Improved Monitoring of P. aeruginosa on Agar Plates

Stock pyocyanin at 5 mg/mL in dimethyl sulfoxide was diluted in TSB, TSB agar, and Kings A agar to concentrations from 0 to 100 μM. TSB samples were scanned using square wave voltammetry (SWV) on three separate disposable carbon electrodes three times each from -0.5 to 0.0 V at a frequency and amplitude voltage of 15 Hz and 50 mV, respectively. Agar samples were scanned three times on a single electrode at the same parameters The peak current values after baseline subtraction were averaged and are reported in Fig. S1. A linear fit over the range of pyocyanin concentrations was obtained, yielding a slope of 1.8x10, 1.7x10, and 1.3x10 A/M for pyocyanin in TSB, TSB agar, and King’s A agar, respectively. The King’s A agar fit was used to calculate the concentration of pyocyanin diffusing through the King’s A agar during experiments.