WALNUT CREEK, CA -- On the road to making biofuels more economically competitive with fossil fuels, there are significant potholes to negotiate. For cellulosic ethanol production, one major detour has being addressed with the characterization of the genetic blueprint of the fungus Pichia stipitis, by the U.S. Department of Energy Joint Genome Institute (DOE JGI) and collaborators at the U.S. Forest Service, Forest Products Laboratory (FPL). The research, entailing the identification of numerous genes in P. stipitis responsible for its fermenting and cellulose-bioconverting prowess, and an analysis of these metabolic pathways, is featured in the March 4 advanced online publication of Nature Biotechnology.
P. stipitis is the most proficient microbial fermenter in nature of the five-carbon wood sugar xyloseabundant in hardwoods and agricultural leftovers, which represent a motherlode of bioenergy fodder.
Increasing the capacity of P. stipitis to ferment xylose and using this knowledge for improving xylose metabolism in other microbes, such as Saccharomyces cerevisiae, brewers yeast, offers a strategy for improved production of cellulosic ethanol, said Eddy Rubin, DOE JGI Director. In addition, this strategy could enhance the productivity and sustainability of agriculture and forestry by providing new outlets for agricultural and wood harvest residues.
Ligonocellulosic biomass, a complex of cellulose, hemicellulose, and lignin, is derived from such plant-based feedstocks as agricultural waste, paper and pulp, wood chips, grasses, or trees such as poplar, recently sequenced by DOE JGI. Under current strategies for generating lignocellulosic ethanol, these forms of biomass require expensive and energy-intensive pretreatment with chemicals and/or heat to loosen up this complex. Enzymes are then employed to break down complex carbohydrate into sugars, such as glucose and xylose, which can then be fermented to produce ethanol. Additi
Contact: David Gilbert
DOE/Joint Genome Institute