, Nattakarn Prasertsung

• 2011

This study examined the effects of the organic loading rate (OLR), pH and the temperature in cassava wastewater treatment and the power generated by a single microbial fuel cell. The study was divided into two parts under temperature of 45 ℃ and 30 ℃. The first part was examined the effect of OLR of 0.56, 1.44, 2.79, 4.14 to 6.25 kg-COD/m³-d at pH 7.0 to remove COD and generate electricity. The second part was examined the effect of pH at 5.0, 5.5, 6.0, 6.5, 7.5, 8.0, 8.5 and 9.0 on OLR of 0.56 kg-COD/m³-d to remove COD and generate electricity. When controlled pH 7.0, the efficiency of COD removal was achieved at maximum from the OLR of 0.56 kg-COD/m³-d at both temperatures. The efficiency of COD removal was 91.44 ± 0.72% and 90.72± 0.87% at 30 ℃ and 45 ๐C respectively. The maximum of power density was obtained from OLR of 6.25 kg-COD/m³-d, which the value was 28.68 W/m3 at 30 ๐C and 27.85 W/m3 at 45 ℃. The maximum of coulombic efficiency was obtained from the OLR of 0.56 kg-COD/m³-d which was 30.2% at 30 ℃ and 28.5% at 45 ℃. The temperature affected on the electron transferring from anode to cathode. At the lower temperature, electron was able to transfer from anode to cathode more effectively than at higher temperature. High temperature caused high electrical resistant, so the power output decreased when temperature increased. At OLR of 0.56 kg-COD/m³-d, the maximum efficiency of COD removal was achieved at a pH of 7.5 at both temperatures. The efficiency of COD removal was as 96.77 ± 0.93% and 95.93± 1.44% at 30 ℃ and 45 ℃ respectively. The maximum of power density obtained from pH 8.5 which the values were 30.30 W/m³ at 30 ℃ and 26.06 W/m³ at 45 ℃. The maximum of coulombic efficiency was obtained from pH 8.5 which was 52.9% at 30 ℃ and 50.6% at 45 ℃. The microbial communities in the anode of a single chamber microbial fuel cell under 30 ℃ could be divided into four groups as Gammaproteobacteria, Betaprotobacteria, Bacteroidetes and Firmicutes. While under 45 ℃ operation, the microbial communities could be divided into three groups as Gammaproteobacteria, Betaprotobacteria and Firmicutes. The microbial communities included several fermentative bacteria, exocellular electron-transfer, methane oxidizers, sulfate-reducing bacteria and groups of facultative bacteria.

, Kamol Rodyou

• 2008

Bacteria enriched under various electricity currents, were selected for tested in mediator-less microbial fuel cell. Total of 72 electricity enriched bacteria were isolated from three sources including, 28 isolates from sediment of pond in front of Physic I building, Chulalongkorn University, 40 and 4 isolates from sub-sediment from Koh Larn, Chonburi and soil from Phu Rua, Loei, respectively. Ferric reduction activity of all isolates under anaerobic condition was also characterized. Preliminary experiment found that acrylic model was not suitable for operating mediator-less MFC. Glass I and Glass II models were later designed and constructed for sterile system that suitable for microbiological aseptic techniques. Pure culture of 40 isolates of electricity enriched bacteria from Koh Larn were determined the ability of their self-mediate electron transfer in Glass I model. It can be concluded that ferric reduction activity has more impact than electricity current that used for selection and enrichment on the electricity generation of isolates in mediator-less MFC. In Glass I model, 12 isolates of Gram’s negative, ferric reducing, swarming bacteria from Koh Larn gave high current density ~11-13 mA m-2. After tested in Glass II, the highest of 18.57 mA m-2 and 0.62 mW m-2 for current density and power density, respectively were generated by KL22. These indicated that the increase of current density and power density more than those of Glass I, 67 % and 179%, respectively. As the results, anaerobic condition in anodic compartment enhanced electron transfer to anode electrode led to the increasing of electricity output. KL22 was identified as Proteus vulgaris by using 16S rDNA analysis and rapid identification kit API 20E. Proteus vulgaris can biocatalyse successfully in mediator-less MFC system from this study is firstly reported. Further improvements by optimizing the physical and chemical parameters of microbial fuel cells for the sustainable alternative energy in the future are required.

, Kamol Rodyou

• 2015

This dissertation studied the effect of anode electric current stimulation on open circuit voltage (Voc), current density and power density of MFC. Parameters which were used for electric current stimulation were stimulation periods, enrichment medium, carbon source in MFC, type and magnitude of electric current, and source of sediment. In addition, effect of nutrient broth (NB) and phosphate buffer basal medium (PBBM) on biofilm formation of stimulated anode were examined. Biofilm formation on anode was investigated under field emission scanning electron microscope (FESEM). It was found that thick biofilm was observed on AC stimulated anode at 10-15 mA. In addition, the different medium used in the enrichment of biofilm during AC stimulation led to the different characteristics of biofilm. Bacterial community on stimulated anode was isolated from biofilm anode. Electrochemical active bacteria (EAB) such as Shewanella putrefaciens, which effectively transferred electron to anode was isolated. The effect of AC stimulation on pure isolate showed that S. putrefaciens viable cell count was dramatically decreased (4 logCFU) when stimulated with 15 mA AC stimulation. In this dissertation, the highest Voc of 989 mV, produced from propionate-fed MFC with 60 days unstimulated anode in PBBM medium. However, the highest current density of 72.9 mA and power density of 13.4 mW m-2, produced from acetate-fed MFC with 60 days, 5-10 mA AC stimulated anode in PBBM medium. Moreover, AC stimulation on anode can be used to stimulate different sources of sediments. Furthermore, application of stimulated anode for COD removal and electricity production was also investigated. It was found that the highest COD removal of 60% and 48 mA m-2 current density was obtained from molasses-fed MFC by using 10 mA AC stimulated anode. Thus, it could be concluded that electric current stimulation is a high potential tool for selecting effective bacterial community on electrode and using as anode for the MFC.

