A young generation of researchers are seeking biofuels in some unlikely sounding places: toxic algae blooms and cow stomachs.
Two University of Wisconsin-Madison professors are drawing on these robust yet simple natural systems in search of new, sustainable sources for alternative fuels to satisfy U.S. transportation demands and reduce the country's dependence on foreign oil.
Jennifer Reed, an assistant professor of chemical and biological engineering, and Garret Suen, an assistant professor of bacteriology, each received five-year, $750,000 early-career awards from the U.S. Department of Energy Office of Biological and Environmental Research to explore new possible ways to produce biofuels.
Reed, a researcher in the Great Lakes Bioenergy Research Center, works with blue-green algae, or cyanobacteria, perhaps best known for its colorful, toxic blooms in lakes. It is also one of the world's oldest and most adaptable bacteria, capable of thriving in both fresh and brackish water and using photosynthesis to produce sugar and oxygen. Although some cyanobacteria already are capable of converting solar energy into biofuels such as hydrogen, Reed is developing ways to make them produce the biofuel butanol from sunlight and carbon dioxide.
Working with a strain of cyanobacteria whose genome has been genetically sequenced and that grows well with a high metabolic rate, Reed is developing computer models to analyze each aspect of the microbe's complex metabolic system to learn how to engineer it to produce butanol. Armed with that knowledge, she can then "tweak" the models to add or subtract genes, alter gene expression, or incorporate other changes to improve cyanobacteria butanol production. "And in our experiments, we will actually implement strains we design on the computer," says Reed.
The result, she says, will be not only a more efficient, effective, biofuel-producing cyanobacteria strain, but also computational tools and approaches that other researchers can use to understand and engineer new organisms. "The general tools we develop will be more broadly applicable to people interested in metabolic engineering," says Reed.
Suen, a researcher with the Wisconsin Bioenergy Initiative, focuses on a very different — though also common on Wisconsin's landscape — natural population of microbes: those found in the stomachs of cows and other ruminants. Ruminant digestive systems are powerful natural biomass breakdown machines, he says.
"Arguably the most optimized natural cellulose degrading system is found in the rumen of domesticated cows," Suen writes in his winning proposal. "The rumen contains a diverse group of bacteria with highly active enzymes that digest cellulose in feed and convert this energy source into nutrients usable by the cow."
Efficiently breaking down cellulose into simpler usable materials is a key challenge in biofuel production. Suen's project will focus on three species of bacteria in the rumen that use different strategies to degrade the cellulose. He will use genetic analyses to identify novel cellulose-digesting enzymes, then purify and test them for potential applications in industrial settings.
"One of the key features of microbial communities like those found in the rumen is that they contain a multitude of organisms that work together to degrade cellulose. Understanding the different strategies and ways in which they accomplish this will provide insight into leveraging these approaches for cellulosic ethanol production," says Suen. "As we've domesticated the cow, we've also domesticated their microbes to be efficient at digesting plant biomass."