Effect of commercial NPK fertilizer on growth and biomass of Navicula sp. and Nannochloropsis sp

Abstract

Microalgae as a source of biodiesel precursor are promising by pointing out several advantages of its cultivation, such as able to be cultivated in non-arable land, high growth rate with high biomass yield, high lipid content, and renewable. Mass cultivation of microalgae requires large amount of nutrients which makes it economically impractical. To overcome this problem, an alternative medium which contains cheaper nutrients sources should be addressed. In this research, the growth and biomass productivity of Navicula sp. and Nannochloropsis sp. were compared in the commonly used F/2 medium and modified medium containing commercial NPK fertilizer. The results indicated that Navicula sp. and Nannochloropsis sp. can thrive in modified F/2-NPK medium under continuous illumination, while NPK-only medium didn’t show any significant increase in growth and biomass accumulation for both strains compared to initial cell inoculation. Cell optical density at 750 nm and biomass dry weight of 80% F/2 and 50% F/2 medium were comparable to that in F/2 control medium for both strains, indicating that Navicula sp. and Nannochloropsis sp. have a similar requirement for nutrients types. Furthermore, higher specific growth rate of Nannochloropsis sp. than Navicula sp. seen in both modified medium showed its favorable condition for growth.