Modulation of the central carbon metabolism of Corynebacterium glutamicum improves malonyl‐CoA availability and increases plant polyphenol synthesis

Abstract

In recent years microorganisms have been engineered towards synthesizing interesting plant polyphenols such as flavonoids and stilbenes from glucose. Currently, the low endogenous supply of malonyl-CoA, indispensable for plant polyphenol synthesis, impedes high product titers. Usually, limited malonyl-CoA availability during plant polyphenol production is avoided by supplementing fatty acid synthesis-inhibiting antibiotics such as cerulenin, which are known to increase the intracellular malonyl-CoA pool as a side effect. Motivated by the goal of microbial polyphenol synthesis being independent of such expensive additives, we used rational metabolic engineering approaches to modulate regulation of fatty acid synthesis and flux into the tricarboxylic acid cycle (TCA cycle) in Corynebacterium glutamicum strains capable of flavonoid and stilbene synthesis. Initial experiments showed that sole overexpression of genes coding for the native malonyl-CoA-forming acetyl-CoA carboxylase is not sufficient for increasing polyphenol production in C. glutamicum. Hence, the intracellular acetyl-CoA availability was also increased by reducing the flux into the TCA cycle through reduction of citrate synthase activity. In defined cultivation medium, the constructed C.glutamicum strains accumulated 24 mg·L −1 (0.088 mM) naringenin or 112 mg·L −1 (0.49 mM) resveratrol from glucose without supplementation of phenylpropanoid precursor molecules or any inhibitors of fatty acid synthesis. K E Y W O R D Scitrate synthase, Corynebacterium glutamicum, malonyl-CoA, naringenin, polyphenols, resveratrol

Expanding targeting scope, editing window, and base transition capability of base editing in Corynebacterium glutamicum

“…Corynebacterium glutamicum is an essential pillar of white biotechnology as well as one of the best studied model organisms (Becker, Rohles, & Wittmann, ; Milke et al, ; Perez‐Garcia & Wendisch, ). Due to its good genomic stability and low homologous recombination efficiency, even CRISPR/Cas‐mediated genome editing method was not efficient enough to measure up to the high throughput requirement of developing a desired strain (J. Liu et al, ).…”

Recent Advances in Metabolically Engineered Microorganisms for the Production of Aromatic Chemicals Derived From Aromatic Amino Acids

“…The final strain produced 59 mg/L of resveratrol from glucose in the presence of 25 µM of cerulenin in shake flask cultures (Kallscheuer et al, 2016). Then, this group found that increasing the intracellular acetyl-CoA availability through the reduction of citrate synthase activity further improved the production of resveratrol to 112 mg/L (Milke et al, 2019). A RppA-coupled malonyl-CoA biosensor was developed for high-throughput screening of targets increasing the malonyl-CoA pool (Yang et al, 2018).…”

Engineering central pathways for industrial-level (3R)-acetoin biosynthesis in Corynebacterium glutamicum

“…Therefore, a reduction rather than inactivation of CS activity was preferable. Moreover, regulation of the gltA gene, which is responsible for 95% of CS activity in C. glutamicum [42], was widely applied to improve the biosynthesis of pyruvate-derived products [34,[43][44][45]. However, the impact of reducing CS activity on acetoin production is still unclear.…”