A Comparative Study of the Effects of Colloidal Nanosilver and Industrial Biocide E-265 on Bacterial Respiration and Biofilm Formation Using Microtiterplate Method

Silver nanoparticles have become one of the most commonly used nanomaterials in consumer products because of their effective antimicrobial properties and low toxicity toward mammalian cells. In the area of water purification, today nanoparticles are widely used for detection and removal of chemical and biological substances. Therefore by the growing use of nanoparticles, further research is certainly needed to study the behavior of them. In this study, the antibacterial and antibiofilm activities of colloidal nanosilver (average size: 40±10 nm) on the growth, cellular respiration and biofilm formation of pathogenic strains and the isolates from the cooling water of Isfahan Oil Refinery (A1 and A2) were compared with biocide E-265 which generally used in this refinery by microtiterplate method. The results showed that different concentration of biocide E-265 had no significant effects on the bacterial growth and even at 20 and 40 ppm showed 100% increase in the biofilm formation of the isolate A1. Also it is detected that low concentration of nanosilver (1-2 ppm) showed unique antibacterial and antibiofilm activities and can be suggested as a suitable biocide for the recirculating water systems