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Effects of combined magnetic fields on bacteria Rhodospirillum rubrum VKM B-1621: Effects of Combined Magnetic Fields on Bacteria
Abstract
Bacteria are the simplest model of living organisms and thus are a convenient object for magnetobiological research. This paper describes some effects of combined magnetic fields (CMFs) on the bacterium Rhodospirillum rubrum strain VKM B‐1621, which is not a pathogen but was selected due to its wide spectrum of growth abilities. The authors chose magnetic field‐resonant phosphorus and iron (Fe³⁺) because P‐containing biochemical compounds (standard abbreviations PP1, AMP, ADP, ATP) provide energy flows in bacteria while iron could take part in formation of magnetosensitive intracellular inclusions. CMFs were produced by interaction of a geomagnetic field (ВDС) and an alternating electromagnetic field (ВАС), which were similar in their intensities. Their magnetic characteristics were as follows: (CMF‐1) ВDC = 46.80 µТ, ВАС = 86.11 µT, f = 807.0 Hz; (CMF‐2) ВDC = 46.80 µТ, ВАС = 86.11 µT, f = 38.3 Hz; that is, the frequencies of applied alternating electromagnetic fields coincided with cyclotron frequencies of phosphorus or ferric ions, respectively. The blank variants were exposed to the geomagnetic field. The CMFs increased bacterial consumption of dissolved iron as measured by residual concentrations of iron in the medium (P > 99%). An increase of bacterial nitrate reduction in the CMFs was statistically insignificant (P > 90%) when measured by residual concentrations of nitrate. Application of CMFs can influence bacterial activity and metabolism. Bioelectromagnetics. 2018;9999:XX–XX. © 2018 Wiley Periodicals, Inc.
... Combined magnetic fields with this intensity ratio also affected calcium efflux from plasma membrane vesicles isolated from Spinacia oleracea L. [14] and inhibited growth in HeLa, VH-10, and Saos-2-His-273 cell cultures [15]. On the other hand, biological effects were found in alternating magnetic fields with a cyclotron frequency for various ions and with an amplitude exceeding the intensity of a static magnetic field by about 1.8 times [5,11,12,16,17,[27][28][29][30][31]. To explain the biological effects of alternating magnetic fields with a frequency that formally corresponds to the cyclotron frequency for different ions and an amplitude ratio of B AC /B DC~0 .9, ...
... This frequency for calcium ions in the geomagnetic field at temperate latitudes of 40-55 µT will be about 30-42 Hz. These values have often been described as B DC and f AC in the experiments testing resonance biophysical models for calcium ions [5,6,16,29,30,90]. The 30-42 Hz frequency should correspond to a chemical oscillation period of approximately 24-33 ms. ...
... The described effects [5,6,16,29,30,90] can be explained by the above model applied to radical pairs in chemical oscillators on the mitochondrial membrane [92]. Under unstressed "physiological" conditions, the mitochondrial membrane potential (∆Ψm) fluctuates with a period close to 25 ms ( Figure 3A). ...
This review covers the phenomenon of resonance-like responses of biological systems to low-frequency magnetic fields (LFMF). The historical development of this branch of magnetobiology, including the most notable biophysical models that explain the resonance-like responses of biological systems to LFMF with a specific frequency and amplitude, is given. Two groups can be distinguished among these models: one considers ion-cofactors of proteins as the primary targets for the LFMF influence, and the other regards the magnetic moments of particles in biomolecules. Attention is paid to the dependence of resonance-like LFMF effects on the cell type. A radical-pair mechanism of the magnetic field’s influence on biochemical processes is described with the example of cryptochrome. Conditions for this mechanism’s applicability to explain the biological effects of LFMF are given. A model of the influence of LFMF on radical pairs in biochemical oscillators, which can explain the frequency–amplitude efficiency windows of LFMF, is proposed.
... Recent research indicates that electromagnetic fields can stimulate or inhibit different biological systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], such as the growth of plants [13], fruits [14], and microorganisms [15]. Similarly, they affect cells in the human [16] and animal [17] body by stimulating or inhibiting different cellular processes [18]. ...
... Recent research indicates that electromagnetic fields can stimulate or inhibit different biological systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], such as the growth of plants [13], fruits [14], and microorganisms [15]. Similarly, they affect cells in the human [16] and animal [17] body by stimulating or inhibiting different cellular processes [18]. ...
... Recently, researchers have begun to investigate the potential impact of EMFs on fermentative processes. Although the role and influence of the magnetic field in this process are undeniable, there are many aspects to consider about its effects [12], which still need to be sufficiently understood [4][5][6][7][12][13][14][15][16][17][18]. ...
A Helmholtz-type electromagnetic emission device, which uses an oscillating magnetic field (OMF), with potential applications in biotechnological research, was built and validated. The coils were connected to an alternating current (AC) generator to generate a 0.5 to 110 mT field at their center. OMF measurements were performed with a Hall effect sensor with a digital signal connection (Arduino nano) and data output to a PC using LabVIEW v2017SP1 software. The fermentation process of the cocoa bean variety CCN 51, exposed to four levels of OMF density for 60 min (0, 5, 40, and 80 mT/60 min), was analyzed. Different variables of the grain fermentation process were evaluated over six days. The ANOVA test probed the device’s linearity, accuracy, precision, repeatability, reliability, and robustness. Moreover, CCN 51 cocoa beans’ EMF-exposure effect was evaluated under different OMF densities for 60 min. The results show the validity of the equipment under working conditions and the impact of EMF (electromagnetic fields) on the yield, deformation, and pH of cocoa beans. Thus, we concluded that the operation of the prototype is valid for use in biotechnological studies.
