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Controls on Iron Reduction and Biomineralization over Broad Environmental Conditions as Suggested by the Firmicutes Orenia metallireducens Strain Z6
journal contribution
posted on 2020-08-06, 21:58 authored by Yiran Dong, Robert A. Sanford, Maxim I. Boyanov, Theodore M. Flynn, Edward J. O’Loughlin, Kenneth M. Kemner, Samantha George, Kaitlyn E. Fouke, Shuyi Li, Dongmei Huang, Shuzhen Li, Bruce W. FoukeMicrobial
iron reduction is a ubiquitous biogeochemical process
driven by diverse microorganisms in a variety of environments. However,
it is often difficult to separate the biological from the geochemical
controls on bioreduction of Fe(III) oxides. Here, we investigated
the primary driving factor(s) that mediate secondary iron mineral
formation over a broad range of environmental conditions using a single
dissimilatory iron reducer, Orenia metallireducens strain Z6. A total of 17 distinct geochemical conditions were tested
with differing pH (6.5–8.5), temperature (22–50 °C),
salinity (2–20% NaCl), anions (phosphate and sulfate), electron
shuttle (anthraquinone-2,6-disulfonate), and Fe(III) oxide mineralogy
(ferrihydrite, lepidocrocite, goethite, hematite, and magnetite).
The observed rates and extent of iron reduction differed significantly
with kint between 0.186
and 1.702 mmol L–1 day–1 and Fe(II)
production ranging from 6.3% to 83.7% of the initial Fe(III). Using
X-ray absorption and scattering techniques (EXAFS and XRD), we identified
and assessed the relationship between secondary minerals and the specific
environmental conditions. It was inferred that the observed bifurcation
of the mineralization pathways may be mediated by differing extents
of Fe(II) sorption on the remaining Fe(III) minerals. These results
expand our understanding of the controls on biomineralization during
microbial iron reduction and aid the development of practical applications.