Immobilized Whole Cells as Effective Catalysts for Chiral Alcohol Production

Jeck Fei Ng; Stephan Jaenicke

doi:10.1071/CH09112

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Immobilized Whole Cells as Effective Catalysts for Chiral Alcohol Production

Jeck Fei Ng ^A and Stephan Jaenicke ^A ^B

+ Author Affiliations

- Author Affiliations

^A Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Republic of Singapore.

^B Corresponding author. Email: chmsj@nus.edu.sg

Australian Journal of Chemistry 62(9) 1034-1039 https://doi.org/10.1071/CH09112
Submitted: 24 February 2009 Accepted: 18 June 2009 Published: 17 September 2009

Abstract

Recombinant Escherichia coli overexpressing the gene LbADH, which encodes for an alcohol dehydrogenase from Lactobacillus brevis, was successfully transformed and cultured. The cells are able to catalyze the reduction of pro-chiral ketones, e.g. ethyl acetoacetate into R-(–)ethyl hydroxybutyrate (EHB) with high conversion and enantiomeric excess >99%. Immobilizing the whole cells in alginate beads leads to a catalyst with improved stability and ease of handling while maintaining the high activity of the free cells. The whole-cell catalyst was tested in a stirred batch reactor (CSTR) and in a continuously operated packed-bed reactor. An Mg²⁺ concentration of 2 mM was crucial for maintaining the activity of the biocatalyst. After a partial optimization of the process conditions, a productivity of 1.4 g_EHB g_wcw^–1 h^–1 could be maintained in a continuous flow reactor over a prolonged period of time.

Acknowledgement

This work was funded by NUS research grant R-143–000–374–112. We are grateful to Professor Christian Wandrey and his research group (Jülich, Germany) for the gift of the plasmid, and for initiating us to the know-how of recombinant technology. The help of Miss Ida Wang, exchange student from the University of British Columbia, Vancouver, Canada, in the early part of this project is gratefully acknowledged.

References

Immobilized Whole Cells as Effective Catalysts for Chiral Alcohol Production

Abstract

Acknowledgement

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