Discover insights from thousands of peer-reviewed papers on microbial electrochemical systems
Vander Baptista
Advances in Physiology Education · 2015
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.
Rose M. Jones, T. D’Angelo, B. Orcutt
Frontiers in Environmental Science · 2020
The crustal sub-seafloor covers a large portion of the Earth’s surface but is poorly understood as a habitat for life. It is unclear what metabolisms support the microscopic cells that have been observed, and how they survive under resource limitation. As the deep crustal subsurface represents a significant portion of the Earth’s surface, microbially mediated reactions may therefore be significant contributors to biogeochemical cycling. In the present study, we used electrochemical techniques to investigate the possibility that crustal subsurface microbial groups can use the solid rock matrix (basalts, etc.) as a source of electrons for redox reactions via extracellular electron transfer (EET). Subsurface crustal fluids and mineral colonization experiments from the cool and oxic basaltic crustal subsurface at the North Pond site on the western flank of the Mid-Atlantic Ridge were used as inocula in cathodic poised potential experiments. Electrodes in oxic microbial fuel cells (MFCs) were poised at −200 mV versus a standard hydrogen electrode to mimic the delivery of electrons in an energy range equivalent to iron oxidation. In this way, microbes that use reduced iron in solid minerals for energy were selected for from the general community onto the electrode surface for interrogation of EET activity, and potential identification by scanning electron microscopy (SEM) and DNA sequencing. The results document that there are cathodic EET-capable microbial groups in the low biomass crustal subsurface at this site. The patterns of current generation in the experiments indicate that these microbial groups are active but likely not growing under the low-resource condition of the experiments, consistent with other studies of activity versus growth in the deep biosphere. Lack of growth stymied attempts to determine the phylogeny of EET-capable microbial groups from this habitat, but the results indicate that these microbial groups are a small part of the overall crustal deep biosphere community. This first demonstration of using electromicrobiology techniques to investigate microbial metabolic potential in the crustal deep biosphere reveals the challenges and opportunities for studying EET in the crustal deep biosphere.
T. Ueki, T. Woodard, D. Lovley
Microbiology Spectrum · 2022
Desulfovibrio ferrophilus is an important pure culture model for Fe(III) oxide reduction and the corrosion of iron-containing metals in anaerobic marine environments. This study demonstrates that D. ferrophilus is genetically tractable, an important advance for elucidating the mechanisms by which it interacts with extracellular electron acceptors and donors. ABSTRACT The sulfate-reducing microbe Desulfovibrio ferrophilus is of interest due to its relatively rare ability to also grow with Fe(III) oxide as an electron acceptor and its rapid corrosion of metallic iron. Previous studies have suggested multiple agents for D. ferrophilus extracellular electron exchange including a soluble electron shuttle, electrically conductive pili, and outer surface multiheme c-type cytochromes. However, the previous lack of a strategy for genetic manipulation of D. ferrophilus limited mechanistic investigations. We developed an electroporation-mediated transformation method that enabled replacement of D. ferrophilus genes of interest with an antibiotic resistance gene via double-crossover homologous recombination. Genes were identified that are essential for flagellum-based motility and the expression of the two types of D. ferrophilus pili. Disrupting flagellum-based motility or expression of either of the two pili did not inhibit Fe(III) oxide reduction, nor did deleting genes for multiheme c-type cytochromes predicted to be associated with the outer membrane. Although redundancies in cytochrome or pilus function might explain some of these phenotypes, overall, the results are consistent with D. ferrophilus primarily reducing Fe(III) oxide via an electron shuttle. The finding that D. ferrophilus is genetically tractable not only will aid in elucidating further details of its mechanisms for Fe(III) oxide reduction but also provides a new experimental approach for developing a better understanding of some of its other unique features, such as the ability to corrode metallic iron at high rates and accept electrons from negatively poised electrodes. IMPORTANCE Desulfovibrio ferrophilus is an important pure culture model for Fe(III) oxide reduction and the corrosion of iron-containing metals in anaerobic marine environments. This study demonstrates that D. ferrophilus is genetically tractable, an important advance for elucidating the mechanisms by which it interacts with extracellular electron acceptors and donors. The results demonstrate that there is not one specific outer surface multiheme D. ferrophilus c-type cytochrome that is essential for Fe(III) oxide reduction. This finding, coupled with the lack of apparent porin-cytochrome conduits encoded in the D. ferrophilus genome and the finding that deleting genes for pilus and flagellum expression did not inhibit Fe(III) oxide reduction, suggests that D. ferrophilus has adopted strategies for extracellular electron exchange that are different from those of intensively studied electroactive microbes like Shewanella and Geobacter species. Thus, the ability to genetically manipulate D. ferrophilus is likely to lead to new mechanistic concepts in electromicrobiology.
Jessica A. Smith, D. Holmes, T. Woodard et al.
Microbiology Spectrum · 2023
ABSTRACT Direct interspecies electron transfer (DIET) is important in anaerobic communities of environmental and practical significance. Other than the need for close physical contact for electrical connections, the interactions of DIET partners are poorly understood. Type VI secretion systems (T6SSs) typically kill competitive microbes. Surprisingly, Geobacter metallireducens highly expressed T6SS genes when DIET-based co-cultures were initiated with Geobacter sulfurreducens. T6SS gene expression was lower when the electron shuttle anthraquinone-2,6-disulfonate was added to alleviate the need for interspecies contact. Disruption of hcp, the G. metallireducens gene for the main T6SS needle-tube protein subunit, and the most highly upregulated gene in DIET-grown cells eliminated the long lag periods required for the initiation of DIET. The mutation did not aid DIET in the presence of granular-activated carbon (GAC), consistent with the fact that DIET partners do not make physical contact when electrically connected through conductive materials. The hcp-deficient mutant also established DIET quicker with Methanosarcina barkeri. However, the mutant also reduced Fe(III) oxide faster than the wild-type strain, a phenotype not expected from the loss of the T6SS. Quantitative PCR revealed greater gene transcript abundance for key components of extracellular electron transfer in the hcp-deficient mutant versus the wild-type strain, potentially accounting for the faster Fe(III) oxide reduction and impact on DIET. The results highlight that interspecies interactions beyond electrical connections may influence DIET effectiveness. The unexpected increase in the expression of genes for extracellular electron transport components when hcp was deleted emphasizes the complexities in evaluating the electromicrobiology of highly adaptable Geobacter species. IMPORTANCE Direct interspecies electron transfer is an alternative to the much more intensively studied process of interspecies H2 transfer as a mechanism for microbes to share electrons during the cooperative metabolism of energy sources. DIET is an important process in anaerobic soils and sediments generating methane, a significant greenhouse gas. Facilitating DIET can accelerate and stabilize the conversion of organic wastes to methane biofuel in anaerobic digesters. Therefore, a better understanding of the factors controlling how fast DIET partnerships are established is expected to lead to new strategies for promoting this bioenergy process. The finding that when co-cultured with G. sulfurreducens, G. metallireducens initially expressed a type VI secretion system, a behavior not conducive to interspecies cooperation, illustrates the complexity of establishing syntrophic relationships. Direct interspecies electron transfer is an alternative to the much more intensively studied process of interspecies H2 transfer as a mechanism for microbes to share electrons during the cooperative metabolism of energy sources. DIET is an important process in anaerobic soils and sediments generating methane, a significant greenhouse gas. Facilitating DIET can accelerate and stabilize the conversion of organic wastes to methane biofuel in anaerobic digesters. Therefore, a better understanding of the factors controlling how fast DIET partnerships are established is expected to lead to new strategies for promoting this bioenergy process. The finding that when co-cultured with G. sulfurreducens, G. metallireducens initially expressed a type VI secretion system, a behavior not conducive to interspecies cooperation, illustrates the complexity of establishing syntrophic relationships.
