Fermentation properties of a wine yeast over-expressing the Saccharomyces cerevisiae glycerol 3-phosphate dehydrogenase gene (GPD2)

Abstract

Wine yeasts efficiently convert sugar into ethanol. The possibility of diverting some of the sugar into compounds other than ethanol by using molecular genetic methods was tested. Over‐expression of the yeast glycerol 3‐phosphate dehydrogenase gene (GPD2) in a laboratory strain of Saccharomyces cerevisiae led to an approximate two‐fold increase in the extracellular glycerol concentration. In the medium fermented with the modified strain, acetic acid concentration also increased approximately two‐fold when respiration was blocked. A strain deleted for the GPD2 gene had the opposite phenotype, producing lower amounts of glycerol and acetic acid, with the latter compound only reduced during non‐respiratory growth. A commercial wine yeast over‐expressing GPD2 produced 16.5 g/L glycerol in a wine fermentation, compared to 7.9 g/L obtained with the parent strain. As seen for the laboratory strain, acetic acid concentrations were also increased when using the genetically modified wine yeast. A panel of wine judges confirmed the increase in volatile acidity of these wines. The altered glycerol biosynthetic pathway sequestered carbon from glycolysis and reduced the production of ethanol by 6 g/L.

Reduction of Ethanol Yield and Improvement of Glycerol Formation by Adaptive Evolution of the Wine Yeast Saccharomyces cerevisiae under Hyperosmotic Conditions

“…Wine can be produced in a large range of fermentation temperaturesusually from 16°C for white wines to 28°C and higher for red wines. We therefore compared the metabolic properties of the ancestral strain and the evolved strain K300.1(b) over a wide range of temperatures (16,20,24,28,32, and 34°C) in MS210 medium containing 260 g/liter sugars. For temperatures between 16 and 28°C, both strains consumed all or most of the sugar, while for the two highest temperatures, residual sugar concentrations of 43 and 53 g/liter for EC1118 and 47 and 59 g/liter for K300.1(b) were observed at 32 and 34°C, respectively.…”

“…It may also confer viscosity at very high concentrations (above 25 g/liter), as in Botrytis wines. Rerouting carbon toward glycerol led to a substantial decrease in ethanol production (13,14,15,16) and accumulation of various compounds, including acetate and acetoin, both undesirable for wine sensorial quality (15,17). Rational engineering of key reactions at the acetaldehyde branch point allowed the accumulation of these undesirable compounds to be limited.…”

Flavor impacts of glycerol in the processing of yeast fermented beverages: a review

“…The genetically modified yeasts promoted glycerol yield up to 5.6 and 6.1 folds and decrease ethanol concentration by 18 % and 21 % under beer and wine fermentations individually (Nevoigt et al 2002;Varela et al 2012). Nonetheless, the engineered strains accumulated dramatic amounts of detrimental flavors such as acetaldehyde, acetate and acetoin in addition to the impaired growth of the yeast and poor social acceptance for their application (Cambon et al 2006;Eglinton et al 2002;Lopes et al 2000;Nevoigt et al 2002;Remize et al 1999;Varela et al 2012).…”

Characterisation of banana wine fermented with recombinant wine yeast strains

“…These advances in DNA technology have made it possible to clone genes with traits of interest to the winemaker and to manipulate organisms' cells to overproduce the desired protein. During the last 18 years, several attempts to construct genetically engineered yeast strains have been published, and very interesting improvements in the wine-making process or the quality of the wine obtained have been reported, including improved primary and secondary flavors, malic acid decarboxylation by yeast, increased resveratrol, lactic acid, or glycerol contents, and improved survival properties (Barros et al, 2000;Dequin et al, 1999;Ganga et al, 1999;Gil and Valles, 2001;Gonzales-Candelas et al, 2000;Lilly et al, 2000;Perez-Torrado et al, 2002;Remize et al, 1999;Smit et al, 2003;Vilanova et al, 2000;Volschenk et al, 2001). Many enzymes have been expressed in manipulated micro-organisms at levels of 10 to 100 times higher than in their natural host cells (Kresse, 1995;.…”