T. chui strain CCFM-03 (belonging to the Culture Collection of Fitoplancton Marino, S.L.) is cultured for industrial production of biomass in the facilities of the company Fitoplancton Marino, S.L. For the purpose of this study, 4000 L closed tubular outdoor photobioreactors were sampled. Microalgae cells were grown in seawater with f/2 culture medium [59] throughout the production cycle, including the first indoor stages during culture up-scaling through to outdoor cultures. The composition of f/2 medium was: 8.82 x 10−4 M NaNO3, 3.62 x 10−5 M NaH2PO4·H2O, 1.06 x 10−4 M Na2CO3, 1.17 x 10−5 M FeCl3·6(H2O), 1.17 x 10−5 M Na2(EDTA)·2(H2O), 3.93 x 10−8 M CuSO4·5(H2O), 2.6 x 10−8 M Na2MoO4·2(H2O), 7.65 x 10−8 M ZnSO4·7(H2O), 4.2 x 10−8 M CoCl2·6(H2O), 9.1 x 10−7 M MnCl2·4(H2O), 2.96 x 10−7 M vitamin B1, 2.05 x 10−9 M vitamin H, and 3.69 x 10−10 M vitamin B12. In outdoor cultures, the microalgae were exposed daily to ambient conditions, with temperature and light intensity being probably the most significant parameters that changed (S1 Table). Culture conditions that were strictly controlled included pH (maintained at 7.5–8.5 by on-demand CO2 injections) and nitrate content, which was maintained over 500 μM. Indoor cultures of microalgae were maintained under controlled conditions at 22°C in a thermoregulated room with a photoperiod of 24 h of cool fluorescent white light, and ~150 μmol photons m-2 s-1 of PAR. All microalgae cultures were continuously aerated using compressed air containing 2% CO2.