2.2.4. Electrochemical measurements
The electrochemical measurements was performed using a CS120 electrochemical work station (CorrTest, China). A three-electrode system was used for the measurement, where a gold disc electrode (d=3.0 mm, Tianjin Aida, China; the same brand for other electrodes below) was used as the working electrode, an Ag/AgCl (saturated KCl, Eo = 0.190 V vs. standard hydrogen electrode) was used as the reference electrode and a platinum sheet as the counter electrode. The electrodes were inserted into a solution of D.r.bacteria (with a concentration of 2×108mL-1) which was directly taken from the incubation mixture with the PYG broth. Next, anodic stripping voltammetry was applied every 1.5 hours to monitor the silver ion concentration of the bulk solution within a total period of 9 hours. Specifically, the stripping voltammetry was conducted by applying in sequence a surface-refreshing potential of 0.6 V vs. Ag/AgCl for 60 seconds, a pre-concentration potential of -0.45 V for 60 seconds again, and a potential cycle between 0.0 and 0.6 V at a scan rate of 0.1 V s-1.