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Introduction: Examination of the potential possibilities of 2-chloro-N-(1-(3,4-dimethoxyphenyl)propan-2-yl)-2-phenylacetamide (IQP) to affect bioelectrogenesis and the contractile activity of isolated smooth muscles (SM) from stomach. Aim: Having in mind the structural similarities between the molecules of papaverine and IQP, the aim of the present study was to examine such features of the newly synthesized molecule that may potentially affect the muscle tonus, spontaneous bioelectrical and contractile activities of smooth muscles isolated from the stomach, basing on specific mechanisms of papaverine. Materials and methods: The synthesis of IQP is based on the initially formed aziridine ring by principles of Gilbert’s reaction. Impact of IQP on the bioelectrogenesis and the contractile activity of isolated smooth muscles from male Wistar rats was measured by the single sucrose-gap method and isometrically recorded. Results: IQP (1×10-5 – 2.5×10-4 mol/l) causes muscle relaxation, producing changes in two processes that have influence on the mechanical activity of smooth muscles:1. Blocked Ca2+ influx through the potential-dependent membrane Ca2+ channels, followed in turn by lowering the Ca2+ intracellular levels. This effect is proved by the changes in the frequency and amplitude of spike-potentials in sucrose-bridge experiments when IQP is applied.2. Activation of a cAMP-dependent signal cascade. The relaxing effect of IQP was significantly reduced in the presence of KT5720(5×10-6 mol/l), an inhibitor of protein kinase A. Conclusion: We assume that there might be interconnections between these two IQP-dependent processes, because PKA-dependent phosphorylation of the L-type Ca2+ channels in smooth muscles provokes a reaction of inactivation.

In this study, we apply a short-term voltage (0.2–0.8 V) to both crude glycerol (CG) and an anaerobic digestion (AD) effluent in a single-chamber microbial fuel cell (MFC) for power production. This improves the bioelectrogenesis in both CG (in MFC-1) and the AD effluent (in MFC-2), but higher power generation is attained in MFC-2. The use of domestic and synthetic wastewaters in the AD process leads to the generation of 195 and 350 mL H2/L-medium, respectively. MFC-2 performs better than MFC-1 in terms of both voltage generation and chemical oxygen demand (COD) reduction. The application of 0.8 V yields a power density of 311 mW/m2 (1.94 times higher than that of the control (160 mW/m2)). In addition, MFC-2 exhibits a 70% COD removal at 0.8 V, which decreases to 56% at 0.2 V. Thus, the application of a short-term voltage in MFC can stimulate both bioelectrogenesis and COD removal.

Insights of microbial community profiles associated with electric energy production in microbial fuel cells (MFCs) fed with food waste hydrolysate (FWH) were investigated in this study. High power density of 0.173 W/m2 was obtained from FWH which was produced from food waste after the pretreatment with fungal mash at an influent COD concentration of 1.2 g/L. The main genera in the MFCs fed with FWH were found to be Rummeliibacillus, Burkholderia, Enterococcus and Clostridium in anodic biofilms, leading to an electrogenesis efficiency of 0.977 kWh/kg COD higher than those obtained in MFCs with single carbon source feed. The key members in the anodic community responsible for electrogenesis were conceptually identified with their metabolic interactions in MFCs fed with FWH. It appeared that the syntrophic cooperation of fermentative species with exoelectrogens played an essential role in the generation of electric energy via specific microbes in anodic biofilm. The power produced from FWH was positively associated with microbial diversity, intermediate community evenness and abundance of functional genes for bioelectrogenesis. This study was partially supported by the Scientific Research Funds of Huaqiao University (605-50Y18055).

Sustainable bioelectrogenesis was evaluated by oxidizing the organics of food waste leachate (FWL) under the influence of magnetic field (MF) and short term applied voltage (electric potential, EP). Adaptation of MF (20–220 m T) and EP (100−500 mV) had enhanced the performance of MFC in terms of power generation and reduction of organic in FWL. The best performance of MFC was noted with a MF at 220 m T and EP at 500 mV. MFC under the influence of applied EP (100−500 mV), the power generation was increased from 493 mW/m2 to 832 mW/m2. During this operation, the chemical oxygen demand removal (CODr) was also increased from 51.3 % to 80.4 %. Whereas the control MFC (MFC-C) had exhibited a maximum power generation and CODr of 224 mW/m2 and 36.3 %, respectively. MFC with MF has showed an increase in power density from 480 mW/m2 to 811 mW/m2. MFCs at 220 m T and 500 mV has exhibited, 262 % and 271 % increase in power density over control, respectively. Adaptation of MFC under the EP and MF were found to be beneficial in treating FWL which has high strength organic content.

