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 orga nisms. Bacteria, which use inorganic phosphate (P-i) as the preferred P source, have evolved complex systems to survive during P-i starvatio n conditions. Recently, we found that Pseudomonas aeruginosa, a monofl agellated, obligately aerobic bacterium, is attracted to P-i. The evid ence that the chemotactic response to P-i (P-i taxis) was observed onl y with cells grown in P-i-limiting medium suggests that P-i taxis play s an important role in scavenging P-i residues under conditions of P-i starvation. Many bacteria also exhibit rapid and extensive accumulati on of polyphosphate (polyP), when P-i is added to cells previously sub jected to P-i starvation stress. Since polyP can serve as a P source d uring P-i starvation conditions, it is likely that polyP accumulation is a protective mechanism for survival during P-i starvation. In the p resent review, we summarize our current knowledge on regulation of bac terial P-i taxis and polyP accumulation in response to P-i starvation stress.