Mutation in the C-Di-AMP Cyclase dacA Affects Fitness and Resistance of Methicillin Resistant Staphylococcus aureus
Figure 3
Analysis of phenotypes associated with cell envelope properties in RA120, ME51 and RA120::dacA-SNP.
A, spontaneous autolysis of RA120 (black squares) and the dacA-SNP strains ME51 (white diamonds) and RA120::dacA-SNP (white squares) in phosphate buffer and B, induced autolysis of strains with 0.01% Triton X-100 in phosphate buffer. Average values with standard deviation from three independent experiments are shown. Asterisks indicate measurement time points with significant difference between both RA120/ME51 and RA120/RA120::dacA-SNP (* p<0.05, ** p<0.01) using Student’s t-test. Two-way ANOVA analysis considering all time points resulted in significant differences (p<0.01) for stain pairs RA120/ME51 and RA120/RA120::dacA-SNP for both spontaneous and induced autolysis. C, NaCl tolerance of RA120, ME51 and RA120::dacA-SNP. Overnight cultures were serially diluted 1∶5 and plated on plain LB agar or LB agar with 2.2 M NaCl. Representative results from three independent experiments are shown. D, left, relative light units (RLU) measured from cell wall stress stimulon reporter construct psas016p-luc+ in RA120 (black squares) and the dacA-SNP strains ME51 (white diamonds) and RA120::dacA-SNP (white squares) and right, the corresponding OD values of the cultures at each sampling point. Average values with standard deviation from three independent experiments are shown. Asterisks indicate measurement time points with significant differences in RLU between both RA120/ME51 and RA120/RA120::dacA-SNP strain pairs. If the strain pairs had different categories of p-values these were indicated separately (* p<0.05, ** p<0.01). Two-way ANOVA analysis considering RLU values from all time points resulted in significant differences (p<0.01) for both strain pairs RA120/ME51 and RA120/RA120::dacA-SNP.