Regulation of bacterial phosphate taxis and polyphosphate accumulation in response to phosphate starvation stress

Phosphorus (P) is an essential constituent in all types of living organisms. Bacteria, which use inorganic phosphate (Pi), as the preferred P source, have evolved complex systems to survive during Pi starvation conditions. Recently, we found thatPseudomonas aeruginosa, a monoflagellated, obligately aerobic bacterium, is attracted to Pi. The evidence that the chemotactic response to Pi (Pi taxis) was observed only with cells grown in Pi-limiting medium suggests that Pi taxis plays an important role in scavenging Pi residues under conditions of Pi starvation. Many bacteria also exhibit rapid and extensive accumulation of polyphosphate (polyP), when Pi is added to cells previously subjected to Pi starvation stress. Since polyP can serve as a P source during Pi starvation conditions, it is likely that polyP accumulation is a protective mechanism for survival during Pi starvation. In the present review, we summarize our current knowledge on regulation of bacterial Pi taxis and polyP accumulation in response to Pi starvation stress.