Hoping to endow the bacteria with light-sensing abilities, Voigt looked for receptors from other simple organisms that could be grafted onto E. coli.
After some searching, Voigt and his team found proteins on photosynthetic blue-green algae that would do the trick.
"We were fairly lucky," said Levskaya, who assisted Voigt. Grafting the receptors onto an E. coli bacterium "is sort of like a knitting operation."
"They did the hard engineering work [at UCSF], and we took advantage of it to implement our idea," said University of Texas graduate student Jeff Tabor, a doctoral student who worked on the project.
The Texas students grew a sample of Voigt's E. coli in dishes of agar, a standard Jellolike growth medium for bacteria.
They built a special projector to shine light through a mask onto a colony of the modified bacteria. Each bacterium produced a black pigment if it did not sense light.
Using this approach, the bacteria generated a photographic reproduction in about 12 hours. Researchers say the image has a resolution a thousand times greater than what can be produced by today's high-end printers.
UCSF student Levskaya said that he is working on finding other biological light-sensors that can produce other wavelengthsperhaps leading to the possibility of producing color photographs in a similar manner.
The research paves the way for producing genetically modified organisms that could be useful in other applications. The researchers say, for example, that the technology could one day be used to program and grow living tissues to help fight cancer.
This approach could be inexpensive, thanks to bacteria's ability to rapidly proliferate when given warmth, oxygen, and food.
"You can start with one bacterium, and you can have billions in a matter of hours," Tabor, of the University of Texas, said.
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