January 27, 2021

Live imaging of bacteria that kill their rivals with phage-derived weapons

In all competitive environments, bacteria have evolved a large arsenal to fight their microbial foes – a variety of released chemical compounds that target other bacteria, but also fungi and protists.

Strikingly, some bacteria have also learned to coopt the killing properties of bacteriophages (viruses that prey on bacteria). In particular, phage tail-like bacteriocins – or tailocins – are proteins produced by bacteria to puncture the membranes of rival cells and hence eliminate them. In natural microbiomes, tailocins could play the role of narrow-spectrum weapons used by bacteria against related strains with which they compete for resources.

A new study from the group of Christoph Keel (University of Lausanne/NCCR Microbiomes) offers an unprecedented visual exploration of the production, release and killing activity of bacterial tailocins at the microscopic scale. To achieve this, the two lead authors, Jordan Vacheron and Clara Margot Heiman, tagged different tailocin particles with a variety of autofluorescent proteins, which permitted them to monitor the dynamics of tailocin production and migration within single bacterial cells with a fluorescence microscope. This experimental set-up revealed how bacterial cells, using a controlled explosive lysis, eject tailocins beyond their immediate vicinity, potentially reaching many target competitors in their microenvironment. 

Reflecting on their findings, the authors suggest that tailocins may be tailored weapons used by bacteria to weaken their direct ecological competitors while leaving other potentially beneficial microbes unscathed. Such precision warfare may take place in a wide variety of habitats, from agricultural soils to the human body.