High-yield β-alanine production from glucose and acetate in Escherichia coli

Abstract

β-Alanine is a versatile amino acid with wide-range industrial applications, but its production from glucose has been limited by a low yield. This study addresses this challenge by developing efficient Escherichia coli strains with modified carbon metabolism as microbial cell factories and implementing a two-stage fermentation strategy. The introduction of aspartate decarboxylase (PanD^E56S/I88M) facilitates the conversion of aspartate to β-alanine, while the overexpression of key enzymes such as phosphoenolpyruvate carboxylase and aspartate dehydrogenase increases the carbon flow from phosphoenolpyruvate to aspartate. To mitigate oxidative stress, the glutathione cycle was enhanced by overexpressing BtuE and Gor. In a bioreactor, the optimized strain achieved β-alanine production of 71.7 g/L with a yield of 1.0 mol/mol glucose, reaching a peak of 1.29 mol/mol. Notably, the utilization of acetate as a carbon feedstock enabled the production of 50 g/L of β-alanine with a 0.33 mol/mol acetate yield, showcasing the potential for sustainable production. This research offers valuable insights into improving the carbon yield in β-alanine production, which is of great importance for industrial applications.