Figure 1.
Growth of biofilms for analysis.
(A) Representative trace showing current production by a G. sulfurreducens biofilm using 30 mM acetate as the electron donor on a polished graphite electrode poised at +0.24 V vs. Standard Hydrogen Electrode. Additional acetate (30 mM) was added where indicated, and the medium was replaced to remove planktonic cells. (B) Cyclic voltammetry (1 mV/s) of the electrode shown in A, producing the characteristic sigmoidal current response of a G. sulfurreducens biofilm-colonized electrode. All biofilms were grown simultaneously from the same inoculum under identical conditions, were harvested and fixed in resin at the same time.
Figure 2.
Representative biofilm and labeling with anti-OmcB antibody.
(A) Low-resolution Transmission Electron Microscopy image showing an entire unlabeled G. sulfurreducens biofilm, illustrating increase in cell density near the electrode surface. (B) Examples from digitally reconstructed high-resolution images representing cells 16–18 µm from the electrode labeled with anti-OmcB antibodies. Red circles indicate proteins within 15 nm of the membrane, black circles indicate intracellular localization. (C) Examples of cells located 6–8 µm from the electrode, taken from the same biofilm reconstructions, with lower abundance of OmcB.
Figure 3.
Abundance of OmcB on G. sulfurreducens cells at different distances from the electrode.
Means shown are the result of six different images compiled from three different biofilms, +/− SEM. Data from labeling after incubation with anti-OmcB antibodies (red circles) vs. labeling with pre-immune serum as a control (black triangles).
Figure 4.
Anti-Acetate kinase labeling of G. sulfurreducens biofims.
(A) Examples from digitally reconstructed high-resolution images representing cells 16–18 µm from the electrode labeled with anti-acetate kinase antibodies. Red circles indicate proteins within 15 nm of the membrane, black circles indicate intracellular localization. (B) Examples of cells located 6–8 µm from the electrode, taken from the same biofilm reconstructions.
Figure 5.
Abundance of acetate kinase isozymes at different distances from the electrode.
Means shown are the result of six different images, +/− SEM. Data from labeling after incubation with anti-acetate kinase antibodies (red circles) vs. labeling with pre-immune serum as a control (black triangles).