In this research, efforts were put to demonstrate synergistic interactions between bioenergy generation and wastewater treatment. The extent of such synergistic effect was assessed against wastewater effluents released from the beverage industry through the operation of a membrane-less truncated conical (TC) microbial fuel cell (MFC). A graphite-based reactor was operated for five cycles in batch mode using beverage industry wastewater as an organic substrate. Maximum bioelectricity produced on the fifth operating cycle corresponded to a voltage of 338 mV and a power of 1.14 mW at 100 Ω. The MFC recorded a higher substrate degradation rate (0.84 kg of chemical oxygen demand [COD]/m3-day) accompanied by the development of an electroactive biofilm and polarization behavior (e.g., a reduction in internal resistance from 323 Ω to 197 Ω over five operation cycles). Cyclic voltammetry showed a maximum performance of the biofilm during the fifth cycle (through its enrichment) as interpreted by oxidation and reduction currents of 2.48 and −2.21 mA, respectively. The performance of the proposed MFC was superior to other designs reported previously in both effluent treatment and bioenergy generation. A maximum treatment efficiency of 84.4% (in 385 h) was seen at an organic load (COD) of 3500 mg/L with the specific power yield (0.504 W/Kg of substrate (COD) removal) and volumetric power yield (15.03 W/m3). Our experimental studies support that the proposed system could be upscaled to realize the commercial operation.

Methane (CH(4)) is a well-known and abundant feedstock for natural gas, and is readily available from various sources. In thermal plants, the CH(4) generated from anthropogenic sources is converted into electrical energy via combustion. Microbial fuel cell (MFC) technology has proven to be an efficient strategy for the biological conversion of a many substrates, including biogas (CH(4)), to electricity. MFC technology uses gaseous substrate along with an enriched and selective microbial consortium. Predominantly, methanotrophs and electrochemically active Geobacter were utilized in a syntrophic association on the anode of an MFC. This review focuses on the exploitation of CH(4) as a substrate for bioelectrogenesis via MFCs.

Algal-microbial fuel cells (A-MFC) are an obligatory paradigm shift to fulfil the water and energy crisis of the present era. The present study investigates the performance of ceramic membrane-based A-MFC treating dairy industry wastewater. Discarded media bottles were used as chassis of dual-chambered A-MFCs. Graphite felt reinforced with stainless steel mesh is used as electrodes. Scenedesmus dimorphus was inoculated in the cathodic chamber while the pre-treated anaerobic sludge with real-time dairy industry wastewater was supplemented in the anode. The maximum working voltage of 285.70 ± 0.45 mV (across 720 Ω) was achieved in A-MFC. A polarization study was conducted and A-MFC achieved a maximum power density (PD) of 0.38 W m−3, whereas MFC with mechanical aeration and MFC without aeration observed 0.31 W m−3, and 0.28 W m−3 respectively. Algal growth obtained a maximum biomass concentration of 0.81 ± 0.02 mg L−1. The COD removal of 72% was attained in real-time dairy wastewater. This study is an attempt to utilize microalgae and real-time dairy wastewater to construct the A-MFCs that can be promoted as a sustainable low-cost alternative to endure the needs of future generations facing water and energy shortages.

Background: Microbial Fuel Cell (MFC) technology is used in various applications such as wastewater treatment with the production of electrical energy. The objective of this study was to estimate the biodepuration of oils and fats, the elimination of blue dye brl and bioelectro-characterization in MFCs with Chlorella vulgaris and bacterial community. Results: The operation of MFCs at 32 d showed an increase in bioelectrogenic activity (from 23.17 to 327.67 mW/m2 ) and in the potential (from 200 to 954 mV), with biodepuration of fats and oils (95%) in the microalgal cathode, and a removal of the chemical oxygen demand COD (anode, 71%, cathode, 78.6%) and the blue dye brl (73%) at the anode, here biofilms were formed by the bacterial community consisting of Actinobacteria and Deltaproteobacteria. Conclusions: These findings suggest that MFCs with C. vulgaris and bacterial community have a simultaneous efficiency in the production of bioelectricity and bioremediation processes, becoming an important source of bioenergy in the future.

