Abstract
Nisin is a known bacteriocin, which exhibits a wide spectrum of antimicrobial activity, while commonly being inefficient against Gram-negative bacteria. In this work, we present a proof of concept of novel antimicrobial methodology using targeted magnetic nisin-loaded nano-carriers [iron oxide nanoparticles (NPs) (11–13 nm) capped with citric, ascorbic, and gallic acids], which are activated by high pulsed electric and electromagnetic fields allowing to overcome the nisin-resistance of bacteria. As a cell model the Gram-positive bacteria Bacillus subtilis and Gram-negative Escherichia coli were used. We have applied 10 and 30 kV cm-1 electric field pulses (100 μs × 8) separately and in combination with two pulsed magnetic field protocols: (1) high dB/dt 3.3 T × 50 and (2) 10 mT, 100 kHz, 2 min protocol to induce additional permeabilization and local magnetic hyperthermia. We have shown that the high dB/dt pulsed magnetic fields increase the antimicrobial efficiency of nisin NPs similar to electroporation or magnetic hyperthermia methods and a synergistic treatment is also possible. The results of our work are promising for the development of new methods for treatment of the drug-resistant foodborne pathogens to minimize the risks of invasive infections.
Highlights
Consumption of food, which is contaminated by pathogenic bacteria represents a serious public health problem (Pinilla and Brandelli, 2016)
gallic acid (Gal) has been used for coating of iron oxide nanoparticles (IONP), which are applicable for trypsin immobilization by physical bonds (Atacan et al, 2016)
We have presented a novel method using targeted magnetic nisin nano-carriers, which are activated by combination of electric and high pulsed electromagnetic field (PEMF), allowing to overcome the initial nisin-resistance of E. coli
Summary
Consumption of food, which is contaminated by pathogenic bacteria represents a serious public health problem (Pinilla and Brandelli, 2016). The drug-resistant foodborne pathogens are of greatest concern due to the invasive infections, high risks of death, and massive outbreaks of disease (Roca et al, 2015; Lammie and Hughes, 2016). The situation is complicated by the increasing rates of antimicrobial resistance, which can be a consequence of the abuse or misuse of antibacterial agents (Roca et al, 2015). The main interest lies within the development of natural additives and minimally processed foods to preserve taste and nutritional value (Chemat et al, 2017). The array of available food preservatives, generally recognized as safe (GRAS) and approved by EU and US food and drug administration committees is limited (Gharsallaoui et al, 2016)
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