A. Franks
Journal of Bacteriology & Parasitology · 2012
Microbes capable of interacting with insoluble electron acceptors and/or donors have broad implications, ranging from geomicrobiological processes, alternative energy production, bioproduction of commodity chemicals, and an understanding energy flow in anaerobic environments. Electromicrobiologists investigate bacteria capable of transferring electrons extracellularly to and/ or from insoluble surfaces, driving internal metabolic processes. Electromicrobiology is a cross-disciplinary field that covers the processes, mechanisms and applications of electric bacteria.
Lucie Semenec, A. Franks
Microbiology Australia · 2014
Electromicrobiology is a new discipline that investigates the ability of microbial species to interact with insoluble external electron acceptors and donors. This ability has most commonly been studied through microbial communities found in association with electrodes as part of a microbial electrolysis cell (MEC). MECs are devices that employ bacteria capable of utilising either an anode as an electron acceptor or a cathode as an electron donor to carry out biologically driven processes. In effect, these devices make use of microbes that are eating and breathing electricity. Potential applications for MECs are ever expanding and currently include bioremediation, biosensing, biofuel production and power generation. MECs that produce overall net power are referred to as microbial fuel cells (MFCs) and have helped to generate much of our initial knowledge regarding electroactive bacteria. Energy consuming MECs have more recently expanded our knowledge on microbial electrosynthesis pathways, whereby microbes reduce CO2 using electrons provided by an electrode. Furthering of our knowledge on electrode-associated microbes has in turn led us to an increased understanding of how microbes in the environment have beendeveloping, powering andutilising their own electricity grids all along. These electrical interactions, between microbes and components of their living and non-living environment, are potentially very important but have been overlooked until very recently.
Andreas Stathoulias, Aphroditi Milioni, S. Kritikou et al.
OMICS: A Journal of Integrative Biology · 2020
Modern microbiology and drug development are in a watershed moment with the advent of electroceuticals. In addition to genomics, electrical impulses in an organism are believed to contribute to tissue and cellular plasticity. Hence, electroceuticals or bioelectronics offers the promise to identify innovative approaches to treat human diseases. However, applications toward electromicrobiology are still limited and rare, despite the high potential to innovate the fields of both microbiology and therapeutics. For example, electric modalities for manipulating microbial growth are highly sustainable; can be combined with biopharmaceuticals, probiotics, and pharmacobiotics; and, thus, are well poised for use in medicine, public health, and ecology and diverse industries. We report here the introduction of a new research framework and technology platform for electroculturomics, by coupling standard solid-state mycological cultures with conductive treatment using a conformité Européene (CE-)-certified medical ionophoresis device. We share our experience with a diverse range of fungi that have been treated with the electroculturomics approach reported herein. We suggest that this line of inquiry can be extended to electrotranscriptomics and electrometabolomics by deploying electroculturomics in tandem with multi-omics approaches in the future. This article makes a specific contribution to fungal microbiology, and a broader contribution to advance the theory and practice of the field of electroculturomics emerging in 21st-century microbiology and ecology research.
Krista M. Cosert, Angelines Castro-Forero, Rebecca J. Steidl et al.
mBio · 2019
The discovery in 2005 of conductive protein appendages (pili) in the metal-reducing bacterium Geobacter sulfurreducens challenged our understanding of biological electron transfer and pioneered studies in electromicrobiology that revealed the electronic basis of many microbial metabolisms and interactions. The protein nature of the pili afforded opportunities for engineering novel conductive peptides for the synthesis of nanowires via cost-effective and scalable manufacturing approaches. However, methods did not exist for efficient production, purification, and in vitro assembly of pilins into nanowires. Here we describe platforms for high-yield recombinant synthesis of Geobacter pilin derivatives and their assembly as protein nanowires with biochemical and electronic properties rivaling those of the native pili. The bottom-up fabrication of protein nanowires exclusively from pilin building blocks confirms unequivocally the charge transport capacity of the peptide assembly and establishes the intellectual foundation needed to manufacture pilin-based nanowires in bioelectronics and other applications. ABSTRACT Metal-reducing bacteria in the genus Geobacter use a complex protein apparatus to guide the self-assembly of a divergent type IVa pilin peptide and synthesize conductive pilus appendages that show promise for the sustainable manufacturing of protein nanowires. The preferential helical conformation of the Geobacter pilin, its high hydrophobicity, and precise distribution of charged and aromatic amino acids are critical for biological self-assembly and conductivity. We applied this knowledge to synthesize via recombinant methods truncated pilin peptides for the bottom-up fabrication of protein nanowires and identified rate-limiting steps of pilin nucleation and fiber elongation that control assembly efficiency and nanowire length, respectively. The synthetic fibers retained the biochemical and electronic properties of the native pili even under chemical fixation, a critical consideration for integration of the nanowires into electronic devices. The implications of these results for the design and mass production of customized protein nanowires for diverse applications are discussed. IMPORTANCE The discovery in 2005 of conductive protein appendages (pili) in the metal-reducing bacterium Geobacter sulfurreducens challenged our understanding of biological electron transfer and pioneered studies in electromicrobiology that revealed the electronic basis of many microbial metabolisms and interactions. The protein nature of the pili afforded opportunities for engineering novel conductive peptides for the synthesis of nanowires via cost-effective and scalable manufacturing approaches. However, methods did not exist for efficient production, purification, and in vitro assembly of pilins into nanowires. Here we describe platforms for high-yield recombinant synthesis of Geobacter pilin derivatives and their assembly as protein nanowires with biochemical and electronic properties rivaling those of the native pili. The bottom-up fabrication of protein nanowires exclusively from pilin building blocks confirms unequivocally the charge transport capacity of the peptide assembly and establishes the intellectual foundation needed to manufacture pilin-based nanowires in bioelectronics and other applications.
