Abstract

Electrotaxis is the property of cells to sense electric fields and use them to orient their displacement. This property has been widely investigated with eukaryotic cells but it remains unclear whether or not bacterial cells can sense an electric field. Here, a specific experimental set-up was designed to form microbial electroactive biofilms while differentiating the effect of the electric field from that of the polarised electrode surface. Application of an electric field during exposure of the electrodes to the inoculum was shown to be required for an electroactive biofilm to form afterwards. Similar biofilms were formed in both directions of the electric field. This result is attributed to the capacity of the cells to detect the K⁺ and Na⁺ ion gradients that the electric field creates at the electrode surface. This microbial property should now be considered as a key factor in the formation of electroactive biofilms and possible implications in the biomedical domain are discussed.

Extract

4. Conclusions

According to the results described here, the ion concentration gradient of K⁺ and Na⁺ created by an electric field at a solid surface can be detected by bacterial cells and used to reach the surface. Here, the interfacial ion gradients resulted from a specific experimental set-up that allowed two different solutions to be separated. Such a set-up was necessary to distinguish the influence of the electric field from that of electrode polarisation. Nevertheless, the same kind of ionic flux is created at the surface of any polarised electrode that supports an electrochemical reaction. Therefore ion gradient at material surfaces should now be considered as a key factor of the long-range detection of electrodes by bacterial cells. As this phenomenon addresses the preliminary phase of biofilm formation, the cell approach phase, it may offer powerful ways to act on, boost, or mitigate the biofilm, or guide it towards a desired state. This would be of particular interest for technological purposes related to both the virtuous side, microbial electrochemical technologies, and the pernicious side, microbial corrosion, of electroactive biofilms.

Considering the ubiquitous presence of endogenous electric fields in living organisms [30,31] and the huge number of interfaces between the different tissues that compose them, the results described here may also impact biomedical research. Similarly to what was achieved in the present experimental set-up, in living organisms, the interfaces between different tissues separate media with different ionic compositions. Endogenous electric fields can consequently create interfacial ion gradients at these interfaces, as observed here. The hosted bacteria may be able to use these ion gradients to detect interfaces, e.g. organ surfaces, and form biofilms on them. This may happen on the natural interfaces that exist between different tissues and also on the artificial interfaces created by implanted materials. The extraordinary capacity of bacteria to detect and infect the surface of prostheses [63], so fast after implanting, is an example for which the ability of bacteria to detect interfacial ionic gradients to move towards surfaces should be considered. Moreover, the recent discoveries of the presence of electroactive microorganisms in living organisms [64,65] warrant the promotion of bacterial electroactivity as a promising field of investigation in the biomedical domain.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8090995/

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Abstract

As part of the energy transition in Germany, high‐voltage direct current (HVDC) lines producing DC electric fields (EF) are in planning. Since the human perception of DC EF was rarely investigated in the past, we aimed to identify environmental and experimental factors influencing the human perception of direct current (DC) EF, alternating current (AC) EF, and the co‐exposure of DC EF and AC EF (hybrid EF) under whole‐body exposure. Additionally, first estimates of DC EF and AC EF perception thresholds as well as differences in human perception of DC EF and AC EF concerning the type of sensation experienced and the affected body part were evaluated. A highly sophisticated exposure lab was built to expose participants to various EF strengths and ask for their assessment concerning the presence of an EF. To estimate the individual perception thresholds of 11 participants, the signal detection theory as well as the single‐interval‐adjustment matrix procedure were applied. Relative humidity could be identified as an environmental factor influencing the perception of AC EF and DC EF in different ways. An appropriate ramp slope and an exposure duration for future studies could be elaborated. Additionally, perception thresholds were lower under hybrid EF exposure than under DC EF or AC EF exposure alone. Cutaneous sensations evoked under DC EF and AC EF exposure were individually different and attributed to various parts of the body. Several environmental and experimental factors influencing the human perception of EF could be identified and provide an essential basis for a large‐scale study. © 2021 Bioelectromagnetics Society.

Extract:

Participants

Eleven healthy participants (9 men and 2 women) between the ages of 23 and 33 (mean: 25.45, SD: 3.17) were included in this pre‐study, whereby two participants dropped out during the period of the experiments (one participant moved; one started a full‐time job). Exclusion criteria were self‐reported electrosensitivity, persons fitted with electronic implants or indelible piercings, pregnant women, and persons suffering from skin diseases as well as neurological and psychiatric disorders, such as claustrophobia. Prior to inclusion, every participant underwent a careful anamnesis followed by a physical examination to assess medication, drug or alcohol abuse as well as cardiovascular, cutaneous, somatosensory, or mental abnormalities as well as signs of infection.

Limitations

The main limitation of the current pre‐study is the small number of ​11 participants, particularly regarding the large interindividual variations in detection thresholds. 

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https://doi.org/10.1016/j.marenvres.2020.104958

Abstract

The goal of clean renewable energy production has promoted the large-scale deployment of marine renewable energy devices, and their associated submarine cable network. Power cables produce both electric and magnetic fields that raise environmental concerns as many marine organisms have magneto and electroreception abilities used for vital purposes. Magnetic and electric fields’ intensities decrease with distance away from the cable. Accordingly, the benthic and the sedimentary compartments are exposed to the highest field values. Although marine invertebrate species are the major fauna of these potentially exposed areas, they have so far received little attention. We provide extensive background knowledge on natural and anthropogenic marine sources of magnetic and electric fields. We then compile evidence for magneto- and electro-sensitivity in marine invertebrates and further highlight what is currently known about their interactions with artificial sources of magnetic and electric fields. Finally we discuss the main gaps and future challenges that require further investigation.

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Abstract

Electromagnetic surveys generate electromagnetic fields to map petroleum deposits under the seabed with unknown consequences for marine animals. The electric and magnetic fields induced by electromagnetic surveys can be detected by many marine animals, and the generated fields may potentially affect the behavior of perceptive animals. Animals using magnetic cues for migration or local orientation, especially during a restricted time-window, risk being affected by electromagnetic surveys. In electrosensitive animals, anthropogenic electric fields could disrupt a range of behaviors. The lack of studies on effects of the electromagnetic fields induced by electromagnetic surveys on the behavior of magneto- and electrosensitive animals is a reason for concern. Here, we review the use of electric and magnetic fields among marine animals, present data on survey generated and natural electromagnetic fields, and discuss potential effects of electromagnetic surveys on the behavior of marine animals.

https://www.researchgate.net/publication/338814097_Electric_and_magnetic_senses_in_marine_animals_and_potential_behavioral_effects_of_electromagnetic_surveys

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