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. Author manuscript; available in PMC: 2014 Jun 1.

Published in final edited form as: Energy Environ Sci. 2013 Apr 8;6(6):1827–1836. doi: 10.1039/C3EE40203G

a, Axial view 2D MRI taken before U^VI addition b, Axial view 2D MRI after two days of U^VI addition. c, Overlay of relative diffusion coefficient profile (yellow), 2D MRI signal intensity (grey), and relative acetate concentration (black), after the addition of U^VI. d, TEM image of a cross section of the biofilm. Top images: top of the biofilm after U^VI addition, corresponding to the dark band seen in the 2D MRI. Biogenic reduced U^VI can be seen precipitated onto strand-like formations encasing the cells. Bottom images: cells near the base of the biofilm. No U^VI precipitates can be observed. However, cells appeared damaged and plasmolyzed, corroborating evidence that the base of the biofilm was electron donor and nutrient limited. e, SEM image of a biofilm cross section. The smooth bottom surface is shown, having been detached from the gold electrode. The white dashed line emphasizes the partition of the U^VI-encrusted (top) and U^VI-absent regions of the biofilm. f, EDS spectrum of the upper portion of the biofilm, revealing cells encrusted in material containing U and P. The background Cu peak is caused by the electrons scattered from the Cu TEM grid.

a, Axial view 2D MRI taken before U^VI addition b, Axial view 2D MRI after two days of U^VI addition. c, Overlay of relative diffusion coefficient profile (yellow), 2D MRI signal intensity (grey), and relative acetate concentration (black), after the addition of U^VI. d, TEM image of a cross section of the biofilm. Top images: top of the biofilm after U^VI addition, corresponding to the dark band seen in the 2D MRI. Biogenic reduced U^VI can be seen precipitated onto strand-like formations encasing the cells. Bottom images: cells near the base of the biofilm. No U^VI precipitates can be observed. However, cells appeared damaged and plasmolyzed, corroborating evidence that the base of the biofilm was electron donor and nutrient limited. e, SEM image of a biofilm cross section. The smooth bottom surface is shown, having been detached from the gold electrode. The white dashed line emphasizes the partition of the U^VI-encrusted (top) and U^VI-absent regions of the biofilm. f, EDS spectrum of the upper portion of the biofilm, revealing cells encrusted in material containing U and P. The background Cu peak is caused by the electrons scattered from the Cu TEM grid.