[Synthesis of flavor esters catalyzed by CALB-displaying Pichia pastoris whole-cells in non-aqueous phase]

Sheng Wu Gong Cheng Xue Bao. 2009 Dec;25(12):1927-32.
[Article in Chinese]

Abstract

An enzyme-displaying yeast as a whole-cell biocatalyst seemed an alternative to immobilized enzyme, due to its low-cost preparation and simple recycle course. Here, we tried to use a recombinant Pichia pastoris displaying Candida antarctica lipase B (CALB) to catalyze the synthesis of short chain flavor esters in n-heptane. We studied some major influential factors of esterification reactions, such as carbon chain length of the substrates, alcohol structure, enzyme concentration, substrates concentration, molar ratio of the substrates. The acid conversions were determined by titration and gas chromatography analysis. About ten kinds of esters were synthesized successfully, and the acid conversions of eight esters reached as high as 90% after reaction for 6 h. The result also indicated that ethanol and hexanoic acid were the most suitable substrates for this whole-cell catalyst. Under the optimal reaction conditions (the amount of lipase 20 g/L (306.0 U/g-dry cell), hexanoic acid concentration 0.8 mol/L, the molar ratio of hexanoic acid to ethanol 1:1.1), hexanoic acid conversion reached 97.3% after reaction for 1.5 h. To our knowledge, the CALB-displaying P. pastoris whole-cell biocatalyst showed good tolerance for high substrates concentration and exhibited high reaction rate on esterification of short chain flavor esters among the present enzyme/cell reported. Thus, CALB-displaying P pastoris whole-cell biocatalyst was promising in commercial application for flavor esters synthesis in non-aqueous phase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biocatalysis
  • Candida / enzymology*
  • Enzymes, Immobilized
  • Esters / metabolism*
  • Fungal Proteins
  • Lipase / biosynthesis*
  • Lipase / genetics
  • Pichia / genetics
  • Pichia / metabolism*
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / genetics

Substances

  • Enzymes, Immobilized
  • Esters
  • Fungal Proteins
  • Recombinant Proteins
  • Lipase
  • lipase B, Candida antarctica