Strength of bacterial adhesion does not depend on size of contact area

Bacteria of the species Staphylococcus aureus are

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among the most widespread and dangerous pathogens of our time. One of the reasons for their effectiveness is their ability to adhere to both synthetic and natural surfaces, where they form very persistent biofilms. These biofilms effectively protect the individual pathogens making them very difficult to remove from a surface. This is why their presence on medical implants is so feared and why they are a major cause of post-operative infection. One approach to preventing infection is therefore to prevent the formation of the biofilm. But in order to be able to influence biofilm growth, scientists need to understand the mechanism by which the bacteria adhere to surfaces. For example, it would be useful to know just what fraction of the surface area of a single bacterial cell is actually in contact with the surface. However, as these spherical bacteria are only a micrometer across (about one hundredth the thickness of a human hair), it was unlikely that conventional light microscopy could be used to determine the contact area.

The Saarland University team led by the experimental physicist Professor Karin Jacobs and the microbiologist Professor Markus Bischoff therefore made use of another property of the bacteria, namely that the strength of adhesion exhibited by different species of bacteria often depends strongly on the type of surface on which it is situated. For instance, the bacteria that were the focus of the present study adhere much more effectively to strongly hydrophobic surfaces than to wettable (hydrophilic) surfaces. The researchers therefore created a silicon-based surface that exhibited both properties – strongly hydrophobic in one region, highly wettable in another – within an extremely small area. The adhesive force exerted by individual bacteria on this specially prepared surface was then measured using a scanning atomic force microscope, known as a force spectroscope.

Read more at: https://phys.org/news/2017-07-strength-bacterial-adhesion-size-contact.html#jCp