Agricultural Research Service scientists have developed a new yeast that makes ethanol from both five-carbon and six-carbon sugars without needing oxygen. ARS molecular biologist Stephen Hughes developed the strain to grow on xylose - a five-carbon plant sugar. Hughes works at the ARS National Center for Agricultural Utilization Research in Peoria, Ill.
Producers already make grain ethanol by using yeast to ferment six-carbon plant sugars like glucose. But cost-effective production of cellulosic ethanol will require using both six-carbon and five-carbon sugars in the process. The importance of this research is that in industrial ethanol production it's difficult to control oxygen levels as yeasts ferment sugars into ethanol. The new yeast strain would help alleviate this problem.
The process makes available glucose that might have been otherwise used by the yeast to grow and reproduce is now available for fermentation and the rate of ethanol conversion increases.