Fig. 3: Phenotypical differences between nirP1 mutant strains and the wild type in BG11 medium.

a Growth of wild type (black), the ΔnirP1 deletion mutant (red), and the strains expressing nirP1 under control of the P_petE promoter in the wild-type background (dark blue, NirP1oex) and ΔnirP1 background (light blue, ΔnirP1::oex). Data points represent the mean ± SD of 3 biological replicates (n = 3; details with growth rates and doubling time are provided in Supplementary Dataset 4). b Growth in liquid medium after shifting to LC conditions. Strains were cultivated for 2 h in medium containing 10 mM NaHCO₃, collected, and transferred to medium without a C_i source. The complementation strain (orange, ΔnirP1::nirP1) expressed nirP1 under the control of its native P_nirP1 promoter in the ΔnirP1 background. Other strains as in (a); n = 3. c Pigmentation phenotype of wild-type and nirP1 overexpressors in the presence of Cu₂SO₄ expressing nirP1 for 24 h. All cultures were set to an OD of ~0.8. d Room temperature absorption spectra for wild-type and nirP1 mutants expressing nirP1 for 24 h from the P_petE promoter in the presence of Cu₂SO₄, normalized to wild-type OD₇₅₀. Same strains and colors as in (a). Spectra were recorded from three biological replicates and averaged (n = 3). Further phenotypical differences in Supplementary Figs. S4 and S5.