BIOFUEL GENOME MAPPED

DURHAM, NC - A strain of yeast that thrives on turning sugar cane and other tough grasses into ethanol that might be used as biofuel has had its genome completely sequenced. This yeast strain studied and mapped is known as PE-2. Understanding this microbe may enable more efficient biofuel production and will produce even more robust industrial organisms that are versatile and capable of producing advanced biofuels from non-food crops like switchgrass.

When oil prices crept to new highs in the 1970s, Brazil invested in alternative biofuels created from the country's abundant sugar cane crops. Commercially available baker's yeast was used to break down sugar cane into ethanol, but genetic tests showed that this yeast quickly disappeared in the harsh environment of industrial fermentation vats.

However, yeast that grew naturally on the sugar cane was still viable in the vats and lasted through many more generations. We took an organism that is hugely important from an industrial standpoint but completely unknown in terms of its genetic and molecular properties. We learned much more about how a complex genome is organized and may contribute to a robust and well-adapted organism.

I worked with researchers from Brazil and the University of North Carolina on the study. Now we have sequenced the genome, so we have a road map that will allow us to build upon its natural abilities. This opens the door to crossing yeast strains to make even more efficient yeasts for enhanced biofuel production.

Knowing more about what makes yeast hearty will help as biofuel production evolves. In addition to the sugar cane fuels of Brazil, scientists and farmers are also looking into new carbohydrate sources that could easily be farmed in the United States and other areas, since sugar cane farming is limited to warm climates. Switchgrass and giant grass, also known as elephant grass, are possibilities, along with miscanthus grass.

The PE-2 genome will aid research into finding the best and strongest yeasts for converting the cellulose in grasses into biofuel.

I believe this strain has a natural talent for carbohydrate biofuels that have not yet been introduced in the United States. When the technology is engineered to effectively break down cellulose, I believe this strain of yeast will be an ideal delivery vehicle for that technology.

The study also yielded some interesting genetic information about Saccharomyces cerevisiae, the most studied and utilized yeast species.

The study was funded by two grants from the National Institutes of Health, a BRASKEM/FAPESP grant, and support from ETH Bioenergia, a Brazilian company that produces ethanol and sugar from sugar cane.

Dr. Argueso, who is from the Duke Department of Molecular Genetics and Microbiology, worked with researchers from Brazil and the University of North Carolina on the study: Margaret Dominska and John H. McCusker, of the Duke Department of Molecular Genetics and Microbiology; Fred S. Dietrich, also of the Department of Molecular Genetics and Microbiology and the Duke Institute for Genome Sciences and Policy; Piotr A. Mieczkowski, of the Department of Genetics at the University of North Carolina, Chapel Hill and Brazilian scientists from Campinas State University; and the University of São Paulo.