Fucoxanthin and eicosapentaenoic acid (EPA) provide significant health benefits for human population. Diatom is a potential natural livestock for the combined production of EPA and fucoxanthin. In this study, first, the effects of three important parameters including light intensity, nitrogen concentration and salinity were evaluated for the production of EPA and fucoxanthin in two diatom strains Phaeodactylum tricornutum and Cylindrotheca fusiformis. And then, two steps method based on light intensity were applied to produce EPA and fucoxanthin in large scale. Higher light intensity was first adopted for the high growth rate and lipid content of diatom, and after a period of time, light intensity was lowered to enhance the accumulation of fucoxanthin and EPA. In final, the highest EPA yields were 62.55 and 27.32 mg L for P. tricornutum and C. fusiformis, and the fucoxanthin yield reached 8.32 and 6.05 mg L, respectively.

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h i g h l i g h t sHeterotrophic ability of microalgae Tribonema minus was identified for the first time. Glucose and urea were the optimal sources for heterotrophic fermentation of T. minus. Heterotrophic fermentation and high valuable co-product producing are thought to be effective ways to improve the economic viability and feasibility of commercial production of microalgae biofuels. This work reported the heterotrophic cultivation of Tribonema minus for lipid and palmitoleic acid (a novel functional fatty acid) production. Firstly, the heterotrophic ability of T. minus was identified for the first time with significant promotion in biomass and lipid productivity, and glucose and urea were then selected as the optimal carbon and nitrogen sources. Moreover, nutrient concentrations and culture conditions were optimized. Highest biomass and lipid productivity of 30.8 g L À1 and 730 mg L À1 d À1 were obtained respectively by adding 80 g L À1 glucose at once. In addition, 2 g L À1 urea, 0.8 g L À1 K 2 HPO 4 , 24 mg L À1 ammonium ferric citrate, initial pH of 6, and temperature of 27°C were determined as the appropriate conditions for heterotrophic growth and lipid production.