LMP Seminar (video conference): A phase diagram for bacterial swarming
LMP Seminar (video conference)
- Date: May 19, 2020
- Time: 02:00 PM - 03:30 PM (Local Time Germany)
- Speaker: Prof. Gil Ariel
- Bar-Ilan University, Israel
- Location: Max-Planck-Institut für Dynamik und Selbstorganisation (MPIDS)
- Room: Link to the talk: https://zoom.us/j/96266444298
- Host: MPIDS / LMP
- Contact: yoav.pollack@ds.mpg.de
Bacterial swarming is a mode of motion in which dense collectives of rod-shaped flagellated cells migrate rapidly on surfaces. The transition into swarming involves several cellular processes, including changes in cell aspect ratio, suggesting that bacteria manipulate these properties in order to promote physical conditions that are favorable for swarming [1]. New results with monolayer swarms of Bacillus subtilis with different aspect ratios – ranging from 5.5 to 19, were analyzed at different cell-densities. Tracking of individual cell trajectories allows a comprehensive analysis of both the individual and collective dynamics of bacteria in a swarm. These are used to compose a phase diagram, showing sharp transitions between phases corresponding to qualitatively different swarm statistics [2].
Comparing with theories of active particles, we find some successful theoretical predictions, but mostly in the large aspect ratio regime. Several aspects (e.g. bimodal cluster-size distributions and giant number fluctuations) are found to some extent, while other prominent experimental features cannot be explained by current theories.
From a biological perspective, we find that under standard conditions bacteria inhabit a region of phase space in which the swarm dynamics is highly robust and insensitive to fluctuations. In this regime, bacteria do not form very large clusters and lack global orientational order, properties which may reduce the colony’s ability to expand rapidly in the absence of external directional cues.
Joint work with Avraham Be’er (BGU), Bella Ilkanaiv (BGU), Renan Gross (Weizmann), Daniel Kearns (Indiana U), Sebastian Heidenreich (PTB) and Markus Bär (PTB).
[1] Avraham Be’er and Gil Ariel, A statistical physics view of swarming bacteria. Movement Ecology 7, 9 (2019).
[2] Avraham Be'er, Bella Ilkanaiv, Renan Gross, Daniel B. Kearns, Sebastian Heidenreich, Markus Bar and Gil Ariel, A phase diagram for bacterial swarming, Communications Physics 3, 66 (2020).
Comparing with theories of active particles, we find some successful theoretical predictions, but mostly in the large aspect ratio regime. Several aspects (e.g. bimodal cluster-size distributions and giant number fluctuations) are found to some extent, while other prominent experimental features cannot be explained by current theories.
From a biological perspective, we find that under standard conditions bacteria inhabit a region of phase space in which the swarm dynamics is highly robust and insensitive to fluctuations. In this regime, bacteria do not form very large clusters and lack global orientational order, properties which may reduce the colony’s ability to expand rapidly in the absence of external directional cues.
Joint work with Avraham Be’er (BGU), Bella Ilkanaiv (BGU), Renan Gross (Weizmann), Daniel Kearns (Indiana U), Sebastian Heidenreich (PTB) and Markus Bär (PTB).
[1] Avraham Be’er and Gil Ariel, A statistical physics view of swarming bacteria. Movement Ecology 7, 9 (2019).
[2] Avraham Be'er, Bella Ilkanaiv, Renan Gross, Daniel B. Kearns, Sebastian Heidenreich, Markus Bar and Gil Ariel, A phase diagram for bacterial swarming, Communications Physics 3, 66 (2020).