Chemotaxis in bacteria

Bacterial chemotaxis, the movement of motile bacteria toward or away from chemicals, was discovered nearly a century ago by Engelmann (1) and Pfeffer (2,3). The subject was actively studied for about 50 years, but then there were very few reports until quite recently. For reviews of the literature up to about 1960, see Berg (4), Weibull (5), and Ziegler (6). The present review will restrict itself to the recent work on chemotaxis in Escherichia coli and Salmonella typhimurium. Some of this is also covered in Berg's review (4), and a review by Parkinson (7) should be consulted for a more complete treatment of the genetic aspects.