Lucie Semenec, A. Franks
AIMS Bioengineering · 2015
The study of electromicrobiology has grown into its own field over the last decades and involves microbially driven redox reactions at electrodes as part of a microbial electrochemical system (MES). The microorganisms known to use electrodes as either electron acceptors; electricigens, or electron donors; electrotrophs, drive the redox reactions within these systems through extracellular electron transfer (EET) processes. These exoelectrogenic microorganisms form biofilms, referred to as electroactive biofilms (EAB), in order to maximize adherence and contact with electrode surfaces and with one another. In this review, we will discuss the key differences between biofilms that utilize the electrode as an electron acceptor or donor, including their mechanisms for electron transfer, structural and functional compositions as well as which species are enriched for in each microenvironment. Lastly, we will discuss the intricacies of interspecies and intraspecies biofilm formation in electrode biofilms and considerations required for future bioengineering efforts.
Brian J. Eddie, L. Bird, Claus Pelikan et al.
mSphere · 2022
Chemolithotrophic bacteria capable of extracellular electron uptake to drive energy metabolism and CO2 fixation are known as electroautotrophs. The recently described order Tenderiales contains the uncultivated electroautotroph “Ca. Tenderia electrophaga.” The “Ca. Tenderia electrophaga” genome contains genes proposed to make up a previously undescribed extracellular electron uptake pathway. ABSTRACT Electromicrobiology can be used to understand extracellular electron uptake in previously undescribed chemolithotrophs. Enrichment and characterization of the uncultivated electroautotroph “Candidatus Tenderia electrophaga” using electromicrobiology led to the designation of the order Tenderiales. Representative Tenderiales metagenome-assembled genomes (MAGs) have been identified in a number of environmental surveys, yet a comprehensive characterization of conserved genes for extracellular electron uptake has thus far not been conducted. Using comparative genomics, we identified conserved orthologous genes within the Tenderiales and nearest-neighbor orders important for extracellular electron uptake based on a previously proposed pathway from “Ca. Tenderia electrophaga.” The Tenderiales contained a conserved cluster we designated uetABCDEFGHIJ, which encodes proteins containing features that would enable transport of extracellular electrons to cytoplasmic membrane-bound energy-transducing complexes such as two conserved cytochrome cbb3 oxidases. For example, UetJ is predicted to be an extracellular undecaheme c-type cytochrome that forms a heme wire. We also identified clusters of genes predicted to facilitate assembly and maturation of electron transport proteins, as well as cellular attachment to surfaces. Autotrophy among the Tenderiales is supported by the presence of carbon fixation and stress response pathways that could allow cellular growth by extracellular electron uptake. Key differences between the Tenderiales and other known neutrophilic iron oxidizers were revealed, including very few Cyc2 genes in the Tenderiales. Our results reveal a possible conserved pathway for extracellular electron uptake and suggest that the Tenderiales have an ecological role in coupling metal or mineral redox chemistry and the carbon cycle in marine and brackish sediments. IMPORTANCE Chemolithotrophic bacteria capable of extracellular electron uptake to drive energy metabolism and CO2 fixation are known as electroautotrophs. The recently described order Tenderiales contains the uncultivated electroautotroph “Ca. Tenderia electrophaga.” The “Ca. Tenderia electrophaga” genome contains genes proposed to make up a previously undescribed extracellular electron uptake pathway. Here, we use comparative genomics to show that this pathway is well conserved among Tenderiales spp. recovered by metagenome-assembled genomes. This conservation extends to near neighbors of the Tenderiales but not to other well-studied chemolithotrophs, including iron and sulfur oxidizers, indicating that these genes may be useful markers of growth using insoluble extracellular electron donors. Our findings suggest that extracellular electron uptake and electroautotrophy may be pervasive among the Tenderiales, and the geographic locations from which metagenome-assembled genomes were recovered offer clues to their natural ecological niche.
S. Sure, L. Ackland, A. Torriero et al.
Microbiology · 2016
Electromicrobiology has gained momentum in the last ten years with advances in microbial fuel cells and the discovery of microbial nanowires (MNWs). The list of MNWs producing microorganisms is growing and providing intriguing insights into the presence of such microorganisms in diverse environments and the potential roles MNWs can perform. This review discusses the MNWs produced by different microorganisms, including their structure, composition and role in electron transfer through MNWs. Two hypotheses, metallic-like conductivity and an electron hopping model, have been proposed for electron transfer and we present a current understanding of both these hypotheses. MNWs are not only poised to change the way we see microorganisms but may also impact the fields of bioenergy, biogeochemistry and bioremediation, hence their potential applications in these fields are highlighted here.
Xueqin Zhang, Zhiguo Yuan, Shihu Hu
Environmental Microbiology Reports · 2021
Anaerobic oxidation of methane (AOM) can be microbially mediated by the reduction of different terminal electron acceptors. AOM coupled to reduction of sulfate, manganese/iron oxides, humic substances, selenate, arsenic and other artificial extracellular electron acceptors are recognized as processes associated with microbial extracellular respiration. In these processes, methane-oxidizing archaea transfer electrons to external electron acceptors or to interdependent microbial species, which are mechanistically dependent on versatile extracellular electron transfer (EET) pathways. This review compiles recent progress in the research of electromicrobiology of AOM based on the catalogue of different electron acceptors. Naturally distributed and artificially constructed EET-mediated AOM is summarized, with the discussion of their environmental importance and application potentials. The diversity of responsible microorganisms involved in EET-mediated AOM is discussed with both methane-oxidizing archaea and their putative bacterial partners. More importantly, the review highlights progress and deficiencies in our understanding of EET pathways in EET-mediated AOM, raising open research questions for future research.
Sukrampal Yadav, Ram B. Singh, Shiva S Sundharam et al.
