Quantifying Microalgal Biomass Compounds

Fatty acids were derivatized, identified, and quantified by gas chromatography and flame ionization detection (Thermo Trace 1300 GC, Thermo Fischer Scientific) according to Remias et al. (2020) (link). Carotenoids, chlorophylls, and alpha-tocopherol were extracted with methyl tert-butyl ether and quantified by HPLC with a C30 Carotenoids column (YMC, Willich, Germany) and a diode array detector (Agilent Technologies, Germany) at 450 nm, according to Procházková et al. (2019) (link). The quantitative results were performed in triplicate and the standard derivation (SD) was calculated. Reactor biomass yield (productivity) of a compound class was expressed in dry mass produced per day and liter reactor volume [mg day⁻¹ L⁻¹], neglecting the minor starting biomass of the inoculum. The yields of the stress phase were calculated in the same manner, however by subtracting the starting biomass and respectively the compound dry weights which were already present in the reactors at the start of the stress phase.