New Herbicide-Degrading Microorganisms for the Biogenic Synthesis of Silver Nanoparticles

In this study, herbicide-degrading soil microorganisms were evaluated as potential agents for the biogenic synthesis of silver nanoparticles (AgNPs). A total of 42 microbial isolates were obtained from anthropogenically stressed soils and the cotton rhizosphere, of which 13 exhibited high resistance to the herbicides pendimethalin and clethodim. The most active strains were identified as Acinetobacter radioresistens R27 and Bacillus pumilus R25. The formation of AgNPs was confirmed by UV-Vis spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD), revealing predominantly spherical nanoparticles with a face-centered cubic structure. According to the Debye–Scherrer analysis, the crystallite sizes ranged from 21.3 to 74.3 nm. Furthermore, the synthesized AgNPs exhibited a pronounced dose-dependent fungicidal efficiency against economically significant phytopathogens, including Aspergillus flavus (with a maximum inhibition zone of up to 35.0 ± 0.5 mm at 100 mg/L), Fusarium spp., and Alternaria alternata . These findings demonstrate the dual potential of the investigated degrading strains for both environmental bioremediation and the eco-friendly production of nanomaterials for plant protection.