Enriched iron(III)-reducing bacterial communities are shaped by carbon substrate and iron oxide mineralogy
Lentini, Christopher J.
Wankel, Scott D.
Hansel, Colleen M.
MetadataShow full item record
Iron (Fe) oxides exist in a spectrum of structures in the environment, with ferrihydrite widely considered the most bioavailable phase. Yet, ferrihydrite is unstable and rapidly transforms to more crystalline Fe(III) oxides (e.g., goethite, hematite), which are poorly reduced by model dissimilatory Fe(III)-reducing microorganisms. This begs the question, what processes and microbial groups are responsible for reduction of crystalline Fe(III) oxides within sedimentary environments? Further, how do changes in Fe mineralogy shape oxide-hosted microbial populations? To address these questions, we conducted a large-scale cultivation effort using various Fe(III) oxides (ferrihydrite, goethite, hematite) and carbon substrates (glucose, lactate, acetate) along a dilution gradient to enrich for microbial populations capable of reducing Fe oxides spanning a wide range of crystallinities and reduction potentials. While carbon source was the most important variable shaping community composition within Fe(III)-reducing enrichments, both Fe oxide type and sediment dilution also had a substantial influence. For instance, with acetate as the carbon source, only ferrihydrite enrichments displayed a significant amount of Fe(III) reduction and the well-known dissimilatory metal reducer Geobacter sp. was the dominant organism enriched. In contrast, when glucose and lactate were provided, all three Fe oxides were reduced and reduction coincided with the presence of fermentative (e.g., Enterobacter spp.) and sulfate-reducing bacteria (e.g., Desulfovibrio spp.). Thus, changes in Fe oxide structure and resource availability may shift Fe(III)-reducing communities between dominantly metal-respiring to fermenting and/or sulfate-reducing organisms which are capable of reducing more recalcitrant Fe phases. These findings highlight the need for further targeted investigations into the composition and activity of speciation-directed metal-reducing populations within natural environments.
© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Microbiology 3 (2012): 404, doi:10.3389/fmicb.2012.00404.
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
The importance of dissimilatory nitrate reduction to ammonium (DNRA) in the nitrogen cycle of coastal ecosystems Giblin, Anne E.; Tobias, Craig R.; Song, Bongkeun; Weston, Nathaniel; Banta, Gary T.; Rivera-Monroy, Victor H. (The Oceanography Society, 2013-09)Until recently, it was believed that biological assimilation and gaseous nitrogen (N) loss through denitrification were the two major fates of nitrate entering or produced within most coastal ecosystems. Denitrification ...
The diversity of sulfide oxidation and sulfate reduction genes expressed by the bacterial communities of the Cariaco Basin, Venezuela Rodriguez-Mora, Maria J.; Edgcomb, Virginia P.; Taylor, Craig D.; Scranton, Mary I.; Taylor, Gordon T.; Chistoserdov, Andrei Y. (Bentham Open, 2016-08-31)Qualitative expression of dissimilative sulfite reductase (dsrA), a key gene in sulfate reduction, and sulfide:quinone oxidoreductase (sqr), a key gene in sulfide oxidation was investigated. Neither of the two could be ...
Response of benthic metabolism and nutrient cycling to reductions in wastewater loading to Boston Harbor, USA Tucker, Jane; Giblin, Anne E.; Hopkinson, Charles S.; Kelsey, Samuel W.; Howes, Brian L. (Elsevier, 2014-10-02)We describe the long-term response of benthic metabolism in depositional sediments of Boston Harbor, MA, to large reductions in organic matter and nutrient loading. Although Boston Harbor received very high loadings of ...