University, China. We thank him as well as Dr. Ruiyong Zhang and Dr. Ostertag-Henning in BGR for fruitful scientific discussions. Many thanks to Evelyn Becker, Wiebke Schulze, Laurin R{\"o}sler, Anna Degtjarev, Isabell Kruckemeyer and Thilo Falkenberg for their technical support. ",
year = "2024",
month = jan,
doi = "10.1016/j.resmic.2023.104110",
language = "English",
volume = "175",
journal = "Research in microbiology",
issn = "0923-2508",
publisher = "Elsevier Masson SAS",
number = "1-2",
}