Microbes and Sustainable Living: Focus on Electric and Magnetic Fields

1. Introduction

Life on earth is dominated by microorganisms existing both as communities living in even the harshest conditions and as co-partners for more complex lifeforms (holobionts). The relationships of microbes partnering with holobionts have existed for millennia [1], and are essential for the wellbeing of higher eukaryotic organisms including humans [2]. Microbes associated with the human microbiome have many roles, some of which are: 1) They drive key developmental changes during critical windows of human developmental vulnerability [3]. 2) They provide key vitamins and metabolites [4]. 3) They regulate fear and risk of mental health issues [5]. 4) They affect circadian rhythm and sleep [6]. 5) They have the capacity to facilitate longevity [7]. and 6) They have the capacity to reduce the risk of both infectious (via colonization resistance) and chronic diseases [8,9].

The critical role of microbes in holobiont health and survival extends well beyond humans to affect animal, plant and insect life. An example is the significant role of the microbiome of honeybees in their health [10], social group membership [11], behavior [12] and queen bee ovarian metabolism [13]. For humans to have a sustainable future, we must ensure that the symbiotic relationship with microbes continues and thrives. For healthy human and other holobionts, we need health and protection for microbial populations [14].

The fundamental yet novel properties exhibited by microbes, such as the capacity to capture, transfer, communicate with and generate electricity [15,16] as well as magnetism [17] makes them prime candidates for restoring ecological environments as well as improving human, animal, and plant holobiont health [18,19]. However, the same features also make microbes potentially sensitive targets for adverse effects of electric, magnetic, and electromagnetic fields (EMFs) and/or transmissions. When unintended consequences arise from exposure to a physical field among microbial ecological communities or holobiont microbiomes, the outcomes can be devastating. If we are to have a sustainable life here on earth, we will need to be effective stewards of earth’s microbial life within and beyond holobionts.

In a series of recent articles, we reviewed the effects of various overt and subtle physical fields [20] on microbes including the key factors of sound, light, and vibrations [21]. In this present narrative review, we extend this consideration to examine two of the most fundamental features of microbes that are critical for the functioning of society, earth’s ecology, and human holobiont wellness: the electrical and magnetic properties of microbes and their responses to changes in electric and magnetic fields. In this paper, we explore 1) fundamental concepts important for microbial communications and a microbially-enhanced, sustainable future, 2) the electric and magnetic nature of microorganisms and 3) the potentially beneficial and detrimental effects of electric and magnetic fields on microorganisms.

While we stress the wide range of electric and magnetic field applications that can benefit the environment and society, we also caution that the misapplication of these magnetic fields can be devastating. Beyond electric and magnetic fields, the topic of EMFs is massive in scope covering the entirety of ionizing and non-ionizing radiation. We introduce this subject but do not attempt to comprehensively review EMF within the present narrative review.

2. Microbial-Driven Capacities and a More Sustainable Future

We begin this review with a glimpse of key microbe-driven concepts and interactions that drive a microbially-enhanced, sustainable future. If part of human holobiont history on Earth was one where separation from Earth’s most predominant lifeforms, microorganisms, was encouraged [22,23] and microbes could be seen as evil [24], then the key concepts shown in Table 1 [25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51] reverse this pattern and envision a future where microbial life is an integral part of future, sustainable living. This Table sets a broader microbial landscape for the subsequent consideration of electric, magnetic effects.

The examples shown in Table 1 emphasize the importance of adopting a core view of humans not as a single species, but rather as a composite, human holobiont form. The key concepts of Table 1 illustrate the importance of discarding the dogma where microbes are seen predominately as germ theory-based threats to our existence. It is important to replace germ theory misapplication with a holobiont-centric view where microbiomes are embraced as the facilitators of maximized human holobiont consciousness, functional capacities, improved healthcare and wellness, sustainable living, and being better prepared to fully engage the biocivilizations described by Slijepcevic [49]. Part of this process is to retire the idea that we are on a mission to destroy life via the Antibiocene [28].

Increased sustainability is gained when the boundary between microbes associated with the human holobiont and other holobionts as well as environmental communities is softened and interconnectivity is fully embraced. For example, benefits can be found within precision medicine where bacterial motors offer new avenues in treatments and healthcare [50]. Similarly, in the environment, microbes represent ready solutions for both the restoration of damaged, polluted ecosystems [34] and sustainable food production systems [48].

