Common baker's yeast, Saccharomyces cerevisiae, is best known for helping to ferment beer and leaven bread. Agricultural Research Service (ARS) scientists at the US Department of Agriculture are working to expand on its applications.
At the ARS Southern Regional Research Center in New Orleans, scientists have altered the yeast's metabolism with plant genes for converting vegetable oil fats (lipids) into value-added by-products. Eventually, harnessing the yeast's metabolism on an industrial scale could help open newmarket outlets for oilseed crops such as soybeans, cotton and linseed,according to John Dyer, a chemist at the ARS centre's Commodity Utilisation Research Unit.
According to the ARS, baker's yeast has little need for lipids except to reinforce cell walls or store energy. It is a diet of sugars and carbohydrates thatreally gets the yeast going - and producing the carbon dioxide and alcohol that bakers and brewers desire.
But when modified with desaturase enzymes from plants, including Arabidopis, and then "fed" a diet of vegetable oil fatty acids, the altered yeast's lipid storage increases up to sevenfold. Depending on which desaturases are activated, and the growth conditions scientists create, the yeast's metabolism converts the lipids into valuable by-products such as alpha eleostearic acid - a main tung oil component - and alpha linolenic acid. Thelatter by-product is an omega 3 fatty acid, shown to help protect the body against heart disease and cancer.
According to Dyer,refining the procedures further should allow for larger-scale production of these valuable lipid compounds in yeasts.