Inactivation of Bacteria Using Bioactive Nanoparticles and Alternating Magnetic Fields

Area of Science:

• Food science and technology
• Microbiology
• Nanotechnology

Background:

• Foodborne pathogens pose significant risks, necessitating robust food safety and processing strategies.
• Controlling bacterial contamination, particularly drug-resistant strains like Listeria monocytogenes, is a critical challenge in food processing.

Purpose of the Study:

• To investigate the efficacy of nisin-loaded magnetic nanoparticles activated by alternating magnetic fields (AMFs) for biocontrol of *Listeria innocua*.
• To evaluate the synergistic effect of AMFs on nisin-nanoparticle treatment for bacterial inactivation.
• To assess the potential of this method as a contactless alternative for food processing.

Main Methods:

• Utilized nisin-loaded magnetic nanoparticles for bacterial inactivation.
• Applied alternating magnetic fields (AMFs) at 10 and 125 mT (peak to peak) for treatment activation.
• Employed scanning electron microscopy (SEM) to observe morphological changes and cellular damage.
• Estimated thermal effects associated with the treatment.

Main Results:

• *Listeria innocua* showed resistance to nisin-nanoparticles alone.
• Application of AMFs (15 and 30 min exposure) significantly enhanced the antimicrobial effect, leading to substantial log reduction of viable cells.
• SEM confirmed significant cellular damage induced by the synergistic treatment.
• Thermal effects were evaluated.

Conclusions:

• The combination of nisin-loaded magnetic nanoparticles and AMFs demonstrates a potent synergistic effect for inactivating foodborne pathogens like *L. innocua*.
• This contactless methodology presents a viable alternative to conventional methods like pulsed electric field treatment for food processing.
• The findings contribute to developing novel strategies for managing drug-resistant foodborne pathogens and reducing infection risks.