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Power plants: Technologies for green fuel

Brian Pfleger and Linda Graham

Linda Graham and Brian Pfleger

California bay trees and clumps of Cladophora algae in the shallows of Madison’s Lake Mendota may not, at first glance, appear to have much in common. However, both species are seeding the future of biofuels research at UW-Madison.

Chemical and Biological Engineering Assistant Professor Brian Pfleger (pictured, with Botany Professor Linda Graham) is working to turn sugars from biomass into hydrocarbon fuels. By inserting a gene from bay trees into E. coli, Pfleger is able to harness bacterial metabolism to convert sugars into free fatty acids. He can extract these fatty acids with hydrocarbons and pass the mixture over a catalyst, creating a form of diesel fuel that can be burned in current engines.

To optimize the expression of biosynthetic enzymes, Pfleger’s team takes a systems biology approach in studying the global picture of a cell’s DNA, RNA, proteins and metabolic processes. The researchers are using a variety of modeling and experimental techniques to understand how engineering a cell to create more fatty acids than it normally would affects enzyme production and overall cell viability. “We’re applying engineering principles to biological systems,” Pfleger says. “If you build the right system, it theoretically should work. But it’s biology, so there’s always a question of the connections we don’t know or don’t understand yet.” 

The many challenges of modeling and creating a working biological system means Pfleger collaborates extensively across campus, particularly with researchers in the Great Lakes Bioenergy Research Center. Some of these collaborations allow Pfleger to expand his work beyond molecular systems to more industrial biofuel issues.

Pfleger is part of a team studying the potential of Cladophora algae as a biomass source. Unlike terrestrial plants like corn stover or switchgrass, aquatic plants don’t have much lignin, the compound that makes breaking plants down to extract sugars difficult. Cladophora naturally produces a “beautiful” form of cellulose, says Pfleger, which can be easily decomposed and converted into fatty acids.

The team has received a grant from the Wisconsin Energy Independence Fund for pilot studies about the algae’s potential. 

Sandra Knisely