title: Increased pyruvate efficiency in enzymatic production of (R)-phenylacetylcarbinol.
abstract: Loss of substrate, pyruvate, a limitation for enzymatic batch production of (R)-phenylacetylcarbinol (PAC), resulted from two phenomena: temperature dependent non-enzymatic concentration decrease due to the cofactor Mg2+ and formation of by-products, acetaldehyde and acetoin, by pyruvate decarboxylase (PDC). In the absence of enzyme, pyruvate stabilization was achieved by lowering the Mg2+ concentration from 20 to 0.5 mM. With 0.5 mM Mg2+ Rhizopusjavanicus and Candida utilis PDC produced similar levels of PAC (49 and 51 g 1(-1), respectively) in 21 h at 6 degrees C; however C. utilis PDC formed less by-product from pyruvate and was more stable during biotransformation. The process enhancements regarding Mg2+ concentration and source of PDC resulted in an increase of molar yield (PAC/consumed pyruvate) from 59% (R. javanicus PDC, 20 mM Mg2+) to 74% (R. javanicus PDC, 0.5 mM Mg2+) to 89% (C. utilis PDC, 0.5 mM Mg2+).
authors.affiliation: School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney NSW 2052, Australia. b.rosche@unsw.edu.au
authors.forename: Bettina
authors.initials: B
authors.lastname: Rosche
authors.forename: Michael
authors.initials: M
authors.lastname: Breuer
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hauer
authors.forename: Peter L
authors.initials: PL
authors.lastname: Rogers
mesh_terms: D000079:Acetaldehyde / Q000737:chemistry; D000093:Acetoin / Q000737:chemistry; D000096:Acetone / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry; D001711:Biotransformation; D002175:Candida / Q000737:chemistry* / Q000145:classification / Q000201:enzymology; D003067:Coenzymes; D004789:Enzyme Activation; D008274:Magnesium / Q000737:chemistry*; D011767:Pyruvate Decarboxylase / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D019289:Pyruvic Acid / Q000737:chemistry*; D011786:Quality Control; D012233:Rhizopus / Q000737:chemistry* / Q000145:classification / Q000201:enzymology; D013045:Species Specificity; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D003067:Coenzymes; D000096:Acetone; D019289:Pyruvic Acid; C035293:1-hydroxy-1-phenyl-2-propanone; D000093:Acetoin; D011767:Pyruvate Decarboxylase; D000079:Acetaldehyde; D008274:Magnesium