Antimicrobial activities of biosynthesized nanosilver using Musa paradisiaca and Citrus sinensis peel extracts against major human and plant pathogens

This study was aimed to evaluate the antimicrobial activities of silver nanoparticles (AgNPs) biosynthesized from aqueous extracts of banana (Musa paradisiaca L.) and sweet orange (Citrus sinensis L.) peels. The AgNPs were successfully biosynthesized using specific amounts of powdered banana and orange peel extracts along with AgNO₃ as a precursor. A noticeable color change in the AgNP solutions, shifting from yellow to dark brown after 24 h, served as an initial indicator of AgNP formation. UV-Vis spectrophotometer and powder XRD absorption spectra for both banana peel-AgNPs (BPAgNPs) and orange peel-AgNPs (OPAgNPs) exhibited distinct peaks confirming the presence of AgNPs. Furthermore, FTIR spectra indicated the presence of phenolic compounds that contribute to AgNP synthesis. SEM and DLS analyses revealed that both types of AgNPs were spherical in shape with an average particle size of less than 100 nm. Additionally, the fruit samples of banana, orange, and papaya examined in this study were found to be contaminated with B. cereus, S. aureus, E. coli, and A. faecalis, which were isolated and identified using MALDI-TOF MS. The study also identified infections by A. niger, A. alternata, P. digitatum, and F. oxysporum as major contributors to fruit spoilage in the area. Both AgNPs demonstrated significant antimicrobial activity, particularly against soil-borne pathogens A. faecalis and M. morganii (which were resistant to Chloramphenicol at 30 µg/mL) and certain fruit spoilage fungi, such as P. digitatum and F. oxysporum (resistant to 2% Ketoconazole), which had not been previously studied. Therefore, biogenic AgNPs show promise as effective antimicrobial agents for applications in medical settings and the preservation of food quality and safety.