Manuela Rueda, Francisco Prieto, Julia Alvarez-Malmagro

ECS Meeting Abstracts • 2016

Biological relevant molecules are known to get adsorbed at the electrode/electrolyte interface and the study of their adsorption is interesting in relation to biosensors design and development of supra-molecular vectors for drugs delivery. On the other hand, the structure and electrical properties of biomembranes are frequently modeled by modifying electrode surfaces with lipidic films. The study of these lipidic film coated electrodes is also relevant in relation to drugs delivery vectors. Both cases of electrode interfaces are usually characterized by capacitance measurements as a function of potential with the implicit assumption of a serial RC model circuit for the metal/solution interface. However, the application of the electrochemical impedance spectroscopy (EIS) and the corresponding analysis of data as a function of the frequency and of the applied potential to the electrode can provide detailed information about the kinetics of adsorption 1,2 , biomembrane reorganization phenomena and electron transfers through the film 3 . In this communication the application of EIS to bioelectrochemical interfaces is illustrated by studying examples of the two kinds of electrode interfaces. The adsorption of adenine, one of the DNA bases, on single crystal Au(111) electrode is presented as an example of a Gibbs adsorption electrode interface, in which the adsorbate is present in the metal and the electrolyte phases, while the study of modified electrodes with phospholipid films exemplifies the electrochemical behavior of organized biomembrane coating the metal with the polar heads of the lipidic chains directed towards the electrolyte solution part of the interface. The experimental procedures In the case of the two kinds of interfaces have to be designed in order to avoid interference of surface reconstruction phenomena (in the case of the work with single crystal electrodes) or film reorganization phenomena (in the case of phospholipids modified electrodes). The results about adenine adsorption as a function of the pH of the solution allow us to evaluate the kinetics of the adsorption and their correlation with results previously obtained by the authors using FT-IR-spectro-electrochemical methods 1,2 . The results about phospholipids film coated electrodes allows us to conclude about the stability of the film as a function of the electric field and to analyze the plausible electron transfer through them, when adding electroactive compounds to the solution phase. [1].- M. Rueda, F. Prieto, A. Rodes, J.M. Delgado, Electrochim. Acta, 82 (2012) 534 [2].- J. Alvarez-Malmagro, F. Prieto, M. Rueda, A. Rodes, Electrochim. Acta, 140 (2014) 476 [3].- M. Rueda, F. Prieto, I. Navarro, R. Romero, J. Electroanal. Chem. 649 (2010) 42

Annemiek ter Heijne, Dandan Liu, Mira Sulonen et al.

Journal of Power Sources • 2018

Peng Cheng, Yingchuan Zhang, Nianfang Ma et al.

Bioresource technology • 2022

Microbial fuel cell (MFC) exhibits huge potentials in disposing wastewater and extra energy consumption. Exploring useful microorganisms for MFC is the crucial section. Herein, the electrochemical mechanism of extracellular anaerobic respiration in MFC inoculated with gram-positive Rhodococcus pyridinivorans HR-1, was first revealed. The MFC exhibited rapid recovery of currents on anode, and could recover to maximum output within one hour, with redox peaks near -0.38 and -0.18 V through electron transfer between the biofilm and anode. When the biofilm-based pathway was blocked by wrapping the anode with Millipore filter membrane, HR-1 inoculated MFC could still generate electricity within a longer recovery period (∼35 h) during anolyte exchange. This was proposed as a self-secreted electron shuttle pathway for electron transfer in R. pyridinivorans HR-1. Cyclic voltammetry analysis revealed that the biofilm-based and self-secreted electron shuttle-based pathways co-existed in R. pyridinivorans HR-1 inoculated MFC, which could play synergistic roles in electricity generation.

Mustapha Omenesa Idris, Mohamad Nasir Mohamad Ibrahim, Nur Asshifa Md Noh et al.

Chemosphere • 2022

Naphthalene is a very common and hazardous environmental pollutant, and its biodegradation has received serious attention. As demonstrated in this study, naphthalene-contaminated wastewater can be biodegraded using a microbial fuel cell (MFC). Furthermore, the potential of MFC for electricity generation appears to be a promising technology to meet energy demands other than those produced from fossil fuels. Nowadays, efforts are being made to improve the overall performance of MFC by integrating biowaste materials for anode fabrication. In this study, palm kernel shell waste was used to produce palm kernel shell-derived graphene oxide (PKS-GO) and palm kernel shell-derived reduced graphene oxide (PKS-rGO), which were then fabricated into anode electrodes to improve the system's electron mobilization and transport. The MFC configuration with the PKS-rGO anode demonstrated greater energy production potential, with a maximum power density of 35.11 mW/m2 and a current density of 101.76 mA/m2, compared to the PKS-GO anode, which achieved a maximum power density of 17.85 mW/m2 and a current density of 72.56 mA/m2. Furthermore, there is simultaneous naphthalene biodegradation with energy production, where the biodegradation efficiency of naphthalene with PKS-rGO and PKS-GO is 85.5%, and 79.7%, respectively. In addition, the specific capacitance determined from the cyclic voltammetry curve revealed a value for PKS-rGO of 2.23 × 10-4 F/g, which is also higher than the value for PKS-GO (1.57 × 10-4 F/g) on the last day of operation. Anodic microbial analysis shows that electrogens thrive in the MFC process. Finally, a comparison with previous literature and the future prospects of the study are also presented.

