Fig. 6
The PtxD/Phi system can be used as a selectable marker in S. elongatus PCC 7942. a Number of isolated colonies obtained 15 days after genetic transformation with psbAI::SeptxD construct. Three different amounts of cells (1.7, 6.1, and 8.7 × 108) were spread onto agar plates with BG-11 medium supplemented with 1.8 mM Phi or 100 μg/mL spectinomycin. b Photographs of the agar plates were taken 15 days after cells were spread. A close-up view of the colonies is presented in the upright corner of the pictures. Values are the mean of three independent experiments with multiple plates each ± SD. Bars with asterisks are significantly different from spectinomycin selective condition (Student’s t test, *P < 0.05, **P < 0.01, ***P < 0.0001; ns, no significant differences)