Antimicrobial Effect of Poly (amidoamine)-G2 and G4 Dendrimers on Some Bacteria in water resources

Background and There is growing application of dendrimers in the world, therefore, this study was conducted to evaluate the effect of antibacterial properties of generation-2 and 4 poly (amidoamine) dendrimer (PAMAM) on some bacteria isolated from water resources. Water samples were collected from drinking water resources. Bacteria were isolated and identified using differential biochemical tests. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against gram-positive and gram-negative bacteria were calculated. Standard discs were prepared by different concentrations of dendrimer (0.5, 5, 50 and 500 μg/ml) and evaluated through disc agar diffusion method on Muller-Hinton agar plates. Finally, the inhibition zone diameter was measured and the effect of temperature and pH was investigated on antimicrobial activity of dendrimers. The main isolated bacteria from water resource were Escherichia coli, Pseudomonas aeruginosa, klebsiella oxytoca, Bacillus subtilis, and staphylococcus aureus. The results showed completely similar MIC and MBC for each isolated bacteria in both generations which were as follows: Escherichia coli 1250 and 2500 μg/ml, klebsiella oxytoca 500 and 1250 μg/ml, staphylococcus aureus 1 and 5 μg/ml, and Bacillus subtilis 2.5 and 5 μg/ml, respectively. No MIC and MBC were observed on Pseudomonas aeruginosa. Also, it was found that PAMAM dendrimer was more potent towards the gram positive bacteria than the gram negative bacteria. Although amino terminated G4 PAMAM dendrimer has more functional groups, but no significant difference was observed in its antimicrobial activity compared to that of the G2 PAMAM dendrimer. Amino-terminated generation 2 poly(amidoamine) dendrimer exhibited a positive impact on the removal of main isolated strains. Therefore, it might be used as a safe and effective material for water disinfection in future.