Fruit peels as solid waste feedstock for astaxanthin production using Xanthophyllomyces dendrorhous fermentation

Area of Science:

• Biotechnology and Bioengineering
• Agricultural Science
• Microbial Fermentation

Background:

• Astaxanthin is a valuable carotenoid with significant antioxidant properties and diverse industrial uses.
• Agricultural waste, such as fruit peels, presents an opportunity for sustainable valorization.
• Xanthophyllomyces dendrorhous is a yeast capable of astaxanthin biosynthesis.

Purpose of the Study:

• To investigate the potential of tangerine, pomegranate, and banana peel extracts as cost-effective substrates for astaxanthin production.
• To evaluate the impact of different pretreatment methods (mild heating, boiling, acid hydrolysis) on astaxanthin biosynthesis.
• To assess the effects of peel concentration and light exposure on astaxanthin yield and biomass formation.

Main Methods:

• Fruit peels were pretreated using mild heating (45 °C), boiling, or acid hydrolysis.
• Pretreated peels were used as substrates for astaxanthin biosynthesis by Xanthophyllomyces dendrorhous.
• Fermentation parameters, including peel concentration and light conditions, were optimized.

Main Results:

• Fruit peel extract media significantly outperformed the conventional YM medium for astaxanthin production.
• Mild heating and boiling pretreatments were more efficient than acid hydrolysis.
• Mild heating at 45 °C demonstrated superior, eco-friendly, and cost-effective performance.
• Light exposure positively influenced astaxanthin biosynthesis, while dark conditions favored higher biomass.
• Tangerine peel extract showed particular promise as a substrate.

Conclusions:

• Sustainable and cost-effective astaxanthin production is achievable through the valorization of fruit peel waste.
• Mild, low-energy pretreatment methods, especially mild heating, are effective for enhancing astaxanthin yield.
• Optimizing light exposure and substrate concentration can further improve biosynthesis efficiency.
• This approach offers a promising strategy for the green production of high-value astaxanthin.