Stimulation of porphyrin production by application of an external magnetic field to a photosynthetic bacterium, Rhodobacter sphaeroides

Improving microbial production of value-added products through the intervention of magnetic fields

The magnetic field application is emerging as an auxiliary physical strategy to facilitate rapid biomass accumulation and intracellular production of compounds. However, the underlying mechanisms and principles governing the application of magnetic fields for microbial growth and biotransformation are not yet fully understood. Therefore, a better understanding of interdisciplinary technologies integration, expanded magnetic field application, and scaled-up industrial implementation is crucial. In this review, the magnetic field characteristics, magnetic field-assisted fermentation devices, and the working mechanism of magnetic field have been reviewed comprehensively from both physical and microbiological perspectives. The review suggests that magnetic fields affect the biochemical processes in microorganisms by mediating nutrient transport across membranes, electron transfer during photosynthesis and respiration, enzyme activity and gene expression. Moreover, the recent advances in magnetic field application for microbial fermentation and conversion in biochemical, food and agricultural fields have been summarized.

Insights into the potential application of magnetic field in controlling sludge bulking and foaming: A review

The formation of bulking and foaming in biological wastewater treatment could cause a series of operational issues with biomass and effluent quality, ultimately affect the treatment performance of the system. The essential parameters influencing the growth of bulking and foaming bacteria are comprehensively summarised in this paper. Existing bulking and foaming control approached are critically reviewed and addressed, as well as their drawbacks and limitations. Despite the abundance of information and implementation, a complete control technique for limiting filamentous sludge bulking and foaming remains insufficient. Magnetic field application is emphasised as a viable control strategy in this regard. The present review study provides new insight of this application by comparing the use of magnetic fields to conventional treatments. Future outlooks on the use of magnetic fields to prevent BFB proliferation were also highlighted.

Bioeffect of static magnetic field on photosynthetic bacteria: Evaluation of bioresources production and wastewater treatment efficiency

Photosynthetic bacteria (PSB) technology is a promising method for biomass, protein, pigments, and other value-added substances generation from wastewater. However, the above bioresources production efficiency is relatively low. In this work, a static magnetic field (SMF) was used to promote bioresources production. Results showed that SMF had positive effects on value-added substances production. With 0.35 Tesla (T) SMF, the PSB biomass, protein, carotenoids, and bacteriochlorophyll concentration were promoted by 31.1%, 22.6%, 56.7%, and 73.1% compared with the control group, respectively. Biomass yield finally reached 0.58 g biomass/g COD removal, which was promoted by 37.1%. The doubling time was shortened by 37.9% in 0.35 T group, showing that SMF can promote cell growth. With 0.35 T SMF, the intracellular NADH dehydrogenase and ATP synthase activities concentration increased by 23.4% and 29.1%, respectively, thus increased the ATP content by 38.0%. Succinic dehydrogenase activity concentration greatly increased by 609.0% at 48 hr, which potentially accelerated the tricarboxylic acid cycle and COD degradation as well as enhanced biomass production. PRACTITIONER POINTS: SMF promoted PSB bioresource production during wastewater treatment processing. Biomass, protein, carotenoids, and Bchl concentration were promoted by 31.1%, 22.6%, 56.7%, and 73.1%, respectively. PSB yield of 0.35 T group was promoted by 37.1% compared with the control group. SDH concentration of 0.35 T was promoted by 609.0% compared with the control group. Increased NADH and ATP synthase activity concentration by SMF enhanced energy metabolism.

Changes of cationic transport in AtCAX5 transformant yeast by electromagnetic field environments

The electromagnetic field (EMF) is newly considered as an exogenous environmental stimulus that is closely related to ion transportation on the cellular membrane, maintaining the internal ionic homeostasis. Cation transports of Ca²⁺ and other metal ions, Cd²⁺, Zn²⁺, and Mn²⁺were studied in terms of the external Ca²⁺ stress, [Ca²⁺]_ext, and exposure to the physical EMF. A specific yeast strain K667 was used for controlling CAX5 (cation/H⁺ exchanger) expression. Culture samples were exposed to 60 Hz, 0.1 mT sinusoidal or square magnetics waves, and intracellular cations of each sample were measured and analyzed. AtCAX5 transformant yeast grew normally under the metallic stress. However, the growth of the control group was significantly inhibited under the same cation concentration; 60 Hz and 0.1 mT magnetic field enhanced intracellular cation concentrations significantly as exposure time increased both in the AtCAX5 transformed yeast and in the control group. However, the AtCAX5-transformed yeast showed higher concentration of the intracellular cations than the control group under the same exposure EMF. AtCAX5-transformed yeasts displayed an increment in [Ca²⁺]_int, [K⁺]_int, [Na⁺]_int, and [Zn²⁺]_int concentration under the presence of both sinusoidal and square-waved EMF stresses compared to the control group, which shows that AtCAX5 expressed in the vacuole play an important role in maintaining the homeostasis of intracellular cations. These findings could be utilized in the cultivation of the crops which were resistant to excessive exogenous ions or in the production of biomass containing a large proportion of ions for nutritional food or in the bioremediation process in metal-polluted environments.

Abiotic degradation of chlorinated ethanes and ethenes in water

INTRODUCTION

Chlorinated ethanes and ethenes are among the most frequently detected organic pollutants of water. Their physicochemical properties are such that they can contaminate aquifers for decades. In favourable conditions, they can undergo degradation. In anaerobic conditions, chlorinated solvents can undergo reductive dechlorination.

