Hui Li, Jun Cheng, Haiquan Dong et al.

The Science of The Total Environment • 2021

Mengjing Cao, Yongxiang Zhang, Yan Zhang et al.

RSC Advances • 2021

A novel and amplifying anaerobic electrochemical membrane bioreactor (AnEMBR, R2) was constructed and operated for a long time (204 days) with synthetic glucose solution having an average chemical oxygen demand (COD) of 315 mg L -1 , at different applied voltages and room temperatures. More than twice sodium bicarbonate was added for maintaining a pH of around 6.7 in the supernatant of the reactor R2, close to that of a control reactor called anaerobic membrane bioreactor (AnMBR, R1), after 138 days. And the transmembrane pressure (TMP) for the R2 system was only 0.534 bar at the end of operation and 0.615 bar for the R1 system. Although the electrostatic repulsion force contributed to pushing away the pollutants (proteins, polysaccharose and inorganic salt deposits, and so on), more microorganisms adsorbed and accumulated on the membrane surface after the whole operation, which might result in a rapid increase in membrane filtration resistance in the long-term operation. There were much more exoelectrogenic bacteria, mainly Betaproteobacteria, Deltaproteobacteria and Grammaproteobacteria, on the cathode and the dominant methanogen Methanothrix content on the cathode was three times higher than the AnMBR. The study provides an important theoretical foundation for the application of AnEMBR technology in the treatment of low organic strength wastewater.

Addissu B. Ergettie, Mustafa Dagbasi

Biofuels • 2018

Excessive amount of ammonia slows down exoelectrogenic bacteria activities in microbial fuel cells (MFCs). The aim of this study is to analyze the impact of wastewater concentration and feed frequency on the ability of exoelectrogenic bacteria to withstand against ammonia inhibition in MFCs, in particular, for total ammonium nitrogen (TAN) concentration ranging from 29 mgNL−1 to 2000 mgNL−1. MFCs were constructed to measure electric current and power density and tested in wastewater of selected TAN concentration samples. The MFCs frequently feed (2-days intervals) with full strength wastewater achieved a maximum power density between 0.8 mWm−2 and 1.2 mWm−2. The MFC less frequently feed (6-days feed intervals) with full strength wastewater and also the MFC frequently feed (2-days feed intervals) with low strength wastewater exhibited a relatively lower electricity generation. Increasing the concentration of total ammonium nitrogen resulted in a gradual decrease of chemical oxygen demand (COD) removal efficiency. Experimental results demonstrated that the frequency of feed and higher substrate concentration increase exoelectrogenic bacteria activities in generating electric current in MFCs.

Yi-Ho Kuo, Ming-Chien Hsu, Wen‐Jyun Wang et al.

Nano Energy • 2024

Chiy En Lim, Chien Ley Chew, Guan‐Ting Pan et al.

International Journal of Hydrogen Energy • 2023

Xiaojun Jin, Nuan Yang, Hong Liu et al.

Chemosphere • 2022

Joseph Oram, Lars J. C. Jeuken

mBio • 2019

Exoelectrogenic bacteria are defined by their ability to respire on extracellular and insoluble electron acceptors and have applications in bioremediation and microbial electrochemical systems (MESs), while playing important roles in biogeochemical cycling. Shewanella oneidensis MR-1, which has become a model organism for the study of extracellular respiration, is known to display taxis toward insoluble electron acceptors, including electrodes. Multiple mechanisms have been proposed for MR-1's tactic behavior, and, here, we report on the role of electrochemical potential by video microscopy cell tracking experiments in three-electrode electrochemical cells. MR-1 trajectories were determined using a particle tracking algorithm and validated with Shannon's entropy method. Tactic response by MR-1 in the electrochemical cell was observed to depend on the applied potential, as indicated by the average velocity and density of motile (>4 µm/s) MR-1 close to the electrode (<50 µm). Tactic behavior was observed at oxidative potentials, with a strong switch between the potentials -0.15 to -0.25 V versus the standard hydrogen electrode (SHE), which coincides with the reduction potential of flavins. The average velocity and density of motile MR-1 close to the electrode increased when riboflavin was added (2 µM), but were completely absent in a Δ mtrC /Δ omcA mutant of MR-1. Besides flavin's function as an electron mediator to support anaerobic respiration on insoluble electron acceptors, we propose that riboflavin is excreted by MR-1 to sense redox gradients in its environment, aiding taxis toward insoluble electron acceptors, including electrodes in MESs. IMPORTANCE Previous hypotheses of tactic behavior of exoelectrogenic bacteria are based on techniques that do not accurately control the electrochemical potential, such as chemical-in-plug assays or microscopy tracking experiments in two-electrode cells. Here, we have revisited previous experiments and, for the first time, performed microscopy cell-tracking experiments in three-electrode electrochemical cells, with defined electrode potentials. Based on these experiments, taxis toward electrodes is observed to switch at about -0.2 V versus standard hydrogen electrode (SHE), coinciding with the reduction potential of flavins.

