United Press International: A German scientist says he has discovered an enzyme that “teaches” yeast cells to ferment xylose into ethanol in just one step. Goethe University Professor Eckhard Boles, co-founder of the Swiss biofuel company Butalco GmbH, said xylose is an unused waste sugar in the cellulosic ethanol production process during which the yeast Saccharomyces cerevisiae is commonly used for ethanol production. But Boles said current bioethanol production technologies can use only parts of the plants, …