DEGRADATION PATHWAYS

Abiotic dechlorination is usually slower than microbial but abiotic dechlorination is usually complete. In favourable conditions, abiotic reactions bring significant contribution to natural attenuation processes. Abiotic agents that may enhance the reductive dechlorination of chlorinated ethanes and ethenes are zero-valent metals, sulphide minerals or green rusts.

OXIDATION

At some sites, permanganate and Fenton's reagent can be used as remediation tool for oxidation of chlorinated ethanes and ethenes.

SUMMARY

Nanoscale iron or bimetallic particles, due to high efficiency in degradation of chlorinated ethanes and ethenes, have gained much interest. They allow for rapid degradation of chlorinated ethanes and ethenes in water phase, but they also give benefit of treating dense non-aqueous phase liquid.

Electromagnetic biostimulation of living cultures for biotechnology, biofuel and bioenergy applications

The surge of interest in bioenergy has been marked with increasing efforts in research and development to identify new sources of biomass and to incorporate cutting-edge biotechnology to improve efficiency and increase yields. It is evident that various microorganisms will play an integral role in the development of this newly emerging industry, such as yeast for ethanol and Escherichia coli for fine chemical fermentation. However, it appears that microalgae have become the most promising prospect for biomass production due to their ability to grow fast, produce large quantities of lipids, carbohydrates and proteins, thrive in poor quality waters, sequester and recycle carbon dioxide from industrial flue gases and remove pollutants from industrial, agricultural and municipal wastewaters. In an attempt to better understand and manipulate microorganisms for optimum production capacity, many researchers have investigated alternative methods for stimulating their growth and metabolic behavior. One such novel approach is the use of electromagnetic fields for the stimulation of growth and metabolic cascades and controlling biochemical pathways. An effort has been made in this review to consolidate the information on the current status of biostimulation research to enhance microbial growth and metabolism using electromagnetic fields. It summarizes information on the biostimulatory effects on growth and other biological processes to obtain insight regarding factors and dosages that lead to the stimulation and also what kind of processes have been reportedly affected. Diverse mechanistic theories and explanations for biological effects of electromagnetic fields on intra and extracellular environment have been discussed. The foundations of biophysical interactions such as bioelectromagnetic and biophotonic communication and organization within living systems are expounded with special consideration for spatiotemporal aspects of electromagnetic topology, leading to the potential of multipolar electromagnetic systems. The future direction for the use of biostimulation using bioelectromagnetic, biophotonic and electrochemical methods have been proposed for biotechnology industries in general with emphasis on an holistic biofuel system encompassing production of algal biomass, its processing and conversion to biofuel.

Effect of static magnetic field on synthesis of polyhydroxyalkanoates from different short-chain fatty acids by activated sludge

The effect of static magnetic field on the production of polyhydroxyalkanoates (PHAs) from different short-chain fatty acids by activated sludge process under aerobic dynamic feeding (ADF) technique was evaluated in four sequencing batch reactors (SBRs) with static magnetic field intensity of 42 mT (SBR1), 21 mT (SBR2), 7 mT (SBR3), 0 mT (SBR4), respectively. It was demonstrated that the static magnetic exposure had definitely influenced the biosynthesis of PHAs when acetate, butyrate and propionate were fed solely or each two mixture or three substrates mixture, and the effect was dependent on field strength: the maximum poly-3-hydroxybutyrate (PHB) production occurring at 7 mT, and the minimum one at 42 mT; the maximum poly-3-hydroxyvalerate (PHV) production occurring at 21 mT, and the minimum one at 0 mT.

Magnetoreception in microorganisms and fungi

The ability to respond to magnetic fields is ubiquitous among the five kingdoms of organisms. Apart from the mechanisms that are at work in bacterial magnetotaxis, none of the innumerable magnetobiological effects are as yet completely understood in terms of their underlying physical principles. Physical theories on magnetoreception, which draw on classical electrodynamics as well as on quantum electrodynamics, have greatly advanced during the past twenty years, and provide a basis for biological experimentation. This review places major emphasis on theories, and magnetobiological effects that occur in response to weak and moderate magnetic fields, and that are not related to magnetotaxis and magnetosomes. While knowledge relating to bacterial magnetotaxis has advanced considerably during the past 27 years, the biology of other magnetic effects has remained largely on a phenomenological level, a fact that is partly due to a lack of model organisms and model responses; and in great part also to the circumstance that the biological community at large takes little notice of the field, and in particular of the available physical theories. We review the known magnetobiological effects for bacteria, protists and fungi, and try to show how the variegated empirical material could be approached in the framework of the available physical models.

Effects of static magnetic field on growth of leptospire, Leptospira interrogans serovar canicola: immunoreactivity and cell division

The effects of the exposure of the bacterium, Leptospira interrogans serovar canicola to a constant magnetic field with magnetic flux density from a permanent ferrite magnet=140+/-5 mT were studied. Changes in Leptospira cells after their exposure to the field were determined on the basis of changes in their growth behavior and agglutination immunoreactivity with a homologous antiserum using dark-field microscopy together with visual imaging. The data showed that the exposed Leptospira cells have lower densities and lower agglutination immunoreactivity than the unexposed control group. Interestingly, some of the exposed Leptospira cells showed abnormal morphologies such as large lengths. We discussed some of the possible reasons for these observations.