Sequential Optimization of Biomass and Lutein Production by <i>Dictyosphaerium</i> sp. HT3

ABSTRACT Microalgae‐synthesized lutein has been received considerable attention in scientific research community. Although several microalgae have recently identified as hyper‐lutein accumulators, further discovery of new microalgae strain owning an outstanding capability in lutein production is necessarily for diversification of large‐scale cultivations. In this work, critical factors, for example, carbon, nitrogen source, and light intensity affecting growth and lutein accumulation by a newly isolate microalgal Dictyosphaerium sp. HT3, were investigated. In particular, biomass and lutein production by Dictyosphaerium sp. HT3 under mixotrophic cultivation were optimized via a sequential process of single‐factor investigation, followed by response surface methodology. The obtained results displayed that Dictyosphaerium sp. HT3 achieved the optimal growth under mixotrophic cultivation in BG‐11 medium with glucose of 8.6–9.2 g/L, sodium nitrate of 1.63–2.1 g/L, light intensity of 240–290 μmol photons m −2 s −1 , aeration rate of 0.1 vvm, and 25°C, achieving the maximal dry biomass of 4.25–4.67 g/L and the highest lutein content of 17.06–18.95 mg/g. The one‐stage cultivation and optimization developed in this study are superior to two‐stage processes for microalgal lutein production reported in the literature. Our trial investigation demonstrated that Dictyosphaerium sp. HT3 holds a promising potential for scaling‐up production of both biomass and lutein via mixotrophic cultivation.