Fungus and bacteria play game theory to make biofuels

To ensure that biofuel production doesn't compete with material that could otherwise provide food, researchers have been trying to produce biofuels from cellulose, the tough polymer that gives wood its strength. Unfortunately, cellulose isn't easy to digest, and the organisms that can digest it are bad at using it to produce something we could burn in an engine.

To get around this, many researchers have attempted to create a single microbe that can do both—digest the cellulose and directly convert it to a usable fuel. So far, however, efforts to engineer all the pathways to digest haven't worked out as well as we might hope. So, a team of researchers has decided to use a pair of organisms instead. And, by testing a variety of conditions, they found that their behavior was predictable based on game theory.

Cellulose is a polymer of the sugar glucose, which can readily be digested and used to power cellular processes. Cellulose, however, is such a large and complex polymer that it resists easy digestion. There are organisms that can break down cellulose—otherwise, forests would be filled with the undigested remains of dead trees—but they're not necessarily easy to manipulate genetically. In contrast, the bacteria we use in labs, such as E. coli, don't normally break down cellulose.