Antimicrobial Activity of Silver Nanoparticles Biosynthesized by Metabolites of Lactic Acid Bacteria Isolated from Fermented Cyperus esculentus Milk
Authors: AMODU Samuel
Journal: International Journal Of Current Microbiology And Applied Sciences
ISSN Number: 2319-770
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Abstract
Antimicrobial resistance is a growing global public health threat, with the rapid rise of
multidrug-resistant microbes becoming alarming. The quest for natural antimicrobials has
increased as consumers seek safer alternatives for ensuring food safety, nutrition, and sensory
quality. This current study investigates the antimicrobial activities of biosynthesized silver
nanoparticles (AgNPs) from metabolites of lactic acid bacteria (LAB) isolated from Cyperus
esculentus milk. LAB were isolated and characterized using conventional and molecular
methods. Metabolites from the LAB strains were used to synthesize AgNPs. The AgNPs were
characterized using UV-Visible Spectroscopy (UV-Vis), Transmission Electron Microscopy
(TEM), Energy Dispersive X-ray (EDX). Antimicrobial assay was done using agar well
diffusion method. Results from the study showed that Lactobacillus plantarum has the highest
occurrence (37.5%) and Lactococcus acidophilus (4.2%) occurred least. UV-Vis confirmed the
formation of LAB metabolite-synthesized AgNPs with absorbance peaks at 450 and 500 nm.
Transmission Electron Microscopy revealed spherical AgNPs ranging from 1.32 to 23.22 nm,
with size variations attributed to different LAB strains. EDX results indicated a significant
presence of silver, with weak signals of other elements. The biosynthesized AgNPs possess
antibacterial and antifungal activities against selected food pathogens. Lactobacillus plantarum
strain 218 had the strongest antibacterial activities (22±2.00 mm) against Staphylococcus
aureus. L. plantarum strain a27 had the strongest antifungal activities (11.5±0.71 mm) against
Aspergillus flavus. Silver nanoparticles synthesized from the metabolites of LAB isolated from
C. esculentus milk therefore show great potential as natural antimicrobials offering an
alternative to combat antimicrobial resistance and improve microbial food safety.
