Friday, November 14, 2008

Diesel from Trees

Gliocladium roseum is a fungus recently discovered living inside trees in Patagonia. It represents a Holy Grail for molecular biologists because it synthesizes diesel from cellulose.

Most of the bulk of a tree--in fact, the vast majority of all the stiff, fibrous tissue found throughout the plant kingdom--is cellulose, consisting of long, polymerized chains of sugar molecules. Although most simple sugars are readily digested, the long chains cannot be broken down easily--which is why humans cannot eat wood. This takes special enzymes (termites have special bacteria in their gut than can digest the cellulose) or, in the laboratory, considerable heat, pressure, and the use of chemical catalysts.

Bio-fuels are usually made by fermenting the free (unpolymerized) sugars (for example, in corn) to produce alcohol. But this leaves the vast majority of the biomass in the corn as waste cellulose.

G. roseum is the first organism discovered in nature that can perform both the necessary steps. It can break the cellulose down into simple sugars, and from these it can synthesize hydrocarbons that closely resemble diesel fuel.