FIGURE 2.

Agar plates showing growth of Synechococcus 7002 WT, chlR mutant (ΔchlR), desF mutant (ΔdesF), and a strain in which the entire region from chlR to desF was deleted (ΔchlR-desF). Cells were streaked on medium A⁺ plates without antibiotics and grown in air or in an anaerobic chamber in an atmosphere of 10% CO₂, 10% H₂, and 80% N₂. All strains could grow on atmospheric O₂ levels, but only the wild type grew under anoxic conditions when the only oxygen available to the cells was that produced by photosynthesis.