Skip to content
1887

Access Microbiology open research platform logo Access Microbiology

Volume 7, Issue 12

Iron oxidation by serovar Typhimurium strain SL1344 is an abiotic byproduct of nitrate respiration Open Access

Abstract

Nitrate-dependent iron (Fe) oxidation (NDFO) is an important biogeochemical process, but whether NDFO provides a direct metabolic benefit to facultative anaerobes with diverse lifestyles, such as , and what role the respiratory nitrate reductases play in this process is unknown.

This study investigated NDFO in serovar Typhimurium strain SL1344. We compared the WT strain with a ∆ ∆ mutant (∆), which lacks the primary respiratory nitrate reductase (Nar). Cultures were grown anaerobically in lysogeny broth medium amended with 4 mM nitrate and 10 mM FeSO₄ as defined nitrate and iron sources. Growth, nitrate depletion, nitrite accumulation, and Fe oxidation were monitored over 14 days. Abiotic controls amended with either nitrate or nitrite were included to control for abiotic iron oxidation.

There was no significant difference in the growth rate and biomass production between the WT and ∆ strains. However, there was significant variation in nitrite reduction and iron oxidation. 56.9% of the nitrate was depleted from the growth medium (initially 4 mM) with the WT cultures compared to 19.7% with the ∆ strain. Fe oxidation in the WT cultures reached a Fe²/Fe total ratio of ~0.52–0.61 during exponential growth and was consistent during the stationary phase, whereas for the mutant, the maximum Fe²/Fe total ratio was ~0.78, which returned to a more reduced state in stationary phase (Fe²/Fe total ~0.95). Abiotic controls amended with nitrite showed rapid Fe oxidation, highlighting the role of nitrite as an oxidant.

The respiratory nitrate reductases are the primary drivers of NDFO in SL1344 and are required for the generation of nitrite, which then abiotically oxidizes Fe to Fe. This did not confer a growth advantage, suggesting NDFO is an indirect consequence of nitrate respiration rather than a direct energy-conserving pathway in this organism.

  • Received:
  • Accepted:
  • Published Online:
Keyword(s): iron and nitrate
Funding
This study was supported by the:
  • Research England (Award Expanding Excellence in England 124.18)
    • Principal Award Recipient: KarenOlsson-Francis
  • The Open University
    • Principal Award Recipient: MichaelChristopher Macey
  • Science and Technology Facilities Council
    • Principal Award Recipient: AlexPrice
© 2025 The copyright remains with the Open University.
  • This is an open-access article distributed under the terms of the Creative Commons Attribution License.
Loading

Article metrics loading...

/content/journal/acmi/10.1099/acmi.0.001078.v3
2025-12-19
2026-02-15

Metrics

Loading full text...

Full text loading...

/deliver/fulltext/acmi/7/12/acmi001078.v3.html?itemId=/content/journal/acmi/10.1099/acmi.0.001078.v3&mimeType=html&fmt=ahah

