Caltech scientists have created a strain of bacteria that can make small but energy-packed carbon rings that are useful starting materials for creating other chemicals and materials. These rings, which are otherwise particularly difficult to prepare, now can be “brewed” in much the same way as beer.
The bacteria were created by researchers in the lab of Frances Arnold, Caltech’s Linus Pauling Professor of Chemical Engineering, Bioengineering and Biochemistry, using directed evolution, a technique Arnold developed in the 1990s. The technique allows scientists to quickly and easily breed bacteria with the traits that they desire. It has previously been used by Arnold’s lab to evolve bacteria that create carbon-silicon and carbon-boron bonds, neither of which is found among organisms in the natural world. Using this same technique, they set out to build the tiny carbon rings rarely seen in nature.
“Bacteria can now churn out these versatile, energy-rich organic structures,” Arnold says. “With new lab-evolved enzymes, the microbes make precisely configured strained rings that chemists struggle to make.”
In a paper published this month in the journal Science, the researchers describe how they have now coaxed Escherichia coli bacteria into creating bicyclobutanes, a group of chemicals that contain four carbon atoms arranged so they form two triangles that share a side. To visualize its shape, imagine a square piece of paper that’s lightly creased along a diagonal.
thumbnail courtesy of Caltech