Fermentative glycerol-free ethanol production

Transgenic yeast cells comprising one or more recombinant heterologous, nucleic acid sequences encoding a protein with NAD+-dependent acetylating acetaldehyde dehydrogenase activity (EC 1.2.1.10),

• wherein said cells lack enzymatic activity needed for the NADH-dependent glycerol synthesis, or
• said cells have a reduced enzymatic activity with respect to the NADH-dependent glycerol synthesis
• compared to a corresponding wild-type yeast cell, and
• wherein said cells are free of NAD-dependent glycerol 3-phosphate dehydrogenase activity or have reduced NAD-dependent glycerol 3-phosphate dehydrogenase activity compared to corresponding wild-type cells, and/or
• wherein the cells are either free of glycerol phosphate phosphatase activity or have reduced glycerol phosphate phosphatase activity compared to corresponding wild-type cells, and
• which comprise a genomic mutation in at least one gene selected from the group consisting of GPD1, GPD2, GPP1 and GPP2, and
• wherein said cells further comprise one or more nucleic acid sequences encoding an acetyl-Coenzyme A synthetase activity (EC 6.2.1.1) and one or more nucleic acid sequences encoding NAD+-dependent alcohol dehydrogenase activity (EC 1.1.1.1).