Abstract:The content of fatty acids in microalgae was directly related to its application value, and the the environmental factors had a significant effect on the content of fatty acids in microalgae.,In this study, cell density, dry weight concentration and fatty acid content were used as the evaluation indexes to investigate the rules of outdoor growth and fatty acid accumulation of Phaeodactylum tricornutum under different environmental factors such as salinity (20‰, 25‰, 30‰), pH value (7.5, 8.0, 8.5) and nitrogen source (urea, ammonium bicarbonate). The results showed that the growth rate of P. tricornutum slowed down with the increase of salinity in culture medium. The maximum biomass (177.78 mg/g) was obtained under the condition of 20‰ salinity and the maximum fatty acid content was 123.99 mg/g under the condition of 30‰ salinity. In addition, the biomass and fatty acid content of P. tricornutum reached the maximum (166.39 mg/L and 145.92 mg/g, respectively) at pH 8.0, and the growth of P. tricornutum was inhibited at pH 7.5. The urea, used as nitrogen source, was more suitable than ammonium bicarbonate for the growth of P. tricornutum and the final biomass was 150.83 mg/L. Compared to urea, the ammonium bicarbonate was more advantageous for the accumulation of fatty acid, and the fatty acid content was 169.72 mg/g. Consequently, the optimum conditions for P. tricornutum were as follows: salinity, 20‰; pH, 8.0; , nitrogen source ,urea.
