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Asymmetric reduction of ?, ?-unsaturated ketone to (R) allylic alcohol by Candida chilensis

Pollard, D J; Telari, K; Lane, J; Humphrey, G; McWilliams, C; Nidositko, S; Salmon, P; Moore, J

Authors

D J Pollard

K Telari

J Lane

G Humphrey

C McWilliams

S Nidositko

P Salmon



Abstract

A pilot scale whole cell process was developed for the enantioselective 1,2‐reduction of prochiral α,β‐unsaturated ketone to (R) allylic alcohol using Candida chilensis. Initial development showed high enantiomeric excess (EE > 95%) but low product yield (10%). Process development, using a combination of statistically designed screening and optimization experiments, improved the desired alcohol yield to 90%. The fermentation growth stage, particularly medium composition and growth pH, had a significant impact on the bioconversion while process characterization identified diverse challenges including the presence of multiple enzymes, substrate/product toxicity, and biphasic cellular morphology. Manipulating the fermentation media allowed control of the whole cell morphology to a predominately unicellular broth, away from the viscous pseudohyphae, which were detrimental to the bioconversion. The activity of a competing enzyme, which produced the undesired saturated ketone and (R) saturated alcohol, was minimized to ≤5% by controlling the reaction pH, temperature, substrate concentration, and biomass level. Despite the toxicity effects limiting the volumetric productivity, a reproducible and scaleable process was demonstrated at pilot scale with high enantioselectivity (EE > 95%) and overall yield greater than 80%. This was the preferred route compared to a partially purified process using ultra centrifugation, which led to improved volumetric productivity but reduced yield (g/day). The whole cell approach proved to be a valuable alternative to chemical reduction routes, as an intermediate step for the asymmetric synthesis of an integrin receptor anatagonist for the inhibition of bone resorption and treatment of osteoporosis. © 2006 Wiley Periodicals, Inc.

Journal Article Type Article
Acceptance Date Sep 14, 2005
Online Publication Date Jan 4, 2006
Publication Date Mar 5, 2006
Deposit Date Apr 22, 2020
Journal Biotechnology and Bioengineering
Print ISSN 0006-3592
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 93
Issue 4
Pages 674-686
DOI https://doi.org/10.1002/bit.20751
Public URL http://doi.wiley.com/10.1002/bit.20751
Publisher URL https://onlinelibrary.wiley.com/doi/abs/10.1002/bit.20751