Biological synthesis of metal nanoparticles was one of the most brilliant green methods for nanoparticles (NPs) synthesis. For this reason, the nitrate reductase-producing bacterium Achromobacter sp. MMT was employed to produce both silver (AgNPs) and nickel (NiNPs) nanoparticles (NPs). Subsequently, produced NPs were characterized by UV-vis, EDX, XRD, ξ potential and TEM. The surface plasmon resonance of AgNPs and NiNPs was exhibited at 420 and 395 nm, respectively. The EDX revealed strong signal with atomic percentages 71.4 % and 5.8% of silver and nickel, respectively. XRD indicated an ultra-fine nature and small crystallite size of studied NPs. Zeta potential (ξ) recorded -52.2 mV and -31.8 mV for AgNPs and NiNPs, respectively. In the same order, TEM analysis revealed that AgNPs and NiNPs have a teeny, uniform, spherical NPs ranging from 0.72 to 1.4 nm and from 31.0 to 31.7 nm. Both studied NPs exhibited antimicrobial activity against aerobic, anaerobic, Gram negative, Gram positive, mold, yeast, biofilm and algae. NPs were applied in various wastewater samples proved their efficiency in disinfection process.
