Effects of initial adhesion events on the physiology of Pseudomonas aeruginosa.

摘要

Bacteria in biofilms have been shown to be metabolically and physiologically different from planktonic bacteria. Most studies have been conducted on mature biofilms that can be days or more old. Previous experiments suggest that wholesale changes in protein expression do occur during the first few hours of attachment, indicating a general change in physiology. An understanding of the physiologic changes that occur in a bacterial cell during initial biofilm development is crucial for the eventual control of biofilm formation.; The goal of this research project was to elucidate the changes in physiology and metabolism that occur in Pseudomonas aeruginosa during biofilm formation with particular interest paid to the processes of initial adhesion, defined as less than or equal to 3 hours. Chemostat grown cultures were used to inoculate flow cells and to inoculate small vessels of Teflon™ mesh for 1, 2 and 3 hours. RNA analysis showed a significant increase in the concentration of total RNA per cell during attachment. SDS PAGE analysis indicated the presence of protein bands at three hours not present in the planktonic samples, suggesting de novo protein synthesis.; Two dimensional (2 D) gel electrophoresis showed changes in protein expression throughout the 3 hour experimental period with a total of 55 proteins found to be differentially expressed. Eight proteins not visualized in planktonic samples were up expressed in as little as 10 minutes of attachment.; Twenty five proteins were selected for analysis using matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry. Proteins involved in LPS and alginate production, virulence factor expression and antibiotic resistance were found to be up regulated during initial adhesion. A comparison of differential protein expression during stress conditions and during attachment was made in order to assess the involvement of global regulatory mechanisms induced during biofilm development. Results suggest that various signal transduction pathways were up regulated.; The relationship of global stress response expression and the induction of signal transduction pathways in the development of biofilms may provide valuable information for future biofilm control methodologies.