Figure 5.

Photosynthetic rates and photoinhibition are similar between wild-type and hydrocarbon-deficient mutants. A and B, Oxygen evolution was measured at different light intensities in Synechocystis (A) and Synechococcus (B) to examine photosynthesis. The maximum photosynthetic rate of wild-type Synechocystis, ΔFAR, and ΔFAR:comp was 0.311 ± 0.025, 0.329 ± 0.024, and 0.299 ± 0.028 µmol O₂ nmol Chl⁻¹ h⁻¹, respectively, and of wild-type Synechococcus and ΔOls was 0.283 ± 0.03 and 0.303 ± 0.018 µmol O₂ nmol Chl⁻¹ h⁻¹, respectively. C and D, Respiration was determined by measuring oxygen consumption following each light period in Synechocystis (C) and Synechococcus (D). The average oxygen consumption rate following dark periods after 95 µmol photons m⁻² s⁻¹ of wild-type Synechocystis, ΔFAR, and ΔFAR:comp was 0.041 ± 0.008, 0.083 ± 0.006, and 0.043 ± 0.01 µmol O₂ nmol Chl⁻¹ h⁻¹, respectively, and of wild-type Synechococcus and ΔOls was 0.027 ± 0.005 and 0.027 ± 0.007 µmol O₂ nmol Chl⁻¹ h⁻¹, respectively. E and F, Photoinhibition was determined by measuring oxygen evolution at a light intensity of 2000 µmol photons m⁻² s⁻¹ in Synechocystis (E) and 3000 µmol photons m⁻² s⁻¹ in Synechococcus (F). All results are from six to nine separate biological replicates. Errors bars indicate sd. Asterisks indicate significant differences between wild-type and hydrocarbon-deficient samples (Student’s paired t test: P < 0.05).