Scientists use directed evolution to improve microbes

By Staff | November 20, 2012

Researchers at Iowa State University are working to optimize microbes capable of converting bio-oil produced from fast pyrolysis into biofuels. The work focuses on the bacteria E. coli and the microalgae C. reinhardtii.

Certain contaminants in the bio-oil have traditionally limited the ability of these microbes to convert pyrolysis oil into fuels and chemicals. The team is experimenting with pretreatments of this bio-oil that could reduce toxicity. They are also developing microbes that can tolerate the contaminants.

The team is using a technique called directed evolution to produce microbes that are more tolerant of bio-oil contaminants. To do this the microbes are grown with higher and higher concentrations of bio-oils. As they divide they replicate their DNA. Sometimes mutations arise during the replication process. Some of these DNA “mistakes” help make the microbe more tolerant of the contaminants. The work is led by Laura Jarboe, an assistant professor of chemical and biological engineering.