SCREENING OF FIVE NANOPARTICLES FOR ANTIMICROBIAL ACTIVITY

ABSTRACT

Several methods have been used to control phytopathogens in tomato plants. However, these methods are associated with several limitations, hence the need to search for an alternative. The aim of this study was to screen five metallic nanoparticles (NPs) for antimicrobial activity against phytopathogens. Fungi and bacteria were isolated from a diseased tomato plant. The isolates were identified using cultural, morphological, and biochemical characteristics. The identity of two of the isolates was confirmed using molecular characterization. CaONPs, CuONPs, MgONPs, FeONPs, and ZnONPs were phytosynthesized using Moringa oleifera, Azadirachta indica, Datura stramonium, and Ocimum gratissimum extracts. The biologically synthesized NPs were characterized using UV-VIS spectrophotometer. The antimicrobial activity of the metallic oxide NPs (25, 50, and 100%) were tested against three fungal and three bacterial isolates using the agar well diffusion method. Ketoconazole and chloramphenicol were used as positive controls for the fungal and bacterial cultures, respectively. The results showed that species of Aspergillus, Rhizopus, and Phytopthora were the fungal isolates while species of Pseudomonas and Ralstonia were the bacterial isolates. Ketoconazole and chloramphenicol inhibited the growth of the fungal and bacterial isolates. The highest growth inhibition was observed in the ZnONP treatment, while minimal inhibition was recorded for the CuONPs and CaONPs treatments. The findings of this study indicate that metallic oxide NPs have the potential of controlling phytopathogens.