The effect of solid surface tension and exposure to elevated hydrodynamic shear on Pseudomonas fluorescens biofilms grown on modified titanium surfaces

Abstract

The solid surface tension of titanium was varied by using organosilane monolayers of various terminations, minimising differences in other material properties. Both the quantity of Pseudomonas fluorescens biofilms grown on the modified surfaces, and the percentage of biofilm remaining after exposure to hydrodynamic shear stress, varied significantly as a function of solid surface tension. The quantity of biofilm was less on chloropropyl-terminated surfaces than on an alkyl-terminated surfaces. However, the percentage of biofilm remaining after exposure to hydrodynamic shear stress (which depends on the adhesion and cohesion strengths of the biofilm) was less for the alkyl-terminated surface than for the chloropropyl-terminated surface, for one of the two sample sets analysed. These results demonstrate the importance of differentiating between the quantity of biofilm on a surface and the adhesion and cohesion strength of the biofilm, and may help explain discrepancies in the existing literature regarding the effect of solid surface tension on the propensity of a surface for microfouling.

Keywords:

• Biofilm
• Pseudomonas fluorescens
• organosilane
• monolayer
• x-ray photoelectron spectroscopy (XPS)

Acknowledgements

The authors are grateful for the assistance of Ms Rebecca Lennen in the organosilane monolayer formation, XPS analysis, flow cell design and flow cell experiments, Dr David Stamper in the microbiological aspects of the work, Dr Azzam Mansour in the XPS analysis and Ms Jamie Chandler in the biofilm growth and flow cell experiments. This work was funded by the NSWC, Carderock Division In-House Laboratory Independent Research program.