Synthetic biologist Christopher Voigt has created an unusual image: the Virgin Mary on a lawn of E. coli. In turning microbes into a "photographic" medium, Voigt and his team have illustrated his approach to synthetic biology: creating genetic parts that can be used interchangeably to achieve different results. They hooked a light receptor from blue-green algae to a protein that normally controls E. coli genes' response to the cell's surroundings.

They then swapped one of these genes for one that turns a certain chemical black. The finished bacterium turned black in the dark; by holding a stencil between a Petri dish and a light source, the researchers could impose an image onto the bacteria.

Though Voigt says the bacteria are just a "toy technology," he is using the same precepts to develop parts for more complex organisms, such as bacteria that spin spider silk or target and kill cancer cells.

--Emily Singer