This video shows you how bacteria evolve to resist antibiotics. What you're seeing is a giant petri dish, striped with antibiotics which rise in strength, each strip 10x more deadly to bacteria than the last, finally reaching a 1,000x dose in the center. Watch, as the bacteria mutate so that they can grow and even thrive in ever-more-dangerous territory.
The dish was made by scientists Harvard Medical School and Technion-Israel Institute of Technology, led by Harvard's Michael Baym. It's a 2x4-foot acrylic dish filled with 14 liters of agar jelly. The edges of the dish are antibiotic-free. The next strip is saturated with the minimum dose need to kill the bacteria, and then each successive strip contains 10x the amount of the previous one. It's called the Microbial Evolution and Growth Arena (MEGA) plate, and shows, in unprecedented scale and detail, the mechanisms of mutation.
"We know quite a bit about the internal defense mechanisms bacteria use to evade antibiotics," said Baym "but we don’t really know much about their physical movements across space as they adapt to survive in different environments." This huge petri dish allows us to see those movements, thanks to its size, and also to some clever, camera-friendly designs: the jelly was dyed black to better show off the bacteria, the lid was kept dry with a heater to stop condensation spoiling the view, and the ceiling was darkened to remove reflections. The result is a compelling two-week time lapse.
But mutating isn't enough. Evolution requires that the mutants survive and reproduce. If a whole bunch of weak bacteria eat the nutrients on the plate, there won't be anything left for the stronger mutants to consume, so they'll wither and die off before colonizing the plate.
The MEGA plate neatly demonstrates exactly how evolution and natural selection work, in a way easy for anyone to understand, even the folks who think that science is something to be "believed in."
"Seeing the bacteria spread for the first time was a thrill," said Technion's Roy Kishony. "Our MEGA plate takes complex, often obscure, concepts in evolution, such as mutation selection, lineages, parallel evolution and clonal interference, and provides a visual seeing-is-believing demonstration of these otherwise vague ideas. It’s also a powerful illustration of how easy it is for bacteria to become resistant to antibiotics."
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