The wine spoilage yeast Dekkera bruxellensis was evaluated for the production of 4-ethylphenol under low concentrations (0.02-20 g L(-1)) of glucose and fructose in synthetic media. Measurable amounts of 4-ethylphenol were produced over 0.2 g L(-1) of each sugar. The yeast growth rate and amount of biomass formed increased from 0.2 to 20 g L(-1) of glucose or fructose, being accompanied by increasing production of 4-ethylphenol. In red wines, the production of 4-ethylphenol was only observed in the presence of growing populations of indigenous or inoculated strains of D. bruxellensis. The production rate of 4-ethylphenol varied between 22 and 93 mug day(-1) either with inoculated strains or wild populations in bottled wines. The production rate of 4-ethylphenol as a function of the increase in the number of cells varied from 349 to 1882 mug L(-1) per one log CFU mL(-1). The effect of temperature on cellular viability and 4-ethylphenol production was tested in red wines with indigenous or inoculated strains of D. bruxellensis. Incubation temperatures of 15, 20 and 25 degrees C allowed cellular growth and volatile phenol production. Increasing incubation temperatures to 36 degrees C induced full viability loss of 10 strains of D. bruxellensis within <12 h.