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Fed‐batch fermentor synthesis of 3‐dehydroshikimic acid using recombinant Escherichia coli
Author(s) -
Li Kai,
Mikola Mark R.,
Draths K. M.,
Worden R. Mark,
Frost J. W.
Publication year - 1999
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/(sici)1097-0290(19990705)64:1<61::aid-bit7>3.0.co;2-g
Subject(s) - fermentation , transketolase , biochemistry , escherichia coli , phosphoenolpyruvate carboxykinase , chemistry , biosynthesis , enzyme , sugar acids , biology , sugar , gene
3‐Dehydroshikimic acid (DHS), in addition to being a potent antioxidant, is the key hydroaromatic intermediate in the biocatalytic conversion of glucose into aromatic bioproducts and a variety of industrial chemicals. Microbial synthesis of DHS, like other intermediates in the common pathway of aromatic amino acid biosynthesis, has previously been examined only under shake flask conditions. In this account, synthesis of DHS using recombinant Escherichia coli constructs is examined in a fed‐batch fermentor where glucose availability, oxygenation levels, and solution pH are controlled. DHS yields and titers are also determined by the activity of 3‐deoxy‐ D ‐ arabino ‐heptulosonic acid 7‐phosphate (DAHP) synthase. This enzyme's expression levels, sensitivity to feedback inhibition, and the availability of its substrates, phosphoenolpyruvate (PEP) and D ‐erythrose 4‐phosphate (E4P), dictate its in vivo activity. By combining fed‐batch fermentor control with amplified expression of a feedback‐insensitive isozyme of DAHP synthase and amplified expression of transketolase, DHS titers of 69 g/L were synthesized in 30% yield (mol/mol) from D ‐glucose. Significant concentrations of 3‐dehydroquinic acid (6.8 g/L) and gallic acid (6.6 g/L) were synthesized in addition to DHS. The pronounced impact of transketolase overexpression, which increases E4P availability, on DHS titers and yields indicates that PEP availability is not a limiting factor under the fed‐batch fermentor conditions employed. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 64: 61–73, 1999.

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