Summary
This study investigated dissimilatory microbial iron reduction (DIR) in Chocolate Pots hot springs, Yellowstone, to elucidate microbial contributions to Fe redox cycling and stable Fe isotope fractionation in geothermal environments. Enrichment cultures of endogenous microbial communities demonstrated active Fe(III) oxide reduction coupled to oxidation of acetate, lactate, and H₂, with molecular analysis identifying Geobacter metallireducens and Ignavibacteriae as dominant Fe-reducing populations. The findings suggest that DIR processes, alongside previously documented photosynthetic Fe(II) oxidation, are important biogeochemical drivers in iron-rich hot springs and may have analogues in understanding early Earth banded iron formation deposition.
UK applicability
This study is a fundamental biogeochemical investigation of a unique geothermal system and does not directly address UK agricultural, soil, or nutrition contexts. However, the microbial iron reduction mechanisms and isotopic fractionation patterns documented may inform understanding of Fe cycling in UK anaerobic soil and wetland environments, though the high-temperature geothermal setting limits direct application.
Key measures
Most probable number enumerations of Fe(III)-reducing microorganisms; sustained DIR rates driven by different electron donors; stable Fe isotope fractionation ratios in Fe(II) products; 16S rRNA pyrosequencing and shotgun metagenomic analysis of microbial communities
Outcomes reported
The study documented that endogenous microbial communities from Chocolate Pots hot springs could reduce native Fe(III) oxides through dissimilatory microbial iron reduction (DIR), driven by oxidation of acetate, lactate, and H₂. Enrichment cultures produced isotopically light Fe(II) relative to bulk solid-phase Fe(III) oxides, with dominant microbial populations identified as Geobacter metallireducens and members of Ignavibacteriae.
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