Effects of sodium bicarbonate supplementation on lipid accumulation of Chlorella sp. cultivated in artificial medium.

Microalgae are promising sources for biofuels, food products, and secondary metabolites for pharmaceutical purposes. Chlorella sp. is one of the microalgae strains known to have relatively high lipid and protein, carbohydrates, and a wide range of secondary metabolites. However, high operation costs and relatively low biomass production are challenges in the mass cultivation of this microalgae. In this study, the effect of sodium bicarbonate on Chlorella sp.'s growth, including biomass, lipid and carbohydrate content, and fatty acid compositions, was studied under the combination of urea and Walne nutrient as the cultivation medium. In the batch cultivation method, sodium bicarbonate in the concentration of 1.0, 2.5, and 5.0 g/L was supplemented to the culture with continuous illumination and constant aeration. The control sample was treated using the same medium without sodium bicarbonate supplementation. As a result, the addition of sodium bicarbonate for all concentrations significantly affected the growth profile of Chlorella sp., shown by its cell and biomass productivity compared to the control culture without sodium bicarbonate (p<0.05). The microalgae cultivation with 1.0 g/L sodium bicarbonate had the highest biomass density, reaching 0.7600±0.0278 g/L and 0.1623±0.0020 specific growth rate. Fatty acid compositions of microalgae oil from Chlorella sp. supplemented with sodium bicarbonate were found to be dominated by unsaturated fatty acid from C14-C20, with linoleic acid in the highest FAME percentage (23.43%). In a comparison, fatty acids of microalgae oil from the control culture were mainly composed of saturated fatty acid, with palmitic acid in the highest concentration (21.91%). From these results, microalgae oil extracted from wet biomass of Chlorella sp. grown in sodium bicarbonate has more potential to be essential lipids that can be consumed as a food supplement. [ABSTRACT FROM AUTHOR]