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Greenhouse gases emitted into the atmosphere by burning of fossil fuels cause global warming. One option is obtaining biodiesel. Nannochloropsis oculata was cultured under different light intensities and reactors at 25°C for 21 days with f/2 medium to assess their effects on cell density, lipid, and fatty acids (FAs). N. oculata improved cell density on fed‐batch glass tubular reactor (7 L) at 200 μmol E m−2 s−1, yielding 3.5 × 108 cells ml−1, followed by fed‐batch Erlenmeyer flask (1 L) at 650 μmol E m−2 s−1 with 1.7 × 108 cells ml−1. The highest total lipid contents (% g lipid × g dry biomass−1) were 44.4 ± 0.8% for the reactor (1 L) at 650 μmol E m−2 s−1 and 35.2 ± 0.2% for the tubular reactor (7 L) at 200 μmol E m−2 s−1, until twice as high compared with the control culture (Erlenmeyer flask 1 L, 80 μmol E m−2 s−1) with 21.2 ± 1%. Comparing the total lipid content at 200 μmol E m−2 s−1, tubular reactor (7 L) and reactor 1 L achieved 35.2 ± 0.2% and 28.3 ± 1%, respectively, indicating the effect of shape reactor. The FAs were affected by high light intensity, decreasing SFAs to 2.5%, and increased monounsaturated fatty acids + polyunsaturated fatty acids to 2.5%. PUFAs (20:5n‐3) and (20:4n‐3) were affected by reactor shape, decreasing by half in the tubular reactor. In the best culture, fed‐batch tubular reactor (7 L) at 200 μmol E m−2 s−1 contains major FAs (16:0; 38.06 ± 0.16%), (16:1n‐7; 30.74 ± 0.58%), and (18:1n‐9; 17.15 ± 0.91%).

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Microalgae are considered sources of compounds of high nutritional value. This study determined whether 400 μE/m2/s (HL) and 80 μE/m2/s (LL) light intensities and algal medium (AM) and f/2 Guillard medium (f/2GM) influence kinetic parameters, moisture, ash, lipids, carbohydrate, protein, amino acid, vitamins contents of the microalgae Nannochloropsis oculata and Porphyridium cruentum. N. oculata recorded the highest cell density of 341.64 ± 2.36 × 106 cells/ml under HL in AM, while P. cruentum achieved 56.60 ± 1.33 × 106 cells/ml under LL in f/2GM. The highest lipids content was 28.66 ± 0.14% for N. oculata, and 13.40 ± 0.25% for P. cruentum, both under LL in f/2GM. The higher carbohydrates content was obtained in AM, 30.41 ± 1.10% at LL and 47.57 ± 1.52% at HL for N. oculata and P. cruentum respectively. The protein content was 34.53 ± 1.33% and 26.03 ± 1.00% both under HL in AM for N. oculata and P. cruentum respectively. In terms of amino acid and vitamins composition, only N. oculata presented high content of essential amino acids and vitamins α‐tocopherol, β‐sitosterol and β‐carotene, based on these results, N. oculata could be recommended as a rich source of lipids, protein, amino acid and vitamin and P. cruentum for their high carbohydrate.