Production of Glutamate and Glutamate-Related Amino Acids: Molecular Mechanism Analysis and Metabolic Engineering

Abstract

Glutamate production is a typical success in industrial fermentation. Annual production of glutamate by Corynebacterium glutamicum is over 1.5 million tons per year worldwide. It is well known that there are some triggers of glutamate overproduc- tion by C. glutamicum: depletion of biotin, which is required for cell growth; addition of detergent; addition of β-lactam antibiotics such as penicillin; and addition of etham- butol or cerulenin. A marked change in metabolic pathways occurs after glutamate overproduction is triggered. In this chapter, recent studies on the molecular mechanisms of glutamate production are described with a particular focus on triggering mechan- isms, changes in key enzyme activities, and secretion of glutamate. Recent advances in genome-wide studies, including genomics, proteomics, metabolomics, and on metabolic flux analysis of flux redistribution during glutamate overproduction are discussed as well. The biosynthesis of the related amino acids glutamine and proline and strategies for their overproduction are also described.