Efficient whole-cell biocatalyst for Neu5Ac production by manipulating synthetic, degradation and transmembrane pathways
To develop a strategy for producing N-acetyl-d-neuraminic acid (Neu5Ac), which is often synthesized from exogenous N-acetylglucosamine (GlcNAc) and pyruvate, but without using pyruvate.
An efficient three-module whole-cell biocatalyst strategy for Neu5Ac production by utilizing intracellular phosphoenolpyruvate was established. In module I, the synthetic pathway was constructed by coexpressing GlcNAc 2-epimerase from Anabaena sp. CH1 and Neu5Ac synthase from Campylobacter jejuni in Escherichia coli. In module II, the Neu5Ac degradation pathway of E. coli was knocked out, resulting in 2.6 ± 0.06 g Neu5Ac l−1 after 72 h in Erlenmeyer flasks. In module III, the transmembrane mode of GlcNAc was modified by disruption of GlcNAc-specific phosphotransferase system and Neu5Ac now reached 3.7 ± 0.04 g l−1. In scale-up catalysis with a 1 l fermenter, the final Neu5Ac yield was 7.2 ± 0.08 g l−1.
A three-module whole-cell biocatalyst strategy by manipulating synthetic, degradation and transmembrane pathways in E. coli was an economical method for Neu5Ac production.
KeywordsCoexpressing vector GlcNAc-specific PTS Neu5Ac NeuNAc synthase Phosphoenolpyruvate Whole-cell biocatalyst
This research was supported by the National High Technology Research and Development Program of China (2012AA021505), the National Natural Science Foundation of China No. 31171640, and the Program of Introducing Talents of Discipline to Universities (111-2-06), the Fundamental Research Funds for the Central Universities (JUSRP51504, JUSRP51632A).
Supplementary Table 1—Strains and plasmids used.
Supplementary Table 2—Primers used.
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