Finally, aspects such as the social brain, microbial interactions aiding peace, and enlarged views of the “human image” and spirituality can offer us new pathways to a more holistic way of living. One of the intriguing aspects of the social brain and the question of where the human mind begins and ends concerns the role of the Internet of Microbes. Microbial networks are within but not bounded by the human body. While we go within to tap the mind, we are unlikely to remain solely within as we process information. Relatively recent findings that the bioelectric and biomagnetic state of microbes is significant in communication across the Internet of Microbes and that bacteria, themselves, respond to neurotransmitters with their own bacteria signaling is shifting our understanding of human-microbial connectivity [52].

From the foundation provided in Table 1, the remainder of this review examines the electric and magnetic nature of microbes, their holobionts and importantly, the sensitive responses of microbes to electric and magnetic fields. Holobiont integrity, health wellness and safety are all important considerations when it comes to the exposure to and various applications of these fields.

3. Bioelectrical and Biomagnetic Processes in Human Cellular Life

The human body itself generates electricity and research has suggested that human electricity/energy can be harvested when useful [53]. Depending upon frequency, strength, duration, and the nature of the externally applied fields (e.g., static. vs. pulsed), these factors can lead to beneficial or detrimental effects on holobionts and their microbial partners [54,55]. These factors have been used to increase the efficiency of medical and industrial applications such as bacterial fuel cells [56], bacteria-driven bioremediation [57] and wound healing [58].

4. Early Examples of Electrical and Magnetic Applications in Human Medicine

According to Luderitz [59] and Ma et al. [60], ideas around electrotherapy (antiarrhythmic) date back at least to the 280 BCE China where a series of ten texts titled “The Pulse Classic” and authored by Wang Shuhe discuss the significance of the pulse forming what would later become core to traditional Chinese medicine [60]. Modern applications of electrotherapy to treat arrhythmia can be found in the 1950s with major developments since that time [reviewed in 59]. As described by Markov [61] magnetic therapeutic centers began to emerge in Europe during the 1960s, while clinical applications in the U.S. can be found in the mid-1970s. One of the major applications of magnetic field therapy pertains to the reduction of inflammation. This specific medical application can be traced back to the 1980s [62,63]. Rumbaut and Mirkovic [64] also discuss earlier historic references concerning the use of magnetism to reduce edema.

6. Electric Microbes and Electrical Field Effects

While this narrative review focuses on electrical field effects on microorganisms, it is important to recognize that many microorganisms are electrically active in nature and large groups of microorganisms have the capacity to produce electrical current [65]. They have the capacity to transfer electrons to anodes within various electrochemical systems and have been termed “Living Electronics” by Thomasy [66]. Observations of bacteria as electrical beings date back to at least 1911 via the research of Potter [67]. Additionally, the application of generating electricity through microbial action was reviewed more than sixty years ago [68]. Additional recent research into the prevalence of microorganisms as electrical beings able to carry out the capacity of many prokaryotes to interact with charged electrodes led to a new field of study called Electromicrobiology [69]. As described by Nealson [69], bacteria are inherently electrically-powered organisms in which electron transport within bacteria lead to electrochemical gradients that power many processes via what has been termed proton motive force (an electrochemical gradient of protons across a membrane). This “force” can drive energy requiring processes and allows the bacterial cell to act much like a micro-battery.

Another group of bacteria go beyond comparatively weak electrical generation constituting a category known as Extracellular Electron Transport (EET) microorgansims. These have the capability to interact with a variety of insoluble electron acceptors and donors. EET microorganisms have opened a vast array of electrically-based technical applications and contributed to new ideas surrounding sustainability (e.g., biobatteries, pollution remediation, electrosynthesis and water reclamation) [69,70].

A final significant aspect of the inherently electrical nature of bacteria is the fact that EET organisms like Geobacter and Shewanella have created a natural global electrical grid via the production of nanowires [71,72]. Metabolic cross-feeding among microbial species is a process known as syntrophy or mutualistic symbiosis [73]. But microbes like EETs can go through a form of electrical syntrophy as recently reviewed by Rotaru et el. [74]. These researchers discuss the direct interspecies electron transfers between alcohol-utilizing Geobacter metallireducens and Methanosarcinales [74]. Remarkably, Geobacter EETs can even draw upon remnant activity in illuminated dead microalgae to boost their own electrical activity [75]. Hence, even dead microorganisms can contribute to what constitutes microbial electrical grids. As a result, the Internet of Microbes is not just about information exchange across a grid but also involves the flow of electrical current.

