Borrelia burgdorferi

Cell Structure

B. burgdorferi are long gram negative spirochetes (some researchers however claim that the organism is neither gram positive or gram negative, since they do not exhibit defining gram negative characteristics). Stained cells are visible under by dark-field or phase-contrast microscopy, but not visible by bright field microscopy. They are flexible helical cells and are much longer than they are wide. They usually have a length of 20-30um but a width of only 0.2-0.3um. The organism is motile with both rotational and translational movements, and the coiling of cells is regular. On the average, seven periplasmic flagella are located at each cell end, and these flagella overlap at the central region of the cell. There are multiple layers of membrane that surround the protoplasmic layer, cytoplasmic membrane, and the enclosed cytoplasmic contents.