Fig. 5: Growth in CS2 medium leads to microaerobic conditions.
From: The complex regulation of competence in Staphylococcus aureus under microaerobic conditions
A wild-type strain (St29) expressing GFP under the control of PcomG was grown in a CS2 medium for 24 h. When growth became detectable, the oxygen concentration, the percentage of GFP-expressing cells, and OD600 nm were measured every 30 min. As the OD increased, the concentration of oxygen quickly dropped from 21% to 0.27%, while the OD only reached 0.5. Importantly, our assay allows us to affirm that complete anaerobic conditions are not reached as our sensors are able to measure with confidence oxygen concentrations that are ten times lower. A few minutes later, the growth reproducibly marked a pause, probably necessary for the cells to adapt to low oxygen conditions, which in turn induced an increase in the percentage of competent GFP-expressing cells. This Figure shows a representative experiment that has been reproduced five times (see Supplementary Fig. 5 for replicates).
