Expression of Glucose-6-Phosphate Dehydrogenase and 6-Phosphogluconate Dehydrogenase Improve L-Citrulline Biosynthesis in argG-Deleted Corynebacterium glutamicum

摘要

Corynebacterium glutamicum, a well-known producer in the amino acids industry, has become a potential platform organism for synthetic biology in industrial biotechnology. During L-citrulline biosynthesis, NADPH is required as a crucial cofactor. Production of L-citrulline requires 2 mol of NADPH per mole of L-citrulline. The strategy focused on engineering of the pentose phosphate pathway (PPP) flux by different genetic modifications. In this study, two NADPH-supplying strategies based on glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase was compared, and their influences on L-citrulline biosynthesis were examined. The zwf and gnd genes were overexpressed in the L-citrulline-producing strain CgΔargG. The expression of both genes greatly enhanced intracellular NADPH concentration and L-citrulline production. The concentration of intracellular NADPH was increased by 287 and 363 %, and the production of L-citrulline was increased by 30.8 and 20.5 % in CgΔargG/pXMJ19-zwf and CgΔargG/pXMJ19-gnd, respectively, compared with CgΔargG. The concentration of NADPH in a zwf- and gnd-expressing strain was increased by 287 and 363 %, respectively. These results are helpful for improving L-citrulline biosynthesis and other biosynthetic processes.