Biofilms: Researchers find the causes of water-repelling properties
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is often very difficult, in part because they are extremely water-repellent. A team of scientists from the Technical University of Munich (TUM) has now been able to show how such biofilms adapt their surface texture to repel water -- similar to leaves.
Bacteria surround themselves with a shell of self-produced chemical building blocks (polymers) to protect themselves from environmental hazards. The combination of bacteria and the slime they produce is called a biofilm. Microorganisms that form biofilms on surfaces have developed clever strategies that prevent running water from washing them away. This can pose a major problem not only in drainpipes but also on medical implants and tubes.
Professor Oliver Lieleg, professor of biomechanics, and his research group "Biological Hydrogels" at the Munich School of BioEngineering are investigating the physical principles that make bacterial biofilms so tough. In a recent study published in the journal NPJ Biofilms and Microbiomes, they precisely measured the surfaces of biofilms using confocal reflection light microscopy.
Nutrient supply determines the surface of biofilms
"Our first realization was: not all biofilms are the same -- even if they are produced by the same bacterium," Oliver Lieleg says. The researchers found that the soil bacterium Bacillus subtilis can produce biofilms with very different properties: In some instances, water droplets spread almost instantly across the surface. In other cases, they roll off the surface or cling to the surface in the form of spherical beads, even if the surface is tilted vertically.
The team showed that the microorganisms employ tricks from the plant world, namely the water-repellent behaviour of the leaves of lotus plants and roses. Lieleg and his team discovered that the surface structure of bacterial films is indeed very similar to those of the plant leaves. Like leaves, biofilms also have rough structures both on the micrometre and the nanometre scale, making them resistant to wetting with water.
However, plant leaves and biofilms both vary in this respect: when the lotus effect is present, small air bubbles are trapped between the water droplet and the surface of the leaf, whereas this does not occur in the rose petal effect. That is why water droplets roll off lotus leaves but stick to rose petals. Whether a biofilm behaves more like a lotus leaf or a rose petal depends on the nutrients available to the bacteria during growth, as this determines the precise surface structure of the biofilm.
A new approach to fighting biofilms
Bacteria in biofilms are often difficult to kill with antibiotics and other chemicals. In part, the increasing prevalence of bacterial resistances is to blame for this. The researchers now propose tackling the water-repellent properties of biofilms: "An antibacterial substance cannot work if it is unable to reach the surface of a biofilm because it rolls off. Thus, we need to modify this water-repellent surface texture," Oliver Lieleg explains. "This would be a new approach to the removal of biofilms from surfaces such as tubes, catheters and infected wounds."
The project was carried out as part of the SFB863 "Forces in Biomolecular Systems".
Werb, M., Falcón Garcia, C., Bach, N., Grumbein, S., Sieber, S., Opitz, M. and O. Lieleg, "Surface topology affects wetting behavior of Bacillus subtilis biofilms", NPJ Biofilms and Microbiomes, DOI: 10.1038/s41522-017-0018-1 (2017) https:/
Prof. Dr. Oliver Lieleg
Technical University of Munich
Professor of Biomechanics / Department of Mechanical Engineering and Munich School of BioEngineering
Tel.: +49 89 289 10952
Professor Oliver Lieleg: http://www.
Research Group "Biological Hydrogels": http://www.
Dr. Vera Siegler | EurekAlert!
Physicists gain new insights into nanosystems with spherical confinement
27.07.2017 | Johannes Gutenberg Universitaet Mainz
Getting closer to porous, light-responsive materials
26.07.2017 | Kyoto University
Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.
Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...
Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers
Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...
Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.
At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...
3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects
A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
26.07.2017 | Event News
21.07.2017 | Event News
19.07.2017 | Event News
27.07.2017 | Life Sciences
27.07.2017 | Life Sciences
27.07.2017 | Health and Medicine