... At the same time, the presence of a geomagnetic field increased the assimilation of the 14 C-carbonate ions (Figure 2). Similar experiments with the bacterial culture Rhodospirillum rubrum VKM B-1621, where a comparable weak electromagnetic background was added to the geomagnetic background, showed that the combined magnetic field increased consumption of nitrate ions by bacteria and transport of iron into cells (Khokhlova et al. 2018). ...
... Electron microscopy of thin bacterial sections also showed that application of a magnetic field increased stores of iron in the form of insoluble intracellular inclusions ( Figure 3) (Anisimov et al. 2005;Khokhlova et al. 2018). ...
... Ultrathin section of an Rhodospirillum rubrum VKM B-1621 cell exposed to combined magnetic field(Khokhlova et al. 2018). Inorganic inclusions are dark spots inside the cell. ...
Recent research has already been shown widespread locations of bacteria in various tissues and organs of a healthy host organism. These bacteria (hereinafter referred to as persistent microbiota, PM) cause neither noticeable destruction nor toxins production – no immune response can be noticed either. The role of the PM is unknown. The host nervous system is not an exception and can also be inhabited by the PM. We found that various bacteria were capable of benefiting from the electromagnetic field (EMF). The main advantage of these bacteria, apparently, lies in the increasing supply of ionic forms of compounds into the cells. Since microorganisms use the energy of electrical impulses, their possible colonization of the host’s nerve circuit will weaken the nerve signals. The presented hypothesis aims to draw attention to the following points: i) microbial colonization of the host nervous system will lead to the weakening of nerve signals, ii) the sensitivity of bacteria to EMF permits to affect on their activity with electromagnetic treatment.
... R. rubrum forms intracellular magnet-sensitive inclusions containing cobalt or chromium in the nutrient media enriched with these metals (Ariskina et al. 2004). Similar Fe-containing inclusions were formed in Fe-enriched medium (Khokhlova et al. 2018). It should be noted that intracellular metal accumulation and polyP accumulation are both interconnected and associated with sequestration in microorganisms (Kulakovskaya 2018). ...
... The strain of R. rubrum VKM B-1621 was deposited in the All-Russian Collection of Microorganisms (VKM) by the Microbial Collection of Moscow State University (strain R2) as the classic Gram-negative purple photosynthetic bacterium. We have chosen R. rubrum for its ability to grow photoautotrophically in the light (Ivanovsky et al. 1997) or organoheterotrophically in the dark (Oelze and Weaver 1982;Schon and Biedermann 1972;Schultz and Weaver 1982) and the ability to accumulate metals accompanied with the formation of magnet-sensitive intracellular inclusions (Ariskina et al. 2004;Khokhlova et al. 2018). ...
... The medium without Fe contained only trace amounts of this metal. The cells were cultivated as described earlier (Ariskina et al. 2004;Khokhlova et al. 2018). ...
Inorganic polyphosphate is involved in metal homeostasis in microorganisms. The aim of the study was to reveal differences in polyphosphate metabolism of Rhodospirillum rubrum under autotrophic and heterotrophic cultivation in the presence of Fe (2.3 mg Fe³⁺ L⁻¹) and without Fe (traces). Heterotrophic conditions without Fe resulted in cell lysis and low biomass yield. High polyphosphate content and low exopolyphosphatase activity were observed in the cells cultivated autotrophically in the presence of Fe. The cells grown heterotrophically in the presence of Fe contained more phosphate and low-molecular polyphosphate; on the contrary, the content of the high molecular polyphosphate decreased in parallel with the increase in exopolyphosphatase activity. The possible involvement of Pi and polyphosphate to the formation of Fe-containing inclusions is discussed.
... It has been seen that the non-thermal effects of the electromagnetic field (EMF) can affect not only microbial growth but also metabolism [6,7]; however, it has also been shown on several occasions that the metabolic activity induced by EMF is linked to the activation of some areas of DNA [8]. Furthermore, some reports describe that EMF can change many processes in a microorganism, such as increasing antibiotic sensitivity and membrane transport [2,9], changing morphology [10], biofilm formation [11], and reproduction [12]. ...
... The higher microbial diversity in LDR and minor diversity in HDR at 24 h could be explained based on EMF effects on microorganisms. Several authors confirm that EMFs can condition both the stimulation and the inhibition of microbial species, affecting the dynamics of microbial populations in each ecosystem [6][7][8][9][10][11][12][13][14]. For example, Strašák et al. demonstrated that OMF of density 2.7-10 mT, frequency 50 Hz, and time 0-12 min reduces the growth of Escherichia coli [53]. ...
Acid and bitter notes of the cocoa clone Cacao Castro Naranjal 51 (CCN 51) negatively affect the final quality of the chocolate. Thence, the fermentative process of cocoa beans using native species and electromagnetic fields (EMF) was carried out to evaluate the effect on the yield and quality of CCN 51 cocoa beans. The variables magnetic field density (D), exposure time (T), and inoculum concentration (IC) were optimized through response surface methodology to obtain two statistically validated second-order models, explaining 88.39% and 92.51% of the variability in the yield and quality of the beans, respectively. In the coordinate: 5 mT(D), 22.5 min (T), and 1.6% (CI), yield and bean quality improved to 110% and 120% above the control (without magnetic field). The metagenomic analysis showed that the changes in the microbial communities favored the aroma profile at low and intermediate field densities (5–42 mT) with high yields and floral, fruity, and nutty notes. Conversely, field densities (80 mT) were evaluated with low yields and undesirable notes of acidity and bitterness. The findings revealed that EMF effectively improves the yield and quality of CCN 51 cocoa beans with future applications in the development and quality of chocolate products.
