2.1 Microalgal strain and pre-culture conditions
The marine diatom, Phaeodactylum tricornutum UTEX 646, was obtained from the Microbial Culture Collection at the National Institute for Environmental Studies (NIES) in Tsukuba, Japan. The microalgae were grown in Erlenmeyer flasks (1000 mL) containing 400 mL medium (minimal medium F/2)[33] for 4 days, under a light regime of 16:8 h and an illumination of 30 μmol m−2 s−1 photosynthetically active radiation (PAR) at 24 °C. The F/2 medium was prepared in artificial seawater as described previously[34, 35].