Biological and Chemical Processes of Nitrate Reduction and Ferrous Oxidation Mediated by <i>Shewanella oneidensis</i> MR-1

Biological and Chemical Processes of Nitrate Reduction and Ferrous Oxidation Mediated by <i>Shewanella oneidensis</i> MR-1

Iron, Earth’s most abundant redox-active metal, undergoes both abiotic and microbial redox reactions that regulate the formation, transformation, and dissolution of iron minerals. The electron transfer between ferrous iron (Fe(II)) and ferric iron (Fe(III)) is critical for mineral dynamics, pollutan...

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Bibliographic Details
Main Authors: Lingyu Hou, Xiangyu Bai, Zihe Sima, Jiani Zhang, Luyao Yan, Ding Li, Yongguang Jiang
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Microorganisms
Subjects:
<i>Shewanella oneidensis</i> MR-1
divalent iron
nitrate reduction
ferrous oxidation
biological and chemical processes
Online Access:https://www.mdpi.com/2076-2607/12/12/2454
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Summary:Iron, Earth’s most abundant redox-active metal, undergoes both abiotic and microbial redox reactions that regulate the formation, transformation, and dissolution of iron minerals. The electron transfer between ferrous iron (Fe(II)) and ferric iron (Fe(III)) is critical for mineral dynamics, pollutant remediation, and global biogeochemical cycling. Bacteria play a significant role, especially in anaerobic Fe(II) oxidation, contributing to Fe(III) mineral formation in oxygen-depleted environments. In iron-rich, neutral anaerobic settings, microbial nitrate-reducing Fe(II) oxidation (NRFO) and iron reduction processes happen simultaneously. This study used <i>Shewanella oneidensis</i> MR-1 to create an anaerobic NRFO system between Fe(II) and nitrate, revealing concurrent Fe(II) oxidation and nitrate reduction. Both gene-mediated biological Fe(II) oxidation and chemical Fe(II) oxidation, facilitated by nitrite (a byproduct of nitrate reduction), were observed. The <i>MtrABC</i> gene cluster was linked to this process. At low Fe(II) concentrations, toxicity and mineral precipitation inhibited nitrate reduction by <i>Shewanella oneidensis</i> MR-1, whereas high Fe(II) levels led to Fe(II) oxidation, resulting in cell encrustation, which further constrained nitrate reduction.
ISSN:2076-2607

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