ERSP Rifle - Ground_Water_2007
Study of Geobacter physiology during stimulated uranium bioremediation
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Evolving geochemical conditions drive changes in Geobacter physiology during stimulated uranium bioremediation

Abstract The efficacy of soluble U(VI) reduction to insoluble U(IV) by iron-reducing bacteria changes as geochemical conditions evolve during bioremediation. Three planktonic Geobacter-dominated communities were recovered from the U-contaminated Rifle, CO aquifer during in situ acetate amendment. Over 2,500 proteins were identified per sample by matching LC MS/MS spectra to peptides predicted from 7 isolate Geobacter genomes. Genome-specific peptides indicate early proliferation of multiple M21 and G. bemidjiensis like strains and later dominance by M21 and G. bemidjiensis like strains more closely related to G. lovleyi. Throughout biostimulation, the proteome is dominated by enzymes that convert acetate to acetyl-CoA and pyruvate for central metabolism. Later in bioreduction, decreasing abundances of ribosomal proteins, ATP synthase, and phosphate and nitrogen acquisition proteins indicate slowing biomass production whereas increases in TCA cycle proteins and flagellin suggest a transition toward attachment, possibly driven by dependence on less readily reducible iron oxides. Results demonstrate that metagenomics-independent proteomics can resolve population physiology and strain composition of subsurface communities.

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