This first-attempt study illustrated the microbial cooperative interactions related to bioelectricity generation from the mixture of sludge fermentation liquid (SFL) and fruit waste extracts (FWEs) via microbial fuel cells (MFCs). The optimal output voltages of 0.65 V for SFL-MFCs, 0.51 V for FWEs-MFCs and 0.75 V for mixture-MFCs associated with bioelectricity conversion efficiencies of 1.061, 0.718 and 1.391 kWh/kg COD were reached, respectively. FWEs addition for substrates C/N ratio optimization contributed considerably to increase SFL-fed MFCs performance via triggering a higher microbial diversity, larger relatively abundance of functional genes and microbial synergistic interactions with genera enrichment of Clostridium, Alicycliphilus, Thermomonas, Geobacter, Paludibaculum, Pseudomonas, Taibaiella and Comamonas. Furthermore, a conceptual illustration of co-locating scenario of wastewater treatment plant(s), waste sludge in situ acidogenic fermentation, fruit waste collection/crushing station and MFC plant was proposed for the first time, which provided new thinking for future waste sludge treatment toward maximizing solid reduction and power recovery.

The ability to generate and detect electric fields has evolved in several groups of fishes as a means of communication, navigation and, occasionally, predation. The energetic burden required can account for up to 20% of electric fishes' daily energy expenditure. Despite this, molecular adaptations that enable electric fishes to meet the metabolic demands of bioelectrogenesis remain unknown. Here, we investigate the molecular evolution of the mitochondrial oxidative phosphorylation (OXPHOS) complexes in the two most diverse clades of weakly electric fishes—South American Gymnotiformes and African Mormyroidea, using codon-based likelihood approaches. Our analyses reveal that although mitochondrial OXPHOS genes are generally subject to strong purifying selection, this constraint is significantly reduced in electric compared to non-electric fishes, particularly for complexes IV and V. Moreover, analyses of concatenated mitochondrial genes show strong evidence for positive selection in complex I genes on the two branches associated with the independent evolutionary origins of electrogenesis. These results suggest that adaptive evolution of proton translocation in the OXPHOS cellular machinery may be associated with the evolution of bioelectrogenesis. Overall, we find striking evidence for remarkably similar effects of electrogenesis on the molecular evolution of mitochondrial OXPHOS genes in two independently derived clades of electrogenic fishes.This article is part of the theme issue ‘Linking the mitochondrial genotype to phenotype: a complex endeavour’.

A highly reproducible plant electrical signal–light-induced bioelectrogenesis (LIB) was obtained by means of periodic illumination/darkness stimulation of broad bean (Vicia faba L.) leaves. By stimulating the same position of the same leaf with different concentrations of NaCl, we observed that the amplitude and waveform of the LIB was correlated with the intensity of stimulation. This method allowed us to link dynamic ion fluxes induced by periodic illumination/darkness to salt stress. The self-referencing ion electrode technique was used to explore the ionic mechanisms of the LIB. Fluxes of H+, Ca2+, K+, and Cl− showed periodic changes under periodic illumination/darkness before and after 50 mM NaCl stimulation. Gray relational analysis was used to analyze correlations between each of these ions and LIB. The results showed that different ions are involved in surface potential changes at different stages under periodic illumination/darkness. The gray relational grade reflected the contribution of each ion to the change in surface potential at a certain time period. The ion fluxes data obtained under periodic illumination/darkness stimulation will contribute to the future development of a dynamic model for interpretation of electrophysiological events in plant cells.