Yaniv Shlosberg, Ailun Huang, Tünde N Tóth et al.

ACS biomaterials science & engineering • 2023

In recent years, extensive scientific efforts have been conducted to develop clean bioenergy technologies. A promising approach that has been under development for more than a hundred years is the microbial fuel cell (MFC) which utilizes exoelectrogenic bacteria as an electron source in a bioelectrochemical cell. The viability of bacteria in soil MFCs can be maintained by integrating plant roots, which release organic materials that feed the bacteria. In this work, we show that rather than organic compounds, roots also release redox species that can produce electricity in a biofuel cell. We first studied the reduction of the electron acceptor Cytochrome C by green onion roots. We integrate green onion roots into a biofuel cell to produce a continuous bias-free electric current for more than 24 h in the dark. This current is enhanced upon irradiation of the onion's leaves with light. We apply cyclic voltammetry and 2D-fluorescence measurements to show that NADH and NADPH act as major electron mediators between the roots and the anode, while their concentrations in the external root matrix are increased upon irradiation of the leaves. Finally, we show that roots can contribute to energy storage by charging a supercapacitor.

Kun Dai, Yang Yan, Qing-Ting Wang et al.

Applied microbiology and biotechnology • 2021

The electricity production via psychrophilic microbial fuel cell (PMFC) for wastewater treatment in cold regions offers an alternative to avoid the unwanted methane dissolution of traditional anaerobic fermentation. But, it is seldom reported by mixed-culture, especially closed to 0 °C. Thus, a two-chamber mixed-culture PMFC at 4 °C was successfully operated in this study using acetate as an electron donor. The main results demonstrated a good performance of PMFC, including the maximum voltage of 513 mV at 1000 Ω, coulombic efficiency of 53%, and power density of 689 mW/m2. The cyclic voltammetry curves of enriched biofilm showed a direct electron transfer pathway. These good performances of mixed-culture PMFC were due to the high psychrophilic activity of enriched biofilm, including exoelectrogens genera of Geobacter (6.1%), Enterococcus (17.5%), and Clostridium_sensu_stricto_12 (3.8%). Consequently, a mixed-culture PMFC provides a reasonable strategy to enrich exoelectrogens with high activity. For low-temperature regions, the mixed-culture PMFC involved biotechnologies shall benefit energy generation and valuable chemical production in the future. KEY POINTS: • PMFC showed a maximum voltage of around 513 mV under a resistance of 1000 Ω. • The coulombic efficiency was 53% and the max power density was 689 mW/m2. • Geobacter, Enterococcus, and Clostridium_sensu_stricto_12 were key exoelectrogens.

Verjesh Kumar Magotra, Sunil Kumar, T W Kang et al.

Scientific reports • 2020

The acute problem of eutrophication increasing in the environment is due to the increase of industrial wastewater, synthetic nitrogen, urine, and urea. This pollutes groundwater, soil and creates a danger to aquatic life. Therefore, it is advantageous to use these waste materials in the form of urea as fuel to generate power using Microbial Fuel Cell (MFC). In this work, we studied the compost soil MFC(CSMFC) unlike typical MFC with urea from the compost as fuel and graphite as a functional electrode. The electrochemical techniques such as Cyclic Voltammetry, Chronoamperometry are used to characterise CSMFC. It is observed that the CSMFC in which the compost consists of urea concertation of 0.5 g/ml produces maximum power. Moreover, IV measurement is carried out using polarization curves in order to study its sustainability and scalability. Bacterial studies were also playing a significant role in power generation. The sustainability study revealed that urea is consumed in CSMFC to generate power. This study confirmed that urea has a profound effect on the power generation from the CSMFC. Our focus is to get power from the soil processes in future by using waste like urine, industrial wastewater, which contains much amount of urea.

Xiaoling Li, Ruiyu Zheng, Xuwu Zhang et al.

Journal of environmental management • 2018

In the past decades, the microbial fuel cell (MFC) technology has caught the attention of the scientific community for its potential in transforming petroleum hydrocarbon (PHC) pollutants directly into electricity through microbial catalyzed anodic. The microbe was one of the most important factors that both influence MFCs and PHC degradation. Here we aimed to identify new microbes to expand the list of microbial species which are both electrogenic and diesel hydrocarbon degrading. In this text, we depicted a strain of microbe named E2, isolated from on the anode surface of MFC, and using diesel as sole carbon source. E2 exhibited electrochemical activity in cyclic voltammetry curve, implicating that it had electrogenic ability. E2 degraded about 50% diesel (3.26 g/L) in maximum during 8 days. Pyrosequencing of 16S rRNA gene of E2 revealed E2 was a sub-strain of Vibrio. Corresponding to salt and alkali tolerant properties of vibrio, the optimal condition for E2 in degrading diesel was 3%-4% in salinity, and pH 8-9 in mineral medium. Collectively, as a member of Gammaproteobacteria class, E2 was novel marine microbe both electricity generation and diesel degradation, which may attract its future application toward artificial microbial community construction in MFC in promoting the PHC pollution removal.

M Amirul Islam, Ahasanul Karim, Puranjan Mishra et al.

