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BorreliaRANK: GenusTAXONOMY: cellular organisms -> Bacteria -> Spirochaetes -> Spirochaetia -> Spirochaetales -> Borreliaceae -> Borrelia OVERVIEW: Helical cells are 0.2–0.5 mm by 3–30 mm, composed of 3–10 loose coils. The cells are surrounded by a surface layer, an outer membrane, periplasmic flagella, and a protoplasmic cylinder (Figure 1). Typically, 15–20 periplasmic flagella (which also have been termed endoflagella, axial fibrils, or periplasmic fibrils) originate at each end of the cell and wind about the protoplasmic cylinder to overlap in the middle of the cell. The protoplasmic cylinder consists of a peptidoglycan layer and an inner membrane which encloses the internal components of the cells. The cells are actively motile with frequent reversal of the direction of translational movement. Gram-stain-negative. Stain well with Giemsa stain. Species which have been grown in vitro are microaerophilic. Nutritional requirements for in vitro growth are complex. Arthropod-borne pathogens of man, other mammals, and birds. The causative agents of tick-borne Lyme disease and relapsing fever and louse-borne relapsing fever in man.DNA G+C content (mol%): 27–32.Type species: Borrelia anserina |