A pristine soil environment supports a healthy soil biodiversity, which is often polluted with recalcitrant compounds. The bioelectrochemical remediation of the contaminated soils using bioelectrochemical systems (BESs) is gaining significant attention with respect to the restoration of the soil ecosystem. In this direction, a microbial fuel cell (MFC, an application of BES), was employed for the treatment of total petroleum hydrocarbons (TPHs) in a soil microenvironment at three ranges of pollution (loading conditions-320, 590 and 840 mg TPH per L). TPHs degraded effectively in the soil-electrode vicinity in the range of 158 mg TPHR per L (320 mg TPH per L) and 356 mg TPHR per L (840 mg TPH per L). The study also demosntrated a maximum bioelectrogenesis of 286.7 mW m-2 (448 mV at 100 ) at the highest TPH loading concentration studied (840 mg TPH per L). The conditions prevailing in the soil MFC also facilitated the removal of sulfates (114 mg SO42- per L; 62.64%) and the removal of total dissolved solids (910 mg TDS per L, 12.08%) at an 840 mg TPH per L loading condition. The pH of the outlet wastewater prevailing in the mild alkaline range of 7.6 and 8.4, along with improved sulfate and TPH removal in the respective conditions suggested suitable conditions for sulfate-reducing bacteria (SRB). This study also signified the sustainability of the process for the effective treatment of hydrocarbon contaminated soil that also generates green energy. This publication was made possible by NPRP grant # NPRP9-093-1-021 from the Qatar National Research Fund (a member of Qatar Foundation). Scopus

The raising pharmaceutical industrial wastewater (PIW) is one of the major health problems nowadays, not only for aquatic life but also for human beings and the environment. Several conventional techniques including coagulation, filtration, biological membranes and advanced oxidation have been used for the treatment of PIW, however, all of these techniques are limited with their applications and results. The present study aimed to build a cost-effective, high biodegradable, eco-friendly and highly efficient PIW treatment technique to generate electricity and reduce the COD of wastewater simultaneously. A novel paraboloid shaped graphite-based microbial fuel cell (MFC) configuration has been designed by eliminating different types of casings and membranes for bio-electrogenesis and treatment of PIW. Municipal solid wastewater (MSW) was used as a substrate for developing the biofilm in paraboloid graphite-based MFC. The PIW treatment showed adequate bioelectricity generation including; current, power, voltage and open-circuit voltage (OCV) of about 2.76 mA, 0.76 mW, 276 mV and 330 mV at 100 Ω respectively after five operating cycles. The cyclic voltammetry showed the maximum generation of 2.01 W/m3 and 168 mA/m2 of power and current densities respectively followed by a considerable reduction in internal resistance from 197 to 99 Ω. The results reported a significant amount of reduction in COD (80.55%) and TDS (35.62%) for PIW by MFC respectively. The reduction in the percentage removal efficiency of COD (80.55%) suggested that the removal of organic compounds from PIW is parallel to bioelectrogenesis. Based on these major findings the novel membrane-less and paraboloid graphite-based MFC operation significantly drag concentration towards the feasibility of using pharmaceutical wastewaters for bio-electrogenesis.

The integration of bioelectrochemical system (BES) into conventional anaerobic composting process can accelerate the degradation of excess dewatered sludge (ES). However, no reports have been made concerning antibiotic resistance genes (ARGs) profile and abundance in BESs fuelled with ES, and the effect of CaO2 on the fate of ARGs within BESs treating excess sludge has rarely been investigated. The aim of this study was to investigate the effect of CaO2 and the bioelectrochemical process on the abundances of ARGs and MGEs and to unravel the mechanism of ARGs attenuation. Results showed that CaO2 addition could enhance the reduction of ARG levels in ES within AnCBE. The mean ARG abundances in the AnCBE samples with high CaO2 doses (0.4 g CaO2/g VSS and 0.5 g CaO2/g VSS) were significantly lower than the values in samples with other CaO2 doses. The abundances of lincosamide nucleotidyltransferase, macB, macrolide transporter ATP-binding proteins, and macrolide-efflux proteins significantly decreased with the increase in the CaO2 dose. Both CaO2 addition and bioelectrochemical assistance played important roles in shaping the ARG composition during the AnCBE process. The variation in the microbial community composition is the most important contributor to the variation in the ARGs composition. The abundances of Actinobacteria and Firmicutes explained 52.8% of the total ARG variance. Of the MGEs, the abundances of plasmids, insertion sequences, and integrons were all reduced in the sludge metagenomes. There was a significantly positive correlation between the abundances of sulI, sulII, tetG, and blaTEM and those of metal resistance genes (MRGs), which decreased significantly after the AnCBE process. This study revealed the potential of the combination of CaO2 and bioelectrogenesis for ARG attenuation.