The Science of the total environment • 2020

An understanding of the inter-species relationships, especially their metabolic network in a mixed-culture system, is crucial to design an effective inoculum for enhancing the power generation of wastewater fed microbial fuel cell (MFC). In the present study, the influence of microbial mutualistic interactions on the power generation of palm oil mill effluent fed MFCs has been widely investigated by designing several co-culture and mixed culture inoculums. Among the different inoculum compositions, the highest power density of 14.8 W/m3 was achieved by Pseudomonas aeruginosa and Klebsiella variicola co-culture inoculum due to their synergistic relationships which were inter-linked via fermentation-based metabolites. Besides, the interaction of K. variicola and Bacillus cereus positively influenced the power generation resulting in a maximum power density of 11.8 W/m3 whereas the antagonistic relationship between B. cereus and P. aeruginosa resulted in a lower power generation of 1.9 W/m3. The microbial mutualistic interactions were investigated with polarization, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), as well as by using metabolite and biofilm analysis. It was observed that the synergism between bacteria enhanced power generation through the production of higher electron shuttling mediators and efficient biofilm formation as evidenced by polarization, CV and EIS analysis. In contrast, the antagonistic relationship resulted in production of cell inhibiting metabolites leading to the formation of ineffective biofilm. These findings demonstrate that the synergistic interaction between or within microorganisms is emergent in designing co-culture or mixed-culture inoculum for achieving maximum power generation in MFCs.

Yue Lang, Yanan Yu, Hongtao Zou et al.

Chemosphere • 2021

Chemical park is regarded as a major contributor of VOCs emissions in China. Currently, a green and safe technology, microbial fuel cells (MFCs), is being developed for the VOCs abatement. Noting that effective electron transfer is critical to the MFC performance. In this work, flavin mononucleotide (FMN) was dosed as an electron shuttle to improve the removal of the typical toxic VOCs, toluene. The experimental results revealed that the performance of toluene removal and power generation were accelerated with the dosage of 0.2-2 μM FMN. With the addition of 1 μM FMN, the removal efficiency, the maximum output voltage and the coulombic efficiency of MFC were increased by 18.4%, 64.4% and 56.3%, respectively. However, a further increase in FMN concentration to 2 μM caused a reduction in the removal efficiency and coulombic efficiency. The images of scanning electron microscopy and confocal laser scanning microscopy showed that the presence of FMN greatly promoted the microbial growth and its activity. Furthermore, microbial community analysis also implied that the moderate dosage of FMN (0.2-1 μM) was beneficial for the growth of the typical exoelectrogens, Geobacter sp., and thus the coulombic efficiency was increased. In addition, an electron transfer pathway involving in cytochrome b, OMCs, cytochrome c, and MtrA was proposed based on the cyclic voltammetry analysis. This work will provide a fundamental theoretical support for its application of toxic VOCs abatement from the chemical park.

Xiaoya Zheng, Shanshan Hou, Charles Amanze et al.

Bioprocess and biosystems engineering • 2021

Low electricity generation efficiency is one of the key issues that must be addressed for the practical application of microbial fuel cells (MFCs). Modification of microbial electrode materials is an effective method to enhance electron transfer. In this study, magnetite (Fe3O4) nanoparticles synthesized by co-precipitation were added to anode chambers in different doses to explore its effect on the performance of MFCs. The maximum power density of the MFCs doped with 4.5 g/L Fe3O4 (391.11 ± 9.4 mW/m2) was significantly increased compared to that of the undoped MFCs (255.15 ± 24.8 mW/m2). The COD removal efficiency of the MFCs increased from 85.8 ± 2.8% to 95.0 ± 2.1%. Electrochemical impedance spectroscopy and cyclic voltammetry tests revealed that the addition of Fe3O4 nanoparticles enhanced the biocatalytic activity of the anode. High-throughput sequencing results indicated that 4.5 g/L Fe3O4 modified anodes enriched the exoelectrogen Geobacter (31.5%), while control MFCs had less Geobacter (17.4%). Magnetite is widely distributed worldwide, which provides an inexpensive means to improve the electrochemical performance of MFCs.

N F Shoparwe, M M Z Makhtar, S A Sata et al.

IOP Conference Series: Earth and Environmental Science • 2021

Abstract The present study aims to investigate the performance of batch culture of Geobacter sulfurreducens (G. sulfurreducens ) for electrical current generation via cyclic voltammetry (CV) method. The CV study was performed with an applied voltage in the range of -0.1 to 0.1 V against the standard calomel electrode (SCE) during the cell growth and attachment of G. sulfurreducens on graphite felt and initial acetate concentration of 20 mM. The kinetics of electrode reaction was investigated by conducting CV experiments at different scanning rates of 5, 10, 20, 50 and 100 mVs -1 . The diffusion coefficients (D) and heterogeneous electron transfer rate constant (k o ) of both anodic and cathodic process were 1.04×10 -5 cm 2 ·s -1 , 1.73×10 -6 cm 2 .s -1 , 0.0004 cm.s -1 and 0.0011 cm.s -1 , respectively. The obtained results showed that the anode exhibits high bioeletrocatalytic activity due to the attachment of G. sulfurreducens on the anode surface.

Miguel Ángel López Zavala, Omar Israel González Peña, Héctor Cabral Ruelas et al.

