Fig. 4.

Photoautotrophic growth of the R. rubrum wild type (UR2), the cbbM mutant (UR5251), and other cbb mutants. A culture grown in SMN medium (0.2 ml) was used to inoculate 10 ml of CO₂-H₂-NH₄⁺ minimal medium supplemented with 0.05% yeast extract and then grown under phototrophic and anaerobic conditions. This fairly heavy inoculum of the culture grown in SMN medium and a small amount of yeast extract allows growth in CO₂-H₂-NH₄⁺ minimal medium to an OD₆₀₀ of approximately 0.2 to 0.3 (after 1 day) before growth defects of cbbM mutants are apparent. All single mutants are listed in A, and all double mutants are shown in B, while the wild type (UR2) and the cbbM mutant (UR5251) are shown in both panels for comparison.