Bioelectromagnetics29:302^311(2008) BacterialResponsetotheExposureof50Hz ElectromagneticFields Luigina Cellini, 1 * Rossella Grande, 1 Emanuela Di Campli, 1 Soraya Di Bartolomeo, 1 Mara Di Giulio, 1 Iole Robuffo, 2 OrianaTrubiani, 3 and Maria A.Mariggio' 4 1 Department of Biomedical Sciences, University ‘‘G. d’Annunzio’’, Chieti, Italy 2 Institute of Molecular Genetics, CNR, Section of Chieti, Italy 3 Department of Applied Sciences of Oral and Dental Diseases, University ‘‘G. d’Annunzio’’, Chieti, Italy 4 Laboratory of Physiology, Aging Research Center, Ce.S.I., ‘‘G. d’Annunzio’’ University Foundation, Department BAMS, Chieti, Italy To investigate the ability of prokaryotic microorganisms to activate strategies in adapting themselves to the environmental stress induced by exposure to extremely low frequency electromagnetic fields (ELF-EMF), cultures of Escherichia coli ATCC 700926 exposed at 50 Hz EMF (0.1, 0.5, 1.0 mT), and the respective sham-exposed controls were studied for: the total and culturable counts, the viability status, the antimicrobial susceptibility pattern, the morphological analysis, the genotypical and transcriptional profile. Exposed samples and controls displayed similar total and culturable counts, whereas an increased cell viability was observed in exposed samples re-incubated for 24 h outside of the solenoid compared to the corresponding controls. An exposure to 50 Hz EMF of 20–120 min produced a significant change of E. coli morphotype with a presence of coccoid cells also aggregated in clusters after re-incubation of 24 h outside of the solenoid. Atypical lengthened bacterial forms were also observed suggesting a probable alteration during cell division. No changes among DNA fingerprintings and some differences in RNA-AFLP analysis were observed for each 50 Hz EMF intensities evaluated. Our results indicate that an exposure to 50 Hz EMF acts as a stressing factor on bacteria which can represent a suitable model to investigate acute and chronic effects related to ELF- EMF exposure. Bioelectromagnetics, 29:302–311, 2008. ß 2008 Wiley-Liss, Inc. Key words: stressed condition; extremely low frequency electromagnetic fields; Escherichia coli ATCC 700926; bacterial morphology; viability status INTRODUCTION Electromagnetic fields spread throughout the planet producing interferences with biological systems [Balcavage et al., 1996; Panagopoulos et al., 2002; Grassi et al., 2004] even though many studies on their effects on health display controversial results [Feycht- ing and Ahlbom, 1993; Valberg et al., 1997; Berg, 1999]. In particular, while some studies report that exposure to extremely low frequency electromagnetic fields (ELF-EMF) can alter the gene transcription and translation, influence the cell proliferation rate, affect enzyme activities and increase the risk for certain types of adult and childhood cancer [Li et al., 1997; Zwirska- Korczala et al., 2005], others have failed to find such an association [Verkasalo et al., 1993]. Studies were conducted to ascertain whether ELF-EMF exposure could influence co-promotion or cancer promotion and also evaluate cell systems [Wertheimer and Leeper, 1979; Pearce et al., 1989; Feychting and Ahlbom, 1993; Scarfi et al., 1999]. Consistent epidemiologic evidence demonstrated a small risk of ELF-EMF on childhood leukemia, thus leading to an International Agency for Research on Cancer (IARC) classification of ELF-EMF as a 2B ‘‘possible’’ carcinogen in 2002 [IARC, 2002]. Few investigations regarding stress effects pro- duced by ELF-EMF have been performed using prokaryotic cells which, because of their short life ß 2008Wiley-Liss,Inc. —————— Grant sponsor: Ministero dell’Ambiente e Tutela del Territorio, Roma, Italy; Grant number: 5377/2002/SIAR. *Correspondence to: Luigina Cellini, Department of Biomedical Sciences, University ‘‘G. d’Annunzio’’ Via dei Vestini, 31—I- 66100 Chieti, Italy. E-mail: l.cellini@unich.it Received for review 11 December 2006; Final revision received 12 September 2007 DOI 10.1002/bem.20391 Published online 3 January 2008 in Wiley InterScience (www.interscience.wiley.com).