A research team from Harvard Medical School and the Israel Institute of Technology – Technion designed a way to observe the evolution of bacteria and prepared a time-lapse video that showed not only the bacteria’s growth but also its resistance to drugs.
The cinematic approach to drug resistance allowed scientists to demonstrate the process in a short film, after executing a series of experiments to understand the bacteria’s relationship with antibiotics, which revealed how the bacteria adapted to it to survive.
The team used a 2-by-4 foot petri dish they constructed, to then fill it with a substance used to nourish biological material. This substance, called agar, seems like a jelly liquid, and it allowed the bacterium grow in the dish. The agar material is a marine-derived component mostly used in labs.
In the Petri Dish, the researchers cultivated the Escherichia coli bacterium and then observe it through its growth process. When the bacterium developed enough, they saturate it with different doses of medication to see the reaction.
Fighting to survive
Escherichia coli adapted to the antibiotic and moved to response to the attack of drugs. In an area of the dish, scientists added the amount of drug enough to kill the bacterium, while in other parts of the plate the amount of antibiotic was not sufficient to kill it but provoked a particular response.
This was an experiment that represented and observed the Microbial Evolution, and Growth Arena (MEGA), what allowed researchers and general public visualize the bacterial movement and the evolutionary challenges biological organisms suffer.
“We know quite a bit about the internal defense mechanisms bacteria use to evade antibiotics, but we don’t really know much about their physical movements across space as they adapt to survive in different environments,” stated Michael Baym, a member of the Harvard team and expert in Biology.
This experiment also proved some interesting facts about bacteria behavior, like their limited capacity to spread when exposed to a concentrated antibiotic dose, the mutations that altered the speed of the growth and the characteristics of the most resistant mutants.
Team’s observations suggested that mutants components that survive high concentrations of drugs are not necessarily the most resistant because the fastest mutants seemed to provide greater resistance to the general life of the bacterium. This means that bacteria evolution is not always led by the most stable mutants but by the fastest. The more resistant a mutant is, the less likely is to help the bacteria survive.
About the film
To create the time-lapse video, the team installed a camera above the petri dish, and this device was always taking pictures and snapshots of the bacteria moving in the agar. Then, all the images were edited to mount a film available to the general public.
The inspiration to create this short scientific video came from the film “Contagion,” where a visual narrative showed microbes moving and forming figures. This way, the scientists felt inspired actually to create something visual to show actual bacteria spread.
“This is a stunning demonstration of how quickly microbes evolve, when shown the video, evolutionary biologists immediately recognize concepts they’ve thought about in the abstract, while nonspecialists immediately begin to ask really good questions,” said Lieberman, a research fellow at MIT.
Source: Harvard Medicine