BIOGENIC SILVER NANOPARTICLES AS A TOOL FOR ANTIFUNGAL CONTROL AND ENVIRONMENTAL BIOSAFETY

Abstract

Purpose. To determine the antifungal activity of biogenic silver nanoparticles synthesized using the cell-free supernatant of Lactobacillus acidophilus UCM B-2691 against the test cultures Fusarium solani , Alternaria alternata 3043, Rhizoctonia solani 16036, Nigrospora oryzae 15966, as well as micromycetes isolated from damaged leaves of the rose cultivar "Black Magic".

Methodology. Biogenic synthesis of silver nanoparticles (AgNPs) was carried out using the cell-free supernatant of Lactobacillus acidophilus UCM B-2691 culture broth. The average size of the synthesized nanoparticles was determined using photon correlation spectroscopy and was 34.66 nm. The poisoned food technique on Sabouraud agar evaluated the antifungal activity of AgNPs. Silver nanoparticles were added to the nutrient medium at concentrations of 0.1, 1, 10, and 100 mM. The test cultures were incubated at 25 ± 1 °C for 7 days. The evaluation of antifungal activity was performed visually by comparing the size, morphology, and density of colonies with the control (without AgNPs). Collection strains from the Institute of Microbiology and Virology named after D.K. Zabolotny of the National Academy of Sciences of Ukraine, and isolates obtained from rose leaves were used in the study.

Findings. Biogenic silver nanoparticles demonstrated a pronounced dose-dependent antifungal activity against all tested phytopathogenic micromycetes. The highest sensitivity was shown by Alternaria alternata 3043: significant growth inhibition was observed already at a concentration of 1 mM, while at 10 mM the mycelial growth was almost completely inhibited. At 0.1 mM, only initial signs of stress were noted. The growth of Rhizoctonia solani and Nigrospora oryzaewas also notably suppressed at 1 mM. Fusarium solani exhibited lower sensitivity: a pronounced inhibitory effect was observed at concentrations of 1–10 mM, with maximum suppression at 10–100 mM. Among the isolates from rose leaves of the «Black Magic» cultivar, one demonstrated high sensitivity to 10 mM AgNPs, while the other showed considerable resistance.

Originality. For the first time, the antifungal activity of biogenic silver nanoparticles synthesized using the cell-free supernatant of Lactobacillus acidophilus UСM B-2691 was investigated against a complex of phytopathogenic micromycetes, including isolates from damaged rose leaves. Species-specific differences in the sensitivity of the tested pathogens were established, and the dose-dependent nature of the inhibitory effect of the nanoparticles was demonstrated.

Practical value. The obtained results indicate the feasibility of using biogenic silver nanoparticles as a promising agent for protecting plants from phytopathogenic micromycetes. Their application can contribute to reducing the use of traditional chemical fungicides, decreasing the environmental load, and minimizing the accumulation of toxic residues in plant products. The established patterns of AgNPs action can serve as a basis for the further development of effective biofungicidal preparations.