Biosynthesis of myo-inositol in Escherichia coli by engineering myo-inositol-1-phosphate pathway

Abstract

Myo-inositol is widely used in drug, food and animal feed industries. In this study, the myo-inositol biosynthetic pathway was established in Escherichia coli by introducing the myo-inositol-1-phosphate synthase-encoding gene (INO1) from Saccharomyces cerevisiae SC288. The production of myo-inositol was also investigated in shake flasks. The results showed that gene INO1 was succefully expressed in E. coli as verified by SDS-PAGE analysis. The initial glucose concentrations in M9 media had a positive impact on the production of myo-inositol and acetic acid, OD600 of cells and plasmid stability. The highest concentration of myo-inositol was obtained at the initial glucose concentration of 30 g/L, which reached 887 mg/L. When the initial concentration of glucose was 40 g/L, a lot of acetic acid was accumulated (8.53 g/L), causing slightly decrease in the concentration of myo-inositol. The recombinant plasmid was more unstable at higher initial concentration of glucose as compared to a lower one. 797 mg/L of myo-inositol was ultimately produced in a 1 L shake flask at the initial glucose concentration of 10 g/L. The maximal OD600 of cells and the highest concentration of acetic acid were 7.18 and 3.05 g/L, respectively. This study lays good foundation for understanding the biosynthesis of myo-inositol in E. coli and provides the possibility of applying myo-inositol to the industrial production by recombinant E. coli in future.