title: Genome-wide transcription analysis of Escherichia coli in response to extremely low-frequency magnetic fields.
abstract: The widespread use of electricity raises the question of whether or not 50 Hz (power line frequency in Europe) magnetic fields (MFs) affect organisms. We investigated the transcription of Escherichia coli K-12 MG1655 in response to extremely low-frequency (ELF) MFs. Fields generated by three signal types (sinusoidal continuous, sinusoidal intermittent, and power line intermittent; all at 50 Hz, 1 mT) were applied and gene expression was monitored at the transcript level using an Affymetrix whole-genome microarray. Bacterial cells were grown continuously in a chemostat (dilution rate D = 0.4 h(-1)) fed with glucose-limited minimal medium and exposed to 50 Hz MFs with a homogenous flux density of 1 mT. For all three types of MFs investigated, neither bacterial growth (determined using optical density) nor culturable counts were affected. Likewise, no statistically significant change (fold-change > 2, P ≤ 0.01) in the expression of 4,358 genes and 714 intergenic regions represented on the gene chip was detected after MF exposure for 2.5 h (1.4 generations) or 15 h (8.7 generations). Moreover, short-term exposure (8 min) to the sinusoidal continuous and power line intermittent signal neither affected bacterial growth nor showed evidence for reliable changes in transcription. In conclusion, our experiments did not indicate that the different tested MFs (50 Hz, 1 mT) affected the transcription of E. coli.
authors.affiliation: Swiss Federal Institute of Technology (ETH Zurich), Institute of Microbiology, Zurich, Switzerland. simona.huwiler@alumni.ethz.ch
authors.forename: Simona G
authors.initials: SG
authors.lastname: Huwiler
authors.forename: Christian
authors.initials: C
authors.lastname: Beyer
authors.forename: Jürg
authors.initials: J
authors.lastname: Fröhlich
authors.forename: Hauke
authors.initials: H
authors.lastname: Hennecke
authors.forename: Thomas
authors.initials: T
authors.lastname: Egli
authors.forename: David
authors.initials: D
authors.lastname: Schürmann
authors.forename: Hubert
authors.initials: H
authors.lastname: Rehrauer
authors.forename: Hans-Martin
authors.initials: HM
authors.lastname: Fischer
mesh_terms: D004574:Electromagnetic Fields / Q000009:adverse effects; D048168:Escherichia coli K12 / Q000235:genetics* / Q000528:radiation effects*; D020869:Gene Expression Profiling; D016680:Genome, Bacterial / Q000235:genetics*; D014158:Transcription, Genetic / Q000528:radiation effects*