Journal
FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY
Volume 9, Issue -, Pages -Publisher
FRONTIERS MEDIA SA
DOI: 10.3389/fbioe.2021.808258
Keywords
3-hydroxypropionic acid; acetate; Corynebacterium glutamicum; metabolomics analysis; fed-batch fermentation; metabolic engineering; malonyl-CoA pathway
Funding
- National Natural Science Foundation of China [NSFC-21776208, NSFC-21621004]
- Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project [TSBICIP-PTJS-001]
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This study explored the potential of using Corynebacterium glutamicum as a host to produce 3-hydroxypropionic acid (3-HP) from acetate. Through optimizing enzyme expression and metabolic pathways, the production yield and titer of 3-HP were successfully increased.
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.
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