Flagella, Chemotaxis and Surface Sensing.

Based on genome analyses, it has been estimated that more than half of the bacteria have made an important investment into motility since they possess genes encoding the flagellar motor, the flagellum, chemosensory pathways and chemoreceptors. The metabolic burden associated with gene maintenance, protein synthesis and operating these systems is very important. A central question is thus to establish the physiological benefits that compensate such an important investment. In this chapter, we illustrate that benefits are multiple and diverse, including access to nutrients and preferred niches, biofilm formation and bacterial dispersal. There is also evidence that the complete range of advantages still remains to be defined. In these research efforts, Pseudomonas aeruginosa (PA) has played a central role and is among the central model species. Research conducted on PA had a significant impact in the field and has motivated many experiments in the study of other model bacterial species.