The development of novel detection methods of pathogenic bacteria remains as anan enormous scientific challenge and a significant practical problem of big significance. We present a novel electrochemical method for rapid and analytical detection of Staphylococcus aureus in pure culture and spiked milk samples through the hydrogen peroxide consumption at a gold screen printed gold electrode (SPGE), modified with cysteine and peroxidase from guinea grass leaves (GGP). Peroxidase (POD) from guinea grass leaves, having a specific activity of 470 U mg-1, was immobilized on the surface of a gold screen printed electrode previously modified with cysteine. Cyclic voltammograms of gold electrodes modified with the peroxidase and cysteine in the presence of potassium ferrocyanide ([Fe(CN)6]3-/4- as a redox probe demonstrated an increase in the electron transfer process compared to the gold bare electrode. The screen printed gold modified electrode exhibits a good electrocatalytic response towards reduction of hydrogen peroxide. A constant hydrogen peroxide concentration of 1x10-6 M was added to the culture medium and the decrease in the reduction current of H2O2 at -780 mV consumed by catalase from S. aureus was measured. Our modified electrode has been proven to be able to sense S. aureus in a range concentration between 3x102 and 3x108 cfu mL-1 with a detection limit of 102 cfu ml-1. The SPGE modified with GGP exhibited good selectivity and sensitivity and is expected to be used in samples contaminated with foodborne pathogens.

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