Food and biofuel

New enzymes could make it possible to get both food and fuel out of crops.

When former U.S. vice-president Al Gore said last fall that his earlier enthusiasm for corn-based ethanol production in the United States was a mistake, he was conceding something that had long been obvious: the practice of diverting food crops to biofuels has contributed to food shortages and driven up prices for staples across the globe. The food-versus-fuel conundrum has seemed intractable.

Researchers at the Technical University of Munich (TUM) think they have hit on a solution. Regular biofuel production works by fermenting the sugars stored in crops such as sugar cane or corn, but the team’s idea is to instead transform the sugar found in the cellulose of the residual crop material — the stalks, stems and leaves. The main problem is that cellulose is extremely sturdy, and it is difficult to break it down into sugar. There are many naturally occurring enzymes that can do this, including in the bacteria found in the stomachs of cows. These bacteria work very slowly, though, which is why the TUM researchers are looking at ways of speeding the process up.

A group led by microbiologist Wolfgang Schwarz is focusing on a soil bacterium called Clostridium thermocellum. It contains what he calls a “toolbox” of more than 70 enzymes, each of which works on a different part of the plant cell wall. His team is experimenting with different combinations of enzymes to determine which variations are most effective for different types of crop residuals. Researcher Jan Krauss told the website e! Science News, “Our ultimate goal is to develop a specialized degradation tool for every individual plant waste material containing cellulose.” If they are successful, we might finally be able to eat our corn, and burn it too.