Response surface-based media optimization for astaxanthin production in Corynebacterium glutamicum.

Area of Science:

• Biotechnology
• Microbial Engineering
• Carotenoid Production

Background:

• Astaxanthin, a C40 carotenoid, possesses potent antioxidant properties valuable in cosmetics and animal feed.
• Current commercial astaxanthin is predominantly chemically synthesized, driving demand for natural, sustainable alternatives.
• Corynebacterium glutamicum is a well-established industrial host for large-scale bioproduction.

Purpose of the Study:

• To optimize astaxanthin production in engineered Corynebacterium glutamicum.
• To identify key medium components influencing astaxanthin yield.
• To enhance sustainable production of natural astaxanthin.

Main Methods:

• A design of experiment (DoE) approach was employed to optimize the minimal medium composition.
• Concentrations of carbon, nitrogen, phosphorus, magnesium, calcium, iron chelator (protocatechuic acid), biotin, and trace metals were systematically varied.
• Astaxanthin production was evaluated under optimized conditions in microcultivation and fed-batch fermentation systems.

Main Results:

• Optimized medium composition led to a significant increase in astaxanthin titers.
• Increasing iron concentration and decreasing manganese concentration were identified as critical factors.
• Astaxanthin yields improved from 7.9–39.6 mg/L in microcultivation and 62–176 mg/L in fed-batch fermentation.

Conclusions:

• The study successfully enhanced astaxanthin production in Corynebacterium glutamicum through medium optimization.
• Specific adjustments in iron and manganese levels are crucial for maximizing astaxanthin biosynthesis.
• This work contributes to the development of sustainable, microbial-based production of natural astaxanthin.