Oxidative Stress in Staphylococcus aureus Treated with Silver(I) Ions Revealed by Spectrometric and Voltammetric Assays

We were focused on the studying oxidative stress in bacterial culture of Staphylococcus aureus induced by silver ions. The effect of the seven concentrations of AgNO3 (10, 25, 50, 75, 150, 225 and 300 μM) in bacterial culture was studied. Further, antioxidant activity of bacterial lysates of Staphylococcus aureus alone and incubated with different concentrations of AgNO3 under conditions of increased oxidative stress caused by the addition of hydrogen peroxide (4, 5, 6, 7, 8, 9 and 10 mM) was observed. Oxidative stress in bacterial lysates was studied spectrophotometrically using two different methods for the determination of antioxidant activity ABTS (2.2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) and DPPH (2.2-diphenyl-1-picrylhydrazyl). Oxidative stress was also studied electrochemically using cyclic voltammetry. Increasing oxidative stress was clearly noticeable with increasing concentrations of silver ions and hydrogen peroxide. Our results indicate the possibility of the application of above-mentioned analytical techniques in microbiology for determination of oxidative stress in bacterial cultures.