Researchers from the Sapienza University of Rome ‘painted’ portraits of the Mona Lisa, Albert Einstein, Charles Darwin and others, by using genetically modified bacteria.

Many bacteria are able to move in response to environmental signals, which help them guide towards better conditions. The bacterium Escherichia coli can swim quickly through liquid, using tiny, propeller like structures. The ‘propellers’ are powered by a cellular motor, which functions similarly to an electric motor, requiring an energy source to drive movement.

One such energy source can be found in the protein proteorhodopsin. This protein works like a solar cell, turning light into energy. The brighter the light, the faster the movement.

E. coli does not naturally contain proteorhodopsin, but can be genetically modified to produce it.

“Swimming bacteria, much like cars in city traffic, are known to accumulate in areas where their speed decreases,” the researchers say. By controlling the swimming speed with the protein, the density of bacteria can be controlled by simply projecting different patterns of light.

Using the genetically modified E. coli bacteria, the team projected light patterns shaped like famous paintings and photographs. The bacteria followed suit, turning in a near perfect copy of the image.

While it’s of course fun to paint with bacteria, the research also has use in further research. It allows to control the movement of large populations of bacteria more precisely. “For example, bacteria could be made to surround a larger object such as a machine part or a drug carrier, and then used as living propellers to transport it where it is needed,” the researchers suggest.

Photos: Sapienza University of Rome