Scientists create mini Mona Lisa using bacteria

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LONDON: Scientists have created an accurate millimetric replica of Leonardo da Vinci’s Mona Lisa, using approximately one million bacteria cells that were genetically engineered to respond to light. The researchers used light patterns to control the swimming speed of bacteria and direct them to form different shapes.
Controlling bacteria in this way means it could be possible to use them as microbricks for building the next generation of microscopic devices. For example, they could be made to surround a larger object and then used as living propellers to transport it where it is needed, researchers said.
Escherichia coli (E coli) bacteria are known to be fantastic swimmers. Recently, scientists found a protein (proteorhodopsin) in ocean-dwelling bacteria that allows them to power their propellers using light. “Much like pedestrians who slow down when they encounter a crowd or cars, swimming bacteria will spend more time in slower regions than in faster ones,” said Giacomo Frangipane, Postdoctoral Scientist at Rome University in the Italy.
“We wanted to exploit this phenomenon ,” Frangipane said. To do this, researchers sent light from a projector through a microscope lens, shaping the light with high resolution, and explored how E coli bacteria alter their speed while swimming through regions with varying degrees of illumination.
They projected the light uniformly onto a layer of bacterial cells, before exposing them to a more complex light pattern – a negative image of the Mona Lisa. After four minutes, a recognisable bacterial replica of Leonardo da Vinci’s painting could be seen.