ScienceShot: Altruistic Bacteria

Even bacteria occasionally take one for the team. The bugs typically develop drug resistance by acquiring genetic mutations that fend off antibiotics; eventually the survivors and their offspring take over the colony, and the drugs stop working altogether. But a new study suggests that resistance can spread in an entirely different way—through altruism. A team of researchers doused an Escherichia coli colony of with a non-lethal dose of antibiotics. Not surprisingly a few cells carried mutations that allowed them to survive. But rather than taking over the colony, these mutant cells began secreting a molecule called indole, which turns on pumps that push drugs out of the cell. Other E. coli, which stop producing indole in times of stress, soaked up the molecule and were able to fight off the antibiotic, the team reports online today in Nature. The mutants did not need to produce indole to survive. They were simply working for the greater good.

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