2.1. Strains and preculture conditions
Four species of microalgae, I. galbana, N. oculata, D. salina, and D. tertiolecta, were obtained from NLP Corp. (Busan, Korea). After preculture in a 1-L flask, the microalgae were cultivated at 20 ± 1 C at a light intensity of 108.9 mmol photon/m2/s in a 5-L circular cylindrical photobioreactor with a working volume of 3 L using f/2 medium, as described by Guillard and Ryther [20]. Aeration with filtered air was provided through an air stone at a rate of 2.5 L/min.
All cultures were carried out with a 12/12-h light/dark cycle.