Wendy Huang, Younggy Kim

Environmental Science and Pollution Research • 2016

Jungyu Park, Beom Lee, Hye-Jeong Kwon et al.

Chemosphere • 2018

Deepak Sharma, Rishi Mahajan, Gunjan Goel

International Journal of Environmental Science and Technology • 2018

Akiho Matsumoto, Misa Nagoya, Miyu Tsuchiya et al.

Bioelectrochemistry • 2020

Xiaoyu Han, Youpeng Qu, Jing Wu et al.

Journal of Hazardous Materials • 2020

Hui Wang, Lei Li, Xian Cao et al.

Water Air & Soil Pollution • 2017

Jinjie Zhou, Jessica A. Smith, Meng Li et al.

mBio • 2023

Methanothrix is widely distributed in natural and artificial anoxic environments and plays a major role in global methane emissions. It is one of only two genera that can form methane from acetate dismutation and through participation in direct interspecies electron transfer (DIET) with exoelectrogens. Although Methanothrix is a significant member of many methanogenic communities, little is known about its physiology. In this study, transcriptomics helped to identify potential routes of electron transfer during DIET between Geobacter metallireducens and Methanothrix thermoacetophila . Additions of magnetite to cultures significantly enhanced growth by acetoclastic methanogenesis and by DIET, while granular activated carbon (GAC) amendments impaired growth. Transcriptomics suggested that the OmaF-OmbF-OmcF porin complex and the octaheme outer membrane c -type cytochrome encoded by Gmet_0930, were important for electron transport across the outer membrane of G. metallireducens during DIET with Mx. thermoacetophila . Clear differences in the metabolism of Mx. thermoacetophila when grown via DIET or acetate dismutation were not apparent. However, genes coding for proteins involved in carbon fixation, the sheath fiber protein MspA, and a surface-associated quinoprotein, SqpA, were highly expressed in all conditions. Expression of gas vesicle genes was significantly lower in DIET- than acetate-grown cells, possibly to facilitate better contact between membrane-associated redox proteins during DIET. These studies reveal potential electron transfer mechanisms utilized by both Geobacter and Methanothrix during DIET and provide important insights into the physiology of Methanothrix in anoxic environments. IMPORTANCE Methanothrix is a significant methane producer in a variety of methanogenic environments including soils and sediments as well as anaerobic digesters. Its abundance in these anoxic environments has mostly been attributed to its high affinity for acetate and its ability to grow by acetoclastic methanogenesis. However, Methanothrix species can also generate methane by directly accepting electrons from exoelectrogenic bacteria through direct interspecies electron transfer (DIET). Methane production through DIET is likely to further increase their contribution to methane production in natural and artificial environments. Therefore, acquiring a better understanding of DIET with Methanothrix will help shed light on ways to (i) minimize microbial methane production in natural terrestrial environments and (ii) maximize biogas formation by anaerobic digesters treating waste.

David Valero, Carlos Rico, Raúl Tapia‐Tussell et al.

Processes • 2020

Corn is one of the main food products in Mexico. The elaboration of corn-derived products generates wastewater with a high organic load (nejayote). Anaerobic digestion is an indicated treatment for wastewater with high organic loads. The results of this study show that the application of microaeration in the hydrolysis-fermentative reactor increased the percentage of volatile fatty acids (VFA) available in the medium by 62%. The addition of a conductive material, such as granulated activated carbon (GAC), promotes DIET (Direct interspecies electrons transfer) in the methanogenic UASB reactor increasing the methane yield by 55%. Likewise, a great diversity of exoelectrogenic bacteria, with the ability to donate electrons DIET mechanisms, were developed in the GAC biofilm, though interestingly, Peptoclostridium and Clostridium (17.3% and 12.75%, respectively) were detected with a great abundance in the GAC biofilm. Peptoclostridium has not been previously reported as a participant in DIET process.

Wenhui Zhong, Lv-Cheng Cai, Zhenggui Wei et al.

CATENA • 2017

Qinzheng Yang, Dianliang Luo, Xiaoliang Liu et al.

Bioelectrochemistry • 2021

Miho Kitayama, Ryota Koga, Takuya Kasai et al.

