Glutaric acid production by systems metabolic engineering of an l-lysine–overproducingCorynebacterium glutamicum

Abstract

There is increasing industrial demand for five-carbon platform chemicals, particularly glutaric acid, a widely used building block chemical for the synthesis of polyesters and polyamides. Here we report the development of an efficient glutaric acid microbial producer by systems metabolic engineering of anl-lysine–overproducingCorynebacterium glutamicumBE strain. Based on our previous study, an optimal synthetic metabolic pathway comprisingPseudomonas putidal-lysine monooxygenase (davB) and 5-aminovaleramide amidohydrolase (davA) genes andC. glutamicum4-aminobutyrate aminotransferase (gabT) and succinate-semialdehyde dehydrogenase (gabD) genes, was introduced into theC. glutamicumBE strain. Through system-wide analyses including genome-scale metabolic simulation, comparative transcriptome analysis, and flux response analysis, 11 target genes to be manipulated were identified and expressed at desired levels to increase the supply of direct precursorl-lysine and reduce precursor loss. A glutaric acid exporter encoded byynfMwas discovered and overexpressed to further enhance glutaric acid production. Fermentation conditions, including oxygen transfer rate, batch-phase glucose level, and nutrient feeding strategy, were optimized for the efficient production of glutaric acid. Fed-batch culture of the final engineered strain produced 105.3 g/L of glutaric acid in 69 h without any byproduct. The strategies of metabolic engineering and fermentation optimization described here will be useful for developing engineered microorganisms for the high-level bio-based production of other chemicals of interest to industry.