Researchers convert red seaweed to ethanol in half the time

By Bryan Sims | September 08, 2011

Hydrolyzing starch to get glucose for fermentation into alcohols such as ethanol may be a straight-forward, mature technique used in many industries, but University of Illinois researchers, in collaboration with colleagues at the University of California-Berkeley, have engineered a unique yeast strain that is capable of converting nonterrestrial biomass, red seaweed, into cellulosic ethanol in half the time.

According to Yong-Su Jin, assistant professor of microbial genomics at the University of Illinois and a faculty member in its Institute of Genomic Biology, red seaweed, when hydrolyzed, yields glucose and galactose—but there’s one problem. Jin said yeast has an appetite for glucose and won’t consume galactose until glucose is gone. To counter this, Jin and his team engineered a Saccharomyces cerevisiae strain that expressed genes coding for a new sugar transporter, cellodextrin, and an enzyme, beta-glucosidase, that’s capable of breaking down cellobiose, a dimeric form of glucose, at the intracellular level. The result is a yeast strain that can conferment cellobiose and galactose simultaneously, which decreases the production time of ethanol in half.

“We’ve been able to cut the fermentation in half from 100 hours to 50 hours,” Jin said. 

Joining Jin on the project, which was funded by the university’s Energy Biosciences Institute, included team members Suk-Jin Ha, Qiaosi Wei and Soo Rin Kim of the University of Illinois and Jonathan Galazka and Jamie Cate of the University of California-Berkeley.

While ethanol was produced via this unique process, Jin said the research intends to shift toward producing other higher alcohols such as isobutanol using the same process.

“We focused mostly on the substrate portion,” Jin said. “Since we’ve engineered the yeast we’re going to use this platform for producing advanced biofuels in the future.”

He added that red seaweed was the biomass of choice for this research due to its abundance found near Asian coastlines and near geographical areas where land may be limited for terrestrial biomasses.

This story first appeared in Biorefining Magazine.