Iogen Corporation (earlier post) has has obtained the first (and non-exclusive license) from the Purdue Research Foundation for a genetically modified yeast that can produce ethanol from agricultural waste.
Purdues genetically altered yeast allows about 40 percent more ethanol to be made from sugars derived from agricultural residues, such as corn stalks and wheat straw, compared with wild-type yeasts that occur in nature.
The agricultural residues are primarily made up of cellulose and hemicellulose, which are known as cellulosic materials. Unlike traditional ethanol feedstocks, such as corn kernels, the cellulosic materials contain two major sugars, glucose and xylose, which cannot both be fermented into ethanol by natural Saccharomyces yeast, the microorganism used by industry to produce ethanol, said Nancy Ho, a senior research scientist and leader of the molecular genetics group in Purdue's Laboratory of Renewable Resources Engineering, or LORRE.
The Purdue researchers altered the genetic structure of the yeast so that it now contains three additional genes that make it possible to simultaneously convert glucose and xylose to ethanol. The ability to ferment xylose increases the yield of ethanol from straw by about 40 percent. Being able to simultaneously ferment glucose and xylose is important because both sugars are found together in agricultural residues, Ho said.
The original paper describing the yeast:Genetically Engineered Saccharomyces Yeast Capable of Effective Cofermentation of Glucose and Xylose, Applied Environmental Microbiology, May 1998, p. 1852-1859, Vol. 64, No. 5.