Growth and lipid accumulation in response to different cultivation temperatures in Nannochloropsis oculata for biodiesel production

Background: Microalgal lipid is a promising feedstock for biodiesel production. The aim of the present study was to investigate the effects of cultivation temperature on the growth and lipid accumulation properties of Nannochloropsis oculata microalgae. Methods: Nannochloropsis oculatacan grow in a wide range of temperatures (5 ~ 35°C). Late in the stationary growth phase of microalgae, biomass production and lipid accumulation were measured. The methanol-chloroform extraction method was used to extract total lipids from dried cells. The direct esterification method was used to measure fatty acids. Constituents were identified by gas chromatography. Results: The results show that the maximum specific growth rate at 20°C was 0.1569 day-1, and the maximum biomass production of microalgae at 25°C was 2.2667 g/L. The highest percentage of biomass conversion into lipid (35.71%) occurred at 30°C. Maximum lipid productivity was seen at temperatures of 15°C, 20°C, and 25°C, but the analysis of fatty acids in the three temperatures shownare maximum accumulations of triglycerides in the microalgae cells at 20°C and 25°C. Conclusion: In the cultivation of Nannochloropsis oculata, the optimal temperature range for maximum efficiency in biodiesel production from lipids is 20°C to 25°C.