Environmental Microbiology · 2022
The extracellular electron transfer (EET)-capable electroactive microorganisms (EAMs) play crucial roles in mineral cycling and interspecies electron transfer in different environments and are used as biocatalysts in microbial electrochemical technologies. Studying EAMs from extreme environments is desired to advance the electromicrobiology discipline, understanding their unique metabolic traits with implications to extreme microbiology, and develop specific bioelectrochemical applications. Here, we present a novel haloalkaliphilic bacterium named Geoalkalibacter halelectricus SAP-1, isolated from a microbial electroactive biofilm enriched from the haloalkaline lake sediments. It is a rod-shaped Gram-negative heterotrophic anaerobe that uses various carbon and energy sources and respires on soluble and insoluble terminal electron acceptors. Besides 16S-rRNA and whole-genome-based phylogeny, the GGDC values of 21.7 %, ANI of 78.5, and 2.77 % genomic DNA GC content difference with the closest validly named species Geoalkalibacter ferrihydriticus (DSM 17813T ) confirmed its novelty. When grown with the solid-state electrode as the only electron acceptor, it produced 460±23 μA/cm2 bioelectrocatalytic current, thereby confirming its electroactivity. Further electrochemical analysis revealed the presence of membrane redox components with high formal potentials, putatively involved in the direct mode of EET. These are distinct from EET components reported for any known electroactive microorganisms, including well-studied Geobacter spp., Shewanella spp. and Desulfuromonas acetexigens. Further the capabilities of G. halelectricus SAP-1 to respire soluble as well insoluble electron acceptors including fumarate, SO4 2- , Fe3+ , and Mn4+ suggests its role in cycling these elements in haloalkaline environments. This article is protected by copyright. All rights reserved.
Xinying Liu, David J. F. Walker, S. Nonnenmann et al.
mBio · 2021
Electroactive microbes have significant environmental impacts, as well as applications in bioenergy and bioremediation. The composition, function, and even existence of electrically conductive pili (e-pili) has been one of the most contentious areas of investigation in electromicrobiology, in part because e-pili offer a mechanism for long-range electron transport that does not involve the metal cofactors common in much of biological electron transport. ABSTRACT Geobacter sulfurreducens is a model microbe for elucidating the mechanisms for extracellular electron transfer in several biogeochemical cycles, bioelectrochemical applications, and microbial metal corrosion. Multiple lines of evidence previously suggested that electrically conductive pili (e-pili) are an essential conduit for long-range extracellular electron transport in G. sulfurreducens. However, it has recently been reported that G. sulfurreducens does not express e-pili and that filaments comprised of multi-heme c-type cytochromes are responsible for long-range electron transport. This possibility was directly investigated by examining cells, rather than filament preparations, with atomic force microscopy. Approximately 90% of the filaments emanating from wild-type cells had a diameter (3 nm) and conductance consistent with previous reports of e-pili harvested from G. sulfurreducens or heterologously expressed in Escherichia coli from the G. sulfurreducens pilin gene. The remaining 10% of filaments had a morphology consistent with filaments comprised of the c-type cytochrome OmcS. A strain expressing a modified pilin gene designed to yield poorly conductive pili expressed 90% filaments with a 3-nm diameter, but greatly reduced conductance, further indicating that the 3-nm diameter conductive filaments in the wild-type strain were e-pili. A strain in which genes for five of the most abundant outer-surface c-type cytochromes, including OmcS, were deleted yielded only 3-nm-diameter filaments with the same conductance as in the wild type. These results demonstrate that e-pili are the most abundant conductive filaments expressed by G. sulfurreducens, consistent with previous functional studies demonstrating the need for e-pili for long-range extracellular electron transfer. IMPORTANCE Electroactive microbes have significant environmental impacts, as well as applications in bioenergy and bioremediation. The composition, function, and even existence of electrically conductive pili (e-pili) has been one of the most contentious areas of investigation in electromicrobiology, in part because e-pili offer a mechanism for long-range electron transport that does not involve the metal cofactors common in much of biological electron transport. This study demonstrates that e-pili are abundant filaments emanating from Geobacter sulfurreducens, which serves as a model for long-range extracellular electron transfer in direct interspecies electron transfer, dissimilatory metal reduction, microbe-electrode exchange, and corrosion caused by direct electron uptake from Fe(0). The methods described in this study provide a simple strategy for evaluating the distribution of conductive filaments throughout the microbial world with an approach that avoids artifactual production and/or enrichment of filaments that may not be physiologically relevant.
Xing Liu, Yin Ye, Naiming Yang et al.
ISME Communications · 2024
Abstract Extracellular electron transfer (EET) of microorganisms is a major driver of the microbial growth and metabolism, including reactions involved in the cycling of C, N, and Fe in anaerobic environments such as soils and sediments. Understanding the mechanisms of EET, as well as knowing which organisms are EET-capable (or can become so) is fundamental to electromicrobiology and geomicrobiology. In general, Gram-positive bacteria very seldomly perform EET due to their thick non-conductive cell wall. Here, we report that a Gram-positive Clostridium intestinale (C.i) attained EET-capability for ethanol metabolism only after forming chimera with electroactive Geobacter sulfurreducens (G.s). Mechanism analyses demonstrated that the EET was possible after the cell fusion of the two species was achieved. Under these conditions, the ethanol metabolism pathway of C.i was integrated by the EET pathway of G.s, by which achieved the oxidation of ethanol for the subsequent reduction of extracellular electron acceptors in the coculture. Our study displays a new approach to perform EET for Gram-positive bacteria via recruiting the EET pathway of an electroactive bacterium, which suggests a previously unanticipated prevalence of EET in the microbial world. These findings also provide new perspectives to understand the energetic coupling between bacterial species and the ecology of interspecies mutualisms.
