Application of an oxygen‐inducible nar promoter system in metabolic engineering for production of biochemicals in Escherichia coli

• Published in: Biotechnology and bioengineering 2017-02, Vol.114 (2), p.468-473
• Main Authors: Hwang, Hee J., Kim, Jin W., Ju, Si Y., Park, Jin H., Lee, Pyung C.
• Format: Article
• Language: English
• Subjects: 1,3‐propandiol; 2,3‐butanediol; Bacteria; Batch culture; Biochemistry; Biodiesel fuels; Bioengineering; Biofuels; Biomass; Butylene Glycols - metabolism; Cell culture; Culture; Dissolved oxygen; E coli; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins - genetics; Feasibility studies; Fuels; Genes; Glucose; Glycerol; lactate; Lactic acid; Metabolic engineering; Metabolic Engineering - methods; Metabolism; Microorganisms; nar promoter; Oxygen - metabolism; Pathways; Plasmids; Productivity; Promoter Regions, Genetic - genetics; Propylene Glycols - metabolism; Y chromosomes; Yield
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.26082

ABSTRACT The nar promoter, a dissolved oxygen (DO)‐dependent promoter in Escherichia coli, is simply induced and functional in any cell growth phase, which are advantageous for producing biochemicals/fuels on an industrial scale. To demonstrate the feasibility of using the nar promoter in the metabolic engineering of biochemicals/biofuels in E. coli, three target pathways were examined: the d‐lactate, 2,3‐butandiol (2,3‐BDO), and 1,3‐propanediol (1,3‐PDO) pathways consisting of one, three, and six genes, respectively. Each pathway gene was expressed under the control of the nar promoter. When the ldhD gene was expressed in fed‐batch culture, the titer, yield, and productivity of d‐lactate were 113.12 ± 2.37 g/L, 0.91 ± 0.07 g/g‐glucose, and 4.19 ± 0.09 g/L/h, respectively. When three 2,3‐BDO pathway genes (ilvBN, aldB, bdh1) were expressed in fed‐batch culture, the titer, yield, and productivity of (R,R)‐2,3‐BDO were 48.0 ± 8.48 g/L, 0.43 ± 0.07 g/g glucose, and 0.76 ± 0.13 g/L/h, respectively. When six 1,3‐PDO pathway genes (dhaB1B2B3, yqhD, gdrA, and gdrB) were expressed in fed‐batch culture, the titer, yield, and productivity of 1,3‐PDO were 15.8 ± 0.62 g/L, 0.35 ± 0.01 g/g‐glycerol, and 0.25 ± 0.01 g/L/h, respectively. Based on the reasonable performance comparable to that observed in previous studies using different promoters in metabolic engineering, the nar promoter can serve as a controlled expression tool for developing a microbial system to efficiently produce biochemicals and biofuels. Biotechnol. Bioeng. 2017;114: 468–473. © 2016 Wiley Periodicals, Inc. A dissolved oxygen‐dependent nar promoter has been utilized as an alternative to commonly‐used promoters for engineering biochemical pathways because of its relatively simple and cost‐effective induction mechanism. The three engineered biosynthetic pathways in which the expression of genes was controlled by the nar promoter showed reasonable performances [113.12 ± 2.37 g/L d‐lactate, 48.0 ± 8.48 g/L (R, R)‐2,3‐butandiol, and 15.8 ± 0.62 g/L 1, 3‐propandiol].