Altruistic Bacteria

What makes bacteria so resistant to antibotics? A team of scientists studying E. coli has found something unexpected happens within populations: It appears that the handful of bacteria that are highly resistant to antibiotics (because they have a mutation that protects them from the drug) sacrifice their own well-being to help less resistant bacteria survive. In other words, the cells seem to cooperate.

As James Collins, a professor of biomedical engineering at Boston University who led the study, explains in a write-up:

In the past it was believed that the resistant bacterial cells would survive and thrive, and all the other cells would die. We discovered instead that cells that develop resistance produce indole, and send it out to other, more susceptible cells in the population that have not yet acquired a mutation to afford them resistance. The indole turns on drug pumps that allow the cell to pump out the antibiotic, and it activates other defense mechanisms against the antibiotic attack.

Yet at the same time, producing the idole molecule reduces the resistant cells’ ability to thrive. As Collins notes, these mutants “don't grow as well as they could because they’re producing indole for everybody else.”