Electronic skins or ‘e-skins’ have recently emerged as a novel platform for electronics, taking on more important roles in health diagnostics, therapeutics, and monitoring. Stand-alone and self-sustained e-skins are essential to providing reliable, effective and sometimes life-saving functions. A stable power supply is the most critical factor in developing practical e-skins because their performance depends significantly on power availability. A realistic and accessible power source is urgently needed for the next generation of smart, stand-alone, always-on e-skin systems. This is by no means a simple challenge because intimately integrating technologically advanced e-skins with human skin requires generating power from an extremely complicated, harsh environment. Skin is cool, dry, acidic and has few potential energy sources. In this work, we create the ability to generate an innovative, practical, and longstanding power from human sweat, which is one of the few available energy resources on skin. We use the metabolisms of sweat-eating bacteria that exist on human skin, Staphylococcus epidermidis, Staphylococcus capitis, and Micrococcus luteus. We also test a microorganism, Nitrosomonas europaea, that oxidizes the ammonia in sweat, but is not usually found on the skin. Bioelectrogenesis from all the bacterial species were observed at levels comparable to that of a well-known wild-type electrogenic bacteria, Shewanella oneidensis MR1, which inhabits the natural environment. A biobattery, or a microbial fuel cell, that uses bacteria as a biocatalyst, transforms the chemical energy of sweat into electrical power through bacterial metabolism. The skin-mountable biobattery is pre-inoculated with the sweat-eating bacteria and operates with human sweat, delivered by an integrated battery-free skin-interfaced microfluidic system. Given that the total non-human microbial cells inhabiting in and on our bodies outnumber the human cells by at least a factor of 10, the direct use of the microbial cells to produce power is conceivable for e-skins. The significance of this work stems from the demand for self-sustainable and stand-alone e-skin systems for healthcare, security, fitness, and environmental monitoring applications.

Produced water (PW) is a wastewater generated in large quantities from the extraction of oil and gas. PW found to have high amounts of dissolved solids (TDS) and residual petroleum hydrocarbons causing considerable damage to the environment. PW also contains sulfates in significant amounts, due to which treating this wastewater is essential prior to discharge. The present study was aimed for bioelectrochemical treatment of PW and simultaneous bioelectrogenesis in the two most studied configurations viz., single and dual chamber microbial fuel cells (MFCs). The study evidenced treatment of recalcitrant pollutants of PW. Both MFCs were operated by keeping similar operating conditions such as anode chamber volume, hydraulic retention time (HRT) for batch mode of operation, electrode materials, inlet characteristics of PW and ambient temperature. Among both configurations, dual chamber MFC showed higher efficiency with respect to bioelectrogenesis (single chamber - 789 mW/m 2 ; dual chamber - 1089 mW/m 2 ), sulfates removal (single chamber - 79.6%; dual chamber - 93.9%), total petroleum hydrocarbons removal (TPH, single chamber - 47.6%; dual chamber - 53.1%) and chemical oxygen demand degradation (COD, single chamber - 0.30 kg COD/m 3 -day (COD removal efficiency, 54.7%); dual chamber - 0.33 kg COD/m 3 -day (COD removal efficiency, 60.2%)). Evaluated polarization behavior of both MFCs were also evidenced the effective response of the electroactive anodic biofilm. 2019 Elsevier B.V. This publication was made possible by NPRP grant # NPRP9-093-1-021 from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors. Scopus

