The goal is to make ethanol not only competitive with the cost of gasoline at the pump, but even much cheaper. Using ethanol produced from plant wastes not only will reduce our country's dependence on foreign oil, but, because it is clean-burning, it also will reduce air pollution and greenhouse gas emissions from cars."
Ho and her colleagues in the Molecular Genetics Group at Purdue's Laboratory of Renewable Resources Engineering (LORRE) won the R&D 100 Award for their work with SWAN Biomass Co., Oakbrook Terrace, Ill., to develop the genetically modified yeast. The annual awards will be given at a Sept. 24 banquet and exhibit at Chicago's Museum of Science and Industry.
The yeast that Ho modified, called Saccharomyces yeast, is an environmentally safe microorganism commonly used by industry to ferment glucose into ethanol. It also has been used since ancient times to make wine. But glucose is only one type of sugar in plant matter. Beginning in the early 1980s, Ho's research group and others around the world attempted to genetically modify the yeast so that it could ferment both glucose and another plant sugar, xylose, into ethanol. A yeast that could ferment both sugars could produce more ethanol from the same amount of plant material, making the process more economical.
"About 30 to 40 percent of the sugar released from plant matter, called cellulosic biomass, is xylose, and the other 60 to 70 percent is glucose," Ho says. "If you can only ferment 60 percent of the sugar into ethanol, you could never make it cheap enough to use to drive your car."
Over several years, all the U.S. research groups gave up pursuing a yeast
that could ferment both glucose and xylose, but Ho's group and three other
international g
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Contact: Amanda Siegfried
amanda_siegfried@uns.purdue.edu
765-494-4709
Purdue University
20-Aug-1998