Identical But Different: The Surprising Individuality of Bacterial Clones

A crowd of runners, all of which looked identical, gathered near the starting line. But this wasn’t your usual 5k. The facilitators of the contest would test both speed and navigational ability as the runners find their way through a maze, as they choose the right direction at every intersection.

At the end of the course, the postdocs Mehdi Salek and Francesco Carrara would be waiting to identify each of the finishers.

The winners, however, won’t receive any medals or trophies. After all, they’re not human: they’re Escherichia coli bacteria.

In recent years, the notion that there could be individual winners in the race have shaken the foundations of microbiology. To test this notion, a team of microbiologists and engineers created a unique endurance event for these bacteria.

The cells at the starting line of Stocker’s microbial marathon were genetically identical, which implied, according to decades of biological dogma, that their resulting physiology and behavior should also be more or less the same, as long as all the cells experienced identical environmental conditions. At the DNA level, every E. coli cell had a roughly equal encoded ability to swim and steer through the course. A pack of cells that started the race at the same time would in theory all finish around the same time. 

But that’s not what Salek and Carrara found. Instead, some bacteria raced through the maze substantially more quickly than others, largely because of varying aptitude for moving toward higher concentrations of food, a process called chemotaxis. What appeared to Salek and Carrara as a mass of indistinguishable cells at the beginning was actually a conglomerate of unique individuals.

Find out more about this study over at Quanta Magazine.

Image Credit: geralt/ Pixabay

By Franzified