Applied and Environmental Microbiology • 2017

An electrochemical flow cell equipped with a graphite working electrode (WE) at the bottom was inoculated with Shewanella oneidensis MR-1 expressing an anaerobic fluorescent protein, and biofilm formation on the WE was observed over time during current generation at WE potentials of +0.4 and 0 V (versus standard hydrogen electrodes), under electrolyte-flow conditions. Electrochemical analyses suggested the presence of unique electron-transfer mechanisms in the +0.4-V biofilm. Microscopic analyses revealed that, in contrast to aerobic biofilms, current-generating biofilm (at +0.4 V) was thin and flat (∼10 μm in thickness), and cells were evenly and densely distributed in the biofilm. In contrast, cells were unevenly distributed in biofilm formed at 0 V. In situ fluorescence staining and biofilm recovery experiments showed that the amounts of extracellular polysaccharides (EPSs) in the +0.4-V biofilm were much smaller than those in the aerobic and 0-V biofilms, suggesting that Shewanella cells suppress the production of EPSs at +0.4 V under flow conditions. We suggest that Shewanella cells perceive electrode potentials and modulate the structure and composition of biofilms to efficiently transfer electrons to electrodes. IMPORTANCE A promising application of microbial fuel cells (MFCs) is to save energy in wastewater treatment. Since current is generated in these MFCs by biofilm microbes under horizontal flows of wastewater, it is important to understand the mechanisms for biofilm formation and current generation under water-flow conditions. Although massive work has been done to analyze the molecular mechanisms for current generation by model exoelectrogenic bacteria, such as Shewanella oneidensis , limited information is available regarding the formation of current-generating biofilms over time under water-flow conditions. The present study developed electrochemical flow cells and used them to examine the electrochemical and structural features of current-generating biofilms under water-flow conditions. We show unique features of mature biofilms actively generating current, creating opportunities to search for as-yet-undiscovered current-generating mechanisms in Shewanella biofilms. Furthermore, information provided in the present study is useful for researchers attempting to develop anode architectures suitable for wastewater treatment MFCs.

Giulia Massaglia, Francesca Frascella, Alessandro Chiadò et al.

Nanomaterials • 2020

Microbial fuel cells (MFCs) are bio-electrochemical devices able to directly transduce chemical energy, entrapped in an organic mass named fuel, into electrical energy through the metabolic activity of specific bacteria. During the last years, the employment of bio-electrochemical devices to study the wastewater derived from the food industry has attracted great interest from the scientific community. In the present work, we demonstrate the capability of exoelectrogenic bacteria used in MFCs to catalyze the oxidation reaction of honey, employed as a fuel. With the main aim to increase the proliferation of microorganisms onto the anode, engineered electrodes are proposed. Polymeric nanofibers, based on polyethylene oxide (PEO-NFs), were directly electrospun onto carbon-based material (carbon paper, CP) to obtain an optimized composite anode. The crucial role played by the CP/PEO-NFs anodes was confirmed by the increased proliferation of microorganisms compared to that reached on bare CP anodes, used as a reference material. A parameter named recovered energy (Erec) was introduced to determine the capability of bacteria to oxidize honey and was compared with the Erec obtained when sodium acetate was used as a fuel. CP/PEO-NFs anodes allowed achieving an Erec three times higher than the one reached with a bare carbon-based anode.

Pengyi Yuan, Younggy Kim

Environmental Science Water Research & Technology • 2017

Bioanode sensors utilizing exoelectrogenic bacteria can be used for real-time and in situ assessment of water quality.

Nannan Zhao, Yanyan Su, İrini Angelidaki et al.

Journal of Power Sources • 2020

Jung-Yeol Lee, Jeong-Hoon Park, Hee‐Deung Park

Waste Management • 2017

Takahiro Yamashita, Teruaki Hasegawa, Yudai Hayashida et al.

Biochemical Engineering Journal • 2021

Xiaoyong Yang, Rusen Zou, Kai Tang et al.

The Science of The Total Environment • 2021

Hiroshi Yokoyama, Mitsuyoshi Ishida, Takahiro Yamashita

Journal of Microbiology and Biotechnology • 2016

The group of Fe(III) oxide-reducing bacteria includes exoelectrogenic bacteria, and they possess similar properties of transferring electrons to extracellular insoluble-electron acceptors. The exoelectrogenic bacteria can use the anode in microbial fuel cells (MFCs) as the terminal electron acceptor in anaerobic acetate oxidation. In the present study, the anodic community was compared with the community using Fe(III) oxide (ferrihydrite) as the electron acceptor coupled with acetate oxidation. To precisely analyze the structures, the community was established by enrichment cultures using the same inoculum used for the MFCs. High-throughput sequencing of the 16S rRNA gene revealed considerable differences between the structure of the anodic communities and that of the Fe(III) oxide-reducing community. Geobacter species were predominantly detected (>46%) in the anodic communities. In contrast, Pseudomonas (70%) and Desulfosporosinus (16%) were predominant in the Fe(III) oxide-reducing community. These results demonstrated that Geobacter species are the most specialized among Fe(III)-reducing bacteria for electron transfer to the anode in MFCs. In addition, the present study indicates the presence of a novel lineage of bacteria in the genus Pseudomonas that highly prefers ferrihydrite as the terminal electron acceptor in acetate oxidation.