Energies • 2019

Cyclic voltammetry (CV) was used in this work to describe the electrochemical behavior of a dual-chamber microbial fuel cell (MFC). The system performance was evaluated under vacuum and non-pressurized conditions, different reaction times, two sweep potentials, 25 and 50 mVs−1 and under different analyte solutions, such as distilled water and domestic wastewater. CV experiments were conducted by using a potentiostat with three different configurations to collect the measurements. A dual-chamber MFC system was equipped with a DupontTM Nafion® 117 proton exchange membrane (PEM), graphite electrodes (8.0 cm × 2.5 cm × 0.2 cm) and an external electric circuit with a 100-Ω resistor. An electrolyte (0.1 M HCl, pH ≈ 1.8) was used in the cathode chamber. It was found that the proton exchange membrane plays a major role on the electrochemical behavior of the MFC when CV measurements allow observing the conductivity performance in the MFC in the absence of a reference electrode; under this potentiostat setting, less current density values are obtained on the scanned window potentials. Therefore, potentiostat setting is essential to obtain information in complex electrochemical processes present in biological systems, such as it is the case in the MFCs. Results of the study showed that wastewater constituents and the biomass suspended or attached (biofilm) over the electrode limited the electron charge transfer through the interface electrode-biofilm-liquor. This limitation can be overcome by: (i) Enhancing the conductivity of the liquor, which is a reduction of the ohmic drop, (ii) reducing the activation losses by a better catalysis, and (iii) by limiting the diffusional gradients in the bulk liquor, for instance, by forced convection. The use of the electrolyte (0.1 M HCl, pH ≈ 1.8) and its diffusion from the cathode to the anode chamber reduces the resistance to the flow of ions through the PEM and the flow of electrons through the anodic and cathodic electrolytes. Also reduces the activation losses during the electron transfer from the substrate to the electrode surface due to the electrode catalysis improvement. On the other hand, vacuum also demonstrated that it enhances the electrochemical performance of the dual-chamber MFC due to the fact that higher current densities in the system are favored.

Ryuhei Kishida

JOURNAL OF MECHANICS OF CONTINUA AND MATHEMATICAL SCIENCES • 2020

Derek R. Lovley

Microbiology • 2022

Geobacter metallireducens has served as the initial model for a substantial number of newly recognized microbial physiologies that play an important role in biogeochemical cycling of carbon, metals and nutrients. The strategies used by G. metallireducens for microbial interaction with minerals, contaminants, other microbes and electrodes have led to new technologies for bioremediation, bioenergy conversion and the sustainable production of ‘green’ electronics.

Ciana Lopez, Carlo Santoro, Plamen Atanassov et al.

ECS Meeting Abstracts • 2016

Bioelectrochemical systems (BESs) are interesting systems that combine electrochemical red-ox reaction with biological activity for generating electricity from organic compounds. In fact, the organic compounds are actually the fuel for the fuel cell in which bacteria on the anode degrade organic molecules and transfer the resulting electrons to the electrode surface. The electrons move through the external circuit generating useful electricity to power devices or sensors. At the cathode, an oxidant is reduced to complete the red-ox reaction. Generally oxygen is used due to its high potential and natural availability. Interestingly, it has been found that some bacteria, named exoelectrogens, are able to transfer electrons extracellularly to a solid support, generally called the anode electrode, if the substrate oxidation reaction occurs in absence of oxygen. The halfway potential represents the potential at which the electron transfer mechanism of an exoelectrogen is most favorable and thus outputs the most electricity. The more negative the halfway potential, the more energy can be produced. The goal of this project is to maximize microbial energy production considering different anode material-bacteria interactions. Carbonaceous-based materials are typically used as anode in BESs due to their simplicity, low-cost fabrication, high surface area, high mechanical strength, high chemical resistance to corrosion and biocompatibility. It has been shown previously that both surface chemistry and surface morphology can affect positively or negatively the bacteria attachment on a surface. Unfortunately, the electrical conductivity of carbonaceous materials is generally low compared to other materials and the durability is often negatively affected in long-term operation mainly due to material deterioration. Materials other than graphite have been proposed as suitable anode materials, but the effect of anode material on the underlying mechanism of extracellular electron transfer (EET) has not been yet addressed. Here, we measure electron transport properties of the model organism, Geobacter sulfurreducens , under turnover (with organic substrate) and nonturnover (without organic substrate) conditions, using an array of materials as working electrodes of an MFC (glassy carbon (GC), graphite (GR), gold (Au), platinum mesh (Pt), nickel (Ni) and indium tin oxide (ITO)). Experimentally, a 1L reactor that accommodates 6 working electrodes was used so all of the working electrodes could be tested under the same conditions with the same reference and counter electrodes. Ag/AgCl (3M KCl) was used as reference electrode while Pt was used as counter. Each material was used as a separate working electrode and connected to a single potentiostat (VMP3, Biologic, Inc., Knoxville, TN) channel. The reactor was operated using a three-electrode configuration at a set anode potential of +0.3 V (vs. Ag/AgCl) to study each material at stable fixed potential, as opposed to a floating potential observed for MFC anodes. Preliminary electrochemical tests produced cyclic voltammograms (CV) of all the materials under turnover and nonturnover conditions that displayed differences in slope and in the difference between halfway potential and formal potential, indicating that different materials yielded different electrochemical responses (Figure 1). The observed differences suggest that the bacteria are either using different electrochemical pathways to perform EET or that the material being used as the working electrode is influencing the environment and therefore altering the formal potential. We are currently conducting chemical measurements to characterize the working electrode surfaces along with a detailed study of the Geobacter biofilm colonization. Finally, we will establish a relationship between the halfway potential and extracellular electron transfer dependence on the surface to which the biofilm is attached. Figure 1. Polarization of Geobacter sulfurreducens grown for 14 days on various materials [Preliminary Data] Figure 1

Toshiyuki Ueki

Applied and Environmental Microbiology • 2021

Extracellular electron transfer (EET) is an important biological process in microbial physiology as found in dissimilatory metal oxidation/reduction and interspecies electron transfer in syntrophy in natural environments. EET also plays a critical role in microorganisms relevant to environmental biotechnology in metal-contaminated areas, metal corrosion, bioelectrochemical systems, and anaerobic digesters. Geobacter species exist in a diversity of natural and artificial environments.

