Enhancement of β-Alanine Biosynthesis in Escherichia coli Based on Multivariate Modular Metabolic Engineering

Abstract

β-alanine is widely used as an intermediate in industrial production. However, the low production of microbial cell factories limits its further application. Here, to improve the biosynthesis production of β-alanine in Escherichia coli, multivariate modular metabolic engineering was recruited to manipulate the β-alanine biosynthesis pathway through keeping the balance of metabolic flux among the whole metabolic network. The β-alanine biosynthesis pathway was separated into three modules: the β-alanine biosynthesis module, TCA module, and glycolysis module. Global regulation was performed throughout the entire β-alanine biosynthesis pathway rationally and systematically by optimizing metabolic flux, overcoming metabolic bottlenecks and weakening branch pathways. As a result, metabolic flux was channeled in the direction of β-alanine biosynthesis without huge metabolic burden, and 37.9 g/L β-alanine was generated by engineered Escherichia coli strain B0016-07 in fed-batch fermentation. This study was meaningful to the synthetic biology of β-alanine industrial production.

Biosynthesis of 1,3-Propanediol via a New Pathway from Glucose in Escherichia coli

“…When overexpressing aspA with the constitutive promoter, J23119, in module II, the strain B06-1 produced 735.2 mg/L 1,3-PDO (Figure 4B), which was higher than that controlled by the tac promoter (strain B06-2) because the constitutive promoter could balance the growth and enzyme expression at the same time. Furthermore, to supply more fumaric acid, the tricarboxylic acid (TCA) cycle was activated by deleting related genes such as glyoxalate circulating transcriptional repressor (iclR), glucose-specific EICB components in the phosphotransferase system (ptsG), 27 and fumarate hydratase (f umAC, fumB). 28 However, the production was not boosted as expected (Supporting Figure 3).…”