Antibacterial effect of a magnetic field on Serratia marcescens and related virulence to Hordeum vulgare and Rubus fruticosus callus cells
The exposure to a static magnetic field of 80+/-20 Gauss (8+/-2 mT) resulted in the inhibition of Serratia marcescens growth. Callus cell suspensions from Hordeum vulgare and Rubus fruticosus were also examined and only the former was found to be affected by the magnetic field, which induced a decreased viability. S. marcescens was shown to be virulent only toward H. vulgare and this virulence was reduced by the presence of the magnetic field. The modification of glutathione peroxidase activity under the different experimental conditions allowed us to speculate on the possibility of an oxidative-stress response of H. vulgare both to S. marcescens infection and magnetic field exposure. Since the control of microbial growth by physical agents is of interest for agriculture, medicine and food sciences, the investigation presented herein could serve as a starting point for future studies on the efficacy of static magnetic field as low-cost/easy-handling preservative agent.
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- "Early investigations explored the possibility of using electromagnetic fields to eliminate P. aeruginosa (Anwar et al. 1992; Khoury et al. 1992; Benson et al. 1994). However, these studies were only conducted on planktonic phases ignoring refractory biofilms, and also failed to meet expected outcomes (Grosman et al. 1992; Piatti et al. 2002; Potenza et al. 2004; Gao et al. 2005; Laszlo & Kutasi 2010). Magnetic nanoparticles (MNP) such as iron oxides have received much attention in anti-tumor therapeutic strategies due to greater biocompatibility, low systemic toxicity, and the ability to release thermal energy in the presence of oscillating magnetic fields (Johannsen *Corresponding author. "
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ABSTRACT: Due to the refractory nature of pathogenic microbial biofilms, innovative biofilm eradication strategies are constantly being sought. Thus, this study addresses a novel approach to eradicate Pseudomonas aeruginosa biofilms. Magnetic nanoparticles (MNP), ciprofloxacin (Cipro), and magnetic fields were systematically evaluated in vitro for their relative anti-biofilm contributions. Twenty-four-hour biofilms exposed to aerosolized MNPs, Cipro, or a combination of both, were assessed in the presence or absence of magnetic fields (Static one-sided, Static switched, Oscillating, Static + oscillating) using changes in bacterial metabolism, biofilm biomass, and biofilm imaging. The biofilms exposed to magnetic fields alone exhibited significant metabolic and biomass reductions (p < 0.05). When biofilms were treated with a MNP/Cipro combination, the most significant metabolic and biomass reductions were observed when exposed to static switched magnetic fields (p < 0.05). The exposure of P. aeruginosa biofilms to a static switched magnetic field alone, or co-administration with MNP/Cipro/MNP + Cipro appears to be a promising approach to eradicate biofilms of this bacterium.
Available from: Fatemeh Abdollahi
- "Several studies have been showed that low-frequency EMFs may influence plant growth and development   . Also the international discussion about the biological effects of electromagnetic fields, in which we were involved in the past , led us to examine the possibility of using such fields to inhibit phytoplasmas growth on plants such as lime. Phytoplasmas are endocellular prokaryotes without cell wall associated with more than 600 diseases in at least 300 plant species . "
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ABSTRACT: Exposure to electromagnetic fields (EMF) has become an issue of concern for a great many people and is an active area of research. Phytoplasmas, also known as mycoplasma-like organisms, are wall-less prokaryotes that are pathogens of many plant species throughout the world. Effects of electromagnetic fields on the changes of lipid peroxidation, content of H(2)O(2), proline, protein, and carbohydrates were investigated in leaves of two-year-old trees of lime (Citrus aurantifolia) infected by the Candidatus Phytoplasma aurantifoliae. The healthy and infected plants were discontinuously exposed to a 10 KHz quadratic EMF with maximum power of 9 W for 5 days, each 5 h, at 25 °C. Fresh and dry weight of leaves, content of MDA, proline, and protein increased in both healthy and infected plants under electromagnetic fields, compared with those of the control plants. Electromagnetic fields decreased hydrogen peroxide and carbohydrates content in both healthy and infected plants compared to those of the controls.
Available from: Zafer Akan
- "A decrease in growth rate of E. coli subjected to 50 Hz, 2 mT for 6 h was demonstrated (El-Sayed et al. 2006). Static magnetic fields were also shown to inhibit growth of bacteria (Piatti et al. 2002, Zhang et al. 2003). These and other studies prompted us to make a thorough investigation on the effects of ELF-EMF on bacteria. "
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ABSTRACT: To determine the effect of extremely low frequency (<300 Hz) electromagnetic fields (ELF-EMF) on the growth rate of Gram-positive and Gram-negative bacteria and to determine any morphological changes that might have been caused by ELF-EMF.
Six bacterial strains, three Gram-negative and three Gram-positive were subjected to 50 Hz, 0.5 mT ELF-EMF for 6 h. To determine growth rate after ELF-EMF application, bacteria exposed to ELF-EMF for 3 h were collected, transferred to fresh medium and cultured without field application for another 4 h. Growth-rate was determined by optical density (OD) measurements made every hour. Morphological changes were determined with Transmission electron microscopy (TEM) for two gram-negative and two gram-positive strains collected after 3 h of field application.
A decrease in growth rate with respect to control samples was observed for all strains during ELF-EMF application. The decrease in growth-rate continued when exposed bacteria were cultured without field application. Significant ultrastructural changes were observed in all bacterial strains, which were seen to resemble the alterations caused by cationic peptides.
This study shows that ELF-EMF induces a decrease in growth rate and morphological changes for both Gram-negative and Gram-positive bacteria.
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