Facile biogenic synthesis of silver nanoparticles (AgNPs) by Citrus grandis (L.) Osbeck fruit extract with excellent antimicrobial potential against plant pathogens

Biogenic silver nanoparticles (AgNPs) were synthesized by using Citrus grandis (L.) Osbeck fruit extract through a simple one step method by reducing silver nitrate (AgNO3) at room temperature. Citrus grandis (L.) Osbeck is an indigenously available edible citrus fruit tree in Northeast India and sub-Himalayan foot hills. Formation of AgNPs were confirmed primarily by UV–Vis spectrophotometer and extensively characterized by TEM and XRD. The plasmon resonance at 435 nm confirmed the formation of AgNPs and TEM analysis showed AgNPs with average size of 11 ± 3.57 nm. XRD analysis showed crystalline nature of the Ag NPs with fcc lattice points attributed to (111), (200), (222) and (311) planes. The AgNPs showed excellent antimicrobial activities against both Gram positive (Bacillus cereus) and negative (Pseudomonas syringae pv. syringae) plant pathogens. It exerted MIC value of 20 and 30 µg/mL, respectively against B. cereus and P. syringae pv. Syringae, whereas MBC value of 70 and 80 µg/mL were observed against B. cereus and P syringae pv. Syringae, respectively. The Ag NPs showed no considerable cytotoxicity against murine macrophage RAW264.7 cell line which indicates its further possible application for animal model trial.