Lower Fructose Uptake Capacity of Genetically Characterized Strains of Saccharomyces bayanus Compared to Strains of Saccharomyces cerevisiae: A Likely Cause of Reduced Alcoholic Fermentation Activity

¹ Getränkemikrobiologie, Swiss Federal Research Station for Fruit-Growing, Viticulture and Horticulture, CH-8820 Wadenswil, Switzerland.

Four strains of the (sparkling) wine yeast Saccharomyces bayanus were identified and characterized by growth tests and chromosomal karyotyping. Physiological properties of these strains were determined in sugar uptake experiments performed with ¹⁴C-labeled glucose and fructose. The total uptake capacity of both sugars, glucose and fructose, varied from strain to strain. High sugar uptake seems to be correlated to the structure of hexokinase encoded sequences. At the end of fermentation all four strains had markedly lower fructose than glucose uptake capacities, which is in contrast to investigated S. cerevisiae strains. The lower fructose uptake capacity of S. bayanus towards the end of alcoholic fermentation with an excess of residual fructose may thus be responsible for the occurrence of decreased alcoholic fermentation activity.

Key words: sugar uptake, Saccharomyces bayanus, alcoholic fermentation

Submitted on April 20, 1994