Polar flagellum

It is an aerobic, gram-negative, nonsporing, rod-shaped bacterium. It is motile with a single polar flagellum. 

E. coU cells in a capillary tube can also be powered by an external voltage. In alkalophilic strains of Bacillus and some Vibrio species a sodium ion gradient will substitute. Several hundred protons or Na+ ions must pass through the motor per revolution. Some estimates, based on energy balance, are over 1000. However, Na+-dependent rotation at velocities of up to 1700 Hz has been reported for the polar flagellum of Vibrio alginolyticus. It is difficult to understand how the bacterium could support the flow of 1000 Na+ per revolution to drive the flagellum. ... 

After three subcultures, a small (1 jam), gram-negative, curved bacterium designated BAL-1 was isolated from agar (Fig. 1) (10). It is strictly anaerobic and very motile, powered by a single polar flagellum. 

McClain, J., RoUo, D. R, Rushing, B. G., and Bauer, C. E. (2002) Rhodospirillum centenum utilizes separate motor and switch components to control lateral and polar flagellum rotation./. Bacteriol. 184, 2429-2438. 

The vibrios are short rod shaped organisms (cocco-bacilli) which are motile. They only consist of one group with a large polar flagellum and are commonly found in polluted water, especially in the tropics where they can cause cholera. 

Kawagishi, I., Maekawa, Y., Atsumi, T., Homma, M. and Imae, Y. (1995). Isolation of the polar and lateral flagellum-defective mutants in Vibrio alginolyticus and identification of their flagellar driving energy sources. /. Bacteriol. 177, 5158-5160. 

Vibrio parahaemolyticus Polar flagellum, which is surface induced, acts as a sensory tactile device for the microbe McCarter et al. (1992), McCarter and Silverman (1989)... 

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