H. Suhad - Department of Biology, College of Science, Mustansiriyah University, Iraq
H.Z. Neihaya - Department of Biology, College of Science, Mustansiriyah University, Iraq
A.L. Raghad - Department of Biology, College of Science, Mustansiriyah University, Iraq

About ۵۰ isolates (۸۳%) of Escherichia coli were identified from ۶۰ stool sample, and ۳۰ examined bacteria formed biofilm. ZnO NPs was synthesized by E. coli and a white cluster pellet appeared, followed by observing absorption peak of UV-Vis. spectroscopy at ۲۶۸ nm. XRD pattern showed the lattice planes of ۱۰۰, ۰۰۲, ۱۰۱, ۱۰۲, ۱۱۰, ۱۰۳ and ۱۱۲ compatible to the ۲θ values of ۳۲.۴۵°, ۳۴.۷۳°, ۳۶.۵۶°, ۴۷.۷۰°, ۵۵.۸۶°, ۶۲.۱۲°and ۶۳.۱۰° respectively, and the diffraction peaks were assigned with the hexagonal phase, while SEM images exhibited that size of the particles ranged between ۳۱.۵۵-۴۵.۹ nm. ZnO NPs displayed antibacterial potentiality against pathogenic bacteria, and inhibition zones around ZnO NPs were as follows: ۵, ۴, ۲, ۲, and ۲ mm for Pseudomonas aeruginosa, Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae, and E. coli respectively. In addition, ZnO NPs was able to decrease biofilm, revealing that after ۴۸ h of incubation, inhibition percentage were ۱۸.۶, ۲۷.۷, ۳۹.۴, and ۱۹.۶ % against S. aureus, P. aeruginosa, A. baumannii, and K. pneumoniae, respectively. A۵۴۹ cells viability was decreased by elevating the concentration of ZnO NPs, and the IC۵۰ values of the A۵۴۹ and WRL cells were ۱۰۵.۸ and ۱۶۷.۳ µg mL-۱ respectively. In this study, the synthesized ZnO NPs using nonpathogenic E.coli showed antibacterial, antibiofilm and anticancer activities against the examined pathogenic bacteria. So, these nanoparticles can be further used in biomedical, pharmaceutical and other applications as an effective antimicrobial and anti-cancerous agent.

Biosynthesized ZnO NPs, E.coli, Antibacterial, antibiofilm, Anticancer