Journal of Natural Sciences Research www.iiste.org ISSN 2224-3186 (Paper) ISSN 2225-0921 (Online) Vol.5, No.24, 2015 153 The Effect of Static Magnetic Field on E. coli, S. aureus and B. subtilis Viability Khaled A. Al-Khaza'leh 1* Abdullah T. Al-fawwaz 2 1. Department of Physics, Al-albayt University, PO box 130040, Mafraq, Jordan 2. Department of Biological Sciences, Al-albayt University, PO box 130040, Mafraq, Jordan Abstract This study investigated the effects of low static magnetic field on the growth of three bacterial strains (Escherichia coli, Staphylococcus aureus and Bacillus subtilis) that plays a versatile role in infecting wounded tissues. The viability of these bacteria was measured with and without different magnetic fields (30, 50, and 80) mT after 24 hours. Results illustrate that magnetic field decreased the growth rate of Escherichia coli and Staphylococcus aureus bacteria, while increased the growth rate of Bacillus subtilis after 24 hours of exposure. Keywords: Magnetic field, Bacillus subtilis, Escherichia coli, Staphylococcus aureus. 1. Introduction Nowadays living tissues are exposed to various types of electric and magnetic fields from power lines, electromagnetic fields (EMF) from cellular phones, and computers (Ikehata et al. 1999). Many studies found that magnetic fields have some biological effects on different livingcells and tissues (Ahuja et al.1999; Faten 2014; Masahiro et al. 2000, Molouk et al. 2010, Pérez et al. 2010, Samarbaf et al. 2006, Svedenstal et al. 1999 and Zmyslony et al. 2000). Several studies indicate that the effect of magnetic fields was variable depending on the type of the microorganism (Masahiro et al.2000). A lot of studies have been done on the effect of magnetic field on biological cells, tissues, and living organisms. The effects are not fully understood, since some of the results have been inconsistent (Nakasono and Saiki 2000). In other cases the results often contradict each other, where an increase or decrease in the rate of cell division at different physiological conditions in E. coli were detected (Makarevich, 1999, Okuno et al.1993, Strašák et al.2002).The general stress response to a magnetic field is found in all bacteria, plant and animal cells and is remarkably conserved across species (Pérez et al.2010). Ikehata et al. (1999) reported that strong static magnetic fields can cause mutations in S. typhimurium and E. coli. Samarbaf et al. (2006) reported that the static magnetic field had no effect on Pseudomonas aeroginosa strains. They also found that cephalothin-resistant bacteria suspension supplied with 16 g/ml cephalothin and subjected to electromagnetic field duration reduced the biomass of bacteria to less than 1/6 of its original population. In this study, three types of bacterial species were used to investigate the impact of static magnetic field on the growth rate of bacteria and to confirm the effect of magnetic field on living cells. 2. Materials and Methods The effect of low static magnetic field on bacterial growth were studied using three bacterial strains (Escherichia coli, Staphylococcus aureus and Bacillus subtilis). The bacterial cultures were cultivated in a nutrient agar medium and incubated at 37°C for 24 hours, and then bacterial colonies were picked by a loop and inoculated in 10 ml nutrient broth. Each bacterial culture was subjected to different magnetic fields (30, 50 and 80) mT. The magnetic fields were measured by Teslameter (model F.W.Bell 4048) in Physics Department, faculty of Science, Al al-Bayt University, Mafraq, Jordan. In this work 0.1 ml of stock bacterial suspension was inoculated into four groups in tubes each contains 5 ml of nutrient broth. Three groups of tubes were subjected to magnetic fields (30, 50 and 80) mT respectively. While the fourth group was used as a negative control (no magnetic field was subjected). All tubes were incubated at 37 ºC for 24 hours. The effects of different magnetic fields on growth rate were evaluated by measuring the optical density at 600 nm using spectrophotometer (JENWAY 6300) (Fouad et al. 2014). On the other hand, a serial dilution using the bacterial culture was performed to determine the colony forming unit (CFU) value per ml. A volume of 100 μl of a (1x10 6 ) dilution factor was inoculated in agar plates by spread plating. Several plates were made for more accuracy. After incubation, the colonies formed on the plates were visually counted. 3. Results and Discussion The magnetic field influenced the growth of the three used types of bacteria; E. coli (gram negative), Bacillus subtilis (gram positive) and Staphylococcus aureus (gram positive). The influence of static magnetic field on the growth of E. coli bacteria is not fully confirmed by previous studies. Indu et al. 2012 and Indu et al. 2014 found that the magnetic field reduces the growth of E. coli bacteria. Other studies such as Marsahiro et al. 2000 and