title: Production of the aroma chemicals 3-(methylthio)-1-propanol and 3-(methylthio)-propylacetate with yeasts.
abstract: Yeasts can convert amino acids to flavor alcohols following the Ehrlich pathway, a reaction sequence comprising transamination, decarboxylation, and reduction. The alcohols can be further derivatized to the acetate esters by alcohol acetyl transferase. Using L: -methionine as sole nitrogen source and at high concentration, 3-(methylthio)-1-propanol (methionol) and 3-(methylthio)-propylacetate (3-MTPA) were produced with Saccharomyces cerevisiae. Methionol and 3-MTPA acted growth inhibiting at concentrations of >5 and >2 g L(-1), respectively. With the wild type strain S. cerevisiae CEN.PK113-7D, 3.5 g L(-1) methionol and trace amounts of 3-MTPA were achieved in a bioreactor. Overexpression of the alcohol acetyl transferase gene ATF1 under the control of a TDH3 (glyceraldehyde-3-phosphate dehydrogenase) promoter together with an optimization of the glucose feeding regime led to product concentrations of 2.2 g L(-1) 3-MTPA plus 2.5 g L(-1) methionol. These are the highest concentrations reported up to now for the biocatalytic synthesis of these flavor compounds which are applied in the production of savory aroma compositions such as meat, potato, and cheese flavorings.
authors.affiliation: Biochemical Engineering Group, Theodor-Heuss-Allee 25, 60486, Frankfurt am Main, Germany.
authors.forename: M M W
authors.initials: MM
authors.lastname: Etschmann
authors.forename: P
authors.initials: P
authors.lastname: Kötter
authors.forename: J
authors.initials: J
authors.lastname: Hauf
authors.forename: W
authors.initials: W
authors.lastname: Bluemke
authors.forename: K-D
authors.initials: KD
authors.lastname: Entian
authors.forename: J
authors.initials: J
authors.lastname: Schrader
mesh_terms: D018533:Biomass; D005818:Genetic Engineering; D007218:Industrial Microbiology; D020005:Propanols / Q000378:metabolism*; D011422:Propionates / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013440:Sulfides / Q000378:metabolism*
chemical_list: C488123:3-(methylsulfanyl)propan-1-ol; C488122:3-(methylsulfanyl)propionic acid; D020005:Propanols; D011422:Propionates; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D013440:Sulfides; C079238:alcohol O-acetyltransferase