As with sound, light and magnetism, electrical fields can have divergent effects on microbial populations depending upon the nature and strength of the field and the specific responding microbial populations. Pulsed electrical fields and a rapidly-acting variation of this called locally enhanced electrical fields are used for microbial inactivation/germicidal outcomes [76,77]. Pulsed electrical fields have also been used to extract desirable compounds from disrupted microorganisms [78].

In contrast to the cell disruptive/germicidal effects of pulsed electric fields, other forms of electric field exposures can aid microbial growth, movement, and/or functional activity. Electric field effects on microorganisms include alteration of microbial populations within holobionts and among environmental microbial populations. Examples of these are illustrated in Table 2 [77,79,80,81,82,83,84,85,86,87,88,89,90,91,92].

Electrical technological applications using microbes have shown significant progress in recent years. Examples of these are the use of microbes in renewable fuel cells [93], conversion of waste organic material into sustainable energy [94], microbial environmental remediation [95], enhanced energy and functionality via nanowire technologies [96], and microbial sensing technologies [97].

Electroculture is an applied agricultural use to enhance plant growth via, at least in part, low electric fields producing rhizosphere microbe-plant enhancement. Not surprisingly, the “technology” associated with directed low level electric field into soil existed well before the delineation of soil-plant rhizosphere. Recent studies have demonstrated that electric field applications affect the status of rhizosphere microbe communities [98]. The history of electroculture dates back at least to the 18^th century and was revisited/extended during the intervening years [99,100,101]. Nineteenth century scientific reports were presented [102]. By the 20^th century, it was sufficiently vested in agricultural history that a publication titled “New Methods in Electro-Culture” appeared in a 1934 issue of the Journal of the Royal Society of Arts [103].

7. Microbes and Various Types of Magnetic Fields

Microorganisms and particularly certain kinds of bacteria and archaea have a variety of ways in which they interact with magnetism, both natural and artificial magnetic fields. These interactions can range for the capacity to: 1) acquire magnetism themselves through their own gene expression capability (e.g., MTB) and to use this to their functional advantage, 2) detect existing magnetic fields with great precision and sensitivity, 3) thrive or be killed by exposure to certain types and strengths of natural or artificial magnetic fields. In fact, magnetosomes have been described as a form of prokaryotic organelle that in conjunction with magnetosome-associated proteins control bacterial geomagnetic sensing [104].

These properties of microbes have implications for both earth’s ecosystems as well as for holobionts. For example, the idea that symbiotic magnetic sensing as a collaboration between MTB and host adaptations has gained increasing support [105]. In fact, magnetoreceptive bacteria have been found to be capable of transferring their capacities by producing a collective magnetic field-assisted motility guided by a chemoaerotaxis system in the holobiont [106].

This same sensitivity of microbes to magnetic fields means that magnetic field interactions can alter the compositions and distribution of microbial populations affecting ecosystems and holobiont health. Therefore, different types and strengths of natural and artificial magnetic fields become a significant tool through which microbial populations can be managed for better outcomes. They also become a significant health risk for holobiont humans, plants, and animals when field-induced microbiome damage occurs.

Microbial populations are known to be affected by both natural and artificial magnetic fields [107,108]. This has implications not only for the Internet of Microbes across planetary media ecosystems but also the microbiome of holobionts including those connected to humans. Humans and other holobiont microbiomes contain groups of highly specialized and in some cases extremophile archaea and bacteria. MTB are one example of highly specialized bacteria. These bacteria appear to be important in several functions including magnetic field detection and navigation via the production of magnetosomes containing magnetite crystals [109]. Simon et al. [110] recently found that several different species of MTB present within the human gut microbiome and their presence appears to be related to the presence of magnetite crystals in brain regions connected with navigation and orientation functions. Are the presence of these specialized bacteria in the human gut microbiome mere happenstance? If not, are they contributing to a much-underutilized human holobiont capacity?

