A novel and effective two-stage cultivation strategy for enhanced lutein production with Chlorella sorokiniana

Microalgae are currently being recognized as a sustainable resource for valuable products such as pigments for their superior antioxidant activities. Chlorella sorokiniana MB-1-M12 is a lutein-rich mutant capable of growth and lutein production in photoautotrophic, mixotrophic, heterotrophic, and photoheterotrophic metabolism. Despite being capable of heterotrophic growth, light and CO2 were found to be critical for lutein accumulation in MB -1-M12. Thus, an innovative two-stage heterotrophic-mixotrophic process (TSHM) was developed and when performed under optimal conditions, about 10 g/L biomass and 7.42 mg/g lutein were obtained. The integration of fed-batch and semi-batch operational strategies and scale-up in a 5 L bioreactor increased biomass production, lutein content, and lutein production to 20 g/L, 8.71 mg/g, and 181.11 mg/L, respectively. This work demon-strated that the integration of the TSHM process with appropriate operational strategies (the integrated fed-batch and semi-batch operation) enhanced lutein accumulation in MB-1-M12, making it apt for commercial lutein production.