Seasonal variation in the growth, lipid accumulation, and fatty acid composition of Chlorella sp. GN1 cultured in flat plate photobioreactors outdoors

To evaluate the feasibility of producing biodiesel feedstock from Chlorella sp. GN1, the growth, lipid, and fatty acid profile in long-term outdoor cultivation during four seasons were studied. The alga grew well in the four seasons, and the dry weight (2.73 g/L) and specific growth rate (0.652 day−1) reached their highest values in the autumn. Nitrogen deficiency induced all the lipid contents to exceed 40% of the dry weight in the four seasons, and higher lipid contents (> 50% of the dry cell weight) were achieved in autumn and summer. The highest lipid content (52.8%) was acquired in autumn. Additionally, in the four seasons, C16 and C18 were primary fatty acids (> 90%) in the alga, which were ideal fatty acid components for biodiesel. Moreover, more saturated fatty acids were synthesized in cells during summer and autumn, while the proportion of polyunsaturated fatty acids reached the highest level in the winter. The study indicated that the alga has great prospects for biodiesel feedstock preparation.