By swapping microbial genes, Chris Voigt designs cells with novel functions.
Bacteria don’t normally take photographs. Nor do they attack tumor cells or produce chemicals. But with some help from biological engineer Chris Voigt, they can do all that and more.
Voigt, who joined MIT’s faculty in July as an associate professor of biological engineering, likes to tinker with bacteria and other microbes to get them to perform myriad useful tasks that nature never intended — an approach known as synthetic biology.
For example, to develop their “bacterial camera,” Voigt and his students inserted a light-detecting sensor from an alga into the bacterium E. coli, coupled with a gene that causes the bacterium to make a black pigment. A sheet of these bacteria acts as the “film,” and when a stencil is laid over the film and light shone upon it, an image of the stencil forms on the sheet of bacteria.
Likewise, his tumor-targeting E. coli incorporate genes from other bacteria that detect low oxygen levels and high cell density, both conditions often found in tumors. Voigt, who had been on the faculty of the University of California at San Francisco before coming to MIT, then linked those genes with a cell circuit that triggers production of a protein called invasin that enables E. coli to invade mammalian cells.
Despite all Voigt has accomplished in synthetic biology, he got into the field almost by accident. As an undergraduate at the University of Michigan, he majored in chemical engineering, focusing mainly on theoretical studies of reaction mechanics and catalysis. But one day, he was in the chemistry building picking up an exam, and a professor who saw him standing near his door invited him in, thinking he was a student who had applied for a summer job. (That student never showed up.)
“I happened to be standing there, so we started talking,” Voigt recalls. “He was doing protein folding and because of the work that I had been doing on catalysis, I was able to converse with him on some of the theoretical underpinnings of protein folding, and that’s how I got the job. That’s how I got into biology, but I had never really taken any classes in it.”
In graduate school at the California Institute of Technology, he started to work on directed evolution of proteins — specifically, developing a computer program that would identify locations in a protein where mutations would produce a better protein. During a postdoctoral stint at the University of California at Berkeley, he became interested in synthetic biology, which was then just emerging as a new field, based on the idea that novel biological circuits could be assembled from a set of standardized parts — in this case, genes.
At Berkeley, Voigt worked on extracting genetic circuits from a bacterium called B. subtilis and reconstituting them in E. coli, so they could be studied in isolation. Upon joining the faculty at UCSF, he started working on building simple circuits such as a sensor that would respond to a specific stimulus, which led to his bacterial camera.