Getting big energy from a small source

Using bacteria for fuel

February 1, 2022

Andrew Perun ’22 (Bensenville, Illinois) is studying a microscopic source to solve a very large problem.

For his Honors project, which he unveiled at Culver Academies’ initial Science and Engineering Fair Saturday, Perun expanded on the initial research began by Cassie Kaplan ’21. Last year, Kaplan took the first step in using genetically-engineered E. coli bacteria as a renewable source for isobutanol, a high-octane biofuel. Kaplan ran out of time to confirm her results, so Perun picked up where her work left off, then took it a step further.

The E. coli bacteria used is one of several harmless strains, Perun said, and investigating it as a fuel source is still in its infancy. The earliest paper Kaplan found on the subject was written in 2008. When genetically altered, the bacteria produces isobutanol, which has the potential to replace everything from gasoline to jet fuel.

Kaplan’s project was to increase the amount of valine, an amino acid, in the bacteria. While she ran out of time to obtain complete results, Perun said, the probability ran high that her work did increase those levels. Using Culver’s spectrophotometer, he was able to confirm an increase in valine, though the actual percentage of the increase could not be determined.

Building off that, Perun went a step further, working to increase the levels of 2-ketoisolvalerate (KIV) in the bacteria, which is the precursor of isobutanol. By increasing the KIV levels, he explained, the bacteria could potentially double its output of the biofuel. A contamination issue did not let him get an accurate measurement, Perun explained, but he was able to establish that the KIV levels did increase.

The eventual goal is to have modified E. coli producing isobutanol directly, making it more cost-effective. While large-scale industrial production is still years away, current research shows this naturally-produced fuel holds several advantages over ethanol, Perun explained.

Production is “virtually carbon-fee,” he said. Also, it doesn’t require the commitment of thousands of acres to grow the corn. When used at 100%, isobutanol will not damage conventional car engines. Ethanol must be mixed with gasoline. Isobutanol can also be safely stored and transported at 100% concentration while ethanol must be diluted, meaning those costs are also reduced.

Perun said the only disadvantage reported has been that isobutanol has a slightly higher level of carbon dioxide emissions – less than 2% – than ethanol. But that deficit is more than offset during the production, transportation, and storage processes.

*Photos by Camilo Morales