Thymidine production by overexpressing NAD+ kinase in an Escherichia coli recombinant strain

Abstract Intracellular NADPH/NADP+ ratio in cells grown on various production media with different carbon and nitrogen sources had a positive correlation with the thymidine production. To improve thymidine production in a previously engineered E. coli strain, NAD+ kinase was overexpressed in it resulting in the NADPH/NADP+ ratio shifting from 0.184 to 0.267. The [NADH + NADP+]/[NAD+ + NADPH] ratio was, however, not significantly altered. In jar fermentation, 740 mg thymidine l-1 was produced in parental strain, while 940 mg l-1 of thymidine was produced in NAD+ kinase-expressing strain.