Effect on Nitrogen, Iron and Temperature on Yield and Composition of Microalgae

Abstract

A laboratory study was conducted to evaluate the response of microalgae Nannochloropsis salina, Chlorella sp., and Pleurochysis carterae to nutrient deficiency and temperature stress. The three species were cultured in three different media- F2 media, K media and Hoagland media, while inducing low and high extreme environmental and nutrient conditions, the response to these treatments reflects in their growth response and fatty acid composition which were compared to the control. Considering response to nitrogen concentration at stationary growth rate, Nannochloropsis sp. and Chlorella sp. had its highest growth rate when cultured in low nitrogen concentration (37.5g/L) in the F2 media, while Pleurochysis carterae did not respond well to nitrogen stress. Nannochloropsis salina. Chlorella sp., Pleurochysis carterae maximum growth rate were at high iron concentration treatment (6.2g/L) in K, H and F2 media respectively. Nannochloropsis salina,and Pleurochysis carterae response to temperature had its highest growth rate at high temp. 32 C in K and F2 media respectively while Chlorella sp at 25 C (control). To assess the effect of different nutrients and temperature treatments on the fatty acid composition, lipid extraction using modified Bligh and Dyer method was conducted. The result shows that fatty acid composition of microalgae required for biofuel production are best cultured at control or required nutrients composition and control temperature of 25 C, culturing at different nutrients and temperature would increase yield of microalgae but the overall fatty acid composition might not be ideal for biofuel production.