References

  1. Hafenbradl D, Keller M, Dirmeier R, Rachel R, Rossnagel P et al. Ferroglobus placidus gen. nov., sp. nov., a novel hyperthermophilic archaeum that oxidizes Fe2+ at neutral pH under anoxic conditions. Arch Microbiol 1996; 166:308–314 [View Article] [PubMed]
     [Google Scholar]
  2. Straub KL, Benz M, Schink B, Widdel F. Anaerobic, nitrate-dependent microbial oxidation of ferrous iron. Appl Environ Microbiol 1996; 62:1458–1460 [View Article] [PubMed]
     [Google Scholar]
  3. Benz M, Brune A, Schink B. Anaerobic and aerobic oxidation of ferrous iron at neutral pH by chemoheterotrophic nitrate-reducing bacteria. Arch Microbiol 1998; 169:159–165 [View Article] [PubMed]
     [Google Scholar]
  4. Weber KA, Pollock J, Cole KA, O’Connor SM, Achenbach LA et al. Anaerobic nitrate-dependent iron(II) bio-oxidation by a novel lithoautotrophic betaproteobacterium, strain 2002. Appl Environ Microbiol 2006; 72:686–694 [View Article] [PubMed]
     [Google Scholar]
  5. Carlson HK, Clark IC, Blazewicz SJ, Iavarone AT, Coates JD. Fe(II) oxidation is an innate capability of nitrate-reducing bacteria that involves abiotic and biotic reactions. J Bacteriol 2013; 195:3260–3268 [View Article] [PubMed]
     [Google Scholar]
  6. Muehe EM, Gerhardt S, Schink B, Kappler A. Ecophysiology and the energetic benefit of mixotrophic Fe(II) oxidation by various strains of nitrate-reducing bacteria. FEMS Microbiol Ecol 2009; 70:335–343 [View Article] [PubMed]
     [Google Scholar]
  7. Bottaro M, Abramov S, Amils R, Martinez-Bonilla A, ThomasArrigo L et al. Coupling of Fe and N cycles by nitrate-reducing Fe(II)-oxidizing microorganisms in the tidal sediments of an extreme acidic river (Río Tinto, Spain). Appl Geochem 2025; 190:106488 [View Article]
     [Google Scholar]
  8. Klueglein N, Kappler A. Abiotic oxidation of Fe(II) by reactive nitrogen species in cultures of the nitrate-reducing Fe(II) oxidizer Acidovorax sp. BoFeN1 - questioning the existence of enzymatic Fe(II) oxidation. Geobiology 2013; 11:180–190 [View Article] [PubMed]
     [Google Scholar]
  9. Klueglein N, Picardal F, Zedda M, Zwiener C, Kappler A. Oxidation of Fe(II)-EDTA by nitrite and by two nitrate-reducing Fe(II)-oxidizing Acidovorax strains. Geobiology 2015; 13:198–207 [View Article] [PubMed]
     [Google Scholar]
  10. Klueglein N, Zeitvogel F, Stierhof Y-D, Floetenmeyer M, Konhauser KO et al. Potential role of nitrite for abiotic Fe(II) oxidation and cell encrustation during nitrate reduction by denitrifying bacteria. Appl Environ Microbiol 2014; 80:1051–1061 [View Article] [PubMed]
     [Google Scholar]
  11. Visser AN, Wankel SD, Frey C, Kappler A, Lehmann MF. Unchanged nitrate and nitrite isotope fractionation during heterotrophic and Fe(II)-mixotrophic denitrification suggest a non-enzymatic link between denitrification and Fe(II) oxidation. Front Microbiol 2022; 13:927475 [View Article] [PubMed]
     [Google Scholar]
  12. Chen D, Cheng K, Liu T, Chen G, Kappler A et al. Novel insight into microbially mediated nitrate-reducing Fe(II) oxidation by Acidovorax sp. strain BoFeN1 using Dual N–O isotope fractionation. Environ Sci Technol 2023; 57:12546–12555 [View Article]
     [Google Scholar]
  13. Kuypers MMM, Marchant HK, Kartal B. The microbial nitrogen-cycling network. Nat Rev Microbiol 2018; 16:263–276 [View Article] [PubMed]
     [Google Scholar]
  14. Kern M, Simon J. Electron transport chains and bioenergetics of respiratory nitrogen metabolism in Wolinella succinogenes and other Epsilonproteobacteria. Biochimica et Biophysica Acta Bioenergetics 2009; 1787:646–656 [View Article]
     [Google Scholar]
  15. Sparacino-Watkins C, Stolz JF, Basu P. Nitrate and periplasmic nitrate reductases. Chem Soc Rev 2014; 43:676–706 [View Article] [PubMed]
     [Google Scholar]
  16. Hoiseth SK, Stocker BAD. Aromatic-dependent Salmonella typhimurium are non-virulent and effective as live vaccines. Nature 1981; 291:238–239 [View Article] [PubMed]
     [Google Scholar]
  17. Rowley G, Hensen D, Felgate H, Arkenberg A, Appia-Ayme C et al. Resolving the contributions of the membrane-bound and periplasmic nitrate reductase systems to nitric oxide and nitrous oxide production in Salmonella enterica serovar Typhimurium. Biochem J 2012; 441:755–762 [View Article] [PubMed]
