Document Detail

Pseudomonas aeruginosa Attachment on QCM-D Sensors: The Role of Cell and Surface Hydrophobicities.
MedLine Citation:
PMID:  22439703     Owner:  NLM     Status:  Publisher    
While biofilms are ubiquitous in nature, the mechanism by which they form is still poorly understood. This study investigated the process by which bacteria deposit and shortly after, attach irreversibly to surfaces by reorienting to create a stronger interaction, which leads to biofilm formation. A model for attachment of Pseudomonas aeruginosa was developed using a quartz crystal microbalance with dissipation monitoring (QCM-D) technology, along with a fluorescent microscope and camera to monitor kinetics of adherence of the cells over time. In this model the interaction differs depending on the force that dominates between the viscous, inertial, and elastic loads. P. aeruginosa, grown to the mid-exponential growth phase (hydrophilic) and stationary phase (hydrophobic) and two different surfaces, bare quartz (SiO2), and polyvinylidene (PVDF), which are hydrophilic and hydrophobic, respectively were used to test the model. The bacteria deposited on both of the sensor surfaces, though on the bare quartz surface the cells reached a steady state where there was no net increase in deposition of bacteria, while the quantity of cells depositing on the PVDF surface continued to increase until the end of the experiments. The change in frequency and dissipation per cell were both positive for each overtone (n), except when the cells and surface are both hydrophilic. In the model three factors, specifically viscous, inertial, and elastic loads, contribute to the change in frequency and dissipation at each overtone when a cell deposits on a sensor. Based on the model, hydrophobic cells were shown to form an elastic connection to either surface, with an increase of elasticity at higher overtones. At lower overtones, hydrophilic cells depositing on the hydrophobic surface, were shown to also be elastic, but as the overtone increases the connection between the cells and sensor becomes more viscoelastic. In the case of hydrophilic cells interacting with the hydrophilic surface, the connection is viscous at each overtone measured, the connection is rigid once the cell deposits on the surface. It could be inferred that the transformation of the viscoelasticity of the cell-surface connection are due to changes in the orientation of the cells to the surface, which allow the bacteria to attach irreversibly and begin biofilm formation.
Ian Marcus; Moshe Herzberg; Sharon Louise Walker; Viatcheslav Freger
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-3-22
Journal Detail:
Title:  Langmuir : the ACS journal of surfaces and colloids     Volume:  -     ISSN:  1520-5827     ISO Abbreviation:  -     Publication Date:  2012 Mar 
Date Detail:
Created Date:  2012-3-23     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882736     Medline TA:  Langmuir     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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