... On the other hand, the effect of Fe 2+ and Fe 3+ frequencies as observed here has never been reported. Khokhlova et al. (2018) investigated the metabolism of the bacterium Rhodospirillum rubrum under the presence of AC and DC magnetic fields in resonance conditions for phosphorous and Fe 3+ . They observed that the consumption of nitrate and iron in the culture medium increased under the presence of the combined magnetic fields. ...
Magnetotactic bacteria are microorganisms that swim following the geomagnetic field lines, because of an intracellular magnetic moment that aligns their body to the magnetic field lines. For that reason, these bacteria are appropriate for the study of microorganisms’ motion. The present paper studies the swimming trajectories of uncultured magnetotactic cocci under the effect of combined constant (DC) and alternating (AC) magnetic fields oscillating at frequencies that formally correspond to the cyclotron frequency for Ca2+, K+, Fe2+ and Fe3+ ions. The swimming trajectories were observed to be cylindrical helixes and their helix radiuses, frequencies, axial velocities and orientation angles of the trajectories relative to the constant magnetic field were determined. The orientation angles were used to calculate the magnetic to thermal energy ratio, which helps the study of the disorientating effect of the flagellar motion. Our results show that combined magnetic fields tuned to the resonance of Ca2+ ions affect all the trajectory parameters. Frequencies associated to Ca2+ and K+ do not affect the bacterial swimming direction relative to the magnetic field direction. On the other hand, frequencies associated to Fe2+ and Fe3+ do change the bacterial swimming direction relative to the magnetic field direction, which means that those frequencies affect the flagellar function. These results show indirect evidence of the action of calcium binding proteins in the motility of magnetotactic cocci.
... The chemical composition of this oscillatory process includes radical-pair reactions as a shunt of electrons of the respiratory chain towards the generation of superoxide anions, following the transport and scavenging of superoxide radicals by superoxide dismutase [54]. The influence of 30-42 Hz ELF-MFs on this oscillatory process could theoretically explain various biological effects of so-called "calcium" ELF-MF [4,52,56]. Concerning the frequencies used in this study, the target oscillations affected by ELF-MFs of 1.44-3 Hz should have a period of 694-333 ms. Various membrane potential oscillations can meet these requirements [57], including oscillations in the membrane potential of cardiac mitochondria [55]. ...
Extremely low-frequency magnetic fields (ELF-MF) up to 100 μT exhibit impacts on physiological processes, including heart function. The mechanisms underlying the influence of these fields on fish heart rates remain insufficiently explored. We assumed that the direct impact of ELF-MF with a frequency close to the heart rate could entrain oscillatory processes responsible for autonomously maintaining heart rhythm in zebrafish embryos. Embryos' heart rates ranged from 1.44 to 3 Hz depending on age, and ELF-MF with frequencies precisely matched, 10% higher, or lower than the heart rate were applied. Additionally, embryos experienced ELF-MF with amplitudes varying by an order of magnitude. Almost all tested ELF-MF induced an increased heart rate effect. This effect was the most pronounced when the exposure occurred earlier during ontogenesis. Fields with frequencies close to the heart rate did not entrain cardiac contractions in zebrafish embryos. A significant negative correlation between heart rate increase and ELF-MF frequency was observed for ELF-MF with amplitudes of 1.98–3.2 μT and 46.8 μT but not 30 μT. Probable molecular mechanisms underlying these effects are discussed in terms of magnetic influence on radical pairs within biochemical oscillating processes.
... By manipulating the magnetic field, researchers can control the behavior of magnetic nanoparticles and use them for a wide range of applications, such as magnetic resonance imaging, drug delivery, and wastewater treatment. It is important to note that even without an artificial magnetic field, magnetic nanoparticles are still affected by the Earth's magnetic field [48]. This can influence their behavior and properties, and researchers must take this into account when designing experiments or applications that involve magnetic nanoparticles. ...
Dark fermentation holds great promise as a game-changing strategy in the field of biological hydrogen generation. With its ability to utilize a diverse range of organic feedstocks as a starting material, it offers the added advantage of waste valorization. Despite this, it has long been plagued by a low yield of hydrogen production when compared to traditional thermochemical processes. Recently, researchers have explored the use of nanoparticles as a means of intensifying the fermentation process. In this paper, the latest research on the use of metallic additives in dark fermentation, with a specific focus on naturally magnetic additives such as iron, nickel, and cobalt, is critically reviewed. The influence of these additives on the hydrogen generation process and the mechanisms that make it all happen are evaluated in detail. Optimal dosages for each additive type are also explored based on previous research. Finally, insightful suggestions for future research in this field are put forth. The conclusion is drawn that metal nanoparticles with natural magnetism, such as Fe, Ni, and Co, can improve hydrogen production, process stability, system start-up, and substrate utilization in dark fermentation. However, further research is needed to address various issues, including optimal dosage, operating conditions, microbial population dynamics, use of unconventional substrates, metal toxicity, morphology of metal additives, and potential risks generated by metals that remain in the system after fermentation. The exploration of combining several additives with complementary characteristics or properties is also proposed as an interesting line of research.
... It acts as a non-critical agent but stimulates cell growth under certain exposure conditions [2]. It can also affect cell activities and metabolism [3]. Magnetic fields can change cell physiology, metabolism, and morphology [4]. ...
... Bacterial (PO 4 − ) n = are polymers of phosphate (PO 4 ≡ ) from 5 to 1000 s units that form intracellular magnet-sensitive inclusions that contain magnesium, calcium, cobalt, chromium, or iron (Mg +2 , Ca +2 , Co +2 , Cr +2 , or Fe +2 ) [11][12][13] and play key roles in stress response, swimming, and swarming, which are essential activities for bacterial infection and colonization [14]. (PO 4 − ) n = accumulation occurs as a result of choline catabolism [3] that may occur through inhibition of the degradation of (PO 4 − ) n = to PO 4 ≡ by exo-polyphosphate phosphatase (PPX) or synthesis via ATP addition to (PO 4 − ) n = by activation of polyphosphate kinase (PPK). ...
