BPLAN · Biological Physics of Living Active Nematics
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2019-10-01 → 2021-09-30
- EU contribution
- €184,708
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Biological Physics of Living Active Nematics
On surfaces, bacterial micro-colonies first develop a monolayer of cells before a bacterium leaves the plane of the monolayer and initiates the formation of a second layer. This transition is a major event in biofilm formation since this extra layer offers shelter for bacteria underneath. Understanding the determinants of this transition will help design new strategies for hampering biofilm development. When growing in monolayers, rod-shaped bacteria behave as active nematics. But unlike most nematics, which are active due to particle motility, nematics made of sessile growing bacteria are active because of cell elongation. In addition, bacterial nematics of such a kind do not only interact by steric repulsion but bacteria also adhere to the substrate and to their neighbours. Bacterial adhesion therefore contributes to the formation of topological defects in bacterial nematics. However, we do not yet know how topological defects are coupled to the distribution of adhesions within the monolayer and which of these two contributions account for the formation of the second layer. The Marie-Curie Action has allowed to unravel the coupling between cell-cell adhesion and topological defects. Our results indicate that the rate of defect generation has a direct impact on the shape of the microcolony. The higher this rate, the rounder the micro-colonies. Surprisingly, we showed that increasing cell-cell adhesion reduces the rate of topological defects generation, resulting in more elongated micro-colonies, which are more exposed to the environment. Our results therefore suggest that treatment including biochemical agents capable of gluing cells together may constitute a strategy to expose more bacteria to antibiotic treatments. Indeed, such treatments will slow down the dynamics topological defect formation and thus increase the exposure of micro-colonies to the environment.
Data: CORDIS, © European Union
Project objective
The growth of a bacterial colony is a fascinating example of a biological process that can be interpreted in physical terms as the interaction of a collection of elementary units - the cells - with the surrounding environment and within themselves, whereby energy is harnessed and dissipated, thus determining inherent non-equilibrium conditions. Although bacterial cells are one of the simplest forms of life, scientists have so far found difficult to build theoretical models of bacterial growth and morphology as well as to perform controlled experiments of the real systems occurring in nature. These difficulties arise from the naturally occurring conditions that are characterized by a large degree of complexity in both morphological and chemical terms.The aim of this project is to investigate through novel experimental approaches the biological physics which is at the foundation of the formation of 2D bacterial microcolony and its successive development to a 3D structure. To this purpose, several experimental techniques, from traction force microscopy, through laser ablation and soft lithography will be exploited. Furthermore, experimental results obtained from these studies will be of great relevance for the validation of numerical and theoretical models of bacterial colony morphogenesis and antibiotics exposure. The planned research activities will be carried out in one of the top research laboratory in Europe for active matter and within the wider context of École Normale Supérieure, a world renowned academic institution in the fields of statistical mechanics, soft matter and optics.This project aims thus at providing fundamental insights into the development of early stages of bacterial community formation, trying to establish what physical parameters related to the cells, the environment and their interactions determine the transitions from a 2D to a 3D structure, and lastly to gain control over these parameters.
Original text from CORDIS.
Participants
- CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS · ParisCoordinatorFrance
Links
- View on CORDIS
- DOI: 10.3030/840915
- https://despratn.wixsite.com/physicsofmicrobes/the-mechanics-of-bacterial-microcolony-morphogenesis
Data: CORDIS, © European Union