Fig. 1.

Overview of culture parameters during six-months repeated-batch cultivation of three Phaeodactylum tricornutum strains (Fito, M28, B58) in flat panel outdoor bioreactors in Bergen, western Norway. A: Biomass dry weight (DW) and B: Photosystem II efficiency of dark-adapted samples (Φ_max, maximum quantum yield) during fifteen repeated batches. Data show average and standard deviation of measurement replicates (n = 3) from one biological batch. C: Daily-integrated irradiance (E) of photosynthetically active radiation (PAR) measured on the reactor surface, and day length. D: Daily average, minimum and maximum temperature inside the cultivation chambers. The three grey bars indicate interruptions of the cultivation process. After interruption (1) and (3), the position of the strains was rotated, and after (2) and (3), the panels were re-inoculated with backup cultures. Grey dotted vertical lines in (B) indicate dilution of the cultures with consequent decrease in biomass concentration (A). Black dotted lines mark the division of the cultivation period into three seasons; spring, summer and autumn.