Effect of extremely low frequency electromagnetic fields on growth rate and morphology of bacteria AYSE INHAN-GARIP 1 , BURAK AKSU 2 , ZAFER AKAN 1 , DILEK AKAKIN 3 , A.NILUFER OZAYDIN 4 , & TANGUL SAN 3 Departments of 1 Biophysics, 2 Microbiology, 3 Histology, and 4 Public Health, School of Medicine, Marmara University, Istanbul, Turkey (Received 17 December 2010; Revised 20 January 2011; Accepted 3 February 2011) Abstract Purpose: To determine the effect of extremely low frequency (5300 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. Materials and methods: 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. Results: 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. Conclusion: This study shows that ELF-EMF induces a decrease in growth rate and morphological changes for both Gram-negative and Gram-positive bacteria. Keywords: ELF-EMF, bacterial growth rate, morphological changes, TEM Introduction During the past few decades it has been well established that non-ionising, non-thermal, extre- mely low frequency (5300 Hz) electromagnetic fields (ELF-EMF) cause a number of different biological effects (Lacy-Hulbert et al. 1998, Volpe 2003, Simko 2004). These fields are emitted from electric devices, electronic appliances, communica- tion systems and electric transmission lines, and affect people in all occupational and residential environments. They have, therefore, attracted much attention and public concern. Although, because of their extremely low frequency and therefore low energy, it has been considered unlikely that they induce DNA damage directly, epidemiological stu- dies have shown increases in the incidence of cancer in environments exposed to these extremely low frequency fields (Tynes et al.1992, The ´riault et al. 1994, Moulder and Foster 1999) and National Institute of Environmental Health Sciences (NIEHS) and International Agency for Research on Cancer (IARC) have classified these fields as potential environmental hazards of class 2B (NIEHS 1998, IARC 2002). Because of the probable effects on cancerogenesis, most investigators have focused their studies on the effects of ELF-EMF on this area. The number of studies of the effect of magnetic fields on prokaryotes has increased significantly in the last decades. These studies include the effects of static magnetic fields, low frequency electromagnetic fields and pulsed electromagnetic fields on the physiology of prokaryotes. The effects of ELF-EMF Correspondence: Dr Ays ¸e Gunseli Inhan-Garip, PhD, Marmara University, School of Medicine, Biophysics Department, Tibbiye cad. 49 Haydarpasa, Kadikoy, Istanbul, 34668, Turkey. Tel: þ90 216 3480585. Fax: þ90 216 3480585. E-mail: aysein9@yahoo.com Int. J. Radiat. Biol., 2011, Early Online, pp. 1–8 ISSN 0955-3002 print/ISSN 1362-3095 online Ó 2011 Informa UK, Ltd. DOI: 10.3109/09553002.2011.560992 Int J Radiat Biol Downloaded from informahealthcare.com by Marmara Univ. on 03/25/11 For personal use only.