Measurement of ROS in Microalgae

During the experiments, the maximum Fv/Fm (maximum photochemical yield) was measured using a PAM 2500 fluorometer, as described in [36 (link)]. ROS levels in G. emersonii cells were detected using an ROS assay kit (S0033S, Beyotime, China). Briefly, 5 mL of mixed cell culture was centrifuged at 5000× g for 5 min, and the cell pellets were resuspended in 1 mL basal medium containing 10 μM DCFH-DA. The suspension was incubated in the dark at 37 °C for 30 min. After labeling, the cells were washed three times with basal medium and resuspended in the original culture medium. Subsequently, the cell suspension was transferred to each well of a black microtiter plate (Greiner Bio, Chimney well, Germany). Fluorescence was analyzed using a fluorescence microplate reader (TECAN, M200 PRO) with excitation and emission wavelengths of 488 and 525 nm, respectively. For each treatment and control, three replicates were performed.