Harvard researchers have fashioned Escherichia coli to act as sensors to monitor the gut environment, as they report in the Proceedings of the National Academy of Sciences this week.
Pamela Silver and her colleagues engineered E. coli with a two-part system consisting of what they've dubbed a "trigger element" in which the Cro gene from phage lambda is hooked up to a tetracycline-inducible promoter and a so-called "memory element" from the phage cI/Cro region. They then fed these E. coli to mice.
A portion of the mice was also given anhydrotetracycline. When the researchers examined the feces from the mice, only those given the drug produced the Cro protein.
"This is a really exciting advance," Chris Voigt from MIT's Synthetic Biology Center, tells the New Scientist. "This is the first use of a genetic circuit in a real environment. It is remarkable that they were able to engineer the cells to perform a computational operation — albeit a simple one — in this environment." Voigt was not involved in the study.
Silver adds that other switches, such as ones that detect inflammation, cancer, or toxins, could be developed.