Seaweed Biofuel Breakthrough Found

Transforming seaweed into fuel has been the dream of many a scientist, entrepreneur, and policy maker for years, particularly as debates have escalated over traditional biofuel crops—namely corn and sugar cane. Those biofuel sources compete with food crops for precious arable land and fresh water. Seaweed doesn't. The great stumbling block for seaweed has been that standard microbes cannot readily metabolize its primary sugar constituent, known as alginate. Two other sugars found in seaweed ferment readily, but without conversion of the alginate, biofuel production from seaweed is simply too inefficient, and thus too expensive, to ever compete seriously with petroleum-based fuels. Now, using synthetic biology and enzyme engineering, Adam Wargacki of Bio Architecture Lab in Berkeley, Calif., and his colleagues have made seaweed more palatable. The team has engineered a new form of E. coli bacteria that can digest all the sugars found in brown seaweed, including alginate. Their fermentation experiments using the new microbe, reported today in the journal Science, successfully achieved 80% of seaweed's maximum theoretical ethanol yield, which is double that of sugar cane and five times that of corn. Whether the good work of this newly engineered microbe can be scaled up economically is the next question. Meanwhile, it is worth reviewing other ideas for sustainable biofuel production. For instance, the same method that is used to decaffeinate coffee and to extract hops to make beer can turn wood into biofuel: Some research shows that making biofuel from grasses and other hearty plants that can grow on land unsuitable for growing food crops could satisfy half of our liquid fuel needs: And as Discovery News correspondent Megan Corbett reminded us recently: "Ranking these different possibilities depends on a variety of aspects such as economic factors, how well developed the technology to produce the fuel is, the amount of material that could be used, and several other factors."