MilliporeSigma
  • Home
  • Search Results
  • Enhanced uranium immobilization and reduction by Geobacter sulfurreducens biofilms.

Enhanced uranium immobilization and reduction by Geobacter sulfurreducens biofilms.

Applied and environmental microbiology (2014-08-17)
Dena L Cologgi, Allison M Speers, Blair A Bullard, Shelly D Kelly, Gemma Reguera
ABSTRACT

Biofilms formed by dissimilatory metal reducers are of interest to develop permeable biobarriers for the immobilization of soluble contaminants such as uranium. Here we show that biofilms of the model uranium-reducing bacterium Geobacter sulfurreducens immobilized substantially more U(VI) than planktonic cells and did so for longer periods of time, reductively precipitating it to a mononuclear U(IV) phase involving carbon ligands. The biofilms also tolerated high and otherwise toxic concentrations (up to 5 mM) of uranium, consistent with a respiratory strategy that also protected the cells from uranium toxicity. The enhanced ability of the biofilms to immobilize uranium correlated only partially with the biofilm biomass and thickness and depended greatly on the area of the biofilm exposed to the soluble contaminant. In contrast, uranium reduction depended on the expression of Geobacter conductive pili and, to a lesser extent, on the presence of the c cytochrome OmcZ in the biofilm matrix. The results support a model in which the electroactive biofilm matrix immobilizes and reduces the uranium in the top stratum. This mechanism prevents the permeation and mineralization of uranium in the cell envelope, thereby preserving essential cellular functions and enhancing the catalytic capacity of Geobacter cells to reduce uranium. Hence, the biofilms provide cells with a physically and chemically protected environment for the sustained immobilization and reduction of uranium that is of interest for the development of improved strategies for the in situ bioremediation of environments impacted by uranium contamination.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Sodium acetate, anhydrous, ReagentPlus®, ≥99.0%
Sigma-Aldrich
Sodium acetate, anhydrous, free-flowing, Redi-Dri, ACS reagent, ≥99.0%
Sigma-Aldrich
Sodium acetate, puriss. p.a., ACS reagent, reag. Ph. Eur., anhydrous
Sigma-Aldrich
Sodium acetate, ACS reagent, ≥99.0%
Sigma-Aldrich
Sodium Acetate Anhydrous, >99%, FCC, FG
Sigma-Aldrich
Sodium acetate, anhydrous, for molecular biology, ≥99%
Sigma-Aldrich
Sodium acetate, meets USP testing specifications, anhydrous
Sigma-Aldrich
Sodium acetate, 99.995% trace metals basis
Sigma-Aldrich
Sodium azide, BioUltra, ≥99.5% (T)
Sigma-Aldrich
Sodium azide, ReagentPlus®, ≥99.5%
Sigma-Aldrich
Carbonyl cyanide 3-chlorophenylhydrazone, ≥97% (TLC), powder
Sigma-Aldrich
Sodium azide, BioXtra
Sigma-Aldrich
Diethyl azodicarboxylate solution, 40 wt. % in toluene
Supelco
Sodium acetate solution, NMR reference standard, 50 mM in D2O (99.9 atom % D), water 1 %, NMR tube size 3 mm × 8 in.
Sigma-Aldrich
Sodium acetate solution, BioUltra, for molecular biology, ~3 M in H2O
Sigma-Aldrich
Sodium azide, purum p.a., ≥99.0% (T)
Sigma-Aldrich
Sodium acetate, anhydrous, BioUltra, for luminescence, for molecular biology, ≥99.0% (NT)
Sigma-Aldrich
Sodium acetate, powder, BioReagent, suitable for electrophoresis, suitable for cell culture, suitable for insect cell culture, ≥99%
Sigma-Aldrich
Sodium acetate, BioXtra, ≥99.0%
USP
Sodium acetate, United States Pharmacopeia (USP) Reference Standard