Bacteria get color vision

If this image (shown) hung in an art gallery, the plaque describing it wouldn’t read “paint on canvas.” Instead, it would say, “Escherichia coli on agar plate.” Synthetic biologists engineered these bacteria such that when the scientists projected a red, green, and blue image onto a mat of the microbes, the cells produced red, green, and blue pigments in the pattern of the original image (Nat. Chem. Biol. 2017, DOI: 10.1038/nchembio.2390). This bacterial artwork serves as a demonstration of a genetic circuit the researchers designed to enable them to use various wavelengths of light to control the expression of multiple genes in the microbes. Such a circuit could allow researchers better control over the production of complex molecules or materials with engineered bacteria, says Christopher A. Voigt of Massachusetts Institute of Technology, who led the work. The circuit consists of 18 genes, including those for the protein sensors of the three colors of light, a biological circuit breaker that ensures none of the signals in the circuit overwhelms the cell, and enzymes to produce the three pigments. Voigt’s team designed a similar circuit to use the three light wavelengths to control three enzymes in a metabolic pathway in E. coli.