Bacteria meet surfaces: from individual to collective dynamics
M2 internship -> fully-funded PhD
Group “Physics of biological systems”, Laboratoire de Physique, ENS de Lyon
The adhesion of bacteria to surfaces initiates the formation of biofilms, organized colonies in which bacteria are protected by an extracellular matrix [1,2]. Although biofilms are an important issue in both industry and healthcare, the signals that regulate irreversible bacterial adhesion are unclear. In particular, the role of mechanical forces during attachment, and the way they impact subsequent gene regulation are yet to be elucidated.
We tackle this question using an interdisciplinary approach based on microfluidics, surface design, and microscopy, combined to microbiology tools. Cohesive colonies form via a highly collaborative process [3], with a complex interplay between motility, matrix production and bacterial organization. We have recently shown that this process strongly depends on the mechanical properties of the underlying substrate [4].
We propose to explore the spatial and temporal dynamics of colony formation by in situ imaging in flow channels, tracking bacteria adhering to hydrogel substrates with well-defined chemical and mechanical properties. Next, using fluorescent intracellular reporters based on adequate genes (collaboration IRIG-BCI, Grenoble), we will quantify the bacterial response to surface-sensing by confocal microscopy. In parallel, efforts will be carried out with collaborators at LIPhy (Grenoble) to implement experimental developments aimed at measuring adhesion forces in situ by imaging substrate deformations. The aim is to obtain a full-picture of bacterial mechanosensing, by correlating mechanical and phenotypical readouts.
These questions can be studied during a Master internship, and could serve as a starting point for a Ph.D. thesis (funding available). Candidates with a background in soft matter physics, biophysics, or experience with image processing are encouraged to apply, but the main prerequisite is a strong interest in interdisciplinary questions.
Contact : Sigolène Lecuyer (sigolene.lecuyer@ens-lyon.fr)
[1] Costerton JW, Stewart PS, Greenberg EP, "Bacterial Biofilms: A Common Cause of Persistent Infections" Science. 284 :1319-22 (1999).
[2] Trinsheck S., John K., Lecuyer S. and Thiele U., "Continuous versus Arrested Spreading of Biofilms at Solid-Gas Interfaces: The Role of Surface Forces" Phys. Rev. Lett., 119, 078003 (2017).
[3] Duvernoy MC, Mora T, Ardré M, Croquette V, Bensimon D, Quilliet C, Ghigo JM, Balland M, Beloin C, Lecuyer S, and Desprat N, "Asymmetric adhesion of rod-shaped bacteria controls microcolony morphogenesis" Nature Communications 9(1120). doi: 10.1038/s41467-018-03446-y (2018).
[4] Gomez S., Bureau L., Debarre D. and Lecuyer S., “Substrate stiffness impacts early colonization by Pseudomonas aeruginosa by modifying twitching motility”, In preparation.