Ethanol is already being produced from broth, but Largus Angenent, associate professor of biological and environmental engineering, the leader of the study, wanted to go farther and produce something that’s both better and cheaper to make.
Already-established ethanol production lines could well be retrofitted for the task of producing caproic acid. Unlike ethanol, whose production requires high amounts of energy (cornstarch to sugar, and then sugar processed by yeast into ethanol), the caproic acid doesn’t require distillation.
The team succeeded turning ethanol into n-caproic acid by using beer, dilute ethanol, and billions of all sorts of microbes they called “an open microbial community.”
Caproic acid is better than ethanol because it’s hydrophobic, which makes it easier to separate from water, it can be used in animal feed applications or as an anti-microbial agent. As a fuel, it does better because it has 6-carbon chain acids, versus the only two of ethanol, which only means higher energy density.
Angenent’s paper has been categorized as “hot” by the Royal Society of Chemistry journal Energy and Environmental Science and solves one of the doubts that the scientists have had so far, that an open microbial community can’t make anything useful but methane.