Pseudomonas aeruginosa is a ubiquitous and opportunistic bacteria found in water, soil, plants, and immunocompromised humans. Cystic fibrosis (CF) patients are the most vulnerable population to lung colonization by these bacteria. Upon infection, choline and succinate are released from the CF lungs and are catabolized by P. aeruginosa. The bacteria accumulate inorganic polyphosphates, rather than succinate, when choline is catabolized, producing physiological and morphological changes leading to ineradicable infection. Thus, we sought to quantify the enzymes responsible for polyphosphate accumulation and to determine how choline catabolism affects energy flow and storage. Subcellular fractions showed that exo-polyphosphate phosphatase (PPX) activity resides mainly in the periplasm, and three isoenzymes of 24, 70, and 200 KD were found. The PPX activity in the periplasm of bacteria grown with choline was inhibited in an anti-competitive manner from Km 0.5 to 1 μM, and their Vmax increased from 50 to 100 nmol PO4≡/min/g of protein in succinate medium. Since PPX inhibition by choline did not explain the 3.8-fold increase in polyphosphates, we quantified the polyphosphate kinase activity, and its significant 2.4-fold increase was consistent with the accumulation. Furthermore, intracellular ATP concentration directly correlated with the energetic yield of the carbon source and was significantly higher for succinate, suggesting that the restriction of energy caused by choline catabolism may induce morphological and physiological changes to the swarm form thus facilitating their migration and tissue colonization
... On the other hand, Lednev's model suggests the maximum biological effects of an alternating magnetic field with an intensity that exceeds that of the static magnetic field by approximately 1.8 times [11]. The effectiveness of this Hac/Hdc ratio has more experimental confirmations that were performed mainly using the organisms but not cell cultures as exposed objects [9,13,[23][24][25][26][27][28][29]. Probably, the above-described effects of alternating magnetic fields with different intensities of 0.9 and 1.8 Hac/Hdc regarding Blanchard-Blackman and Lednev's models [11,12] might be due to the specificity of cells and organisms as objects with different levels of biological organization. ...
A biophysical model for calculating the effective parameters of low-frequency magnetic fields was developed by Lednev based on summarized empirical data. According to this model, calcium ions as enzyme cofactors can be the primary target of low-frequency magnetic fields with different parameters tuned to calcium resonance. However, the effects of calcium-resonant combinations of static and alternating magnetic fields that correspond to Lednev’s model and differ by order in frequency and intensity were not studied. It does not allow for confidently discussing the primary targets of low-frequency magnetic fields in terms of the magnetic influence on ions-enzyme cofactors. To clarify this issue, we examined the response of freshwater crustaceans Daphnia magna to the impact of combinations of magnetic fields targeted to calcium ions in enzymes according to Lednev’s model that differ in order of magnitude. Life-history traits and biochemical parameters were evaluated. Exposure of daphnids to both combinations of magnetic fields led to a long-term delay of the first brood release, an increase in the brood size, a decrease in the number of broods, and the period between broods. The amylolytic activity, proteolytic activity, and sucrase activity significantly decreased in whole-body homogenates of crustaceans in response to both combinations of magnetic fields. The similarity in the sets of revealed effects assumes that different magnetic fields tuned to calcium ions in biomolecules can affect the same primary molecular target. The results suggest that the low-frequency magnetic fields with parameters corresponding to Lednev’s model of interaction between biological molecules and ions can remain effective with a significant decrease in the static magnetic background.
Aims
Magnetotactic bacteria (MTB) can use their unique intracellular magnetosome organelles to swim along the Earth's magnetic field. They play important roles in the biogeochemical cycles of iron and sulfur. Previous studies have shown that the applied magnetic fields could affect the magnetosome formation and antioxidant defense systems in MTB. However, the molecular mechanisms by which magnetic fields affect MTB cells remain unclear. We aim to better understand the interactions between magnetic fields and cells, and the mechanism of MTB adaptation to magnetic field at molecular levels.
Methods and results
We performed microbiological, transcriptomic and genetic experiments to analyze the effects of a weak static magnetic field (SMF) exposure on the cell growth and magnetosome formation in MTB strain Magnetospirillum magneticum AMB-1. The results showed that a 1.5 mT SMF significantly promoted the cell growth but reduced magnetosome formation in AMB-1, compared to the geomagnetic field. Transcriptomic analysis revealed decreased expressions of genes primarily involved in the sulfate reduction pathway. Consistently, knockout mutant lacking adenylyl-sulfate kinase CysC did no more react to the SMF and the differences in growth and Cmag were disappeared. Together with experimental findings of increased reactive oxidative species in the SMF-treated Wild-type strain, we proposed that cysC, as a key gene, can participate in the cells growth and mineralization in AMB-1 by SMF regulation.
Conclusions
This study suggests that the magnetic field exposure can trigger a bacterial oxidative stress response involved in AMB-1 growth and magnetosome mineralization by regulating sulfur metabolism pathway. CysC may serve as a pivotal enzyme in mediating sulfur metabolism to synchronize the impact of SMF on both growth and magnetization of AMB-1.
