Materials and Methods: The biosynthesis of AgNPs were done by reduction of AgNO3 in the sewage of leather factory as a mixed bacterial culture and corn steep liquor under anaerobic condition while protecting from light.

Results: The AgNPs were found to have a characteristic absorption peak at 416 nm on the ultraviolet-visible spectrum. Characterization of AgNPs was performed by x-ray diffraction (XRD) and Fourier-transform infrared (FTIR). The scanning electron microscopy (SEM) and transmission electron microscopes (TEM) images showed poly-dispersed spherical stable AgNPs with a maximum diameter of 20 nm. Moreover, the dynamic light scattering (DLS) showed that the average size of AgNPs was 15.57 nm with a zeta potential value of -19.2 mV. The synthesized nanoparticles demonstrated more antibacterial activity in opposition to gram-negative bacteria. The zone of inhibition of biosynthesized AgNPs in 1 mM concentration of AgNO₃ against Escherichia coli was equal to that of gentamicin.

Conclusions: The interaction of protein residues with AgNPs was identified, supporting that the proteins not only act as a reducing agent but also as a capping. The synthesized AgNPs showed antibacterial activity, providing commercial viability in biomedicine.