Optimization of lutein production with a two-stage mixotrophic cultivation system with Chlorella sorokiniana MB-1

The major purpose of this study was to investigate the effects of operational factors and bioprocess strategies on the mixotrophic cultivation of a microalgae Chlorella sorokiniana MB-1 for lutein production. Aeration with CO₂ showed the highest biomass productivity and lutein productivity of 0.89 g/L/d and 3.49 mg/L/d, respectively. Semi-batch operation performed with 80% medium replacement ratio resulted in the highest biomass productivity and lutein productivity of 1.55 g/L/d and 5.51 mg/L/d, respectively. A two-stage strategy was developed to enhance the biomass production of the MB-1 strain in stage 1 with semi-batch mixotrophic culture and to optimize lutein accumulation in stage 2 under photoautotrophic conditions. The maximum biomass productivity and lutein productivity was 1.98 g/L/d and 7.62 mg/L/d, respectively, with a medium replacement ratio of 80% in stage 1. Compared with batch cultivation, the lutein productivity was enhanced by 32.7% for semi-batch operation alone and 85.9% for the semi-batch-integrated two-stage process.