THE CHANGES IN GROWTH AND COMPOSITION OF MARINE MICROALGAE IN RESPONSE TO SODIUM BICARBONATE AND NITROGEN

Abstract

Currently biofuel is produced from plants as well as microbes. The oils, carbohydrates or fats generated by the microorganisms or plants are refined to produce biofuel. Algae can be converted directly into energy and therefore can be a source of renewable energy. In this biofuels research, two marine phytoplankton (Phaeodactylum tricornutum and Nannochloropsis salina) were grown in various sodium bicarbonate (NaHCO3) concentrations (0, 0.5, 1.0, 2.0, 5.0 gL-1) in f/2 medium during the growth phase (GP) and lipid phase (LP). The effects of NaHCO3 levels and N-limitation on growth and biochemical composition of P.tricornutum and N. salina were investigated. The average growth rate in P.tricornutum is 0.102 ± 0.006 d-1 for concentrations of 0.0 to 2.0 g L -1 NaHCO3 except for 5.0 g L-1 which was approximately 0.223 ± 0.013 d-1. Respectively for N. salina, growth rates were generally 0.20 ± 0.006 d -1 for concentrations of 0.0 to 2.0 g L -1 NaHCO3 except for 5.0 g L-1 which was higher around 0.256 ± 0.019 d -1.The relative lipid content, exhibited the highest oil index value in 5.0 g L -1 NaHCO3 for both species in LP but showed variations in lower concentrations which can indicate species-specific responses to changing NaHCO3 conditions. The preliminary findings reveal the importance of considering NaHCO3 as a supplemental C source in the culturing marine phytoplankton in large scale production of biofuels.