Aerotaxis

Discovery

The discovery of aerotaxis was first reported by Theodor Wilhelm Engelmann, as he showed microaerophilic Spirillum tenue were attracted by low oxygen concentrations. Ten decades after the first discovery of this movement, it was observed that bacteria are actually bound to areas with optimal oxygen concentrations; resulting in the formation of bands. It was concluded that the creations of these bands was largely in part to oxygen's important role in metabolic pathways as they allowed for surveying aerotaxis in many bacterial species. This ability proves to be important for survival as efficient metabolism directly relates to growth. Aerotaxis not only describes the response to energy source, but also the signal transductions across organisms to create ecosystems.

As growing conditions change, such as the availability of oxygen, bacteria capable of energy taxis travel towards nutrient concentrations which are metabolically beneficial. The direction of travel is determined utilizing a transducer, such as Aer or Tsr proteins in E. coli, which detect changes in either electron transport or proton motive force.

Aerotaxis, similar to other types of bacterial taxis, involves repeated cycles of straight-line swimming followed by short reversals that reorient bacteria so that they are constantly drawn up their oxygen gradients toward attractants and away from repellants. Aerotaxis is a dominant sensory system and will cause organisms to follow their oxygen gradient even if it makes them move against other chemical gradients.