Enhanced 3-Hydroxypropionic Acid Production From Acetate via the Malonyl-CoA Pathway in Corynebacterium glutamicum

Abstract

Acetate is an economical and environmental-friendly alternative carbon source. Herein, the potential of harnessing Corynebacterium glutamicum as a host to produce 3-hydroxypropionic acid (3-HP) from acetate was explored. First, the expression level of malonyl-CoA reductase from Chloroflexus aurantiacus was optimized through several strategies, strain Cgz2/sod-N-C* showed an MCR enzyme activity of 63 nmol/mg/min and a 3-HP titer of 0.66 g/L in flasks. Next, the expression of citrate synthase in Cgz2/sod-N-C* was weakened to reduce the acetyl-CoA consumption in the TCA cycle, and the resulting strain Cgz12/sod-N-C* produced 2.39 g/L 3-HP from 9.32 g/L acetate. However, the subsequent deregulation of the expression of acetyl-CoA carboxylase genes in Cgz12/sod-N-C* resulted in an increased accumulation of intracellular fatty acids, instead of 3-HP. Accordingly, cerulenin was used to inhibit fatty acid synthesis in Cgz14/sod-N-C*, and its 3-HP titer was further increased to 4.26 g/L, with a yield of 0.50 g 3-HP/g-acetate. Finally, the engineered strain accumulated 17.1 g/L 3-HP in a bioreactor without cerulenin addition, representing the highest titer achieved using acetate as substrate. The results demonstrated that Corynebacterium glutamicum is a promising host for 3-HP production from acetate.

Metabolic engineering of Corynebacterium glutamicum for efficient production of optically pure (2R,3R)-2,3-butanediol

“…The resulting fragment was digested with Sda I/ Sal I and ligated between the corresponding sites of pD-sacB- ldh . AAAGGAGGACAACC was used as RBS sequence in plasmid pD- ldh- A1, which was used in our previous studies [ 51 ]. The plasmids pD- ldh- A2 and pD- ldh- AU were constructed analogously to integrate the P sod - bdhA and P sod - bdhA-udhA into the chromosome respectively.…”

Production of 3-Hydroxypropionic Acid from Renewable Substrates by Metabolically Engineered Microorganisms: A Review

“…Notably, it is important to balance the TCA cycle and the pathway for 3-HP production, since the whole process from acetate to 3-HP requires the provision of additional reducing power and energy. Chang et al [ 47 ] achieved a balance between the TCA cycle and 3-HP synthesis by regulating the expression of citrate synthase, and the engineered C. glutamicum produced the highest titer of 3-HP from acetate reported to date, reaching 17.1 g/L.…”

“…Acetate must be maintained at a low concentration when used as substrate for 3-HP synthesis because a high concentration of acetate is toxic to cells. According to Chang et al [ 47 ], the initial concentration of acetate was only 1.4 g/L in fed-batch fermentation for the synthesis of 3-HP from acetate by engineered E. coli . A sugar-limited fed-batch fermentation that maintains basal levels of glucose and xylose in the medium was designed for 3-HP synthesis by engineered E. coli via the glycerol pathway, because high concentrations of glucose and xylose would prevent the efficient conversion of glycerol to 3-HP [ 69 ].…”

The Potential of Sequential Fermentations in Converting C1 Substrates to Higher-Value Products

“…Among the products obtained from microbial conversion of acetate listed in the reviews cited above are organic acids (malic, succinic and itaconic acid and 3-HP), long-chain alcohols (isobutanol, isopropanol), hydroxyalkanoates (PHB, PHA), lipids (long-chain triacylglycerols, rhamnolipids) and proteins. Very recently, also recombinant C. glutamicum strains have been reported to produce 3-HP to concentrations of up to 17.1 g L −1 (Chang et al, 2022) and itaconic acid with titers of 29 g L −1 from acetate as sole carbon source (Merkel et al, 2022), the latter using an integrated pH-coupled feeding control.…”