期刊
BIOTECHNOLOGY JOURNAL
卷 8, 期 6, 页码 699-708出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/biot.201200322
关键词
Candida tenuis; (S)-1-(2-Chlorophenyl)ethanol; Pichia stipitis; Whole-cell biocatalyst; Xylose reductase
资金
- Austrian Science Fund (FWF) [V191-B09]
- Austrian Science Fund (FWF) [V191] Funding Source: Austrian Science Fund (FWF)
- Austrian Science Fund (FWF) [V 191] Funding Source: researchfish
Generally, recombinant and native microorganisms can be employed as whole-cell catalysts. The application of native hosts, however, shortens the process development time by avoiding multiple steps of strain construction. Herein, we studied the NAD(P)H-dependent reduction of o-chloroacetophenone by isolated xylose reductases and their native hosts Candida tenuis and Pichia stipitis. The natural hosts were benchmarked against Escherichia coli strains co-expressing xylose reductase and a dehydrogenase for co-enzyme recycling. Xylose-grown cells of C. tenuis and P. stipitis displayed specific o-chloroacetophenone reductase activities of 366 and 90 U g(CDW)(-1), respectively, in the cell-free extracts. Fresh biomass was employed in batch reductions of 100 mM o-chloroacetophenone using glucose as co-substrate. Reaction stops at a product concentration of about 15 mM, which suggests sensitivity of the catalyst towards the formed product. In situ substrate supply and product removal by the addition of 40% hexane increased catalyst stability. Optimisation of the aqueous phase led to a (S)-1-(2-chlorophenyl)ethanol concentration of 71 mM (ee > 99.9%) obtained with 44 g(CDW) L-1 of C. tenuis. The final difference in productivities between native C. tenuis and recombinant E. coli was < 1.7-fold. The optically pure product is a required key intermediate in the synthesis of a new class of chemotherapeutic substances (polo-like kinase 1 inhibitors).
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