Table 3 provides select examples of reviews and research studies focused on the importance of magnetic fields and microbes. Rather than being a comprehensive survey, these examples are presented to illustrate 1) unanticipated effects of magnetic fields on microbial populations producing potential hazards, 2) designed magnetic field alterations to enhance microbial functions, and 3) the potential origins and significance of magnetoreceptive microbes. Examples of the effects of magnetic fields on microbial populations via review articles and research studies are provided in Table 3 [105,110,111,112,113,114,115,116,117,118,119].

8. Electromagnetic Waves and Microbes

The effects of electromagnetic (EMF) waves (the vibrational interactions of electric and magnetic fields) is a massive, complex subject of its own. While it is beyond the focus of the the current review, it is clearly related to both considerations of electric and maganetic fields and present day exposures. For this reason we: 1) introduce the significance of this topic, 2) indicate the massive range of environmental conditions that it encompasses, and 3) point to the differential sensitivities and responses among microbes to varying forms and strengths of electromagnetic waves. Electromagentic waves include infrared (IR) waves, radio frequency waves, ultraviolet, microwaves (MWs), visible light, X-rays, and gamma rays within the designations of both non-ionizing and ionizing radiation [120,121,122]. Electromagnetic waves have many industrial applications [123,124], and under certain circumstances they can be a source of potential health benefits via alterations in the gut microbiome and microbe-directed metabolism [125]. However, there is also evidence that they can be health hazards spanning cells, microbes, and holobionts [126,127]. For this reason, relevant exposure-outcome information is important. This is a topic that deserves both more attention in the literature and more research particularly when it comes to microbiomes, holobionts, and safety.

9. Perspectives on Sustainble Living and Conclusions

The consideration of sustainable living covers virtually every aspect of life on Earth running the gauntlet of levels from planetary to the biosphere and finally, to individual humans, plants, animals, insects, and microorganisms. At the planetary level, microbes are viewed as Earth’s ancient lifeforms capable of residing in virtually every location and condition on the planet. Importantly, microbes have not only adapted to these various conditions but have also played a critical role in earth’s biogeochemical cycles [128,129,130]. Obviously, this historic interconnection between microbial life and planetary level “health” leads to a conclusion that microbial life needs to be protected and sustained if other life on earth is to persist. It is intriguing to consider that ancient indigenous cultures emphasizing shamanic guidance and healing gave microbes a proper respect and role in their societies [43]. Much of the 20^th century and its scientific dogmas emphasized the demonizing of microbes and the overkilling of bacteria [25,131,132,133]. Ancient wisdom is worth remembering.

At the level of the human holobiont, acceptance of humans as a composite of the human mammal and thousands of different microbial species has been slow to be reflected in medicine and public health. This has led to calls for microbiome first approaches to medicine and public health that approach the human body as majority microbial [134,135]. Most aspects of human development and function are significantly regulated by the human microbiomes [3,136,137]. Strategies of health maintenance, disease prevention, and disease treatment need to place our microbes first.

Another aspect of human sustainable life concerns the decades-long erosion of human health and functionality brought about by increasing disease burden. Rather than applauding a reasonable lifespan that is filled with ever increasely co-morbid chronic diseases and polypharmacy, we should be evaluating our progress toward sustainability with a different yardstick: by the length of our healthspan (days, week, months, or years spent in health) [6,138,139] not via a disease-ridden existence. An increasing number of prescription drugs consumed on a daily basis is not a sign of sustainable progress.

Finally, the focus of this paper is on microbes and particularly bacteria as premier producers, communicators, transferers, and collaborators when it comes to electricity and magnetism. Because electricity and magnetism are so important to microbes, natural and artificial electric and/or magnetic fields can either be beneficial or detrimental to microbial health and function. This extends not only to microbial communities in the environment but also to human, and other microbiomes. If electric and magnetic fields are particularly important for microbe community status, these are not the only physical fields to consider. In prior reviews, we considered the microbe-modifying effects of sound, light, and vibrations [21] as well as subtle energies associated with ancient and alternative health practices [20]. There is a broad spectrum of tools at our disposal to protect microbes as well as holobionts.

Beyond safety, the present narrative review illustrated examples of technological benefits by using electric and/or magnetic fields in conjunction with microbes. Advancement in medical applications and treatments as well as industrial applications (e.g., microbial fuel cells, bioremediation) will be a major part of our sustainable living. In this way, our progress to a sustainable future should be bright and it should be microbial.