Evolving Microbes Eat Sugar, Make Gas for Iowa State Engineers

Small organisms are working away in an Iowa State University laboratory turning bio-oil into diesel.

A research team led by Laura Jarboe, an Iowa State assistant professor of chemical and biological engineering is feeding bio-oil to E. coli and C. reinhardtii.

E. coli turns it into ethanol and lactic acid and the C. reinhardtii turns acetate-rich fractions into lipids for biodiesel, according to a report from Iowa State University's News Service, which follows below:

Iowa State researchers are using a hybrid approach to produce the next generation of biofuels. They’re combining two conversion paths – thermochemical and biochemical – to find efficient ways to produce renewable fuels and chemicals.

“The goal is to produce biorenewable fuels and chemicals in a manner that’s economically competitive with petroleum-based processes,” Jarboe said.

There are, however, contaminants and toxins in the bio-oil that are getting in the way of the fuel production. Jarboe and a research team are experimenting with pre-treatments of the bio-oil that could reduce the toxicity. And they’re working to develop microbes that can tolerate the contaminants.

The researchers are using a technique called directed evolution to produce microbes that are more tolerant of the contaminants in bio-oil. The microbes are grown with higher and higher concentrations of bio-oil and as they divide, they replicate their DNA. Sometimes there are replication mistakes that lead to mutations.

“It could be a mistake that’s immediately lethal,” Jarboe said. “Or it could be a mistake that helps the microbe tolerate the problematic compounds and it grows faster.

“At the end of the process, we want to say, ‘Hey, I’ve got a great bug.’”