Fig. 2.

TEM images and elemental maps showing the intimate association of the G. ferruginea cell and its stalk. (a) TEM image showing the connecting site of the bacterial mother cell and the fibers. Fibers originate from the wall region (stars) of the cell. At the export sites (arrows), fibers are extremely thin but become thicker within about 500 nm of the cell wall. (b) HAADF-STEM image of the cell with stretched stalk fibers from panel a. Note the uneven electron density of the fibers. Also shown are elemental maps of Fe (c), Si (d), and P (e) in the same image site with the same magnification as used for panel b. Note the following: (i) intense signals of Fe are detected in the fibers, but only traces are detected in the cell; (ii) a larger number of Si signals are detected in the fibers than in the cell; (iii) P is distributed almost evenly in the cell and fibers; and (iv) a noticeable number of Si and P signals occur in the background outside the cell and stalks. Scale bars, 0.1 μm (a) and 500 nm (b to e).