Effect of the oxidation rate and Fe(II) state on microbial nitrate-dependent Fe(III) mineral formation

Applied and Environmental Microbiology
By: , and 

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Abstract

A nitrate-dependent Fe(II)-oxidizing bacterium was isolated and used to evaluate whether Fe(II) chemical form or oxidation rate had an effect on the mineralogy of biogenic Fe(III) (hydr)oxides resulting from nitrate-dependent Fe(II) oxidation. The isolate (designated FW33AN) had 99% 16S rRNA sequence similarity to Klebsiella oxytoca. FW33AN produced Fe(III) (hydr)oxides by oxidation of soluble Fe(II) [Fe(II)sol] or FeS under nitrate-reducing conditions. Based on X-ray diffraction (XRD) analysis, Fe(III) (hydr)oxide produced by oxidation of FeS was shown to be amorphous, while oxidation of Fe(II)sol yielded goethite. The rate of Fe(II) oxidation was then manipulated by incubating various cell concentrations of FW33AN with Fe(II)sol and nitrate. Characterization of products revealed that as Fe(II) oxidation rates slowed, a stronger goethite signal was observed by XRD and a larger proportion of Fe(III) was in the crystalline fraction. Since the mineralogy of Fe(III) (hydr)oxides may control the extent of subsequent Fe(III) reduction, the variables we identify here may have an effect on the biogeochemical cycling of Fe in anoxic ecosystems.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effect of the oxidation rate and Fe(II) state on microbial nitrate-dependent Fe(III) mineral formation
Series title Applied and Environmental Microbiology
DOI 10.1128/AEM.71.11.7172-7177.2005
Volume 71
Issue 11
Year Published 2005
Language English
Publisher American Society for Microbiology
Contributing office(s) Toxic Substances Hydrology Program
Description 6 p.
First page 7172
Last page 7177