Development of a 2-hydroxyglutarate production system by Corynebacterium glutamicum.

Area of Science:

• Metabolic Engineering
• Synthetic Biology
• Biotechnology

Background:

• 2-Oxoglutarate (2-OG) is a key metabolic intermediate with potential for producing valuable compounds.
• Limited research exists on fermentative production of 2-OG derivatives beyond glutamate.
• Developing efficient microbial production systems for 2-OG derivatives is crucial for industrial applications.

Purpose of the Study:

• To establish an efficient microbial cell factory for 2-hydroxyglutarate (2-HG) production using Corynebacterium glutamicum.
• To identify optimal fermentation conditions for 2-OG accumulation and subsequent 2-HG synthesis.
• To investigate the export mechanism of 2-HG in the engineered strain.

Main Methods:

• Construction of a D3 strain of Corynebacterium glutamicum lacking specific NADH-consuming enzymes and isocitrate lyase.
• Optimization of aerobic growth conditions, specifically biotin- and nitrogen-limited (B/N-limited) media, to induce 2-OG accumulation.
• Overexpression of the Acidaminococcus fermentans hgdH gene encoding 2-HG dehydrogenase using a strong constitutive promoter.

Main Results:

• The engineered Corynebacterium glutamicum strain achieved a 2-HG titer of 80.1 mM and a yield of 0.390 mol/mol glucose.
• Biotin- and nitrogen-limited aerobic growth conditions were identified as optimal for 2-OG accumulation.
• Reverse genetics indicated that the YggB protein (a mechanosensitive channel) facilitates partial export of the produced 2-HG.

Conclusions:

• An efficient 2-HG production system was successfully developed in Corynebacterium glutamicum.
• Specific B/N-limited aerobic growth conditions are critical for inducing 2-OG accumulation and subsequent 2-HG production.
• The YggB protein plays a role in the extracellular export of 2-HG, offering insights for further strain improvement.