Metabolic schemes of glycerol catabolism in the used strains. a Glycerol catabolism (from glycerol to dihydroxyacetone phosphate) in the S. cerevisiae wild-type strain CBS 6412-13A and in engineered derivatives in which a heterologous aquaglyceroporin (CBS 6412-13A FPS1) and/or the DHA pathway was established (CBS DHA and CBS DHA FPS1). b Conversion of dihydroxyacetone phosphate to pyruvate (glycolysis), of pyruvate to carbon dioxide (pyruvate dehydrogenase and TCA cycle) and of pyruvate to ethanol (alcoholic fermentation). Ethanol formation has been demonstrated to only occur in strains that carry the DHA pathway as described in the main text. Dotted arrows indicate the expression of a heterologous gene and the metabolic reaction catalyzed by the respective gene product. The bold arrows indicate the overexpression of an endogenous gene (DAK1); and the dashed arrows represent metabolic conversions that consist of more than one enzymatic reaction. Metabolites: 1,3-BPG: 1,3-bisphosphoglycerate; l-G3P: l-glycerol-3-phosphate; DHA: dihydroxyacetone; DHAP: dihydroxyacetone phosphate; Genes: CjFPS1: FPS1 homolog (aquaglyceroporin) from C. jadinii; GUT1: glycerol kinase; GUT2: mitochondrial (membrane bound) FAD-dependent l-G3P dehydrogenase; DAK1/DAK2: DHA kinase (DAK1oe: DAK1 overexpression), Opgdh: glycerol dehydrogenase from O. parapolymorpha; STL1: glycerol/H+ symporter.