FIGURE 3.

Transmission electron microscopy (TEM) image contrast from microbial cells associated with extracellular nanoparticles. (A) Typical small sphere observed in Figure 2E. (B) TEM image of Geobacter sulfureducens extracellularly precipitated with uraninite nanoparticles. (C) High-resolution TEM image of uraninite nanoparticles produced by G. sulfureducens. (D,E) TEM image of Desulfovibrio desulfuricans with periplasmic uraninite nanoparticles. (F), High-resolution TEM image of uraninite nanoparticles produced by D. desulfruicans. (G) Schematic explanation of the appearance of microbial cells extracellularly coated with nanoparticles by TEM observations. This illustration shows how a 150-nm thick FIB section was fabricated for rod and coccoid cells (left) and an expected TEM image from the FIB section (right). Gray color indicates the presence of extracellular nanoparticles in the right illustration.