Deacidification by Schizosaccharomyces: interactions with Saccharomyces

Abstract

The objective of this work was to study the partial consumption of malic acid in a semi-synthetic medium by Schizosaccharomyces yeast under wine-making conditions. The aim was to control the extent of deacidification by stopping the activity of Schizosaccharomyces by the addition of Saccharomyces yeast at different delayed intervals of time. This was thought possible because the Schizosaccharomyces yeasts are much more slower than the Saccharomyces yeasts and may be inhibited by the latter. In fact, the opposite was observed. Schizosaccharomyces exhibited a amensal effect against Saccharomyces: the Saccharomyces growth was inhibited by Schizosaccharomyces, this inhibition being proportional to the Schizosaccharomyces concentration, reversible, and sensitive to temperature. Such interactions similar to a killer effect have not been described before. At the same time a competition towards sugar was noted, being negative for Schizosaccharomyces since these yeasts have slower metabolic rates. Nevertheless, total demalication was nearly always possible because sufficient concentrations of Schizosaccharomyces were always reached. The delayed inoculation of Saccharomyces after Schizosaccharomyces was not a good solution to obtain partial deacidification.