Bacteria Use Collective Behavior to Generate Diverse Combat Strategies

Abstract

Animals have evolved a wide diversity of aggressive behavior often based upon the careful monitoring of other individuals. Bacteria are also capable of aggression, with many species using toxins to kill or inhibit their competitors. Like animals, bacteria also have systems to monitor others during antagonistic encounters, but how this translates into behavior remains poorly understood. Here, we use colonies of Escherichia coli carrying colicin-encoding plasmids as a model for studying antagonistic behavior. We show that in the absence of threat, dispersed cells with low reproductive value produce colicin toxins spontaneously, generating efficient pre-emptive attacks. Cells can also respond conditionally to toxins released by clonemates via autoinduction or other genotypes via competition sensing. The strength of both pre-emptive and responsive attacks varies widely between strains. We demonstrate that this variability occurs easily through mutation by rationally engineering strains to recapitulate the diversity in naturally occurring strategies. Finally, we discover that strains that can detect both competitors and clonemates are capable of massive coordinated attacks on competing colonies. This collective behavior protects established colonies from competitors, mirroring the evolution of alarm calling in the animal world.

Plastic responses to competition: Does bacteriocin production increase in the presence of nonself competitors?

“…While similar estimates for the frequency of cells actively producing bacteriocin remain to be determined for the natural isolates of Xenorhabdus spp., our functional assays clearly show no evidence in support of the hypothesis that bacteriocin production increases in the presence of nonself competitors. Recently published work demonstrates that E. coli populations increase colicin production in response to attacking competitors (Mavridou, Gonzalez, Kim, West, & Foster, ). Intriguingly, the competitor strain used in our experiment does not attack the producer strain.…”

Environmental microbiology to the rescue of planet earth

“…New questions, new technologies and a large number of fresh biological systems at every scale (from specific genes and proteins to large, global scenarios) have found the right audience in the authors and the readership of the journal. Once in a while, the field even has gone beyond the pure microbiological realm and has become a source of model systems to study intricate sociological questions on collaboration versus competition, cheating, division of labour and other matters difficult to experiment with human subjects (McDonald et al, 2017;Mavridou et al, 2018). That the journal has been in the leading group of primary microbiology publications for a quite some time -way ahead of other well established counterparts -indicates not only the wisdom of its sustained editorial policy and the efficacy of its Editors and Editorial Board at large.…”

The Evolution of Mass Cell Suicide in Bacterial Warfare

“…Producing cells permeabilize their own membrane with a dedicated lysis protein to release toxins into the environment, killing themselves in the process [1–3]. When a colicin producing strain is growing alone, the colicin operon is typically only expressed in a small fraction of the population [9–15]. Expression can be upregulated by DNA damage as the colicin operon is regulated by the SOS response pathway [14,16,17], which is often done artificially via the addition of DNA-damaging agents such as mitomycin C [12,14,16,18,19].…”