Prokaryotic phototaxis

Phototaxis has been examined in some detail in a number of photosynthetic prokaryotes (9), particularly halophilic Archaea, purple photosynthetic Proteobacteria, and Cyanobacteria (for purple bacteria and Archaea, see Fig. 1). Two very different mechanisms of photosensing are at the basis of these photo taxis responses some responses are triggered via light absorption by the photosynthetic machinery, while others involve dedicated photosensory proteins. 

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