Matthew J. Guberman-Pfeffer

Biophysical Journal • 2024

Daniel Härrer, Ahmed Elreedy, Rowayda Ali et al.

SSRN Electronic Journal • 2021

Rebecca J. Steidl, Sanela Lampa-Pastirk, Gemma Reguera

Nature Communications • 2017

Nature Communications 7: Artilce number: 12217 (2016); Published 2 August 2016; Updated 28 April 2017 Two previous studies (Vargas et al. 2013, Liu et al. 2014) reporting that conductive pili are required for long-range electron transport in Geobacter sulfurreducens were inadvertently omitted from the reference list of this Article, and should have been cited in the Introduction section where the possibility that pili function as biofilm electron carriers is discussed.

Rebecca J. Steidl, Sanela Lampa-Pastirk, Gemma Reguera

Nature Communications • 2016

Abstract Electricity generation by Geobacter sulfurreducens biofilms grown on electrodes involves matrix-associated electron carriers, such as c -type cytochromes. Yet, the contribution of the biofilm’s conductive pili remains uncertain, largely because pili-defective mutants also have cytochrome defects. Here we report that a pili-deficient mutant carrying an inactivating mutation in the pilus assembly motor PilB has no measurable defects in cytochrome expression, yet forms anode biofilms with reduced electroactivity and is unable to grow beyond a threshold distance (∼10 μm) from the underlying electrode. The defects are similar to those of a Tyr3 mutant, which produces poorly conductive pili. The results support a model in which the conductive pili permeate the biofilms to wire the cells to the conductive biofilm matrix and the underlying electrode, operating coordinately with cytochromes until the biofilm reaches a threshold thickness that limits the efficiency of the cytochrome pathway but not the functioning of the conductive pili network.

Guiqin Yang, Lingyan Huang, Lexing You et al.

Electrochemistry Communications • 2017

Jessica E. Butler, Richard H. Glaven, Abraham Esteve-Núñez et al.

Journal of Bacteriology • 2006

ABSTRACT The mechanism of fumarate reduction in Geobacter sulfurreducens was investigated. The genome contained genes encoding a heterotrimeric fumarate reductase, FrdCAB, with homology to the fumarate reductase of Wolinella succinogenes and the succinate dehydrogenase of Bacillus subtilis . Mutation of the putative catalytic subunit of the enzyme resulted in a strain that lacked fumarate reductase activity and was unable to grow with fumarate as the terminal electron acceptor. The mutant strain also lacked succinate dehydrogenase activity and did not grow with acetate as the electron donor and Fe(III) as the electron acceptor. The mutant strain could grow with acetate as the electron donor and Fe(III) as the electron acceptor if fumarate was provided to alleviate the need for succinate dehydrogenase activity in the tricarboxylic acid cycle. The growth rate of the mutant strain under these conditions was faster and the cell yields were higher than for wild type grown under conditions requiring succinate dehydrogenase activity, suggesting that the succinate dehydrogenase reaction consumes energy. An orthologous frdCAB operon was present in Geobacter metallireducens , which cannot grow with fumarate as the terminal electron acceptor. When a putative dicarboxylic acid transporter from G. sulfurreducens was expressed in G. metallireducens , growth with fumarate as the sole electron acceptor was possible. These results demonstrate that, unlike previously described organisms, G. sulfurreducens and possibly G. metallireducens use the same enzyme for both fumarate reduction and succinate oxidation in vivo.

Allison M. Speers, Gemma Reguera

Biofilm • 2021

Kelly P. Nevin, Dawn E. Holmes, Trevor L. Woodard et al.

International Journal of Systematic and Evolutionary Microbiology • 2005

Fe(III)-reducing isolates were recovered from two aquifers in which Fe(III) reduction is known to be important. Strain Bem T was enriched from subsurface sediments collected in Bemidji, MN, USA, near a site where Fe(III) reduction is important in aromatic hydrocarbon degradation. Strains P11, P35 T and P39 were isolated from the groundwater of an aquifer in Plymouth, MA, USA, in which Fe(III) reduction is important because of long-term inputs of acetate as a highway de-icing agent to the subsurface. All four isolates were Gram-negative, slightly curved rods that grew best in freshwater media. Strains P11, P35 T and P39 exhibited motility via means of monotrichous flagella. Analysis of the 16S rRNA and nifD genes indicated that all four strains are δ -proteobacteria and members of the Geobacter cluster of the Geobacteraceae . Differences in phenotypic and phylogenetic characteristics indicated that the four isolates represent two novel species within the genus Geobacter . All of the isolates coupled the oxidation of acetate to the reduction of Fe(III) [iron(III) citrate, amorphous iron(III) oxide, iron(III) pyrophosphate and iron(III) nitrilotriacetate]. All four strains utilized ethanol, lactate, malate, pyruvate and succinate as electron donors and malate and fumarate as electron acceptors. Strain Bem T grew fastest at 30 °C, whereas strains P11, P35 T and P39 grew equally well at 17, 22 and 30 °C. In addition, strains P11, P35 T and P39 were capable of growth at 4 °C. The names Geobacter bemidjiensis sp. nov. (type strain Bem T =ATCC BAA-1014 T =DSM 16622 T =JCM 12645 T ) and Geobacter psychrophilus sp. nov. (strains P11, P35 T and P39; type strain P35 T =ATCC BAA-1013 T =DSM 16674 T =JCM 12644 T ) are proposed.