ELF (Exemelly Low Frequency) is a spectrum of electromagnetic waves with a frequency of less than 300 Hz. This study aims to determine the effect of exposure to the ELF magnetic field on the degree of acidity (pH) in the maturation process of cassava tape. The research method used is a true experiment, namely by giving exposure to the ELF magnetic field in the experimental group and not giving exposure to the ELF magnetic field in the control group. Exposure to the ELF (Extremely Low Frequency) magnetic field on cassava tape used intensities of 100𝜇T, 200𝜇T, and 300𝜇T with various exposure times, namely 30 minutes, 60 minutes, and 90 minutes. The type of research used is experimental research with a completely randomizedidesign (CRD) which aims to examine the effect of treatment by repeating the experiment. Data collection was carried out after the 1st day to the 4th day. The results showed that exposure to ExtremelyiLowiFrequencyi(ELF) magnetic fields can affect the average pH value in the cassava tape fermentation process which is shown through variations in the bar chart. The experimental group samples (E100𝜇T 60') and (E300𝜇T 30') on day 1 to day 4 there was a significant change in pH value.
A significant decrease in the respiratory burst activity of a neutrophil suspension has been recorded in response to N-formyl-Met-Leu-Phe peptide activation after a 40-min exposure to weak combined magnetic fields: a static magnetic field (60 μT) and a collinear low-frequency magnetic field with a frequency of 49.5 Hz within the 60-180 nT range. This lower response was shown by luminol-dependent chemilumines-cence. The frequency of 49.5 Hz of the alternating component of combined magnetic fields nominally corresponds to the Fe 3+ ion cyclotron resonance frequency. At closely spaced frequencies (46 Hz and 48.5 Hz), the biological effect of the combined magnetic fields was three times less pronounced. There was no biological effect at 33 Hz, the frequency of the alternating component of combined magnetic fields. The exposure to a magnetic signal that is the sum of all of the investigated frequencies (33.0, 46.0, 48.5 and 49.5 Hz) resulted in a effect that was two times less pronounced compared to that after the exposure to combined magnetic fields at 49.5 Hz.
It has been shown that various chemical agents (ethylenediaminetetraacetic acid, zinc sulphate, ethyl alcohol, and rotenone) have different effects on preactivation (priming) of neutrophils that develop under weak combined collinear static and alternating magnetic fields (combined magnetic fields: a static field of 42 μT and an alternating field of 0.86 μT with the sum of frequencies 1.0, 4.4 and 16.5 Hz). Low concentrations (0.05%) of ethylenediaminetetraacetic acid decrease the intensity of luminol dependent chemilumi-nescence of neutrophils in response to an activator of the respiratory burst the peptide N-formyl-Met-Leu-Phe under the action of combined magnetic fields to a lesser extent than in the control. In contrast, ethyl alcohol (0.45%) and zinc sulphate (0.1 mM) have a greater effect on this process under the action of combined magnetic fields. Rotenone (1 μM) has a weak effect on neutrophil chemiluminescence both under the action of combined magnetic fields and in the control.
Since the beginning of their lives, all living organisms are exposed to the influence of geomagnetic fields.
With respect to the positive effects that magnetic fields have on human tissues, especially the bactericidal effect, this investigation aimed to assess their influence on the reduction of oral microorganisms.
In order to obtain adequate specimens of dental plaque deposit, microbes such as Streptococcus parasanguinis, Staphylococcus epidermidis, Rhodococcus equi and Candida albicans were isolated from the human mouth. To establish the intensity of microbial growth on the basis of the modified optical density (OD) of agar turbidimetry assay, microbial count and spectrophotometry were applied. The study was carried out with two microbial concentrations (1 and 10 CFU/ml) after periods of incubation of 24 and 48 h and using micromagnets.
A positive effect of the magnetic field, resulting in the reduction of dental plaque microbes in vitro, was found. In the first 24 hours of exposure to the magnetic field, the number of all isolated microbes was significantly reduced. The most potent influence of magnets and the most intensified reduction after 24 hours were evident in Candida albicans colonies. The decrease in the influence of magnets on microbes in vitro was also detected.
Magnets reduce the number of microbes and might be recommended as a supplement in therapy for reduced periodontal tissues. This is important because periodontal tissues that are in good conditions provide prolonged support to the oral tissues under partial and supradental denture.
Abstract The impact of different types of extremely low-frequency electromagnetic fields (ELF-EMF) on the growth of Staphylococcus aureus and Escherichia coli O157:H7 was investigated. The cultures of bacteria in broth media were exposed to sinusoidal homogenous ELF-EMF with 2 and 4 mT magnetic intensities. Each intensity for each bacteria was combined with three different frequencies (20, 40 and 50 Hz), and four different exposure times (1, 2, 4 and 6 h). A cell suspension of each experiment was diluted for the appropriate range and inoculated to Mueller-Hinton Agar (MHA) plates after exposure to ELF-EMF. The number of colony forming units (CFU) of both strains was obtained after incubation at 37 °C for 24 h. Data were statistically evaluated by one-way analysis of variance (ANOVA), statistical significance was described at p < 0.05 and data were compared with their non-exposed controls. Magnetic intensity, frequency and exposure time of ELF-EMFs changed the characteristic responses for both microorganisms. Samples exposed to ELF-EMF showed a statistically significant decrease compared to their controls in colony forming capability, especially at long exposure times. An exposure to 4 mT-20 Hz ELF-EMF of 6 h produced maximum inhibition of CFU compared to their controls for both microorganisms (95.2% for S. aureus and 85% for E. coli).
This work presents results of the study which concerns the influence of the rotating magnetic field (RMF) on
the growth rate, cell metabolic activity and ability to form biofilms by E. coli and S. aureus. Liquid cultures of
the bacteria were exposed to the RMF (RMF frequency f = 1-50 Hz, RMF magnetic induction B = 22-34 mT,
time of exposure t = 60 min, temperature of incubation 37 °C). The present study indicate the exposition to the
RMF, as compared to the unexposed controls causing an increase in the growth dynamics, cell metabolic
activities and percentage of biofilm-forming bacteria, in both S. aureus and E. coli cultures. It was also found
that the stimulating effects of the RMF exposition enhanced with its increasing frequencies and magnetic
inductions.
