FIG. 2.

TEMs showing Tc-containing precipitates formed by G. sulfurreducens via direct hydrogen-dependent and indirect Fe(II)-mediated mechanisms. (A) TEM of thin sections of cells containing an electron-dense Tc precipitate formed by hydrogen-dependent reduction at the periphery of the cell. (B) EDAX spectrum from the electron-dense deposit at the cell periphery. (C) TEM of air-dried whole-cell preparations showing Tc-containing extracellular magnetite crystals (m). (D) EDAX spectrum from extracellular magnetite crystals. Bars, 0.5 μm.