Biosynthesis of L-Arginine Using Metabolically Engineered Corynebacterium Glutamicum

For overproduction of L-arginine, Corynebacterium glutamicum was genetically engineered. As a strategy for enhancing cell tolerance to L-arginine, random mutagenesis was firstly conducted. After that, the genes argR and farR encoding the proteins which repress arginine expressing operon were inactivated. Then, pgi gene encoding phosphoglucose isomerase was downregulated by point mutation and the opcA, pgl, tal, tat and zwf genes in an opreon were overexpressed for the stronger PPP flux. For blocking the export of L-glutamate, which can be further conversed toward L-arginine, Ncgl1221 gene encoding L-glutamate exporter protein was inactivated. The next step was enhancing expression rate of the argF and carAB genes for optimized conversion of L-ornithine to L-citrulline. The last step was overexpressing of argGH operon to resolve the bottleneck of arginine synthesis. The final strain went through the large scale fed-batch fermentation in 1,500 L bioreactor and produced 81 g/L of L-arginine. The strategies used here for overproduction of arginine will provide useful information in metabolic engineering of Corynebacteria strains. [This work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries from the Ministry of Science, ICT and Future Planning (MSIP) through the National Research Foundation (NRF) of Korea (NRF-2012M1A2A2026556 and NRF-2012M1A2A2026557).]