Article Figures & Data
Figures
- FIG. 1.
Anaerobic, oxidative dissolution of two different synthetic U(IV) oxides by washed cell suspensions of T. denitrificans: (A) freshly prepared U(IV) oxide with a slurry consistency and (B) aggregated grains of U(IV) oxide that had dried under anaerobic conditions. Datum points represent the averages of duplicate suspensions.
- FIG. 2.
Production of dissolved uranium (A) and consumption of nitrate (B) during anaerobic, oxidative dissolution of biogenic uraninite by washed cell suspensions of T. denitrificans. Datum points represent the averages of triplicate suspensions, and error bars represent 1 standard deviation (error bars are plotted for all datum points but are obscured by the symbol in some cases).
- FIG. 3.
Correlation between net U(IV) oxidation and nitrate consumption during the oxidative dissolution of biogenic uraninite by washed cells of T. denitrificans (experiment represented in Fig. 2). Datum points represent the averages of triplicate suspensions. A linear regression fit is plotted.
Tables
- TABLE 1.
Summary of experiments testing nitrate-dependent U(IV) oxidation by T. denitrificans
U(IV) oxide form Net U(IV) dissolved (μM)a Portion of U(IV) dissolved (%)b Positive-control denitrification activityc Active culture Sterile control Live control without nitrate Synthetic, slurryd 42 0.92 0.18 4 1.2 Synthetic, driede 0.067 0.0027 <0 0.02 1.2 Biogenic UO2f 39 15 13 22 3.3 ↵ a Net U(IV) dissolved is defined as the final U concentration minus the initial U concentration. Values represent the averages of duplicate cultures for synthetic U(IV) oxides or of triplicate cultures for biogenic uraninite.
↵ b Approximate fraction of initial U(IV) that was dissolved in the active cultures, expressed as a percentage. The amounts of initial U(IV) present were approximately 1, 0.4, and 0.18 mmol/liter, respectively, in the experiments with slurry (synthetic), dried (synthetic), and biogenic U(IV) oxide.
↵ c In micromoles of electron equivalents per minute. Positive controls contained thiosulfate as the electron donor rather than a U(IV) oxide (see text). Protein content ranged from approximately 1.1 to 1.3 mg.
↵ d See Fig. 1A. Net U(IV) dissolved data are calculated for day 17.
↵ e See Fig. 1B. Net U(IV) dissolved data are calculated for day 20.
↵ f See Fig. 2A. Net U(IV) dissolved data are calculated for day 14.