Background
This study investigated the effects of extremely low frequency (ELF) pulsed electromagnetic field (PEMF) radiation on the growth of bacterium Staphylococcus aureus (ATCC 25923) that plays a versatile role in infecting wounded tissues. The viability of these bacteria (number of live cells as colony-forming units (CFUs)) was measured before and after the ELF PEMF exposures to quantify their survival rate.
Methods
S. aureus cultures were first cultivated in an agar medium, and then picked and suspended in Columbia broth medium. Optical density reading for the suspended bacteria was measured at 600 nm and adjusted to a specific value of 0.1 ± .005A prior to experimentation and placement of bacteria into 2.5 mL centrifuge tubes. Sham-exposed tubes filled with bacteria were kept under the same experimental conditions and used as controls. The constructed exposure system, emitting uniform time varying magnetic fields (frequency of 2-500 Hz, and magnetic induction of 0.5-2.5 mT), was employed to irradiate S. aureus bacteria for 90 min. To determine the CFU per ml of the exposed bacteria, five serial dilutions were performed. A volume of 100 μl from the last tube was suspended onto agar plates by spread plating. After incubation, the colonies formed on the plates were visually counted.
Results
All irradiated S. aureus bacteria showed decrease in their growth rate compared to control samples. The results demonstrated that ELF PEMF exposures at 150-500 Hz are more effective than exposures at 3-100 Hz in reducing the viability of S. aureus in broth. The lowest CFU value was achieved with the exposure at 300 Hz and 1.5 mT. The decrease of at least 20% in CFU value was obtained for frequencies above 200 Hz and all five studied magnetic flux densities (0.5 mT. 1.0 mT, 1.5 mT, 2.0 mT, and 2.5 mT).
Conclusions
In summary, the growth rate of the irradiated S. aureus bacteria is affected by radiation of particular parameters, thus revealing resonant effects induced by the applied radiation. The decreased CFU values in all irradiated samples compared to control samples (non-exposed) were observed. Findings provide important insight towards selecting the optimal parameters of ELF PEMF for possible treatment of infected tissue and thus, wound healing promotion.
The results of theoretical and experimental investigations of V.V. Lednev on interactions of weak and extremely weak magnetic
fields with biosystems are reviewed. The period since 1989, when the first version of the interference model has been suggested,
until now is considered. Some mathematical expressions are presented, which have been published earlier in the papers that
are now bibliographic rarity. The results of experimental investigations are also summarized that have been performed in this
period under the supervision of V.V. Lednev in the Laboratory of Biophysics of Intracellular Regulation at the Insitute of
Theoretical and Experimental Biophysics of the Russian Academy of Sciences.
Keywordscombined magnetic fields-extremely weak alternating magnetic fields-interference model-magnetic parametric resonance-nuclear spins-magnetic moments-planarian regeneration
We aimed to investigate the effects of exposure to extremely low-frequency electromagnetic fields (2 mT; 50 Hz) on the growth rate and antibiotic sensitivity of E. coli ATCC 25922 and P. aeruginosa ATCC 27853. The electromagnetic field treatment significantly influenced the growth rate of both strains when incubated in the presence of subinhibitory concentrations of kanamycin (1 μg/mL) and amikacin (0.5 μg/mL), respectively. In particular, at 4, 6, and 8 h of incubation the number of cells was significantly decreased in bacteria exposed to electromagnetic field when compared with the control. Additionally, at 24 h of incubation, the percentage of cells increased (P. aeruginosa∼42%; E. coli∼5%) in treated groups with respect to control groups suggesting a progressive adaptive response. By contrast, no remarkable differences were found in the antibiotic susceptibility and on the growth rate of both bacteria comparing exposed groups with control groups.
It was shown that the rate of gravitropic response in apical segments excised from the 4-day-old seedlings of flax (Linum bienne) may be substantially influenced by combined magnetic fields (CMF) of two different types: 1) CMF tuned to the parametric resonance for Ca2+; 2) CMF containing extremely weak alternating component with the values of magnetic density ranging trom 10-6 to 10-10 T. Our experimental data indicate that CMF affect the gravitropic response via at least two different mechanisms. The first one corresponds to the ion parametric resonance well established earlier in studies with test - systems prepared from animals. The origin of the bioeffects induced by CMF containing extremely weak alternating component remains to be established.
The magnet-sensitive inclusions of a new type were discovered in cells of Rhodopseudomonas and Ectothiorhodospira species. The inclusions formed thread of beads along the main axis of cells and provided a movement of the biomass to the next pole of an applied static magnet. The electron microscopy of ultrathin sections showed a heterogeneous structure of the inclusions. The magnet-sensitive inclusions were the spherical particles containing an electron-transparent core surrounded with electron-dense matrix. The matrix was separated from cytoplasm with a homogeneous envelope of low electron density. X-ray microanalysis demonstrated that the matrix was enriched with iron.
During phototrophic growth on acetate and CO2Rhodospirillum rubrum 2R contained malate synthase but lacked isocitrate lyase. Acetate assimilation by R. rubrum cells was stimulated by pyruvate, propionate glyoxylate, CO2 and H2. Acetate photoassimilation by R. rubrum cells in the presence of bicarbonate was accompanied by glyoxylate secretion, which increased after addition of fluoroacetate and decreased after addition of malonate. When acetyl-CoA was incubated with pyruvate in cell-free extracts, citramalate was formed. Citramalate was also formed from propionyl-CoA and glyoxylate. The existence in R. rubrum of a CO2-dependent cyclic pathway of acetate oxidation to glyoxylate with citramalate as an intermediate is proposed. Inhibitor analysis of acetate and bicarbonate assimilation indicated that pyruvate synthase is not involved in acetate assimilation in R. rubrum. The possible anaplerotic sequences employed by R. rubrum during phototrophic growth on acetate are discussed.