Algae are autotrophic organisms that are widespread in water bodies. Increased pollution in water bodies leads to eutrophication. However, algae growing in lakes undergoing eutrophication could be utilized towards the generation of added-value bio-electricity using microbial fuel cells (MFCs). In the present study, two methods of electricity generation using raw algae (RA) and RA + acetate (AC) as co-substrate were analyzed in single chamber air cathode MFCs. MFCs supplemented with RA and RA + AC clearly showed higher power density, greater current generation, and improved COD (chemical oxygen demand) removal, which demonstrated the feasibility of using AC as substrate for MFC. The MFC–RA + AC (0.48 mA) generated 28% higher current relative to that generated by MFC with RA alone. Notably, the maximum power densities generated by MFC–RA and MFC–RA + AC were 230 and 410 mW/m2, respectively. MFC–RA and MFC–RA + AC exhibited TCOD (total chemical oxygen reduction) removal values of 77% and 86.6%, respectively. Despite the high influent TCOD (758 mg/l) concentration, the MFC–RA + AC exhibited an 8.5% higher COD removal relative to that of MFC–RA (525 mg/l). Our current findings demonstrated effective energy generation using algae biomass with a co-substrate. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2018H1D3A2001746, 2015R1D1A1A01061279, 2013M3A6A8073184). This research was supported by 2017 KU Brain Pool of Konkuk University. Scopus

Cylindrical graphite microbial fuel cell (MFC) configuration designed by eliminating distinct casing and membrane was evaluated for bioelectrogenesis and treatment of real-field wastewaters. Both petroleum refinery wastewater (PRW) and Labanah whey wastewater (LW) were used as substrates, and investigated for electricity generation and organic removal under batch mode operation. PRW showed higher bioelectricity generation (current and power generation of 3.35 mA and 1.12 mW at 100 ) compared to LW (3.2 mA and 1.02 mW). On the contrary, higher substrate degradation efficiency was achieved using LW (72.76%) compared to PRW (45.06%). Superior function of MFC operation in terms of volumetric power density (PRW, 28.27 W/m3; LW, 23.23 W/m3) suggesting the feasibility of using these wastewaters for bioelectricity generation. Large sources of wastewater that generating in the Middle-East countries have potential to produce renewable energy from the treatment, which helps for the sustainable wastewater management and simultaneous renewable energy production. This publication was made possible by NPRP grant # 6-289-2-125 from the Qatar National Research Fund (a member of Qatar Foundation). Scopus

Electrochemically active anodic biofilm that has adapted under mild applied potentials in the range 100-500 mV was evaluated for its improved bioelectrogenesis and bioelectrochemical treatment of petroleum refinery wastewater (PRW) in a single chamber air cathode microbial fuel cell (MFC). MFC operation with 500 mV as supplemental voltage has exhibited a maximum power density of 132 mW/m2, which was three times higher than control MFC (45 mW/m2). Similarly, highest substrate removal efficiency (48%) was also obtained with the MFC of 500 mV, followed by 300 mV (37%), 100 mV (32%) and control (27%). Adaptation under applied potential conditions also exhibited enhanced degradation efficiency of diesel range organics (DROs)/straight chain-alkanes. The strategy efficiently reduced DROs with the maximum efficiency of 89% (500 mV), which is almost 50% higher than that of the control system (59%), demonstrating the effectiveness of using supplemented voltage in treating PRW. 2018 Elsevier Ltd This publication was made possible by NPRP grant # 6-289-2-125 from the Qatar national research fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. The Authors would like to acknowledge the Environmental Science Centre (ESC), Qatar University for evaluating the samples for diesel range organics (DROs). Scopus

Summary Exoelectrogens are catalytic microorganisms competent to shuttle electrons exogenously to the electrode surface without utilizing artificial mediators. Diverse microorganisms acting as exoelectrogens in the fluctuating ambience of microbial fuel cells (MFCs) propose unalike metabolic pathways and incompatible, specific proteins or genes for their inevitable performance toward bioelectricity generation. A pivotal mechanism known as quorum sensing allows bacterial population to communicate and regulates the expression of biofilm-related genes. Moreover, it has been found that setting the anode potential affects the metabolism of the exoelectrogens and hence the output of MFCs. Microscopic, spectrometry investigations and gene deletion studies have confirmed the expression of certain genes for outer-membrane multiheme cytochromes and conductive pili, and their potential roles in the exoelectrogenic activity. Further, cyclic voltammetry has suggested the role of multifarious redox-active compounds secreted by the exoelectrogens in direct electron transport mechanisms. Besides, it also explores the various mechanisms of exoelectrogens with genetic and molecular approaches, such as biofilm formation, microbial metabolism, bioelectrogenesis, and electron transfer mechanisms from inside the exoelectrogens to the electrodes and vice versa. Copyright © 2015 John Wiley & Sons, Ltd.

