Quorum sensing is crucial to Emphasis Type="Itali

Authors: Jeesun Lim KangMu Lee Chan Yong Park Han Vit Kim Younghoon Kim Sungsu Park

Publish Date: 2016/09/07

Volume: 10, Issue: 3, Pages: 241-249

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Abstract

Quorum sensing QS is defined as a cellto cell signaling process that collectively regulates the gene expression of bacteria via small signaling molecules called autoinducers AIs It was reported that QSregulated gene expression in Pseudomonas aeruginosa failed to occur at a high Reynolds number Re= 3000 since AI2 a secreted interspecies signaling molecule was washed away and so could not reach the minimum concentration required for QS In this study we describe the effects of flow speed on QSstimulated biofilm formation in Escherichia coli O157H7 inside a very thin microchannel 3 cm×1 cm×45 μm In microtiter plates the wildtype strain produced high amounts of exopolysaccharide whereas its QS mutants ΔluxS and ΔlsrK defective in AI2 production and phosphorylation made less exopolysaccharide Confocal laser scanning microscopy showed that at a flow rate of 1 μL/min the wildtype strain formed rounded biofilms whereas such biofilms formed by the QS mutants were fewer and thinner At a flow rate of 10 μL/min none of the tested strains formed mature biofilms Our results suggest that QS is essential in the biofilm maturation under static or very slow laminar flow conditions where the biofilm signal can be easily accumulated and transported to the sessile cells

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