Joana M. Dantas, Leonor Morgado, Muktak Aklujkar et al.

Frontiers in Microbiology • 2015

Shun'ichi Ishii, Kazuya Watanabe, Soichi Yabuki et al.

Applied and Environmental Microbiology • 2008

ABSTRACT An electricity-generating bacterium, Geobacter sulfurreducens PCA, was inoculated into a single-chamber, air-cathode microbial fuel cell (MFC) in order to determine the maximum electron transfer rate from bacteria to the anode. To create anodic reaction-limiting conditions, where electron transfer from bacteria to the anode is the rate-limiting step, anodes with electrogenic biofilms were reduced in size and tests were conducted using anodes of six different sizes. The smallest anode (7 cm 2 , or 1.5 times larger than the cathode) achieved an anodic reaction-limiting condition as a result of a limited mass of bacteria on the electrode. Under these conditions, the limiting current density reached a maximum of 1,530 mA/m 2 , and power density reached a maximum of 461 mW/m 2 . Per-biomass efficiency of the electron transfer rate was constant at 32 fmol cell −1 day −1 (178 μmol g of protein −1 min −1 ), a rate comparable to that with solid iron as the electron acceptor but lower than rates achieved with fumarate or soluble iron. In comparison, an enriched electricity-generating consortium reached 374 μmol g of protein −1 min −1 under the same conditions, suggesting that the consortium had a much greater capacity for electrode reduction. These results demonstrate that per-biomass electrode reduction rates (calculated by current density and biomass density on the anode) can be used to help make better comparisons of electrogenic activity in MFCs.

Feng Zhang, Shengsong Yu, Jie Li et al.

Frontiers of Environmental Science & Engineering • 2015

Dandan Deng, Yichi Zhang, Ying Liu

RSC Advances • 2014

A novel electrochemically active strain D-8 was successfully isolated from rice paddy soil. The strain D-8 can use more carbon sources and show higher current density than G. sulfurreducens PCA. It might be a promising bioanodic organism in MFCs.

Enrico Marsili, Jian Sun, Daniel R. Bond

Electroanalysis • 2010

Abstract The ability of Geobacter sulfurreducens to utilize electrodes as electron acceptors provides a system for monitoring mechanisms of electron transfer beyond the cell surface. This study examined the physiology of extracellular electron transfer during many stages of growth, and in response to short‐ and long‐term changes in electron acceptor potential. When G. sulfurreducens was grown on planar potentiostat‐controlled electrodes, the magnitude of early cell attachment increased with initial cell density. However, the first cells to attach did not demonstrate the same electron transfer rates as cells grown on electrodes. For example, following initial attachment of fumarate‐grown cells, the electron transfer rate was 2 mA/mg protein, but increased to nearly 8 mA/mg protein within 6 h of growth. Once attached, all biofilms grew at a constant rate (doubling every 6 h), and sustained a high specific electron transfer rate and growth yield, while current density was below 300 μA/cm 2 . Beyond this point, the rate of current increase slowed and approached a stable plateau. At all phases, slow scan rate cyclic voltammetry of G. sulfurreducens showed a similar well‐defined sigmoidal catalytic wave, indicating the general model of electron transfer to the electrode was not changing. Short‐term exposure to reducing potentials (3 h) did not alter these characteristics, but did cause accumulation of electrons which could be discharged at potentials above −0.1 V. Sustained growth at lower potentials (−0.16 V) only slightly altered the pattern of detectable redox species at the electrode, but did eliminate this pattern of discharge from the biofilm. Single‐turnover voltammetry of colonized electrodes showed at least 3 redox couples at potentials similar to other recent observations, with redox protein coverage of the electrode on the order of ca. 1 nmol/cm 2 . The consistent electrochemistry, growth rate, and growth yield of the G. sulfurreducens biofilm at all stages suggests an initial phase where cells must optimize attachment or electron transfer to a surface, and that after this point, the rate of electron production by cells (rate electrons are delivered to the external surface) remains rate limiting compared to the rate electrons can be transferred between cells, and to electrodes.

Douglas F. Call, Bruce E. Logan

Applied and Environmental Microbiology • 2011

ABSTRACT Geobacter sulfurreducens PCA completely oxidized lactate and reduced iron or an electrode, producing pyruvate and acetate intermediates. Compared to the current produced by Shewanella oneidensis MR-1, G. sulfurreducens PCA produced 10-times-higher current levels in lactate-fed microbial electrolysis cells. The kinetic and comparative analyses reported here suggest a prominent role of G. sulfurreducens strains in metal- and electrode-reducing communities supplied with lactate.