Para transmitir conceptos científicos complejos en un entorno escolar, la utilización de experimentos llamativos representa una herramienta muy útil. En este artículo se presenta la columna bioelectrogénica, un sistema experimental que une la columna de Winogradsky clásica con las más recientes investigaciones en el campo de la microbiología aplicada. A través de su implementación es posible visualizar procesos físicos, químicos y biológicos que forman parte de la enseñanza científica en institutos de secundaria. Además, la columna bioelectrogénica ha sido ideada para demostrar la existencia de bacterias capaces de producir energía eléctrica, un fenómeno que induce curiosidad y estupor, elementos claves para estimular la participación de los estudiantes. Este sistema ha sido presentado en varias actividades de divulgación para estudiantes de secundaria y siempre ha despertado un elevado grado de interés., The use of inspiring experimental demonstrations is a fundamental tool for teaching complex scientific concepts in secondary schools. In this article we present the bioelectrogenic column, an experimental system that joins the classic Winogradsky column to the most recent findings in the field of applied microbiology. With this system we can visualise physical, chemical and biological processes that are at the heart of a sound scientific education. Furthermore, the bioelectrogenic column had been designed to demonstrate the existence of bacteria capable of producing electric energy, an astonishing phenomenon that leaves students highly inquisitives, a key for stimulating their participation. This system has been presented in various scientific outreaching activities for secondary school, always awakening a strong interest in the audience.

Bioelectrogenic activity of microbial fuel cells (MFC) augmented with electrochemically active bacteria (EAB, Pseudomonas aeruginosa) and non-EAB (Escherichia coli) as biocatalysts was investigated. Anodic microflora augmented with P. aeruginosa (AMFCP) yielded higher electrogenic activity (418 mV; 3.87 mA) than E. coli (AMFCE; 254 mV; 1.67 mA) and non-augmented native microflora (MFCC; 235 mV; 1.37 mA). Higher redox currents along with lower Tafel-slopes were observed with AMFCP operation compared to AMFCE and MFCC due to manifestation of bioaugmentation thereby minimizing the losses. A fourfold and twofold increase in capacitance and exchange current was observed with AMFCP and AMFCE operation respectively, when compared to MFCC. Tracking of augmented biocatalyst by fluorescent in situ hybridization (FISH) with defined probes documented the survivability of Pseudomonas sp. in higher numbers than Enterobacteriaceae. Study corroborated enhanced electron transfer capability of mixed consortia owing to the synergistic interaction with EAB due to augmentation.

Influence of inherent buffering nature of real field pharmaceutical wastewater (PW) was evaluated in a microbial fuel cell (MFC) at varying organic loads (OL1-OL4). Dynamics of in situ buffers present in the wastewater during remediation enhanced the electrogenic activity. Improvement in power density (PD) and open circuit voltage (OCV) was observed as the organic load increased from OL1 to OL4 (PD of 62.45 to137 mW/m2; OCV-245 to 324 mV). It was concluded from the buffering capacity (β) profiles that base β values were relatively more stable than acid β values indicating the dynamics of nutrients and salts present in PW. pH increased with increase in OL documenting improvement in power output and waste remediation. Present study depicted an optimum pH range suitable for effective operation of MFC for bioelectrogenesis using PW as substrate. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 454–462, 2014

With more than four billion years evolution and selection, natural creatures inherit almost perfect functional structures to harvesting clean energy from their living environments. Particularly, biological ion channels and pumps on cell membrane play a crucial role in many bioelectrogenesis processes. Learning from Nature, such as the electric eels, the synthesis of ATP molecules, the Bacteriorhodopsin on retina, etc, provides new approaches for the construction of novel energy conversion systems. In this review article, we briefly summarize the three most intensively studied topics on the clean energy conversion system with bio-inspired nanochannels and nanopores, which are the nanofluidic electrokinetic conversion systems, the nanofluidic reverse electrodialysis systems, and these newly arisen advanced energy conversion system with smart synthetic ion channels. In a predictable future, the performance of these bio-inspired energy conversion system will surly exceed the present achievements of the conventional man-made systems. The bio-mimetic and bio-inspired strategies provide new insights into future energy conversion techniques.