Cheng Sun, Qilin Yu, Zhiqiang Zhao et al.

ACS Sustainable Chemistry & Engineering • 2023

Efficient electron transfer among anaerobes is critical to maintaining the high performance of anaerobic digestion. In this study, photosynthetic bacteria (PSB), as exoelectrogenic bacteria, were added to a light anaerobic digester to establish the electroactive microorganism community for the improvement of methane production during anaerobic digestion. Results showed that the daily methane production increased by 37% and the chemical oxygen demand (COD) removal efficiency increased from 70% to over 90%, accompanied by the increase of F420, ATP, and NADH/NAD+ of the sludge. The electrochemical activity of the anaerobic sludge such as capacitance and conductance increased by 28 and 16%, respectively, and the extracellular electron transfer capacity of the sludge nearly doubled. In addition, the PSB agents promoted the secretion of conductive proteins and EPS, such as the OmcS copy number increasing more than 100 times, which provided a bridge for electron transfer between other microorganisms in the sludge. Correspondingly, PSB promoted the enrichment of electrotrophic methanogens, Methanosarcina, whose abundance increased from 0.76 to 34.7%. Also, it increased the proliferation of other exoelectrogenic bacteria such as Syntrophomonas. In brief, a mutually beneficial electroactive community was established by the addition of PSB agents to facilitate electron transfer for methane production during anaerobic digestion.

Chao Li, Yang Liu, Miaomiao Luo et al.

Journal of Power Sources • 2023

Míriam Cerrillo, Judit Oliveras, Marc Viñas et al.

Bioelectrochemistry • 2016

Dao‐Bo Li, Yu‐Xi Huang, Jie Li et al.

Electrochimica Acta • 2016

Xiaolin Zhang, Ruixiang Li, Jinning Wang et al.

Chemical Engineering Journal • 2021

Meng Li, Hongguo Zhang, Tangfu Xiao et al.

Electrochimica Acta • 2017

Αsimina Tremouli, Michalis Martinos, S. Bebelis et al.

Journal of Applied Electrochemistry • 2016

Khaled Elmaadawy, Jingping Hu, Shengxia Guo et al.

Bioresource Technology • 2020

Jungyu Park, Wonbeom Shin, Wei-Qi Shi et al.

Energies • 2019

Bacterial communities change in bulk solution of anaerobic digestion (AD) and bio-electrochemical anaerobic digestion reactors (BEAD) were monitored at each organic loading rate (OLR) to investigate the effect of voltage supply on bacterial species change in bulk solution. Chemical oxygen demand (COD) degradation and methane production from AD and BEAD reactors were also analyzed by gradually increasing food waste OLR. The BEAD reactor maintained stable COD removal and methane production at 6.0 kg/m3·d. The maximum OLR of AD reactor for optimal operation was 4.0 kg/m3·d. pH and alkalinity decline and volatile fatty acid (VFA) accumulation, which are the problem in high load anaerobic digestion of readily decomposable food wastes, were again the major factors destroying the optimal operation condition of the AD reactor at 6.0 kg/m3·d. Contrarily, the electrochemically activated dense communities of exoelectrogenic bacteria and VFA-oxidizing bacteria prevented VFAs from accumulating inside the BEAD reactor. This maintained stable pH and alkalinity conditions, ultimately contributing to stable methane production.

Xiang Xiao, Qiuyue Liu, Jianrong Li et al.

Bioresource Technology • 2017

Qian Liu, Bing-Feng Liu, Wei Li et al.

