Bacterial Altruism

Bacteria, like humans, will go the extra mile to save a member of their kin, even at some personal cost. Researchers now report that this kind of familial benevolence helps Escherichia coli develop antimicrobial resistance (Nature 2010, 467, 82). Drug developers could target this altruistic mechanism to prevent resistance and better combat bacterial infection.

A team led by biomedical engineer James Collins at Boston University carefully observed individual E. coli cells when a whole population was under attack by the antimicrobial agent norfloxacin. They found that individual E. coli in the population had vastly different abilities to resist the chemical attack. A small population of the most resistant individuals produce indole, which helps the less resistant siblings survive the attack because the molecule activates efflux pumps that rid the cells of the antibiotic. The chemical lifeline enables the weak individuals to survive long enough to build resistance.

"Because the highly resistant mutants invest energy to produce indole, which is not required for their own resistance, their help for their kin can be considered a form of altruism," Massachusetts Institute of Technology researchers Hyun Youk and Alexander van Oudenaarden note in a commentary about the work. They add that this altruism enables E. coli "to mount a more formidable defense against antibiotics" and could be of interest to scientists trying to tackle antibiotic resistance.

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