Recombinant expression of glpK and glpD genes improves the accumulation of shikimic acid in E. coli grown on glycerol.

Shikimic acid (SA) is an industrially important chiral compound used in diverse commercial applications, and the insufficient supply by isolation from plants and expensive chemical synthesis of SA has increased the importance of developing strategies for SA synthesis. In our previous studies, glycerol was observed to be an effective carbon source for SA accumulation in E. coli DHPYAAS-T7, where the PTS operon (ptsHIcrr) and aroL and aroK genes were inactivated, and the tktA, glk, aroE, aroF (fbr) , and aroB genes were overexpressed. For further investigation of the effects of glycerol aerobic fermentation on SA accumulation in E. coli BL21(DE3), the glpD, glpK genes and tktA, glk, aroE, aroF (fbr) , aroB genes were overexpressed simultaneously. The results indicated that SA production was increased 5.6-fold, while the yield was increased 5.3-fold over that of parental strain in shake flasks. It is demonstrated that the aerobic fermentation of glycerol associated with glpD and glpK gene overexpression increased glycerol flux, resulting in higher SA accumulation in E. coli BL21(DE3)-P-DK.