# Effects of Resonant Electromagnetic Fields on Biofilm Formation in _Pseudomonas aeruginosa_
## 1 Introduction
In 2002, the first explanation [19] of the quantum mechanism underlying the effect, earlier described by [PERSON]. [7], was published. It describes the arising of ion currents in water under the ion cyclotron resonance (ICR) due to weak electromagnetic fields in the ELF band in the presence of a static magnetic field (in the order of the geomagnetic one), and of a static electric field in the order of the one existing across a eukaryotic cell membrane (app. \(-\)100 mV). However, the crucial point was to extend the mechanism to include biomolecules, i.e., bioactive ions or zwitterions (dipoles) in prokaryotic or eukaryotic cells. In 2006, [PERSON] et al. demonstrated how a weak electromagnetic signal in the ELF band is indeed able to trigger the release of a bioactive molecules and ion currents [20]. The mechanism of the Zhadin effect can be summarized in three steps: (1) first, zwitterions and ions are captured by coherent clusters and are located on the boundary, provided their absorption peaks are close to the ones of water (mainly to the peaks corresponding to the electron excitation or to the phonons vibration); (2) within the cluster, zwitterions are ionized due to the action of the high electromagnetic vector potential gradient, at the boundary of the water cluster [21]; and (3) under the push of a proper ICR magnetic field, ions escape, provided by the energy of the cluster, and are accelerated by an electric field, provided by the transmembrane electric gradient. In addition, the Zhadin effect is based on the increase of the conductivity of the aqueous solution, the so-called protonation of water, as we detail in the discussion section [5; 22]. All this presumed, we hypothesized that prokaryotic cells as bacteria should also be subjected to the electromagnetic interaction provided by ion cyclotron resonance, and we argued that ICR should interfere differently on the prokaryotic cells of bacteria and upon the secreted biofilm due to the different content of water. Indeed, pioneer studies have shown that exposure to electric and electromagnetic fields affect the growth of planktonic and biofilm forming bacteria and may enhance the efficacy of antibiotics [23; 24]. This includes the bacterial pathogen _Pseudomonas aeruginosa_, which colonizes the lungs of patients with cystic fibrosis and reduces their lung capacity. In this exploratory pilot study, we have chosen _P. aeruginosa_, and investigate if bacteria exposed to an oscillating, pulsed electromagnetic field of extremely low intensity and frequency are affected in their growth pattern and ability to adhere to surfaces and eventually form biofilm. In most laboratory experiments, the control condition refers to a situation unaffected by variable conditions such as chemical and physical factors. However, the ambient field of the electromagnetic environment is rarely taken into consideration but may vary from day to day. Changes in solar or electrical storms, geomagnetic conditions, telecommunication equipment nearby, or the activity of large equipment (freezers, centrifuges, etc.) may influence the local and ambient electromagnetic environment. This challenge was addressed by using a mu-metal alloy magnetic chamber shielding external low-frequency magnetic fields. After pilot experiments, we found that the most stable results came when using the ICR frequency of the potassium ion, K\({}^{+}\), at a certain static magnetic field strength (10 microT). The observation that targeting the biologically important K\({}^{+}\) ion can modify bacterial physiology was also supported by a previous study [24].