Files
Abstract
NADPH and NADH serve as electron carriers for various reactions in organisms. Transhydrogenases provide cells to interchange these electron carriers. Escherichia coli has two transhydrogenases, PntAB and SthA. In this study, pgi, coding for phosphoglucose isomerase, and sthA, coding for soluble transhydrogenase, were deleted in Escherichia coli to direct more carbon into the pentose phosphate pathway and increase NADPH production. These strains were examined for their growth on glucose, fructose or sucrose. A 3-hydroxybutyrate (3HB) pathway was introduced into Escherichia coli, and experiments were completed to determine whether pgi or sthA deletions affected 3HB formation. In addition, F383M and M327S substitutions in citrate synthase, coded by the gltA gene, were evaluated for their effect on 3HB formation. The sthA pgi strain grown on glucose generated 3HB at a yield of 0.057±0.001 g/g, greater than the wild-type strain. The F383M variants were generally able to produce more 3HB than M372S variants.