Fig. 1: Competence for genetic transformation naturally develops with high efficiency in CS2 medium.
From: The complex regulation of competence in Staphylococcus aureus under microaerobic conditions
a Growth of a wild-type strain expressing gfp under the control of the comG promoter (St29) in CS2 medium, between 16 and 21.5 h. Dilutions from 10−2 to 10−5 are shown. The 10−2 dilution was already in the stationary phase, while the 10−3 dilution was entering the stationary phase after 16 h of growth. The 10−4 and 10−5 dilutions were, respectively, in the late and early exponential phase at the beginning of the experiment. All the dilutions reached a similar final OD between 2.4 and 2.6. b The percentage of competent cells was measured using flow cytometry by analyzing the percentage of cells expressing GFP under the control of the comG promoter (PcomG). In each diluted culture presented in panel a), the percentage of competent GFP-expressing cells increased in the late exponential phase and reached a maximum at the entry in the stationary phase. This graph shows a representative experiment that has been repeated three times (biological replicates, see Supplementary Fig. 2a). c Transformation efficiencies of wild type (N315ex w/o Phi), comGA (St137), sigH (St45), comK1 (St37), comK2 (St38), and srrA (St117) mutant strains using plasmidic (pCN34, KanR, white bars) or chromosomal DNA (gray bars) (see Material and methods for details). Results are presented as mean ± SD. For each strain, the experiment was repeated at least five times (biological replicates). Individual experiments are shown as blue circles. d Transformation efficiencies of laboratory strains (N315, RN4220, and USA300) and MRSA (NL10, NL27) or MSSA (NL36) clinical isolates using chromosomal DNA (gray bars) (see material and methods for details). Results are presented as mean ± SD. For each strain, the experiment was repeated at least five times (biological replicates). Individual experiments are shown as blue circles.
