Bacterial motility: links to the environment and a driving force for microbial physics

• Published in: FEMS microbiology ecology 2006-01, Vol.55 (1), p.3-16
• Main Authors: Mitchell, James G., Kogure, Kazuhiro
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Bacteria; Bacteria - metabolism; bacterial motility; Bacterial Physiological Phenomena; Bacteriology; Biological and medical sciences; Biosensing Techniques; Brownian motion; chemoreceptor; Chemotaxis; Ecology; Environmental gradient; Flagella; Flagella - physiology; Fundamental and applied biological sciences. Psychology; Ion pumps; Locomotion; Microbial ecology; Microbiology; Microorganisms; Miscellaneous; Motility; Physical analysis; Physics; quorum sensing; Receptors; Species Specificity; Swimming; swimming cost; Translocation
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2005.00003.x

Abstract Bacterial motility was recognized 300 years ago. Throughout this history, research into motility has led to advances in microbiology and physics. Thirty years ago, this union helped to make run and tumble chemotaxis the paradigm for bacterial movement. This review highlights how this paradigm has expanded and changed, and emphasizes the following points. The absolute magnitude of swimming speed is ecologically important because it helps determine vulnerability to Brownian motion, sensitivity to gradients, the type of receptors used and the cost of moving, with some bacteria moving at 1 mm s−1. High costs for high speeds are offset by the benefit of resource translocation across submillimetre redox and other environmental gradients. Much of environmental chemotaxis appears adapted to respond to gradients of micrometres, rather than migrations of centimetres. In such gradients, control of ion pumps is particularly important. Motility, at least in the ocean, is highly intermittent and the speed is variable within a run. Subtleties in flagellar physics provide a variety of reorientation mechanisms. Finally, while careful physical analysis has contributed to our current understanding of bacterial movement, tactic bacteria are increasingly widely used as experimental and theoretical model systems in physics.