Systems metabolic engineering of Corynebacterium glutamicum for high-level production of β-alanine

Abstract

β-Alanine is an important beta-amino acid with a growing demand, especially in the fine chemical and pharmaceutical industries. Most of the current industrial production of β-alanine relies on chemical synthesis, which usually utilizes harmful raw materials and harsh operational conditions, causing the final product difficult to meet safety requirements for human use. Thus, alternative routes of β-alanine production are highly desirable to enhance both workplace safety and environmental sustainability. In this study, we constructed an efficient cell factory of Corynebacterium glutamicum for high-level β-alanine production through systems metabolic engineering that involved genome-scale metabolic simulations and extensive genome engineering. First, various L-aspartate-α-decarboxylases (ADCs) from different bacteria were screened to select the best enzymes for the β-alanine biosynthesis in C. glutamicum. Next, enhancement of glucose uptake system and anaplerotic pathway as well as attenuation of TCA cycle were implemented in accordance with prediction results from the genome-scale metabolic simulation. Furthermore, a novel β-alanine exporter was identified and overexpressed. These systems metabolic engineering strategies generated a strain that could produce 166.6 g/L of β-alanine with 1.74 g/L/h productivity from fed-batch fermentation, the highest titer and productivity ever reported. This work presents a promising result for high-titer production of β-alanine using recombinant C. glutamicum on the basis of systems metabolic engineering strategies.