title: Polyphosphate degradation in stationary phase triggers biofilm formation via LuxS quorum sensing system in Escherichia coli.
abstract: In most natural environments, association with a surface in a structure known as biofilm is the prevailing microbial life-style of bacteria. Polyphosphate (polyP), an ubiquitous linear polymer of hundreds of orthophosphate residues, has a crucial role in stress responses, stationary-phase survival, and it was associated to bacterial biofilm formation and production of virulence factors. In previous work, we have shown that Escherichia coli cells grown in media containing a critical phosphate concentration >37 mM maintained an unusual high polyP level in stationary phase. The aim of the present work was to analyze if fluctuations in polyP levels in stationary phase affect biofilm formation capacity in E. coli. Polymer levels were modulated by the media phosphate concentration or using mutant strains in polyP metabolism. Cells grown in media containing phosphate concentrations higher than 25 mM were defective in biofilm formation. Besides, there was a disassembly of 24 h preformed biofilm by the addition of high phosphate concentration to the medium. These phenotypes were related to the maintenance or re-synthesis of polyP in stationary phase in static conditions. No biofilm formation was observed in ppk(-)ppx(-) or ppk(-)ppx(-)/ppk(+) strains, deficient in polyP synthesis and hydrolysis, respectively. luxS and lsrK mutants, impaired in autoinducer-2 quorum sensing signal metabolism, were unable to form biofilm unless conditioned media from stationary phase wild type cells grown in low phosphate were used. We conclude that polyP degradation is required for biofilm formation in sufficient phosphate media, activating or triggering the production of autoinducer-2. According to our results, phosphate concentration of the culture media should be carefully considered in bacterial adhesion and virulence studies.
authors.affiliation: Instituto Superior de Investigaciones Biológicas (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán), and Instituto de Química Biológica Dr Bernabé Bloj (Universidad Nacional de Tucumán), San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: Mariana
authors.initials: M
authors.lastname: Grillo-Puertas
authors.forename: Josefina M
authors.initials: JM
authors.lastname: Villegas
authors.forename: María R
authors.initials: MR
authors.lastname: Rintoul
authors.forename: Viviana A
authors.initials: VA
authors.lastname: Rapisarda
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D013437:Carbon-Sulfur Lyases / Q000235:genetics* / Q000378:metabolism; D003470:Culture Media / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006714:Homoserine / Q000031:analogs & derivatives / Q000096:biosynthesis; D007783:Lactones; D011122:Polyphosphates / Q000378:metabolism* / Q000494:pharmacology; D053038:Quorum Sensing / Q000187:drug effects / Q000235:genetics*; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D017077:Culture Media, Conditioned; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D011122:Polyphosphates; D037521:Virulence Factors; D006714:Homoserine; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria