Comparable effects of low-intensity electromagnetic irradiation at the frequency of 51.8 and 53 GHz and antibiotic ceftazidime on Lactobacillus acidophilus growth and survival

5G mobile networks and health-a state-of-the-science review of the research into low-level RF fields above 6 GHz

The increased use of radiofrequency (RF) fields above 6 GHz, particularly for the 5 G mobile phone network, has given rise to public concern about any possible adverse effects to human health. Public exposure to RF fields from 5 G and other sources is below the human exposure limits specified by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). This state-of-the science review examined the research into the biological and health effects of RF fields above 6 GHz at exposure levels below the ICNIRP occupational limits. The review included 107 experimental studies that investigated various bioeffects including genotoxicity, cell proliferation, gene expression, cell signalling, membrane function and other effects. Reported bioeffects were generally not independently replicated and the majority of the studies employed low quality methods of exposure assessment and control. Effects due to heating from high RF energy deposition cannot be excluded from many of the results. The review also included 31 epidemiological studies that investigated exposure to radar, which uses RF fields above 6 GHz similar to 5 G. The epidemiological studies showed little evidence of health effects including cancer at different sites, effects on reproduction and other diseases. This review showed no confirmed evidence that low-level RF fields above 6 GHz such as those used by the 5 G network are hazardous to human health. Future experimental studies should improve the experimental design with particular attention to dosimetry and temperature control. Future epidemiological studies should continue to monitor long-term health effects in the population related to wireless telecommunications.

Growth properties and hydrogen yield in green microalga Parachlorella kessleri: Effects of low-intensity electromagnetic irradiation at the frequencies of 51.8 GHz and 53.0 GHz

The current research reports the effects of low-intensity extremely high frequency electromagnetic irradiation (EMI) of 51.8 GHz and 53.0 GHz on green microalga Parachlorella kessleri RA-002 isolated in Armenia. EMI demonstrated different effects on the growth properties of microalgae under various conditions. Under aerobic conditions a positive effect of EMI on the growth rate of P. kessleri and the content of photosynthetic pigments were observed. The data obtained indicates a significant role of O₂, since the enhancing effect of EMI was determined only under aerobic conditions. Meanwhile under anaerobic conditions EMI with both frequencies caused inhibition of algal growth and a decrease in the amount of photosynthetic pigments. EMI also inhibited the yield of H₂ production in P. kessleri, which was partially restored after 5-day cultivation due to the existence of protective mechanisms in this alga. The results might indicate membrane-bound mechanisms of EMI action on algae, which can be associated with the effects on photosynthetic pigments and membrane-associated enzymes responsible for H₂ production. The results are useful for the development of algae biotechnology and the possibility of using EMI as a factor which regulates the production of biomass and biohydrogen by green microalgae.

The survival of irradiated lactobacilli in the simulated gastrointestinal conditions with antibiotic ceftazidime

Lactobacillus acidophilus is one of the widespread probiotic bacteria that can overcome acid and bile barrier of stomach and intestine, respectively, and then have beneficial effects on the host improving its intestinal microbial balance. The cell membrane F_O F₁ -ATPase is an important factor in the response and tolerance to low pH through the action of controlling the H⁺ concentration between the cell cytoplasm and external medium. In this study, the effects of extremely high-frequency EMI at the frequencies of 51·8 GHz and 53 GHz and cetfazidime ( μmol l^-1 ) on survival of L. acidophilus VKM B-1660 in the gastrointestinal model in vitro and on ATPase activity of their membrane vesicles were investigated. Irradiated L. acidophilus survived in media with acid pH; the irradiation stimulated N,N'-dicyclohexylcarbodiimide-sensitive F_O F₁ -ATPase activity under acidic conditions, but enhanced the inhibitory effects of ceftazidime. Probably irradiated L. acidophilus is overcoming the acid barrier even in the presence of ceftazidime due to the F_O F₁ -ATPase. The obtained results can allow the use of L. acidophilus in food industry, veterinary and medicine. SIGNIFICANCE AND IMPACT OF THE STUDY: The probiotic property of lactobacilli is defined with survival in different conditions of human digestive tract even in the presence of antibiotics and subjected to electromagnetic irradiation (EMI) at the extremely high frequency. Despite the fact that EMI and antibiotic ceftazidime affected Lactobacillus acidophilus; the viable number of bacterial cells was decreased in in vitro gastrointestinal model, but they could to grow in fresh growth medium. The changes in the F_O F₁ -ATPase activity were obtained at acidic pH. Thus, these bacteria can overcome acid barrier due to the F_O F₁ -ATPase: the irradiation stimulates the F_O F₁ -ATPase activity in the acidic conditions, but enhances the effects of ceftazidime. The results are important for identifying the mechanisms of lactobacilli survival for physical and chemical factors and valuable for use.

The Effects of Low Doses of Gamma-Radiation on Growth and Membrane Activity of Pseudomonas aeruginosa GRP3 and Escherichia coli M17

Microorganisms are part of the natural environments and reflect the effects of different physical factors of surrounding environment, such as gamma (γ) radiation. This work was devoted to the study of the influence of low doses of γ radiation with the intensity of 2.56 μW (m² s)^-1 (absorbed doses were 3.8 mGy for the radiation of 15 min and 7.2 mGy-for 30 min) on Escherichia coli M-17 and Pseudomonas aeruginosa GRP3 wild type cells. The changes of bacterial, growth, survival, morphology, and membrane activity had been studied after γ irradiation. Verified microbiological (specific growth rate, lag phase duration, colony-forming units (CFU) number, and light microscopy digital image analysis), biochemical (ATPase activity of bacterial membrane vesicles), and biophysical (H⁺ fluxes throughout cytoplasmic membrane of bacteria) methods were used for assessment of radiation implications on bacteria. It was shown that growth specific rate, lag phase duration and CFU number of these bacteria were lowered after irradiation, and average cell surface area was decreased too. Moreover ion fluxes of bacteria were changed: for P. aeruginosa they were decreased and for E. coli-increased. The N,N'-dicyclohexylcarbodiimide (DCCD) sensitive fluxes were also changed which were indicative for the membrane-associated F₀F₁-ATPase enzyme. ATPase activity of irradiated membrane vesicles was decreased for P. aeruginosa and stimulated for E. coli. Furthermore, DCCD sensitive ATPase activity was also changed. The results obtained suggest that these bacteria especially, P. aeruginosa are sensitive to γ radiation and might be used for developing new monitoring methods for estimating environmental changes after γ irradiation.

The effect of a high frequency electromagnetic field in the microwave range on red blood cells

The effect of red blood cells (RBC) exposed to an 18 GHz electromagnetic field (EMF) was studied. The results of this study demonstrated for the first time that exposure of RBCs to 18 GHz EMF has the capacity to induce nanospheres uptake in RBCs. The uptake of nanospheres (loading efficiency 96% and 46% for 23.5 and 46.3 nm nanospheres respectively), their presence and locality were confirmed using three independent techniques, namely scanning electron microscopy, confocal laser scanning microscopy and transmission electron microscopy. It appeared that 23.5 nm nanospheres were translocated through the membrane into the cytosol, while the 46.3 nm-nanospheres were mostly translocated through the phospholipid-cholesterol bilayer, with only some of these nanospheres passing the 2D cytoskeleton network. The nanospheres uptake increased by up to 12% with increasing temperature from 33 to 37 °C. The TEM analysis revealed that the nanospheres were engulfed by the cell membrane itself, and then translocated into the cytosol. It is believed that EMF-induced rotating water dipoles caused disturbance of the membrane, initiating its deformation and result in an enhanced degree of membrane trafficking via a quasi-exocytosis process.

The distinguishing effects of low-intensity electromagnetic radiation of different extremely high frequencies on Enterococcus hirae: growth rate inhibition and scanning electron microscopy analysis

A low-intensity electromagnetic field of extremely high frequency has inhibitory and stimulatory effects on bacteria, including Enterococcus hirae. It was shown that the low-intensity (the incident power density of 0·06 mW cm^-2 ) electromagnetic field at the frequencies of 51·8 GHz and 53 GHz inhibited E. hirae ATCC 9790 bacterial growth rate; a stronger effect was observed with 53 GHz, regardless of exposure duration (0·5 h, 1 h or 2 h). Scanning electron microscopy analysis of these effects has been done; the cells were of spherical shape. Electromagnetic field at 53 GHz, but not 51·8 GHz, changed the cell size-the diameter was enlarged 1·3 fold at 53 GHz. These results suggest the difference in mechanisms of action on bacteria for electromagnetic fields at 51·8 GHz and 53 GHz.

SIGNIFICANCE AND IMPACT OF THE STUDY

A stronger inhibitory effect of low-intensity electromagnetic field on Enterococcus hirae ATCC 9790 bacterial growth rate was observed with 53 GHz vs 51·8 GHz, regardless of exposure duration. Scanning electron microscopy analysis showed that almost all irradiated cells in the population have spherical shapes similar to nonirradiated ones, but they have increased diameters in case of irradiated cells at 53 GHz, but not 51·8 GHz. The results are novel, showing distinguishing effects of low-intensity electromagnetic field of different frequencies. They could be applied in treatment of food and different products in medicine and veterinary, where E. hirae plays an important role.

Biohydrogen production by purple non-sulfur bacteria Rhodobacter sphaeroides: Effect of low-intensity electromagnetic irradiation

The present work was focused on the effects of low-intensity (the flux capacity was of 0.06mWcm(-2)) electromagnetic irradiation (EMI) of extremely high frequencies or millimeter waves on the growth and hydrogen (H2) photoproduction by purple non-sulfur bacteria Rhodobacter sphaeroides MDC6521 (from Armenian mineral springs). After exposure of R. sphaeroides, grown under anaerobic conditions upon illumination, to EMI (51.8GHz and 53.0GHz) for 15min an increase of specific growth rate by ~1.2-fold, in comparison with control (non-irradiated cells), was obtained. However, the effect of EMI depends on the duration of irradiation: the exposure elongation up to 60min caused the delay of the growth lag phase and the decrease specific growth rate by ~1.3-fold, indicating the bactericidal effect of EMI. H2 yield of the culture, irradiated by EMI for 15min, determined during 72h growth, was ~1.2-fold higher than H2 yield of control cells, whereas H2 production by cultures, irradiated by EMI for 60min was not observed during 72h growth. This difference in the effects of extremely high frequency EMI indicates a direct effect of radiation on the membrane transfer and the enzymes of these bacteria. Moreover, EMI increased DCCD-inhibited H(+) fluxes across the bacterial membrane and DCCD-sensitive ATPase activity of membrane vesicles, indicating that the proton FoF1-ATPase is presumably a basic target for extremely high frequency EMI related to H2 production by cultures.

The Bioeffects Resulting from Prokaryotic Cells and Yeast Being Exposed to an 18 GHz Electromagnetic Field

The mechanisms by which various biological effects are triggered by exposure to an electromagnetic field are not fully understood and have been the subject of debate. Here, the effects of exposing typical representatives of the major microbial taxa to an 18 GHz microwave electromagnetic field (EMF)were studied. It appeared that the EMF exposure induced cell permeabilisation in all of the bacteria and yeast studied, while the cells remained viable (94% throughout the exposure), independent of the differences in cell membrane fatty acid and phospholipid composition. The resulting cell permeabilisation was confirmed by detection of the uptake of propidium iodine and 23 nm fluorescent silica nanospheres using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Upon EMF exposure, the bacterial cell membranes are believed to become permeable through quasi-endocytosis processes. The dosimetry analysis revealed that the EMF threshold level required to induce the uptake of the large (46 nm) nanopsheres was between three and six EMF doses, with a specific absorption rate (SAR) of 3 kW/kg and 5 kW/kg per exposure, respectively, depending on the bacterial taxa being studied. It is suggested that the taxonomic affiliation and lipid composition (e.g. the presence of phosphatidyl-glycerol and/or pentadecanoic fatty acid) may affect the extent of uptake of the large nanospheres (46 nm). Multiple 18 GHz EMF exposures over a one-hour period induced periodic anomalous increases in the cell growth behavior of two Staphylococcus aureus strains, namely ATCC 25923 and CIP 65.8^T.