Forum for Science, Industry and Business

Bacteria optimise their swimming behaviour

Bacteria are unicellular organisms that measure just a few micrometres in size. By rotating a propeller-like appendage, the flagellum, they are able to move in liquid environments. This ability to propel themselves is of critical importance for many pathogenic bacteria, such as Salmonella. The motility organelle of the bacteria is a complex, macromolecular structure that comprises thousands of building blocks and measures several micrometres in length.

Elektronenmikroskopische Aufnahme eines Salmonellenbakteriums mit langen Fortsätzen, den Flagellen. Foto: Prof. Dr. Manfred Rhode, Helmholtz-Zentrum für Infektionsforschung, Braunschweig

Interestingly, bacteria can precisely measure the substructures of their flagella on a nanometre scale. In particular, the length of an extracellular joint linking structure – the flagellar hook – is fixed to around 55 nanometres.

To enable this precise length measurement, bacteria use a ‘molecular ruler protein’, which determines the length of the hook structure during the construction of flagella. Why the precisely defined length of the hook structure is important for flagella function, however, was previously unknown.

Researchers at the Humboldt-Universität zu Berlin (HU), together with national and international colleagues from the Helmholtz Centre for Infection Research in Braunschweig, the Braunschweig Integrated Centre of Systems Biology, the University of Edinburgh, the University of Fribourg and Michigan State University, have now determined that the optimal length of the hook structure is critically important for the efficient motility of Salmonella.

As part of this research, the scientists analysed the swimming behaviour of genetically modified bacteria with various hook lengths in different environments and were able to demonstrate that Salmonella can move most efficiently in liquid environments when the hook structure measures around 55 nanometres in length.

These findings are a fascinating example that show why the locomotory organelle of bacteria has developed through the constant process of evolution into the complex, macromolecular structure seen today. The conclusions drawn by the researchers based on the structure of the locomotory organelle with regard to the swimming behaviour of bacteria could also play an important role for the future development of swimming robots at the micrometre scale.

The complete study has been published with the title ‘Hook length of the bacterial flagellum is optimized for maximal stability of the flagellar bundle’ in the scientific journal PLoS Biology.

Wissenschaftliche Ansprechpartner:

Prof. Dr. Marc Erhardt
Institute for Biology
Tel.: 030 2093-49780
marc.erhardt@hu-berlin.de

Originalpublikation:

I. Spöring, V.A. Martinez, C. Hotz, J. Schwarz-Linek, K. L. Grady, J. M. Nava-Sedeño, T. Vissers, H. M. Singer, M. Rohde, C. Bourquin, H. Hatzikirou, W. C. K. Poon, Y. S. Dufour, M. Erhardt. (2018) Hook length of the bacterial flagellum is optimized for maximal stability of the flagellar bundle. PLoS Biology 16(9): doi.org/10.1371/journal.pbio.2006989

Weitere Informationen:

http://www.baktphys.hu-berlin.de

Hans-Christoph Keller | idw - Informationsdienst Wissenschaft
Further information:
https://www.hu-berlin.de

Im Focus: The coldest reaction

With ultracold chemistry, researchers get a first look at exactly what happens during a chemical reaction

The coldest chemical reaction in the known universe took place in what appears to be a chaotic mess of lasers. The appearance deceives: Deep within that...

Im Focus: How do scars form? Fascia function as a repository of mobile scar tissue

Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.

Fibroblasts kit - ready to heal wounds

Im Focus: McMaster researcher warns plastic pollution in Great Lakes growing concern to ecosystem

Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.

In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...

Im Focus: Machine learning microscope adapts lighting to improve diagnosis

Prototype microscope teaches itself the best illumination settings for diagnosing malaria

Im Focus: Small particles, big effects: How graphene nanoparticles improve the resolution of microscopes

Conventional light microscopes cannot distinguish structures when they are separated by a distance smaller than, roughly, the wavelength of light. Superresolution microscopy, developed since the 1980s, lifts this limitation, using fluorescent moieties. Scientists at the Max Planck Institute for Polymer Research have now discovered that graphene nano-molecules can be used to improve this microscopy technique. These graphene nano-molecules offer a number of substantial advantages over the materials previously used, making superresolution microscopy even more versatile.

Microscopy is an important investigation method, in physics, biology, medicine, and many other sciences. However, it has one disadvantage: its resolution is...