Frontiers in Microbiology • 2017

The performance of microbial electrochemical cells depends upon microbial community structure and metabolic activity of the electrode biofilms. Iron as a signal affects biofilm development and enrichment of exoelectrogenic bacteria. In this study, the effect of ferrous iron on microbial communities of the electrode biofilms in microbial fuel cells (MFCs) was investigated. Voltage production showed that ferrous iron of 100 μM facilitated MFC start-up compared to 150 μM, 200 μM, and without supplement of ferrous iron. However, higher concentration of ferrous iron had an inhibitive influence on current generation after 30 days of operation. Illumina Hiseq sequencing of 16S rRNA gene amplicons indicated that ferrous iron substantially changed microbial community structures of both anode and cathode biofilms. Principal component analysis showed that the response of microbial communities of the anode biofilms to higher concentration of ferrous iron was more sensitive. The majority of predominant populations of the anode biofilms in MFCs belonged to Geobacter , which was different from the populations of the cathode biofilms. An obvious shift of community structures of the cathode biofilms occurred after ferrous iron addition. This study implied that ferrous iron influenced the power output and microbial community of MFCs.

Yiyang Liu, Xiaoyan Sun, Di Yin et al.

RSC Advances • 2020

Electricity generation in microbial fuel cells can be restricted by a few factors, such as the effective area of the anode for biofilm attachment, diffusion limitation of substrates and internal resistance. In this paper, a suspended anode (carbon-based felt granule)-type microbial fuel cell was developed to make full use of the volume of the anode chamber and provide a larger surface area of the anode for the growth of exoelectrogenic bacteria. The current collector was rotated in the anodic chamber to contact with the suspended granules intermittently and achieve better mixing. The open-circuit voltage reached steady state at around 0.83 V. The maximum power density obtained from each scenario increased steadily with the increase in mixing rate. The internal resistance decreased when the rotational rate and the content of the carbon granules were increased. The maximum power density reached 951 ± 14 mW m -3 with a corresponding minimum internal resistance of 162.9 ± 3.5 Ω when the mass of carbon granules was 50 g and the rotational rate was 300 rpm. The suspended microbes made negligible contribution to the power density. The microbial fuel cell with a higher content of carbon granules had lower coulombic efficiency and lower relative abundance of exoelectrogenic bacteria.

Svetlana Fernandes, Aninda Mazumdar, Sabyasachi Bhattacharya et al.

Scientific Reports • 2018

Biogeochemistry of oxygen minimum zone (OMZ) sediments, which are characterized by high input of labile organic matter, have crucial bearings on the benthic biota, gas and metal fluxes across the sediment-water interface, and carbon-sulfur cycling. Here we couple pore-fluid chemistry and comprehensive microbial diversity data to reveal the sedimentary carbon-sulfur cycle across a water-depth transect covering the entire thickness of eastern Arabian Sea OMZ, off the west coast of India. Geochemical data show remarkable increase in average total organic carbon content and aerial sulfate reduction rate (J SO4 2- ) in the sediments of the OMZ center coupled with shallowing of sulfate methane transition zone and hydrogen sulfide and ammonium build-up. Total bacterial diversity, including those of complex organic matter degraders, fermentative and exoelectrogenic bacteria, and sulfate-reducers (that utilize only simple carbon compounds) were also found to be highest in the same region. The above findings indicate that higher organic carbon sequestration from the water-columns (apparently due to lower benthic consumption, biodegradation and biotransformation) and greater bioavailability of simple organic carbon compounds (apparently produced by fermetative microflora of the sediments) are instrumental in intensifying the carbon-sulfur cycle in the sediments of the OMZ center.

Anna Vilajeliu-Pons, Lluı́s Bañeras, Sebastià Puig et al.

PLoS ONE • 2016

Microbial fuel cells (MFCs) can be designed to combine water treatment with concomitant electricity production. Animal manure treatment has been poorly explored using MFCs, and its implementation at full-scale primarily relies on the bacterial distribution and activity within the treatment cell. This study reports the bacterial community changes at four positions within the anode of two almost identically operated MFCs fed swine manure. Changes in the microbiome structure are described according to the MFC fluid dynamics and the application of a maximum power point tracking system (MPPT) compared to a fixed resistance system (Ref-MFC). Both external resistance and cell hydrodynamics are thought to heavily influence MFC performance. The microbiome was characterised both quantitatively (qPCR) and qualitatively (454-pyrosequencing) by targeting bacterial 16S rRNA genes. The diversity of the microbial community in the MFC biofilm was reduced and differed from the influent swine manure. The adopted electric condition (MPPT vs fixed resistance) was more relevant than the fluid dynamics in shaping the MFC microbiome. MPPT control positively affected bacterial abundance and promoted the selection of putatively exoelectrogenic bacteria in the MFC core microbiome (Sedimentibacter sp. and gammaproteobacteria). These differences in the microbiome may be responsible for the two-fold increase in power production achieved by the MPPT-MFC compared to the Ref-MFC.

Jae-Hoon Hwang, Kyoung‐Yeol Kim, Eleazer P. Resurreccion et al.

Journal of Hazardous Materials • 2019