Fig. 2.

In strains which don’t contain the sil operon mutations in CusS are observed at sub-MIC AgNO3 exposure concentrations whereas mutations in OmpC were only found after exposure to supra-MIC silver concentrations. Strains which contain a sil operon (NCTC 13443 and KPUK04a) and strains which don’t (CFI_124_NDM1OXA232 and CFI_134_NDM1) were adapted to the presence of silver using a stepwise adaption method as already described where the AgNO₃ concentration was doubled every two days starting at 4 mg/L and ending at 128 mg/L. At each exposure concentration the MIC values to AgNO₃ (black bar) and AgSD (grey bar) were measured and compared to pre-exposure values (0 mg/L). Cultures from individual exposure concentrations were streaked onto TSA plates and individual colonies whole genome sequenced. Identified CusS, SilS and OmpC mutations are shown above the AgNO₃ challenge concentration where they were observed. Values plotted are the mean of three repeats and the error bars represent the standard deviation (highest concentration tested 512 mg/L)