Interrelations between the action of acetylcholine (ACh) and cadmium ions (Cd2+) on bioelectrogenesis of Nitellopsis obtusa cells were investigated. We analyzed repetitively triggered action potentials (AP), their reproducibility, shape and dynamics of membrane potential after AP induction. ACh significantly increased membrane permeability only at high concentrations (1 mM and 5 mM). Repolarisation level of action potential after the first stimulus was much more positive in all cells treated with ACh as compared to the control. Differences of membrane potentials between points just before the first and the second stimuli were 23.4±.0 mV (control); 40.4±5.9 mV (1 mM ACh solution) and 57.7 ± 8.5 mV (5 mM ACh solution). Cd2+ at 20 μM concentration was examined as a possible inhibitor of acetylcholinesterase (AChE) in vivo. We found that cadmium strengthens depolarizing effect of acetylcholine after the first stimulus. The highest velocity of AP repolarization was reduced after ACh application and Cd2+strengthened this effect. There were no differences in dynamics of membrane potential after repetitively triggered action potentials in ACh or ACh and Cd2+ solutions. This shows that cadmium in small concentration acts as inhibitor of acetylcholinesterase.

From a Cartesian perspective of rational analysis, the electric potential difference across the cell membrane is one of the fundamental concepts for the study of physiology. Unfortunately, undergraduate students often struggle to understand the genesis of this energy gradient, which makes the teaching activity a hard task for the instructor. The topic of bioelectrogenesis encompasses multidisciplinary concepts, involves several mechanisms, and is a dynamic process, i.e., it never turns off during the lifetime of the cell. Therefore, to improve the transmission and acquisition of knowledge in this field, I present an alternative didactic model. The design of the model assumes that it is possible to build, in a series of sequential steps, an assembly of proteins within the membrane of an isolated cell in a simulated electrophysiology experiment. Initially, no proteins are inserted in the membrane and the cell is at a baseline energy state; the extracellular and intracellular fluids are at thermodynamic equilibrium. Students are guided through a sequence of four steps that add key membrane transport proteins to the model cell. The model is simple at the start and becomes progressively more complex, finally producing transmembrane chemical and electrical gradients. I believe that this didactic approach helps instructors with a more efficient tool for the teaching of the mechanisms of resting membrane potential while helping students avoid common difficulties that may be encountered when learning this topic.

Noninvasive, ion-selective vibrating microelectrodes were used to measure the kinetics of H+, Ca2+, K+, and Cl− fluxes and the changes in their concentrations caused by illumination near the mesophyll and attached epidermis of bean (Vicia fabaL.). These flux measurements were related to light-induced changes in the plasma membrane potential. The influx of Ca2+ was the main depolarizing agent in electrical responses to light in the mesophyll. Changes in the net fluxes of H+, K+, and Cl− occurred only after a significant delay of about 2 min, whereas light-stimulated influx of Ca2+ began within the time resolution of our measurements (5 s). In the absence of H+ flux, light caused an initial quick rise of external pH near the mesophyll and epidermal tissues. In the mesophyll this fast alkalinization was followed by slower, oscillatory pH changes (5–15 min); in the epidermis the external pH increased steadily and reached a plateau 3 min later. We explain the initial alkalinization of the medium as a result of CO2 uptake by photosynthesizing tissue, whereas activation of the plasma membrane H+ pump occurred 1.5 to 2 min later. The epidermal layer seems to be a substantial barrier for ion fluxes but not for CO2diffusion into the leaf.

The most basic property of all living organisms to process matter — for extracting from their milieu the free energy, necessary for their maintenance and growth-, imposes the existence of well-defined domains of the Universe, in which proper concentrations of reactants and products are maintained against the entropic tendency of dilution. This fundamental requirement was recognized more than one and a half century ago by Theodore Schwann and repeatedly stressed since that. It is confirmed by the fact that all the cells, including the most primitive prokaryotes, are surrounded by a continuous and flexible structure the plasma membrane which appears as a distinctive feature of living system.