Directing vanillin production from ferulic acid by increased acetyl‐CoA consumption in recombinant Escherichia coli

ABSTRACT: The amplification of gltA gene encoding citratesynthase of TCA cycle was required for the efficient con-version of acetyl-CoA, generated during vanillin productionfrom ferulic acid, to CoA, which is essential for vanillinproduction. Vanillin of 1.98 g/L was produced from theE. coli DH5a(pTAHEF-gltA) with gltA amplification in 48 hof culture at 3.0 g/L of ferulic acid, which was about twofoldhigher than the vanillin production of 0.91 g/L obtained bythe E. coli DH5a (pTAHEF) without gltA amplification.The icdA gene encoding isocitrate dehydrogenase of TCAcycle was deleted to make the vanillin producing E. coliutilize glyoxylate bypass which enables more efficient con-version of acetyl-CoA to CoA in comparison with TCA cycle.The production of vanillin by the icdA null mutant of E. coliBW25113 harboring pTAHEF was enhanced by 2.6 times.The gltA amplification of the glyoxylate bypass in the icdAnull mutant remarkably increased the production rate ofvanillin with a little increase in the amount of vanillinproduction. The real synergistic effect of gltA amplificationand icdA deletion was observed with use of XAD-2 resinreducing the toxicity of vanillin produced during culture.Vanillin of 5.14 g/L was produced in 24 h of the culture withmolar conversion yield of 86.6%, which is the highest so farin vanillin production from ferulic acid using recombinantE. coli.Biotechnol. Bioeng. 2009;102: 200–208. 2008 Wiley Periodicals, Inc.KEYWORDS: E. coli; vanillin; acetyl-CoA; citrate synthase;glyoxylate bypass