Evolutionary branching in action: Bacteria adapt to antibiotics

Watch E. coli bacteria encounter increasing strengths of antibiotics, the medicine that we use to fight infections or infectious diseases. A team led by Harvard Medical School’s Michael Baym set up the video demonstration to observe exactly how bacteria evolve antibiotic resistance. From The Scientist:

For 10 days, the researchers imaged the E. coli every 10 minutes as the microbes expanded across the plate, and saw that the bacteria paused briefly at the boundaries of increasingly stringent antibiotic concentrations until a mutant struck out into the higher-drug territory. By challenging the bacteria with differing doses of antibiotic in the first step of the gradient, the team demonstrated that E. coli evolve higher resistance more quickly if they first encounter an intermediate, rather than a high, concentration of antibiotic…

The scientists were also intrigued to find that many bacteria behind those at the frontier—those that became resistant to antibiotics, but grew more slowly as a result—acquired mutations that further boosted both growth and antibiotic resistance later on. In fact, in a head-to-head race with the bacteria that originally outstripped them, these slow-to-grow bacteria were much more successful by the end of the experiment.

Watch this next: Bacteria Growth, a time lapse.

Thanks. @onyxfish.