Microbe’s use of toxic weaponry creates single-strain clumps
WASHINGTON — Bacteria assassinating each other when crowded together ironically can favor the evolution of cooperation.
When a Vibrio cholerae bacterium jostles neighbors in crowds on crab shells, it fires a spring-loaded toxin injection. Siblings with the same immunity genes don’t die, but genetically different strains of V. cholerae can succumb.
In both laboratory battles and computer simulations, these neighbor-to-neighbor harpoonings over time can separate a random mix of strains into a patchy landscape of same-strain clumps. The change from all mixed up to irregular patches works like a separation process of phases of metals (called the Model A order-disorder transition) and has not been reported before in living things, William Ratcliff of Georgia Institute of Technology in Atlanta said August 5 at the 2nd American Society for Microbiology Conference on Experimental Microbial Evolution.