High-efficiency production of 5-hydroxyectoine using metabolically engineered Corynebacterium glutamicum

Area of Science:

• Biotechnology
• Metabolic Engineering
• Microbial Production

Background:

• Extremolytes are microbial compounds with protective properties, valuable for cosmetics and pharmaceuticals.
• Ectoine is a commercial extremolyte, but its derivative 5-hydroxyectoine (hydroxyectoine) lacks an economically viable production route.

Purpose of the Study:

• To establish a cost-effective method for producing hydroxyectoine.
• To engineer Corynebacterium glutamicum for efficient hydroxyectoine synthesis.

Main Methods:

• Metabolically engineered C. glutamicum strains expressing codon-optimized heterologous ectD genes.
• Utilized sucrose as a growth substrate for ectoine conversion to hydroxyectoine.
• Screened 16 ectD variants from diverse microbial donors.

Main Results:

• Hydroxyectoine production achieved up to 97% yield using ectD genes from Pseudomonas stutzeri (PST) and Mycobacterium smegmatis (MSM).
• Engineered C. glutamicum Ptuf ectD^PST reached 74 g L^-1 hydroxyectoine at 70% selectivity within 12 hours.
• Demonstrated a two-step hydroxyectoine production from fermentatively synthesized ectoine without intermediate purification.

Conclusions:

• C. glutamicum is a safe and industrially proven host for hydroxyectoine production, benefiting cosmetic and pharmaceutical applications.
• Using commercially available ectoine as a precursor simplifies hydroxyectoine production.
• Future research may enable de novo hydroxyectoine synthesis from sugar using two-step processes.