Thus, the microorganisms are modified to reduce the activity of pyruvate kinase and/or pyruvate decarboxylase.
A polypeptide with pyruvate decarboxylase activity, derived from the pyruvate decarboxylase from Zymomonas mobilis by substitution of an amino acid in position 553.
The enzymes have alcohol acyl transferase, alcohol dehydrogenase, pyruvate decarboxylase, thiolase, aminotransferase and esterase activities, respectively.
Both organisms produce near theoretical ethanol yields without expressing pyruvate decarboxylase
The invention provides isolated nucleic acids molecules which encode pyruvate decarboxylase enzymes having improved decarboxylase activity, substrate affinity, thermostability, and activity at different pH.
The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions.