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Resting cells of recombinant E. coli show high epoxidation yields on energy source and high sensitivity to product inhibition
Author(s) -
Julsing Mattijs K.,
Kuhn Daniel,
Schmid Andreas,
Bühler Bruno
Publication year - 2012
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.24404
Subject(s) - biocatalysis , product inhibition , chemistry , biochemistry , monooxygenase , redox , enzyme , biophysics , biology , catalysis , organic chemistry , reaction mechanism , non competitive inhibition , cytochrome p450
Metabolically active resting (i.e., nongrowing) bacterial cells have a high potential in cofactor‐dependent redox biotransformations. Where growing cells require carbon and energy for biomass production, resting cells can potentially exploit their metabolism more efficiently for redox biocatalysis allowing higher specific activities and product yields on energy source. Here, the potential of resting recombinant E. coli containing the styrene monooxygenase StyAB was investigated for enantioselective styrene epoxidation in a two‐liquid phase setup. Resting cells indeed showed twofold higher specific activities as compared to growing cells in a similar setup. However, product formation rates decreased steadily resulting in lower final product concentrations. The low intrinsic stability of the reductase component StyB was found to limit overall biocatalyst stability. Such limitation by enzyme stability was overcome by increasing intracellular StyB levels. Beyond that, product inhibition was identified as a limiting factor, whereas complete toxification of the bacterial cells, as it was observed with growing cells, and deactivation of the multicomponent enzyme system did not occur. The resting cell setup allowed high product yields on glucose of more than 5 mol mol glucose −1 , which makes the use of resting cells a promising approach for ecologically as well as economically sustainable oxygenase‐based whole‐cell biocatalysis. Biotechnol. Bioeng. 2012; 109:1109–1119. © 2011 Wiley Periodicals, Inc.