Khaled Bin Bandar
King Abdullah University of Science and Technology Repository (King Abdullah University of Science and Technology) · 2014
Electromicrobiology of Dissimilatory Sulfur Reducing Bacterium Desulfuromonas acetexigens Khaled Bin Bandar Bioelectrochmical systems (BES) are engineered electrochemical devices that harness hidden chemical energy of the wastewater in to the form of electricity or hydrogen. Unique microbial communities enrich in these systems for oxidation of organic matter as well as transfer of resulted electron to anode, known them as “electricigens” communities. Exploring novel electricigenesis microbial communities in the nature and understanding their electromicrobiology is one the important aspect for BES systems scale up. Herein, we report first time the electricigenesis property of an anaerobic, fresh water sediment, sulfur reducing bacterium Desulfuromona acetexigens. The electrochemical behavior of D. acetexigens biofilms grown on graphite-rod electrodes in batch-fed mode under an applied potential was investigated with traditional electroanalytical tools, and correlate the electron transfer from biofilms to electrode with a model electricigen Geobacter sulfurreducens electrochemical behavior. Research findings suggest that D. acetexigens has the ability to use electrode as electron acceptor in BES systems through establishing the direct contact with anode by expressing the membrane bound redox proteins, but not due to the secretion of soluble redox mediators. Preliminary results revealed that D. acetexigens express three distinct redox proteins in their membranes for turnover of the electrons from biofilm to electrode, and the
D. Lovley
BIO Web of Conferences · 2016
One of the most exciting developments in the field of electromicrobiology has been the discovery of electrically conductive pili (e-pili) in Geobacter species that transport electrons with a metallic-like mechanism. The e-pili are essential for extracellular electron transport to Fe(III) oxides and longrange electron transport through the conductive biofilms that form on the anodes of microbial fuel cells. The e-pili also facilitate direct interspecies electron transfer between Geobacter and Methanosaeta or Methanosarcina species. Metatranscriptomic studies have demonstrated that Geobacter/Methanosaeta DIET is an important process in anaerobic digesters converting brewery wastes to methane. Increasing e-pili expression through genetic modification of regulatory systems or adaptive evolution yields strains with enhanced rates of extracellular electron transfer. Measurement of the conductivity of individual e-pili has demonstrated that they have conductivities higher than those of a number of synthetic conducting organic polymers. Multiple lines of evidence have demonstrated that aromatic amino acids play an important role in the electron transport along e-pili, suggesting opportunities to tune e-pili conductivity via genetic manipulation of the amino acid composition of e-pili. It is expected that e-pili will be harnessed to improve microbe-electrode processes such as microbial electrosynthesis and for the development of novel biosensors. Also, e-pili show promise as a sustainable ‘green’ replacement for electronic materials that contain toxic components and/or are produced with harsh chemicals.
C. Obi, Grace Chigozirim Asogwa
OALib · 2015
Electromicrobiology is the study of the interactions between the novel electrical properties of microorganisms and electronic devices. A diversity of microorganisms such as Geobacter and Shewanella species is capable of interacting electrically with the environment. Many recent advances in Electromicrobiology stem from studying Microbial Fuel Cells (MFCs) which are a device designed for the harvesting of electric current from organic compounds. Three types of Microbial Fuel Cells are known which are heterotrophic microbial fuel cells, photosynthetic microbial fuel cells (bio-solar cells) designed to harness the most abundant and promising energy source (solar irradiation) of earth and the hybrid microbial fuel cell. Electric microorganisms especially Sporomusa ovata can use electron derived from electrodes to reduce carbondioxide to multicarbon extracellular organic compounds in a process known as Microbial Electrosynthesis. The mechanism of electron transfer to electrodes by electric microbes is either by the use of electron shuttling molecules, redox-active proteins or via conductive pili. Conductive microorganisms and/or their nanowires have a number of potential practical applications but additional basic research will be necessary for rational applications. This review looks at the Microbial Fuel Cells, the associated mechanisms and applications.
N. Risgaard-Petersen, A. Rotaru
Frontiers in Microbiology · 2023
COPYRIGHT © 2023 Risgaard-Petersen and Rotaru. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Editorial: Electromicrobiology—from electrons to ecosystems, volume II
Kenneth H. Nealson, Annette R. Rowe
Microbial Biotechnology · 2016
Summary Electromicrobiology is a subdiscipline of microbiology that involves extracellular electron transfer (EET) to (or from) insoluble electron active redox compounds located outside the outer membrane of the cell. These interactions can often be studied using electrochemical techniques which have provided novel insights into microbial physiology in recent years. The mechanisms (and variations) of outward EET are well understood for two model systems, Shewanella and Geobacter , both of which employ multihaem cytochromes to provide an electron conduit to the cell exterior. In contrast, little is known of the intricacies of inward EET, even in these model systems. Given the number of labs now working on EET, it seems likely that most of the mechanistic details will be understood in a few years for the model systems, and the many applications of electromicrobiology will continue to move forward. But emerging work, using electrodes as electron acceptors and donors is providing an abundance of new types of microbes capable of EET inward and/or outward: microbes that are clearly different from our known systems. The extent of this very diverse, and perhaps widely distributed and biogeochemically important ability needs to be determined to understand the mechanisms, importance, and raison d'etre of EET for microbial biology.
Derek R. Lovley
Annual Review of Microbiology · 2012
Electromicrobiology deals with the interactions between microorganisms and electronic devices and with the novel electrical properties of microorganisms. A diversity of microorganisms can donate electrons to, or accept electrons from, electrodes without the addition of artificial electron shuttles. However, the mechanisms for microbe-electrode electron exchange have been seriously studied in only a few microorganisms. Shewanella oneidensis interacts with electrodes primarily via flavins that function as soluble electron shuttles. Geobacter sulfurreducens makes direct electrical contacts with electrodes via outer-surface, c-type cytochromes. G. sulfurreducens is also capable of long-range electron transport along pili, known as microbial nanowires, that have metallic-like conductivity similar to that previously described in synthetic conducting polymers. Pili networks confer conductivity to G. sulfurreducens biofilms, which function as a conducting polymer, with supercapacitor and transistor functionalities. Conductive microorganisms and/or their nanowires have a number of potential practical applications, but additional basic research will be necessary for rational optimization.
Yanran Li, Yiwu Zong, Chunying Feng et al.
Microorganisms · 2025
Electroactive microorganisms are capable of exchanging electrons with electrodes and thus have potential applications in many fields, including bioenergy production, microbial electrochemical synthesis of chemicals, environmental protection, and microbial electrochemical sensors. Due to the limitations of low electron transfer efficiency and poor stability, the application of electroactive microorganisms in industry is still confronted with significant challenges. In recent years, many studies have demonstrated that modulating anode potential is one of the effective strategies to enhance electron transfer efficiency. In this review, we have summarized approximately 100 relevant studies sourced from PubMed and Web of Science over the past two decades. We present the classification of electroactive microorganisms and their electron transfer mechanisms and elucidate the impact of anode potential on the bioelectricity behavior and physiology of electroactive microorganisms. Our review provides a scientific basis for researchers, especially those who are new to this field, to choose suitable anode potential conditions for practical applications to optimize the electron transfer efficiency of electroactive microorganisms, thus contributing to the application of electroactive microorganisms in industry.
