FIGURE 1.

Distinctive placement of bacterial flagellum. (A) Bacteria with flagella distributed all over the cell (e.g., Escherichia coli) are peritrichous. (B) Monotrichous bacteria, such as Vibrio cholerae, Pseudomonas aeruginosa, and Caulobacter crescentus, have a single flagellum present at one end of the cell. (C) Spirochetes, including species of Borrelia, Treponema, and Leptospira, possess specialized flagella located within the periplasmic space. The rotation of the periplasmic flagella allows the bacterium to swim forward in a corkscrew-like motion.