Antibacterial activity of partially purified bacteriocin loaded chitosan nanoparticles against Staphylococcus aureus and Escherichia coli

This study evaluated the incorporation of a partially purified bacteriocin from Bifidobacterium longum strain MM2 into chitosan nanoparticles and assessed its antibacterial activity against Staphylococcus aureus and Escherichia coli . Antibacterial effects were determined using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) assays. Nanoparticles were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and zeta potential analysis. SEM revealed predominantly spherical nanoparticles with an apparent particle size of 24–61 nm. DLS analysis showed a substantially larger hydrodynamic diameter of approximately 8,000–9,000 nm. The difference between the SEM-derived particle size and the DLS hydrodynamic diameter may indicate particle association or aggregation in aqueous dispersion. The bacteriocin-loaded nanoparticles exhibited measurable antibacterial activity against both pathogens. The MIC and MBC values were 100 mg/mL for both S.aureus and 100 mg/mL for E.coli under the experimental conditions used. These findings support the feasibility of formulating partially purified bacteriocin in a chitosan nanoparticle system and provide preliminary data for further optimization and characterization.