With the introduction of a single bacterial gene into yeast, researchers from Delft University of Technology in the Netherlands achieved three improvements in bioethanol production from agricultural waste material: more ethanol, less acetate, and elimination of the byproduct glycerol. Bioethanol is produced by the yeast Saccharomyces cerevisiae from sugars obtained from plant biomass. The same microorganism converts such sugars into ethanol, or alcohol, in beer and wine. The production of bioethanol is increasing rapidly due to its growing use as a car fuel. With an annual world production of 65 billion liters, bioethanol is already the largest product of the fermentation industry. Ideally, bioethanol should be produced from resources that do not compete with food production, so efforts are made to produce second-generation bioethanol using agricultural residues such as wheat straw and corn stover. However, the sugars released from these raw materials form significant quantities of acetate, which can slow or even halt bioethanol production by yeast. Conventional bioethanol production also loses about 4% of sugar to formation of the byproduct glycerol — long considered an inevitable consequence of bioethanol production conditions.<\/p>\n
TU Delft researchers solved these issues by introducing a single gene from the bacterium Escherichia coli into the yeast, enabling the conversion of harmful acetate to ethanol. This process replaced the normal role of glycerol so efficiently that key genes in glycerol production could be removed, thus preventing glycerol production as well. “In the laboratory, this simple genetic modification kills three birds with one stone: no glycerol formation, higher ethanol yields, and consumption of toxic acetate,” explains principal researcher Jack Pronk, professor and leader of the Industrial Microbiology Group in TU Delft’s department of biotechnology. A paper describing the invention was published in Applied and Environmental Microbiology<\/em><\/a>. The researchers have applied for a patent on their invention and hope to collaborate with industrial partners to accelerate its industrial implementation.<\/p>\n