M. xanthus is known for coordinated behaviors such as collective social motility (S-motility or swarming), bacterial predation and formation of fruiting bodies. S-motility is powered by retraction of polar pili and their interaction with a complex self-secreted extracellular EPS.

Individual cells can also adopt a distinct motility strategy called Adventurous motility (A-motility or gliding). A-motility involves transient adhesion complexes also known as focal adhesion complexes (FAC). We are using a multidisciplinary approach from the realms of genetics, biochemistry, cell biology, bioinformatics and quantitative physics to study the motility mechanism and its regulation in response to environmental cues, both at the single cell and multicellular levels.

M. xanthus (in green) can hunt, attack, kill and consume other bacteria (E. coli in red). However, in M. xanthus, the prey recognition and the killing mechanism that target environmental microorganisms remain poorly understood. In the lab, we are working on understanding the M. xanthus predation process and elucidate the molecular and cellular mechanisms that couple invasion, prey cell consumption and Myxococcus proliferation.

M. xanthus is a fascinating model system because several extensive motility transitions occur during its life cycle: (i) initial colony expansion, (ii) prey penetration, (iii) prey consumption (involving rippling) and (iv) fruiting body formation. Although this multicellular cycle has been known for a long time, what governs these transitions and how these cooperative cell behaviours emerge by the exchange of signals and cell-cell interactions remain largely unknown. Our goal is to construct a spatially resolved molecular and cellular map of the Myxococcus lifecycle and propose a model explaining multicellular transitions in this bacterium before, during, and after predation.

Rippling is a prey-induced motility behavior that occurs immediately after the invasion phase. It is a visual impression that emerges from the collision of synchronous cell rafts that reverse simultaneously when they collide. Rippling has been proposed to enhance the predation process, possibly by facilitating physical disruption of the prey biofilm, or enhancing the dwelling times of Myxococus cells. In the lab, we are trying to decipher the molecular mechanisms involved in rippling induction and propagation.

Multicellular cooperation arises from cell-cell signalling, environment sensing and chemotaxis. Myxococcus has a total of 21 chemoreceptors and eight complete chemosensory systems. Some of them have been characterized genetically and biochemically. Similar to enteric bacteria, these receptors might be cross-linked with each other and form complex arrays ultimately generating sensory machineries. We are trying to characterize these sensory machineries and understand the link between the localization of bacterial chemoreceptors in cells and their function during chemotaxis.