What do biofuels look like on the Wisconsin landscape? Some might think of corn or switchgrass. But what about that herd of cows?

What you can’t see might fool you. Cows are walking natural biodigesters, says CALS bacteriology professor Garret Suen. Their rumens are filled with rich bacterial communities that break down the cellulose found in feed into nutrients usable by the animal.

“The cow is arguably one of the most efficient cellulose degraders around, and the main reason why is that we’ve domesticated them to be that way through selection,” Suen explains. “What I argue is that we didn’t just domesticate the cow, we domesticated their microbes.”

Efficiently breaking down cellulose into simpler usable materials—a key challenge in biofuel production—is a feat naturally performed primarily by microbes. “A cow couldn’t exist without its bacteria, because it has no way on its own to break down the plants that it eats,” he says.

Suen, a researcher with the Wisconsin Bioenergy Initiative, is exploring the workings of the ruminant system in the hope of harnessing its power for industrial applications. He’s focusing on three strains of bacteria in the rumen that use different strategies to degrade cellulose. Drawing upon his background in both computational biology and genomics, Suen is using next-generation sequencing to hone in on the individual genes, enzymes and other proteins used by each and how they work together.

“Understanding the different ways that nature has come up with to degrade recalcitrant plant material will be very useful,” he says.

To date, Suen’s research group has identified some sets of genes they believe are involved, including some interesting surprises that he isn’t quite ready to share. He recently received a five-year, $750,000 early career award from the U.S. Department of Energy to advance the project. Suen hopes the work could ultimately extend even beyond bioenergy.

“Understanding how the microbes are breaking down these plant biomasses doesn’t only impact biofuels. It also has implications for areas like improving digestibility of feed and nutrient yield for the cow—which could directly affect everything from milk production to feed costs to beef quality,” he says.