Biobased production of arginine by metabolically engineered Escherichia coli

Arginine is a high-value product, especially for the pharmaceutical industry. Growing demand for environmental-friendly and traceable products have stressed the need for microbial production of this amino acid. Arginine has also been identified as an environmental friendly alternative to conventional fertilizers with a potential in various growth settings. Therefore, the aim of this study was to establish a fermentation process for the production of arginine using genetically modified Escherichia coli.

E. coli strains K-12 C600 genetically engineered by alteration of genes involved in arginine repression (argA, argR), arginine and ornithine degradation (adiA, speC, speF) and arginine export (argO, argP) were used. A fermentation process in 1-L scale bioreactors was developed based on studies using C. glutamicum for arginine production since such process has not yet been reported with E. coli. The main challenge was the large quantity of oxygen required to support cell growth and arginine production. If insufficient air was provided the dissolved oxygen (DO) level quickly dropped to zero and no arginine was excreted. Nitrogen is essential for cell growth; efficient supply of this nutrient is especially important for arginine production as this amino acid contains 4 atoms of nitrogen. Consequently, different strategies for oxygen and nitrogen supply were investigated. An effective process for the production of arginine in 1-L scale bioreactor using an arginine overproducing E. coli strain is reported.