Fig. 5: Phototrophy provides a major benefit to Porphyrobacter sp. ULC335 in stationary phase.

A Bchla content at different timepoints during batch culture. The barplots represent the absorbance at 770 nm (Bchla) corrected by the optical density of the culture (average of two replicates), normalized so that the average of the first timepoint of the wild type strain equals 1. The wild type strain is shown in blue, the Bchla overproducer (B⁺⁺C⁺⁺) in yellow. The experiment was done under 12 h/12 h dark-light cycles, under continuous darkness, or under continuous light. B Percent survival, based on colony forming units, of the wild type, the Bchla null mutant (B⁻C⁺) and the Bchla overproducer (B⁺⁺C⁺⁺) after five days in stationary phase. The experiment was done under 12 h/12 h dark-light cycles, under continuous darkness, or under continuous light. The baseline is taken in early stationary phase (48 h of growth). C, D Outcome of competitions between the wild type and each of the two mutants after five days in stationary phase. The two competing strains were mixed in equal proportions after they had reached stationary phase (48 h of growth). E Figure summarizing the competitiveness of each strain under different illumination conditions. The inner color of the circles varies with relative Bchla/carotenoid content; the most competitive strains are outlined in red; the relative competitiveness is represented by arrows of three different thicknesses.