Dalibor Matýsek, Jakub Jirásek
Bulletin Mineralogie Petrologie · 2021
Dolníček (2020) described several occurrences of bog iron (limonite), which according to his article originates in recent streams by chemical precipitation, without the important role of microorganisms on this process. However, similar occurrences of reddish or orange slime, frequently accompanied by oil-like films floating on the water, are according to many papers ascribed to the biogenic iron oxidation by bacteria. To solve the origin of such precipitates, we have sampled similar materials in four places near Ostrava - Hrabová, two close to Řepiště and Staříč, and also two sites in the vicinity of Hulín investigated by Dolníček (2020). In all cases, scanning electron microscopy of dried samples at the low vacuum (ca 50 Pa) revealed a dominant share of tubular sheaths of the Leptothrix-Sphaerotilus group of bacteria. The prevailing diameter of 1.5 to 1 μm should point to genus Leptothrix, while those with a diameter up to 2.5 μm (genus Sphaerotilus) are far less common. Spiral chains of Gallionella were recognized in all samples, as well as rare pennate diatoms. Space between bacterial filaments is predominantly filled with densely stacked particles micrometer to submicrometer in size, sometimes with oval, fibrous, or tabular shape. It might be both decomposed material of previously mentioned genera and some other small-sized bacteria. Energy-dispersive spectroscopy shows dominant content of iron and oxygen, with a minor admixture of Si, Ca, Al, and P. Powder X-ray diffraction of such microbial mats is showing clastic admixtures (quartz, feldspar group minerals, illite-muscovite, and kaolinite) and two broad low-intensity peaks of ferrihydrite. Only sample D from Řepiště locality shows an absence of ferrihydrite and the presence of hematite and magnetite and/or maghemite. Therefore, we demonstrated that bacterially-induced precipitation plays a major role in the genesis of such recent bog iron occurrences and there are ways how to characterize such material by both biological and mineralogical procedures.
Dengfeng Li, Jingkun Zhou, Zichen Zhao et al.
Science Advances · 2024
Miniaturized mobile electronic system is an effective candidate for in situ exploration of confined spaces. However, realizing such system still faces challenges in powering issue, untethered mobility, wireless data acquisition, sensing versatility, and integration in small scales. Here, we report a battery-free, wireless, and miniaturized soft electromagnetic swimmer (SES) electronic system that achieves multiple monitoring capability in confined water environments. Through radio frequency powering, the battery-free SES system demonstrates untethered motions in confined spaces with considerable moving speed under resonance. This system adopts soft electronic technologies to integrate thin multifunctional bio/chemical sensors and wireless data acquisition module, and performs real-time water quality and virus contamination detection with demonstrated promising limits of detection and high sensitivity. All sensing data are transmitted synchronously and displayed on a smartphone graphical user interface via near-field communication. Overall, this wireless smart system demonstrates broad potential for confined space exploration, ranging from pathogen detection to pollution investigation.
Siying An, Zhi-Hao Zhao, Jun Bu et al.
Angewandte Chemie International Edition · 2024
As bulky pollutants in industrial and agricultural wastewater, nitrate and formaldehyde pose serious threats to the human health and ecosystem. Current purification technologies including chemical and bio-/photo-/electro-chemical methods, are generally high-cost, time-consuming, or energy-intensive. Here, we report a novel formaldehyde-nitrate battery by pairing anodic formaldehyde oxidation with cathodic nitrate reduction, which simultaneously enables wastewater purification, electricity generation, and the production of high-value-added ammonia and formate. As a result, the formaldehyde-nitrate battery remarkably exhibits an open-circuit voltage of 0.75 V, a peak power density of 3.38 mW cm-2 and the yield rates of 32.7 mg h-1 cm-2 for ammonia and 889.4 mg h-1 cm-2 for formate. In a large-scale formaldehyde-nitrate battery (25 cm2), 99.9% of nitrate and 99.8% of formaldehyde are removed from simulated industrial wastewater and the electricity of 2.03 W·h per day is generated. Moreover, the design of such a multi-functional battery is universally applicable to the coupling of NO3- or NO2- reduction with various aldehyde oxidization, paving a new avenue for wastewater purification and chemical manufacturing.
Shah Mohazzem Hossain, M. M. Hasan
TELKOMNIKA (Telecommunication Computing Electronics and Control) · 2018
The scarcity of energy especially electrical energy is an acute problem and hinders the modern economic development of a country. Most of the time only a small percentage of peoples have access to use continuous electricity supply. But in this modern era, all types of arena like economies, households and companies have extensive demand for electricity which is due to industrialization, extensive urbanization, population growth, rising standard of living and modernization of the agricultural sector of a country. Electricity generation from bio-gas plant through cowdungs of a dairy firm can mitigate the electricity demand to some extends in rural areas, where biogas plant will act act as a backup supply especially during load shedding. This research paper proposed an electricity generation system from bio-gas, which can work as a secondary source of the electricity for all electrical appliances of a particular area in a cost effective manner.
Jubin Thomas
Journal of Electrical Systems · 2024
In response to global warming and the dwindling reservoirs of fossil fuels, Thailand has increasingly embraced alternative energy sources. Central to its energy development strategy is the Alternative Energy Development Plan (AEDP), which aims to reduce energy intensity, capitalize on residual resources, and mitigate greenhouse gas emissions. While significant strides have been made in meeting various consumption targets set forth by the AEDP, notable challenges persist, particularly in the realms of bio-mass-derived electricity generation, bio-gas utilization, and bio-ethanol production from bio-mass. Therefore, this study delves into the factors contributing to the shortfall in achieving AEDP targets and proposes strategies to enhance the efficiency of the bio-energy supply chain. Leveraging mathematical and linear programming techniques, our research optimizes the supply chain dynamics, accounting for monthly supplier profiles spanning 77 provinces, 17 distinct biomasses, and 427 bio-energy plants equipped with diverse energy conversion technologies. Our findings indicate that Thailand currently boasts adequate bio-mass resources to fulfill the electricity and bio-ethanol targets outlined in the AEDP—provided enhancements are made to supply chain efficiency. To fully realize the objectives of the AEDP, we recommend augmenting bio-mass cultivation efforts and implementing new power plant installations. Additionally, we advocate for the consideration of high-methane content fuels, such as solid waste, as a means to alleviate bio-mass demand. This study underscores the paramount importance of strategic planning and optimization in propelling Thailand towards its alternative energy ambitions while surmounting supply chain impediments.
Libin Zeng, Xinyong Li, Qidong Zhao et al.
Nanoscale · 2019
Recently, molybdenum disulfide (MoS2) has stimulated significant research interest as a promising electrode candidate in solar cells and energy conservation fields. Unfortunately, the short lower electron/hole migration lifetimes and easy agglomeration hamper its wide practical applications to some extent. Herein, interface engineering coupled with a bio-assisted photoelectrochemical (PEC) strategy is presented to construct a 0D MoS2 quantum dot (QD)/1D TiO2 nanotube electrode for pollutant elimination. Aimed at accelerating charge transfer over the 0D/1D composite interface, three types of coupling PEC models were developed to optimize the catalytic performance. The single chamber microbial fuel cell (SCMFC)-PEC integrated system was found to be the best alternative for levofloxacin (LEV) elimination (0.029 min-1), and the sequential SCMFC-PEC further realized the whole system self-running independently. In addition, the interfacial electron migration and LEV degradation pathways were thoroughly investigated by LC/TOF/MS coupled with density functional theory (DFT) calculations to clearly elucidate the electron transfer paths, LEV-attacked sites and mineralization pathways in a joint sequential SCMFC-PEC system. As such, the constructed self-recycling system provides a new platform for bio-photo-electrochemical utilization, which could exhibit promising potential in environmental purification.
