Controlling the level of hydrogen sulphide production in lager brewing yeast by the introduction of heterologous enzymatic pathways for cysteine biosynthesis

摘要

Brewer’s yeast produces H2S which in large amounts leads to an unpleasant flavor. We have developed a system, which potentially is able to reduce H2S formation 2-3 fold. In yeast H2S condenses with O-acetylhomoserine to produce sulphur-containing amino acids, whereas plants and bacteria condense H2S to activated serine. This pathway was expressed in two strains of brewing yeast. The effect in one strain was that the maximal H2S content decreased 2.5-fold, with the onset of H2S production delayed one day, and ceasing one day earlier. In the other strain, total H2S production was comparable, but delayed a few hours by the pathway.