Sarvenaz Esmaeilee - Department of Microbiology, Faculty of Basic Sciences, Islamic Azad University, Lahijan Branch, Lahijan, Iran
Mohammad Dehsaraei - Electroanalytical Chemistry Laboratory, Faculty of Science, University of Guilan, Rasht, Iran

Background and Aim:Detection of pathogen microorganisms, such as Staphylococcus aureus, which can be harmful for public health is so important. This study tried to design a simple and sensitive biosensor based on multi-walled carbon nanotubes.Methods:S. aureus PTCC1112 was sub-cultured in tryptic soy agar medium and incubated at 37 °C . 20 µL of 0.001 g of MWCNTs suspension in 1mL ethanol were spiked on the polished surface of glassy carbon electrode and dried at room temperature. Three different concentrations of S. aureus suspension in PBS were prepared in accordance with 0.5, 1 and 2 McFarland concentrations. Current increased by increasing the concentration of S. aureus suspension. The effect of modifier on microorganism detection, scan rate (νopt=0.05 V s–1) and linear dynamic range (3.7 × 106–3.0 × 108 cfu mL–1) were studied by electrochemical methods. The antibacterial effect of three herbal essential oils, tea, bergamot and lemon, were compared by electrochemical and biological methodsResults:The results of the study based on disk diffusion agar method and symmetrically by cyclic voltammetry revealed that this biosensor can be used for comparing the effectiveness tea essential oil, bergamot essential oil and lemon essential oil to inhibit the growth of bacteria. By adding the essential oils into the S. aureus growth media, the related currents were vanished or largely decreased.Conclusion:It demonstrates the anti-bacterial effect of these herbal essential oils and the ability of MWCNTs/GCE to detect the presence or absence of S. aureus in a few minutes.

Staphylococcus aureus; antibacterial effect; modified electrode; herbal essential oils