Pablo Sebastián Bonanni, Germán David Schrott, Juan Pablo Busalmen

Biochemical Society Transactions • 2012

The mechanism of electron transport in Geobacter sulfurreducens biofilms is a topic under intense study and debate. Although some proteins were found to be essential for current production, the specific role that each one plays in electron transport to the electrode remains to be elucidated and a consensus on the mechanism of electron transport has not been reached. In the present paper, to understand the state of the art in the topic, electron transport from inside of the cell to the electrode in Geobacter sulfurreducens biofilms is analysed, reviewing genetic studies, biofilm conductivity assays and electrochemical and spectro-electrochemical experiments. Furthermore, crucial data still required to achieve a deeper understanding are highlighted.

Hiroyuki Kashima, John M. Regan

Environmental Science & Technology • 2015

Alternative metabolic options of exoelectrogenic biofilms in bioelectrochemical systems (BESs) are important not only to explain the fundamental ecology and performance of these systems but also to develop reliable integrated nutrient removal strategies in BESs, which potentially involve substrates or intermediates that support/induce those alternative metabolisms. This research focused on dissimilatory nitrate reduction as an alternative metabolism to dissimilatory anode reduction. Using the exoelectrogenic nitrate reducer Geobacter metallireducens, the critical conditions controlling those alternative metabolisms were investigated in two-chamber, potentiostatically controlled BESs at various anode potentials and biofilm thicknesses and challenged over a range of nitrate concentrations. Results showed that anode-reducing biofilms facultatively reduced nitrate at all tested anode potentials (-150 to +900 mV vs Standard Hydrogen Electrode) with a rapid metabolic shift. The critical nitrate concentration that triggered a significant decrease in BES performance was a function of anode biofilm thickness but not anode potential. This indicates that these alternative metabolisms were controlled by the availability of nitrate, which is a function of nitrate concentration in bulk solution and its diffusion into an anode-reducing biofilm. Coulombic recovery decreased as a function of nitrate dose due to electron-acceptor substrate competition, and nitrate-induced suspended biomass growth decreased the effluent quality.

Jerome T. Babauta, Haluk Beyenal

ECS Meeting Abstracts • 2016

Model electrochemically active bacteria such as Geobacter sulfurreducens are well-established and are often used to study microbial interactions within biofilms that transfer electrons to electrodes. In the presented work, we utilized a quartz crystal microbalance (QCM) coupled to electrochemical impedance spectroscopy (EIS) to simultaneously monitor biofilm growth and the microbial interaction with the electrode. The QCM monitored the frequency shift from the background resonant frequency in real time while the current increased because of biofilm growth. At select times during biofilm growth, we halted the current and obtained biofilm impedance spectra. The short-term and long-term electrode interactions of G. sulfurreducens biofilms were demonstrated. In the short-term, the frequency shift was linear with respect to current for the biofilm. In long-term biofilm growth up to the exponential phase, a second linear region was observed. Biofilm impedance spectra taken across these times revealed a reproducible electrochemical signal. Conductance of the biofilm was linear with current whereas capacitance reached a limiting value towards the end of exponential growth. We show that a simple iV relationship can explain the linear behavior of conductance and current. Capacitance could be used to identify the transition between different growth phases. We compare the biofilm response on the QCM to capacitive, electrochemically-deposited polyaniline films. Our results suggest that the QCM can be used in applications where it is beneficial to identify electrochemically active bacteria that form efficient current-producing biofilms.

Merve TINGIR, Elif TARLAKAZAN

ODÜ Sosyal Bilimler Araştırmaları Dergisi (ODÜSOBİAD) • 2022

The original print painting has survived to the present day by changing with the progress of societies and time in the historical process. The development of technology has led to the use of the art of printmaking only for individual or educational purposes in schools. Today, 3D printing production techniques emerge as a new field in both design and production areas. Thanks to the convenience it offers, an alternative art creation tool emerges for designers. Using 3D printing with different disciplines, it creates diversity in the name of design and art. Thanks to the renewed technological developments, it contributes to its development by taking a new field into its sphere of influence every day. In the study, historical and general information about the art of printmaking is included, and the transition processes to 3D printing technology are discussed and compared. In addition, the transition processes and applications to 3D printing systems were examined. Qualitative research method will be used in the research. By making a literature review, the studies on the subject will be discussed and interpreted. This method covers the comparison of original print painting and 3D printing technology by referring to the point they have reached.

Arpine Galstyan, Michael J. Bunker, Fluvio Lobo et al.

3D Printing in Medicine • 2021

Abstract Three-dimensional (3D) printing is a method by which two-dimensional (2D) virtual data is converted to 3D objects by depositing various raw materials into successive layers. Even though the technology was invented almost 40 years ago, a rapid expansion in medical applications of 3D printing has only been observed in the last few years. 3D printing has been applied in almost every subspecialty of medicine for pre-surgical planning, production of patient-specific surgical devices, simulation, and training. While there are multiple review articles describing utilization of 3D printing in various disciplines, there is paucity of literature addressing applications of 3D printing in breast cancer management. Herein, we review the current applications of 3D printing in breast cancer management and discuss the potential impact on future practices.

Margaret Flavell, Cherie Chu-Fuluifaga

Teachers' Work • 2023

The low participation of Pacific students in tertiary STEM studies has implications for schools as they consider how best to engage these learners in STEM subjects (Science, Technology, Engineering and Mathematics). This article reports on an innovative project that supports Pacific learners with STEM learning through 3D printing technology. Creative STEM Pathways is a university-led initiative which has successfully brought 3D technology to the classroom, providing culturally-sustaining, hands-on and relevant learning opportunities. We used an Appreciative Inquiry lens to help us explore how the programme could create positive learning experiences. In this article, we share experiences of its development and delivery. We highlight successes and challenges, offering practical insight to those considering similar innovation in the classroom.