New herbicide-degrading microorganisms for the biogenic synthesis of silver nanoparticles

Herbicide-resistant microorganisms were investigated for their potential in pendimethalin biodegradation and the biogenic synthesis of silver nanoparticles (AgNPs). Among the selected strains, Acinetobacter radioresistens R27, Bacillus pumilus R25, and Streptomyces variabilis R35 demonstrated pronounced pendimethalin-degrading activity. At a herbicide concentration of 125 mg/L, biomass increases after 7 days reached 87.5%, 92.0%, and 58.5%, while pendimethalin degradation efficiencies were 92.5%, 86.0%, and 62.0%, respectively. A. radioresistens R27 exhibited the highest degradation efficiency. Biogenic AgNP synthesis was confirmed by UV-Vis spectroscopy and X-ray diffraction, which demonstrated a face-centred cubic crystalline structure. The synthesized AgNPs showed predominantly spherical morphology, with particle sizes varying depending on the biosynthesis conditions. AgNPs synthesized using A. radioresistens R27 at 75 mg/L exhibited a zeta potential of - 20.5 mV. The synthesized AgNPs demonstrated pronounced concentration-dependent antifungal activity against Aspergillus flavus, Alternaria alternata, and Fusarium oxysporum. Thus, the investigated microorganisms, particularly A. radioresistens R27, demonstrated a combination of high pendimethalin-degrading capacity and biogenic AgNP synthesis associated with pronounced antifungal activity.