T. Ayodele, A. Ogunjuyigbe, O. Durodola et al.
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects · 2020
ABSTRACT In this paper, an estimation of the electricity generating potential as well as the environmental implications of bio-oil derivable from pyrolysis of plastic in some selected cities of Nigeria is conducted. The estimation premise on the experimental results obtained across different literatures, which gave the possible bio-oil yield of different mixture of plastics. First, the amount of plastic in different streams of municipal solid waste across the selected cities are sourced from the local literature and are used to estimate the theoretical amount of bio-oil obtainable through pyrolysis of plastics. Thereafter, the electricity generation potential of the bio-oil is estimated. The environmental impact assessment is conducted through the determination of its global warming and acidification impact. Some of the key results show that pyrolysis of plastic waste has great potential for electricity generation in Nigeria with total electricity generation potential of 87.5 MW with total global warming potential 634.9 kgCO2 (i.e. 0.634922769 tCO2e) and acidification potential of 16.4 kgSO2. The paper is important as it gives an insight into the probable opportunities in waste to energy technology for electricity generation using plastic wastes. This could be an eye-opener to the investors, researcher, policy makers, relevant government parastatals, and legislators.
Pelin Cavdar, Emel Yilmaz, A. E. Tugtas et al.
Water Science and Technology · 2011
Acidogenic fermentation of organic municipal solid waste (MSW) and the bio-electricity production potential from its volatile fatty acid (VFA)-rich leachate using an air-cathode microbial fuel cell (MFC) was investigated in this study. The acidogenic fermentation of 2 kg of MSW has been carried out in a 6 L anaerobic leach-bed reactor (LBR) under mesophilic conditions (30 degrees C). Total production of 92 g VFA expressed as chemical oxygen demand (COD) in 3 L leachate mainly containing acetic, propionic, butyric, and valeric acids has been achieved with manual leachate recirculation and without pH control in 74 days of incubation. Leachate collected on day 32 was used as a feed to an air-cathode MFC after being diluted and supplemented with NaCl or NaHCO3. The maximum power density in the diluted leachate was only 5.9 W/m3, but reached up to 8.6 W/m3 upon the addition of 7 mmol/L NaCl. Increase in coulombic efficiency from 6 to 22% was also observed as a result of NaCl supplementation. On the other hand, NaHCO3 addition did not improve the power output.
G. De Gioannis, Alessandro Dell’Era, A. Muntoni et al.
Clean Technologies and Environmental Policy · 2021
This study investigated the performance of a novel integrated bio-electrochemical system for synergistic hydrogen production from a process combining a dark fermentation reactor and a galvanic cell. The operating principle of the system is based on the electrochemical conversion of protons released upon dissociation of the acid metabolites of the biological process and is mediated by the electron flow from the galvanic cell, coupling biochemical and electrochemical hydrogen production. Accordingly, the galvanic compartment also generates electricity. Four different experimental setups were designed to provide a preliminary assessment of the integrated bio-electrochemical process and identify the optimal configuration for further tests. Subsequently, dark fermentation of cheese whey was implemented both in a stand-alone biochemical reactor and in the integrated bio-electrochemical process. The integrated system achieved a hydrogen yield in the range 75.5–78.8 N LH_2/kg TOC, showing a 3 times improvement over the biochemical process. Graphical abstract
H. Raheman, D. Padhee
Recent Patents on Biotechnology · 2016
BACKGROUND The review of patents reveals that Handling of Jatropha seed cake after extraction of oil is essential as it contains toxic materials which create environmental pollution. METHODS The goal of this work is complete utilisation of Jatropha seeds. For this purpose, Jatropha oil was used for producing biodiesel and the byproduct Jatropha seed cake was gasified to obtain producer gas. Both biodiesel and producer gas were used to generate electricity. To achieve this, a system comprising gasifier, briquetting machine, diesel engine and generator was developed. RESULTS Biodiesel was produced successfully using the method patented for biodiesel production and briquettes of Jatropha seed cake were made using a vertical extruding machine. Producer gas was obtained by gasifying these briquettes in a downdraft gasifier. A diesel engine was then run in dual fuel mode with biodiesel and producer gas instead of only diesel. Electricity was generated by coupling it to a generator. CONCLUSION The cost of producing kilowatthour of electricity with biodiesel and diesel in dual fuel mode with producer gas was found to be 0.84 $ and 0.75 $, respectively as compared to 0.69 $ and 0.5 $ for the same fuels in single fuel mode resulting in up to 48 % saving of pilot fuel. Compared to singlefuel mode, there was 25-32 % reduction in system and brake thermal efficiency along with significantly lower NOx, higher CO and CO2 emissions when the bio-electricity generating system was operated in dual fuel mode. Overall, the developed system could produce electricity successfully by completely uti- lising Jatropha seeds without leaving any seed cake to cause environmental pollution.
A. Sophia, V. M. Bhalambaal
Current Science · 2016
Microbial desalination cells (MDCs) are modified microbial fuel cells (MFC) that are energy-sustainable. They use organic matter in wastewater as the energy source for desalination. The electric potential gradient is caused by exoelectrogenic bacteria. A typical MDC has a middle compartment for water desalination between the anode and cathode chambers. Our study reports lab-scale desalination, for evaluating the role of carbon from biomass waste, i.e. coconut shells. Control experiments were performed in the absence of activated carbon. Different initial salt concentrations (25 and 35 gl -1 ) were investigated. MDC produced a maximum voltage of 460 ± 13 mV simultaneously removing about 83.3 ± 1.3% of Na + and 57.8 ± 1.1% of Cl - , in the desalination cycle. The control MDC produced a maximum of 260 ± 8 mV and 69.3 ± 2% of Na + removal and 51 ± 1.5% Cl - removal. These results explain the role of using activated carbon for improved power production and water desalination. The SEM image of the biofilm shows pili (nanowires) with rod-shaped microorganisms. EDAX confirmed the presence of minerals such as Al, P, K, O, N, which may be due to chemical scale formation (especially P, Na and Ca).
