title: Yeast pyruvate decarboxylases: variation in biocatalytic characteristics for (R)-phenylacetylcarbinol production.
abstract: Based on previous studies, Candida utilis pyruvate decarboxylase (PDC) proved to be a stable and high productivity enzyme for the production (R)-phenylacetylcarbinol (PAC), a pharmaceutical precursor. However, a portion of the substrate pyruvate was lost to by-product formation. To identify a source of PDC which might overcome this problem, strains of four yeasts -- C. utilis, Candida tropicalis, Saccharomyces cerevisiae and Kluyveromyces marxianus -- were investigated for their PDC biocatalytic properties. Biotransformations were conducted with benzaldehyde and pyruvate as substrates and three experimental systems were employed (in the order of increasing benzaldehyde concentrations): (I) aqueous (soluble benzaldehyde), (II) aqueous/benzaldehyde emulsion, and (III) aqueous/octanol-benzaldehyde emulsion. Although C. utilis PDC resulted in the highest concentrations of PAC and was the most stable enzyme, C. tropicalis PDC was associated with the lowest acetoin formation. For example, in system (III) the ratio of PAC over acetoin was 35 g g(-1) for C. tropicalis PDC and 9.2 g g(-1) for C. utilis PDC. The study thereby opens up the potential to design a PDC with both high productivity and high yield characteristics.
authors.affiliation: School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia.
authors.forename: Cindy
authors.initials: C
authors.lastname: Gunawan
authors.forename: Gernalia
authors.initials: G
authors.lastname: Satianegara
authors.forename: Allen K
authors.initials: AK
authors.lastname: Chen
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
authors.forename: Bettina
authors.initials: B
authors.lastname: Rosche
mesh_terms: D000096:Acetone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D001547:Benzaldehydes / Q000378:metabolism; D002175:Candida / Q000145:classification / Q000201:enzymology*; D002384:Catalysis; D007218:Industrial Microbiology / Q000379:methods; D007716:Kluyveromyces / Q000201:enzymology*; D011767:Pyruvate Decarboxylase / Q000378:metabolism*; D011773:Pyruvates / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D001547:Benzaldehydes; D011773:Pyruvates; D000096:Acetone; C035293:1-hydroxy-1-phenyl-2-propanone; D011767:Pyruvate Decarboxylase; C032175:benzaldehyde