[Application of high efficiency promoters in microbial production of 4-hydroxybutyric acid]

4-Hydroxybutyric acid (4HB) is a psychotropic drug used for polymer synthesis such as poly (4-hydroxybutyric acid) (P4HB) and poly (3-hydroxybutyric acid-co-4-hydroxybutyric acid) (P3HB-co-4HB). 1,4-butanediol (BD) can be converted to 4-hydroxybutyric acid by alcohol dehydrogenase (DhaT) and aldehyde dehydrogenase (AldD). In this study, high efficiency promoters including T7 promoter and P(Re) promoter were cloned to increase expression of dhaT and aldD, and thus accelerate the conversion from BD to 4HB. A. hydrophila 4AK4 (pZQ01), the recombinant strain under the control of T7 promoter, produced 6.00 g/L 4HB from 10 g/L BD with the productivity increased by 43.20%. While A. hydrophila 4AK4 (pZQ04), the strain under the control of T7 promoter, produced 4.87 g/L 4HB from 10 g/L BD, and the productivity was increased by 16.23%. Thus, the gene expression was increased by T7 and P(Re) promoters, leading to an accelerated biosynthesis of 4HB.