Vitamin E (α-tocopherol) production by the marine microalgae Nannochloropsis oculata (Eustigmatophyceae) in nitrogen limitation

Effects of nitrogen (N) sources and their concentration on the accumulation of α-tocopherol of Nannochloropsis oculata (Eustigmatophyceae) were examined. Sodium nitrate and ammonium chloride were used as inorganic nitrogen sources at the concentrations of 882 μmol l− 1 and in half the strength of F/2 medium in N. Maximum content of α-tocopherol was 2325.8 ± 39 μg g− 1 dry weight (DW) in NO3−-N in the medium. N. oculata grew rapidly at 882 μmol l− 1 concentration of NO3−-N and NH4+-N in the medium and maximum cell numbers were obtained as 5.2 ± 0.3 × 107 cells ml− 1 and 4.9 ± 0.1 × 107 cells ml− 1, respectively. The research showed that decreasing N concentrations led to an increase in α-tocopherol accumulation, but reduced growth rate. Significant differences in the α-tocopherol content of N. oculata were found to be dependant on factors such as; N source, concentration and growth phase.