     [Google Scholar]
  18. Kröger C, Dillon SC, Cameron ADS, Papenfort K, Sivasankaran SK et al. The transcriptional landscape and small RNAs of Salmonella enterica serovar Typhimurium. Proc Natl Acad Sci USA 2012; 109:E1277–86 [View Article] [PubMed]
     [Google Scholar]
  19. Datsenko KA, Wanner BL. One-step inactivation of chromosomal genes in Escherichia coli K-12 using PCR products. Proc Natl Acad Sci USA 2000; 97:6640–6645 [View Article] [PubMed]
     [Google Scholar]
  20. Bertani G. Studies on lysogenesis. I. The mode of phage liberation by lysogenic Escherichia coli. J Bacteriol 1951; 62:293–300 [View Article] [PubMed]
     [Google Scholar]
  21. Ammendola S, Pasquali P, Pistoia C, Petrucci P, Petrarca P et al. High-affinity Zn2+ uptake system ZnuABC is required for bacterial zinc homeostasis in intracellular environments and contributes to the virulence of Salmonella enterica. Infect Immun 2007; 75:5867–5876 [View Article] [PubMed]
     [Google Scholar]
  22. Shelton CD, Yoo W, Shealy NG, Torres TP, Zieba JK et al. Salmonella enterica serovar Typhimurium uses anaerobic respiration to overcome propionate-mediated colonization resistance. Cell Rep 2022; 38:110180 [View Article] [PubMed]
     [Google Scholar]
  23. Macey MC, Ramkissoon NK, Cogliati S, Toubes-Rodrigo M, Stephens BP et al. Habitability and biosignature formation in simulated martian aqueous environments. Astrobiology 2023; 23:144–154 [View Article] [PubMed]
     [Google Scholar]
  24. Lovley DR, Phillips EJP. Rapid assay for microbially reducible ferric iron in aquatic sediments. Appl Environ Microbiol 1987; 53:1536–1540 [View Article] [PubMed]
     [Google Scholar]
  25. Vodyanitskii YN. On the dissolution of iron minerals in tamm’s reagent. Eurasian Soil Science 20011217–1229
     [Google Scholar]
  26. Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 1976248–254 [View Article]
     [Google Scholar]
  27. Koontz L. TCA precipitation. In Methods in Enzymology Academic Press; 2014 pp 3–10 [View Article]
     [Google Scholar]
  28. Dopffel N, Jamieson J, Bryce C, Joshi P, Mansor M et al. Temperature dependence of nitrate-reducing Fe(II) oxidation by Acidovorax strain BoFeN1 - evaluating the role of enzymatic vs. abiotic Fe(II) oxidation by nitrite. FEMS Microbiol Ecol 2022; 97:fiab155 [View Article] [PubMed]
     [Google Scholar]
  29. Kopf SH, Henny C, Newman DK. Ligand-enhanced abiotic iron oxidation and the effects of chemical versus biological iron cycling in anoxic environments. Environ Sci Technol 2013; 47:2602–2611 [View Article] [PubMed]
     [Google Scholar]
  30. Millero FJ. Effect of Ionic Interactions on the Oxidation of Fe(II) and Cu(I) in Natural Waters*, Vol. 28 Chemistry of the Mediterranean; 1989 [View Article]
     [Google Scholar]
  31. Santana-Casiano JM, Gonzalez-Davila M, Millero FJ, Jesus Rodrıguez M. The Effect of Organic Compounds in the Oxidation Kinetics of The Effect of Organic Compounds in the Oxidation Kinetics of Fe II. Vol. 70 Marine Chemistry; 2000 [View Article]
     [Google Scholar]
  32. Millero FJ, Sotolongo S, Izaguirre M. The oxidation kinetics of Fe(II) in seawater. Geochim Cosmochim Acta 1987; 51:793–801 [View Article]
     [Google Scholar]
  33. Krupińska I. Effect of organic substances on the efficiency of Fe(II) to Fe(III) oxidation and removal of iron compounds from groundwater in the sedimentation process. Civ Environ Eng Rep 2017; 26:15–29 [View Article]
     [Google Scholar]
  34. Robinson TC, Latta DE, Notini L, Schilling KE, Scherer MM. Abiotic reduction of nitrite by Fe(II): a comparison of rates and N2O production. Environ Sci Process Impacts 2021; 23:1531–1541 [View Article] [PubMed]
     [Google Scholar]
/content/journal/acmi/10.1099/acmi.0.001078.v3
Loading
Iron oxidation by Salmonella enterica serovar Typhimurium strain SL1344 is an abiotic byproduct of nitrate respiration
Access Microbiology 7, 001078.v3 (2025); https://doi.org/10.1099/acmi.0.001078.v3
/content/journal/acmi/10.1099/acmi.0.001078.v3
/content/journal/acmi/10.1099/acmi.0.001078.v3
Loading

Data & Media loading...

Most cited Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An error occurred
Approval was partially successful, following selected items could not be processed due to error