Figure 5. Pigment contents and non-photochemical quenching (NPQ) of the wild-type strain and the two mutants (PTS23 and PTS42) according to different light conditions.

Cells were grown photoautotrophically in low (50 μmol photons m^-2s^-1) and high (300 μmol photons m^-2s^-1) light. (a) Chlorophyll contents (per cell), chlorophyll a/b ratio, chlorophyll/carotenoid ratio contents (b) Pictures showing flask cultures of the wild-type strain and the two mutants grown in low (50 μmol photons m^-2s^-1, upper image) and high (300 μmol photons m^-2s^-1, lower image) light. All cultures were adjusted to the same cell density (1 × 10⁷cells/ml). (c) NPQ in the wild-type strain and the two mutants grown in high light (HL, 300 μmol photons m^-2s^-1) and low light (LL, 50 μmol photons m^-2s^-1), indicating less heat dissipation of the selected mutants in high light compared to the wild type. The cells were exposed to an actinic light of 800 μmol photons m^-2s^-1 (white bar) followed by darkness (black bar). Data and errors are mean ± SD of three biological replicates.