Optimized Production Astaxanthin on Sugarcane molasses by X. dendrorhous in 3-LBioreactor

Astaxanthin, a high-value xanthophyll carotenoid with potent antioxidant properties, has garnered significant interest in nutraceutical and pharmaceutical industries. Xanthophyllomyces dendrorhous is a promising microbial source for astaxanthin biosynthesis; however, its industrial application is often constrained by suboptimal yields and high production costs. In this study, central composite design with 20 run was used to optimize process parameters of glucose concentration (7–13 g/L), yeast extract (1.5–4.5 g/L), and initial pH (5.5–7.5) in shake flask cultures. The optimized conditions (7 g/L glucose, 1.5 g/L yeast extract, pH 5.5) led to a 1.7-fold increase in astaxanthin production, with maximum biomass yields of 14.20 g/L (wet) and 4.139 g/L (dry). The regression model showed high predictive accuracy (R² = 0.9741; F = 41.78). To further reduce production costs, alternative carbon sources, including sodium acetate, sodium citrate, and sugarcane molasses (10 g/L), were evaluated. sugarcane molasses supported pigment yields comparable to glucose-based media while substantially lowering media costs. Among four extraction methods tested, DMSO-based extraction demonstrated the highest recovery efficiency. The extracted pigment exhibited 96% DPPH radical scavenging activity, indicating strong antioxidant potential. Results were validated in a 3-L bioreactor (at 22–25 °C, 120 rpm, 4 L/min aeration, and initial pH 5.5), confirming process scalability. These findings demonstrate that integrating medium optimization and low-cost substrates represents a viable and scalable strategy for enhanced microbial astaxanthin production in biotechnological applications.