Modular pathway engineering of Corynebacterium glutamicum for production of the glutamate-derived compounds ornithine, proline, putrescine, citrulline, and arginine

Abstract

The glutamate-derived bioproducts ornithine, citrulline, proline, putrescine, and arginine have applications in the food and feed, cosmetic, pharmaceutical, and chemical industries. Corynebacterium glutamicum is not only an excellent producer of glutamate but also of glutamate-derived products. Here, engineering targets beneficial for ornithine production were identified and the advantage of rationally constructing a platform strain for the production of the amino acids citrulline, proline, and arginine, and the diamine putrescine was demonstrated. Feedback alleviation of N-acetylglutamate kinase, tuning of the promoter of glutamate dehydrogenase gene gdh, lowering expression of phosphoglucoisomerase gene pgi, along with the introduction of a second copy of the arginine biosynthesis operon argCJBA49V,M54VD into the chromosome resulted in a C. glutamicum strain producing ornithine with a yield of 0.52g ornithine per g glucose, an increase of 71% as compared to the parental ΔargFRG strain. Strains capable of producing 0.41g citrulline per g glucose, 0.29g proline per g glucose, 0.30g arginine per g glucose, and 0.17g putrescine per g glucose were derived from the ornithine-producing platform strain by plasmid-based overexpression of appropriate pathway modules with one to three genes.