Glutamate production from aerial nitrogen using the nitrogen-fixing bacterium Klebsiella oxytoca

Glutamate is an essential biological compound produced for various therapeutic and nutritional applications. The current glutamate production process requires a large amount of ammonium, which is generated through the energy-consuming and CO 2 -emitting Haber–Bosch process; therefore, the development of bio-economical glutamate production processes is required. We herein developed a strategy for glutamate production from aerial nitrogen using the nitrogen-fixing bacterium Klebsiella oxytoca . We showed that a simultaneous supply of glucose and citrate as carbon sources enhanced the nitrogenase activity of K. oxytoca . In the presence of glucose and citrate, K. oxytoca strain that was genetically engineered to increase the supply of 2-oxoglutarate, a precursor of glutamate synthesis, produced glutamate extracellularly more than 1 g L −1 from aerial nitrogen. This strategy offers a sustainable and eco-friendly manufacturing process to produce various nitrogen-containing compounds using aerial nitrogen.