Biosynthesis and antibiotic activity of silver nanoparticles using different sources: Glass industrial sewage-adapted Bacillus sp. and herbaceous Amaranthus sp.

Synergistic effects of metallic nanoparticles (NPs) with commonly used antibiotics have encouraged the exploration of novel biological entities, including bacteria and weed plants. The present study for the first time reports the capability of an extracellular fraction of Bacillus sp. isolated from effluents of a glass-manufacturing unit to biosynthesis silver nanoparticles (AgNPs) without hazardous materials. Besides, the biosynthesis of AgNPs using an aqueous extract of herbaceous weed plant (Amaranthus sp.), as a low-cost natural source, has been addressed in this study. Our findings confirmed the fabrication of microbial and plant-sourced AgNPs, being thoroughly characterized by UV-vis, transmission electron microscopy, X-ray diffraction, dynamic light scattering, energy dispersive X-ray spectroscopy, and zeta potential measurements. Further, biological activities of the plant- and bacterium-derived AgNPs were investigated against several pathogenic bacteria, in combination with streptomycin. The antibacterial effectiveness of the antibiotic coated with 400 µg/disk of AgNPs increased over 50% toward all the pathogenic bacteria. The data presented here demonstrate that both industrial wastewater-adapted Bacillus sp. and wild-growing Amaranthus sp. are efficient natural sources with excellent capabilities for creating biologically active AgNPs, which would be of considerable interest for circumventing bacterial resistance to current antibiotics.