PHOB MODULATION BY POLYPHOSPHATE LEVELS IN Escherichia coli AND ITS INVOLVEMENT IN BIOFILM FORMATION

GRILLO PUERTAS, MARIANA; RINTOUL, MARIA REGINA; RAPISARDA, VIVIANA ANDREA

Conferencia; SAIB; 2015

Sociedad Argentina de Investigación en Bioquimica y Biología Molecular

Polyphosphate (polyP) in Escherichia coli stationary phase is modulated by the media phosphate (Pi) concentrationand its degradation induces biofilm formation via LuxS quorum sensing system. PhoB, the regulator of the twocomponentsystem phoBR, responds to media Pi limitation and inhibits biofilm formation. The aim of this work wasto investigate if PhoB is implicated in the formerly studied biofilm formation regulated by fluctuations in polyPlevels. Cells were statically grown at 30ºC in minimal medium varying Pi concentration (0.003, 2 and 40 mM).Alkaline phosphatase (AP) activity was measured as an indicator of PhoB activity. In stationary phase, a high APactivity was observed when polyP was accumulated, while it was similar to that of phoB mutant when polyP wasdegraded or absent. Consequently, when PhoB is repressed (polyP degradation) or absent (phoB related-mutants)cells form biofilm independently of the media Pi concentration, indicating that PhoB inhibits biofilm formation in apolyP accumulating condition. Data shows that PhoB activity is modulated in non-limiting Pi condition by fluctuationin polyP. PhoB seems to be a component in the signal cascade that regulates biofilm formation triggered by polyPlevels in stationary phase.