PhoB activation in non-limiting phosphate condition by the maintenance of high polyphosphate levels in stationary phase inhibits biofilm formation in Escherichia coli.

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

MICROBIOLOGY-UK

SOC GENERAL MICROBIOLOGY

Lugar: London; Año: 2016

1350-0872

Polyphosphate (polyP) degradation in Escherichia coli stationary phase triggers biofilm formation via LuxS quorum sensing system. In media containing excess of phosphate (Pi), high polyP levels in stationary phase are maintained with the consequent biofilm formation inhibition. The transcriptional-response regulator PhoB, which is activated under Pi limitation, is involved in the inhibition of biofilm formation in several bacterial species. In the current study, we report for the first time that E. coli PhoB can be activated in non-limiting Pi condition, leading to inhibition of biofilm formation. In fact, PhoB was activated when high polyP levels were maintained in stationary phase, while it was inactive when the polymer was degraded or absent. The PhoB activation was mediated by acetyl phosphate with the consequent repression of biofilm formation due to the downregulation of c-di-GMP synthesis and the inhibition of AI-2 production. These results allowed us to propose a model showing that PhoB is a component in the signal cascade regulating the biofilm formation triggered by fluctuations of polyP levels in E. coli stationary phase cells.