How confinement impacts flagellar dynamics and motility of bacteria

• Applicants: Professor Dr. Carsten Beta; Professor Dr. Kai Thormann
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms ; Biophysics
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 443369470

A large number of bacterial species are motile by means of polar flagella — helical proteinaceous fibers that are driven by a rotary motor. So far, flagella-mediated motility and the dynamics of flagellar filaments have been studied almost exclusively during free swimming in planktonic environments and, to some extent, during swarming across surfaces. However, in their native habitat, many bacterial species have to move through narrow and obstructed surroundings, in which the cells are constantly in mechanical contact with the environmental matrix, such as polysaccharide networks (as for example in mucus or biofilms) or granular solid surfaces (as in wet soils or sediments). It is largely unknown how bacteria use their flagella to move through such environments. In the research project proposed here, we will combine holographic imaging, high-speed fluorescence microscopy, microfluidics, molecular microbiology, and mathematical modeling to explore the motility of the two differently flagellated model species Shewanella putrefaciens and Pseudomonas putida in densely structured environments. In particular, we will perform three-dimensional holographic tracking of multiple cells in a polysaccharide matrix in the presence and absence of chemical gradients to determine and model their movement patterns in dense environments. These cell-tracking studies will be complemented by high-speed fluorescence imaging of the flagellar filament dynamics to elucidate how the motile machinery is operating under such conditions. We will furthermore study whether bacteria can modify the composition of their flagellum to optimize spreading under confinement. Finally, we will extend our analysis towards real-world environments and study the movement patterns of bacteria during biofilm invasion, plant root colonization, or while approaching redox-active surfaces. Overall, we expect our results to reveal fundamentally novel aspects of flagella-mediated bacterial motility in complex and structured environments.

• DFG Programme: Research Grants
• International Connection: United Kingdom
• Cooperation Partner: Dr. Laurence Wilson