Researchers at Delft University of Technology – working with the Kluyver Centre for Genomics for Industrial Fermentation - introduced a single gene from Escherichia coli into the yeast Saccharomyces cerevisiae and achieved a greater yield of ethanol, less acetate and the elimination of the major by-product glycerol.

“In the laboratory, this simple genetic modification kills three birds with one stone: no glycerol formation, higher ethanol yields and consumption of toxic acetate,” said principal researcher Jack Pronk from the university’s department of biotechnology.

Saccharomyces cerevisiae – which also converts sugars in beer and wine into ethanol– uses sugar contained within plant biomass to produce bioethanol.  When these sugars are released, a large quantitiy of acetate is formed, which can slow down or even halt bioethanol production. 

By introducing the E. coli gene into the yeast, the yeast converted the toxic acetate into ethanol.  This replaced the normal role of glycerol, so the key genes in glycerol production could be removed, abolishing the production of the by-product completely.

The researchers at Delft – who have applied for a patent for their invention – realise that follow-up research is necessary and will work on transferring this concept to industrial yeast strains and real-life process conditions.

It is preferable that bioethanol is produced from resources that do not complete with food production, so efforts are being made to use agricultural waste such as wheat straw and corn stover to produce second-generation bioethanol, which can be used as a car fuel.