L-citrulline production by metabolically engineered Corynebacterium glutamicum from glucose and alternative carbon sources

Abstract

L-citrulline plays an important role in human health and nutrition and is an intermediate of the L-arginine biosynthetic pathway. L-citrulline is a by-product of L-arginine production by Corynebacterium glutamicum. In this study, C. glutamicum was engineered for overproduction of L-citrulline as major product without L-arginine being produced as by-product. To this end, L-arginine biosynthesis was derepressed by deletion of the arginine repressor gene argR and conversion of L-citrulline towards L-arginine was avoided by deletion of the argininosuccinate synthetase gene argG. Moreover, to facilitate L-citrulline production the gene encoding a feedback resistant N-acetyl L-glutamate kinase argBfbr as well as the gene encoding L-ornithine carbamoylphosphate transferase argF were overexpressed. The resulting strain accumulated 44.1 ± 0.5 mM L-citrulline from glucose minimal medium with a yield of 0.38 ± 0.01 g⋅g−1 and a volumetric productivity of 0.32 ± 0.01 g⋅l−1⋅h−1. In addition, production of L-citrulline from the alternative carbon sources starch, xylose, and glucosamine could be demonstrated.