The results of theoretical and experimental investigations of V.V. Lednev on interactions of weak and extremely weak magnetic fields with biosystems have been reviewed. The period since 1989, when the first version of the interference model has been suggested, until now has been considered. Some mathematical expressions, are presented, which have been published earlier in the papers that are now bibliographic rarity. The results of experimental investigations are also summarized that have been performed in this period under the supervision of V.V. Lednev in the laboratory of biophysics of intracellular regulation in the Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences.
A method was discovered for adapting the cells of Rhodospirillum rubrum to grow on a nitrate medium, a capacity initially lacking in the organism. The adapted cells were able to grow with nitrate as the sole source of nitrogen. The growth responses of the adapted cells towards various nitrogenous sources were investigated under various conditions of incubation (aero- and anaerobiosis, light and dark).
The adapted cells were found to have simultaneously acquired the capacity for reducing nitrite and hydroxylamine as well as nitrate. The path of nitrogen in the adapted cells was assumed to be as follows: NO 3 − → NO 2 −→ NH 2 OH→ Cellular Nitrogen.
Nitrate metabolism of the adapted cells was investigated under various conditions. In the light, nitrate was reduced and further assimilated, leaving insignificant amounts of nitrite in the medium. In this case, consumption of nitrate was markedly inhibited by other forms of nitrogen ( e.g ., nitrite, hydroxylamine, amino acids and ammonium salts). In the dark, nitrate was reduced as the terminal hydrogen acceptor in the oxidative breakdown of organic substances ( e.g ., malate) in the medium ( i.e ., nitrate respiration). More nitrite was accumulated in this case than in the light. Molecular oxygen inhibited the reduction of, as well as the growth on, nitrate in any of the above cases.
The effects on the rate of nitrate reduction (and respiratory oxygen uptake) caused by various experimental factors (pH, nitrate concentration, electron donors, and addition of hydroxylamine) were investigated, using the resting cells of the adapted organism.
1. From nitrate-adapted cells of Rhodospirillum rubrum, an active preparation of nitrate reducing enzyme was isolated in partially purified state. The enzyme was found to be localized in the chromatophores of the cell and, on sonication, readily released into the upernatant fraction. The purified enzyme, catalyzing the electron transfer between DPNH and nitrate, contained a b-type cytochrome, flavin and non-heme iron, which was removed on dialysis in the presence of cyanide. Besides DPNH, only methylviologen (reduced form) was effective as electron donor.
2. The effects of pH and the addition of various activators and inhibitors on the rate of nitrate reduction were investigated, using DPNH or reduced methylviologen as the electron donor. The oxidation-reduction of the flavin and the heme in the enzyme was followed spectrophotometrically. A pathway of electron in the nitrate reduction through this enzyme was proposed.
3. The nitrate reductase of this bacterium was compared with other nitrate reductases obtained from other sources, and the metabolic roles of this enzyme were discussed. In the nitrate-adapted cells of Rsp. rubrum, only one and the same enzyme was obtained under different growth conditions of nitrate assimilation (i. e., nitrate as N-source; light as energy source) and nitrate-respiration (i. e., in the dark; nitrate as hydrogen acceptor and N-source).
Magnetotactic bacteria produce nanometer-size intracellular magnetic crystals. The superior crystalline and magnetic properties of magnetosomes have been attracting much interest in medical applications. To investigate effects of intense static magnetic field on magnetosome formation in Magnetospirillum magneticum AMB-1, cultures inoculated with either magnetic or non-magnetic pre-cultures were incubated under 0.2 T static magnetic field or geomagnetic field. The results showed that static magnetic field could impair the cellular growth and raise C(mag) values of the cultures, which means that the percentage of magnetosome-containing bacteria was increased. Static magnetic field exposure also caused an increased number of magnetic particles per cell, which could contribute to the increased cellular magnetism. The iron depletion in medium was slightly increased after static magnetic field exposure. The linearity of magnetosome chain was also affected by static magnetic field. Moreover, the applied intense magnetic field up-regulated mamA, mms13, magA expression when cultures were inoculated with magnetic cells, and mms13 expression in cultures inoculated with non-magnetic cells. The results implied that the interaction of the magnetic field created by magnetosomes in AMB-1 was affected by the imposed magnetic field. The applied static magnetic field could affect the formation of magnetic crystals and the arrangement of the neighboring magnetosome.
A physical mechanism is suggested for a resonant interaction of weak magnetic fields with biological systems. An ion inside a Ca(2+)-binding protein is approximated by a charged oscillator. A shift in the probability of ion transition between different vibrational energy levels occurs when a combination of static and alternating magnetic fields is applied. This in turn affects the interaction of the ion with the surrounding ligands. The effect reaches its maximum when the frequency of the alternating field is equal to the cyclotron frequency of this ion or to some of its harmonics or sub-harmonics. A resonant response of the biosystem to the magnetic field results. The proposed theory permits a quantitative explanation for the main characteristics of experimentally observed effects.
