Antimicrobial silver nanoparticles derived from Synadenium glaucescens exhibit significant ecotoxicological impact in waste stabilization ponds

In recent years, there has been an exponential increase in the production of silver bionanoparticles due to their widespread commercialization and technological applications. However, there is limited understanding of the impact of silver bionanoparticles on biological agents commonly used in wastewater treatment, particularly in waste stabilization ponds (WSPs). This study aimed to synthesize new silver nanoparticles (sg-AgNPs) from Synadenium glaucescens root using an environmentally friendly method and optimized biosynthesis parameters, and evaluate their antimicrobial activity and ecotoxicological impact on WSPs using standardized approaches. The average primary sizes of the sg-AgNPs in the five samples were not significantly different (P > 0.05), indicating the effectiveness of the eco-friendly method and the importance of optimal biosynthesis conditions. Analysis from UV–Vis spectroscopy, energy-dispersive spectroscopy (EDX), transmission electron microscope (TEM), and X-ray diffraction (XRD) confirmed that sg-AgNPs exhibited typical characteristics of green silver nanoparticles. Furthermore, sg-AgNPs showed strong antimicrobial activity (MIC, 0.012–0.094 mg/ml) against gram-positive bacteria (Escherichia coli), gram-negative bacteria (Staphylococcus aureus), non-filamentous fungi (Candida albicans) and filamentous fungi (Aspergillus niger). While the Synadenium glaucescens root proved to be a valuable precursor for producing effective antimicrobial sg-AgNPs, the introduction of sg-AgNPs into WSPs significantly impacted algal chlorophyll-a production and survival of ostracod population. These results shed light on the ecotoxicological risks of sg-AgNPs for WSPs organisms and highlight the suitability of algae and ostracods as model organisms for ecotoxicological studies in WSPs.