Role of sodium nitrate concentration in BG-11 medium used for autotrophic growth of Anabaena vaginicola cyanobacterium
Volume Title: 1
Department of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
Because of its multiple applications in biotechnology, in recent years, there has been a considerable focus on cyanobacteria as a nitrogen fixer prokaryote capable of carrying out photosynthesis. Due to the high lipid content present in their thylakoid membranes, cyanobacteria have a considerable potential to be used as a source of raw material in third generation biofuels. The present study was undertaken to characterize the autotrophic growth of Anabaena vaginicola (A. vaginicola) as the cyanobacterium under different concentrations of sodium nitrate. NaNO3 is the main source of nitrogen in BG-11 medium for autotrophic growth of cyanobacteria. By changing the concentration of NaNO3 in the formulation of BG-11 medium, it was found that growth rate constants of the cultures with different initial concentrations of NaNO3 differed significantly from each other, suggesting that the initial NaNO3 concentrations in BG-11 medium can have considerable effects on the growth of A. vaginicola. Absorbance readings for A. vaginicola culture grown in BG-11 media containing 1.875 and 2.25 g/L NaNO3 were highest among seven groups of cultures and expressed highest specific growth rate (0.386 and 0.408 day-1, respectively). BG-11 medium prepared with NaNO3 at the lower level than the original amount of this inorganic salt (25% of 1.5 g/L) was not able to fully support the growth of A. vaginicola culture and the longer exponential phase of growth was with the lower rate constant (0.191 day-1). This growth rate in comparison with the growth in the nitrate-free BG-11 medium (BG-110) was also lower.