The growth of photosynthetically precultured cells of Rhodospirillum rubrum under aerobic condition in light is investigated. Special emphasis is given to the question of whether the photosynthetic electron transport chain is influenced under these conditions. Light-induced absorbance changes under anaerobic conditions show that although in whole cells a variation can be noted, the reactions of isolated membranes decrease only very slowly and parallel to each other. The photophosphorylation activity remains constant on a bacteriochlorophyll basis. On a cell mass basis this activity decreases parallel to the decreasing bacteriochlorophyll content. Light-dependent NAD+ reduction by ascorbate-DCPI remains constant on a bacteriochlorophyll basis, whereas succinate supported NAD+ reduction in light increases. On a cell mass basis the activity of succinate supported NAD+ reduction stays nearly constant, thus showing similar responses to the presence of oxygen in light as the NADH oxidase system. NADH oxidase activity increases on a bacteriochlorophyll basis and does not change on a cell mass basis. Parallel to the NADH-oxidase system, oxygen uptake in the dark by whole cells does not change after aerobiosis in light. Light inhibits respiration even after several generations of growth in the presence of oxygen; however, the inhibition decreases slowly. Light inhibition of respiration can be totally overcome by the addition of the uncoupler CCCP. These results indicate that light-dependent electron transport is not influenced significantly by the presence of oxygen. Although the respiratory system is formed, cells preferentially grow photosynthetically. Respiration takes over when the amount of bacteriochlorophyll reaches very low values.
R. rubrum bildet anaerob im Dunkeln aus exogenen und endogenen Substraten hauptschlich Acetat und Propionat.In Kulturen mit Pyruvat als Substrat wurde in der Regel mehr Acetat als Propionat gebildet (4:1–1:1), mit Fructose dagegen weniger Acetat (1:2–1:3). Ruhende Zellen produzierten aus Pyruvat, im Vergleich zu Kulturen mit (NH4)2SO4 im Medium, relativ mehr Propionat als Acetat.Beim Abbau von gespeicherter PHBS wurde relativ mehr Acetat und weniger Propionat als beim Abbau endogener Polysaccharide produziert.Eine Zugabe von Ascorbat (0,8 u. 1,6%) oder K3[Fe(CN)6] (0,08 u 0,32%) hatte nur einen geringen Effekt auf das Verhltnis von Acetat zu Propionat. Exogenes CO2 war, besonders bei Zugabe von Fructose als Substrat, fr die Synthese von Propionat notwendig. Die Wege der Acetat- und Propionatbildung unter anaeroben Bedingungen im Dunkeln werden diskutiert.Under anaerobic conditions in the dark R. rubrum produced mainly acetate and propionate from exogenous and endogenous substrates.With pyruvate as a substrate usually less propionate than acetate was synthesized, with fructose, however, more propionate than acetate was produced.In resting cells, compared with cultures having (NH4)2SO4 in the medium, more propionate than acetate was synthesized from pyruvate.By degradation of stored poly--hydroxybutyric acid under anaerobic dark conditions relatively more acetate is produced than by degradation of endogenous polysaccharide.Addition of ascorbate (0.8 and 1.6%) or K3[Fe(CN)6] (0.08 and 0.32%) had little influence on the relative concentrations of acetate and propionate.Exogenous CO2 was necessary for the synthesis of propionate, especially when fructose was the substrate. The pathways of acetate and propionate production anaerobically in the dark are discussed.
Rhodospirillum rubrum and Rhodopseudomonas capsulata were able to grow anaerobically in the dark either by a strict mixed-acid fermentation of sugars or, in the presence of an appropriate electron acceptor, by an energy-linked anaerobic respiration. Both species fermented fructose without the addition of accessory oxidants, but required the initial presence of bicarbonate before fermentative growth could begin. Major products of R. rubrum fermentation were succinate, acetate, propionate, formate, hydrogen, and carbon dioxide; R. capsulata produced major amounts of lactate, acetate, succinate, hydrogen, and carbon dioxide. R. rubrum and R. capsulata were also capable of growing strictly through anaerobic, respiratory mechanisms. Nonfermentable substrates, such as succinate, malate, or acetate, supported growth only in the presence of an electron acceptor such as dimethyl sulfoxide or trimethylamine oxide. Carbon dioxide and dimethyl sulfide were produced during growth of R. rubrum and R. capsulata on succinate plus dimethyl sulfoxide. Molar growth yields from cultures grown anaerobically in the dark on fructose plus dimethyl sulfoxide were 3.8 to 4.6 times higher than values obtained from growth on fructose alone and were 56 to 60% of the values obtained from aerobic, respiratory growth with fructose. Likewise, molar growth yields from anaerobic, respiratory growth conditions with succinate plus dimethyl sulfoxide were 51 to 54% of the values obtained from aerobic, respiratory growth with succinate. The data indicate that dimethyl sulfoxide or trimethylamine oxide as a terminal oxidant is approximately 33 to 41% as efficient as O(2) in conserving energy through electron transport-linked respiration.
The model for the interaction of weak magnetic fields with biosystems, which has been suggested earlier by the author for the case of impulse-like excitation of oscillators (i.e. of ions bound in the Ca(2+)-dependent enzymes or in the protein-enzyme complexes) is extended for the more realistic case of continuous excitation of oscillators. The expressions for the polarization degree of oscillator's vibrations in combined, static and alternating magnetic fields are derived. It is postulated that the value of bioeffect induced by magnetic field in a biosystem is proportional to the polarization degree of the ion's vibration. The available experimental data are shown to be in a remarkably good fit with theoretical predictions.
Bacteria belonging to different taxonomic and physiological groups (members of the genera Pseudomonas, Brevibacterium, Rhodopseudomonas, and Lactococcus) are able to form intracellular cobalt- and chromium-containing magnetic inclusions. The paper deals with the structure and the intracellular localization of these inclusions and their similarity to the known noncrystalline iron-containing magnetic inclusions. The possible biological role of the magnetic inclusions is discussed.
Extremely weak alternating magnetic fields affect the gravitropic response in plants (in Russian, English summary)
- Belova NA
Possible mechanism for the influence of weak magnetic fields on biological systems
- Lednev
Analytische chemie (3. Auflage)
- Ottom
Otto M. 2006. Analytische chemie (3. Auflage). Weinheim,
Germany: Wiley-VCH Verlag, p 756. (In German).