Surface-association of Pseudomonas aeruginosa

Abstract

Bacteria inhabit many complex environments ranging from soil, to humans, and hospital equipment. Most studies have focused on the chemical cues in different environments, but recently the importance of the physical environment on bacteria response has been revealed. In fact many behaviors such as biofilm formation, and virulence have been found to be surface dependent. Interestingly, these behaviors have also all been shown to require a bacterial communication system called quorum sensing (QS). QS regulates resource intensive communal production and surface behaviors in bacteria. However, little is known about how QS signaling is specifically involved in surface phenotypes. Here, we find that lasR, the QS master regulator gene, is upregulated after adhesion to a surface in Pseudomonas aeruginosa, resulting in the hypersensitivity of surface-associated cells to QS. The surface-specific increase of lasR expression may explain why so many surface phenotypes are QS-dependent. We also explore the effects of media and stiffness on surface-association. Due to the necessity of surface-association for virulence in P. aeruginosa elucidating the surface pathway can lead to alternative to antibiotic therapeutics.