Two-stage bioprocess for hyper-production of lutein from microalga Chlorella sorokiniana FZU60: Effects of temperature, light intensity, and operation strategies

Lutein is a metabolite produced by plants or microalgae, and offers various health benefits. Chlorella sorokiniana FZU60 is considered a hyper-lutein producing microalga. In this study, the effects of temperature and light intensity on cell growth and lutein accumulation by FZU60 under mixotrophic conditions were investigated. Maximal lutein productivity and production were obtained at 33 degrees C, and high light intensity enhanced cell concentration but decreased lutein content when nitrate was replete. Further, two fed-batch strategies with gradient (fed-batch strategy I) or constant (fed-batch strategy II) NaAc feeding concentrations were compared. Results showed that the second strategy was more desirable for lutein production. Moreover, two types of mixotrophy/photoautotrophy two-stage strategies with a light intensity of 750 mu mol/m(2)/s (two-stage strategy I) or 150 mu mol/m(2)/s (two-stage strategy II) in stage 2 were explored. Under the two-stage strategy I, high lutein content (11.22 mg/g), productivity (8.25 mg/L/d), and production (65.96 mg/L) were achieved. The lutein content, productivity, and production obtained in this study are higher than those reported in most related studies, indicating that the proposed strategy can be used in commercial production.