A. S. Jatoi, M. Siddique, A. N. Mengal et al.
· 2016
Pakistan facing problem with respect to energy having abounded source of fossil fuel. On the basis of that one of new technology which getting importance nowadays is nothing but MFC. In this regard work were carried out on different biomass as substrate in Microbial Fuel Cell for electricity generation. Among the different biomass sewage sludge had potential for generation of 2500mv/l. When compare it other sources the yield is 270mv/l for carbo manure, 229mv/l for waste water, 330mv/l for cow manure. Sewage sludge containing organic compound higher percentage of glucose, due to this will give the good results for power generation and environment.
M. Radha, S. Kanmani
Current Science · 2017
This work deals with the performance of a microbial fuel cell, focusing on the electrocatalytic activity of selected cathodes constructed by coating nanocomposites over graphite felt under neutral pH in a doublechamber configuration using paper-recycled waste water as a typical electrolyte. Among all cathodes, iron phthalocyanine (FePc) combined multiwalled carbon nanotubes (MWCNT) shows the highest power density (9.34 W/m) compared to other two catalysts, FePc/Ketjan black (4.68 W/m) and MWCNT (2.9 W/m) under similar conditions of using a reference platinum/carbon (Pt/C) loading of 0.5 mg/cm. The morphology of these catalyst coated electrodes was characterized by scanning electron microscopy. Their electrocatalytic activities were examined using cyclic voltammetry. This work provides an appropriate alternative for cathode catalysts in treatment as well as in electricity production as demonstrated by the high power density of the above catalysts compared to that using precious Pt metal catalyst in microbial fuel cells.
Lizheng Chen, Hongyi Zhang, Yongqi Li et al.
Fermentation · 2023
In this study, an algal–bacterial symbiotic consortium was integrated with the sediment microbial fuel cell (SMFC) to construct an algal–bacterial cathode SMFC (AC-SMFC) for excess sewage sludge treatment and electricity generation. A bacterial cathode SMFC (BC-SMFC) and a static settling system (SS-system) were used as controls. Electrochemical analysis confirmed that the algal–bacterial biofilm on the cathode improved electricity production. The maximum power density of AC-SMFC was 75.21 mW/m2, which was 65.70% higher than that of the BC-SMFC (45.39 mW/m2). After 60 days of treatment, AC-SMFC achieved much higher removal efficiencies of the total chemical oxygen demand (TCOD) (59.60%), suspended solids (SS) (62.42%), and volatile suspended solids (VSS) (71.44%) in the sediment, compared to BC-SMFC and the SS-system, exhibiting an effective degradation of the organic matter in the sediment sludge. Moreover, the lower concentration of total nitrogen (TN) and total phosphorus (TP) in the overlying water of AC-SMFC demonstrated that the algae on the cathode could inhibit the accumulation of nitrogen and phosphorus released from the sediments. The three-dimensional excitation–emission matrix (EEM) fluorescence spectroscopy revealed that the tryptophan protein and aromatic protein in the loosely bound extracellular polymeric substances (LB-EPS) of the sediment sludge in the AC-SMFC were significantly decreased. Additionally, the abundance of functional microbiota in the AC-SMFC increased, such as Trichococcus, Alphaproteobacteria, and Clostridia, which contributed to electricity generation and sludge degradation. The combined application of microalgae and the SMFC provided a promising approach for excess sludge reduction and energy recovery.
Chao Liu, Yue Yin, Chuang Chen et al.
Energies · 2023
Medium chain carboxylic acids (MCCAs, e.g., caproic acid, caprylic acid, etc.) with 6–12 carbon atoms are valuable platform chemicals produced from organic waste via microbial chain elongation metabolism named as reversed β-oxidation and fatty acid-biosynthesis cyclical pathway. Recently, many articles reported that electricity could not only serve as the external electron donor and provide the reduction equivalent required for chain elongation but also regulate the microbiome structure and metabolic behaviors to promote MCCAs formation. Electricity-steering MCCAs bioproduction has become an appealing technique to valorize low-value organic waste, paving an alternative pathway for net-zero carbon emission energy systems and sustainable socio-economic development. However, the MCCAs’ bioproduction from organic waste steered by electric field has not been comprehensively reviewed. From a systematical analysis of publicly available literature, we first covered the basic working principle, fermentation architecture, functional microflora, and metabolic pathway of MCCAs production driven by electricity. The strategies of substrate modulation, applied voltage/current regulation, electrode optimization, and microbial cooperation and stimulation for boosting electricity-driven MCCAs bioproduction are then scrutinized and extensively discussed. Ultimately, the pressing knowledge gaps and the potential path forward are proposed to provide pointers for consistently higher MCCAs yield and the transition from laboratory to market.
A. S. Jatoi, H. Mahar, S. Aziz et al.
SHILAP Revista de lepidopterología · 2016
With the development of industrial revolution environmental pollution greatly affected by various pollutants emitted from industries. A part from this energy requirement also increased due to growing civilization. Ethanol is one of the future fuel that is produced from sugar cane molasses. During distillation of alcohol waste water also drawn off, this waste water contain many organic matter. Microbial fuel cell (MFC) is one of the major source for treating waste water and generating electricity. This study deals with electricity generation from distillery waste and factor affecting salt bridge used for proton transfer. The maximum voltage and electricity generation was seen at 10% agarose,1 M Kcl, 1 M NaCl, 5 cm length and 1cm diameter of salt bridge about 0.67 mv and 0.0642 mA.
Xing Zhou, Huilong Jin, N. Li et al.
Molecules · 2023
Fe-based chemical looping gasification is a clean biomass technology, which has the advantage of reducing CO2 emissions and the potential of self-sustaining operation without supplemental heating. A novel process combining Fe-based chemical looping and biomass pyrolysis was proposed and simulated using Aspen Plus. The biomass was first subjected to pyrolysis to coproduce biochar, bio-oil and pyrolysis gas; the pyrolysis gas was subjected to an Fe looping process to obtain high-purity hydrogen and carbon dioxide. The influences of the pyrolysis reactor operating temperature and fuel reactor operation temperature, and the steam reactor and air reactor on the process performance are researched. The results showed that, under the operating condition of the established process, 23.07 kg/h of bio-oil, 24.18 kg/h of biochar, 3.35 kg/h of hydrogen and a net electricity of 3 kW can be generated from 100 kg/h of rice straw, and the outlet CO2 concentration of the fuel reactor was as high as 80%. Moreover, the whole exergy efficiency and total exergy loss of the proposed process was 58.98% and 221 kW, respectively. Additionally, compared to biomass direct chemical looping hydrogen generation technology, the new process in this paper, using biomass pyrolysis gas as a reactant in the chemical looping hydrogen generation process, can enhance the efficiency of hydrogen generation.
M. Siddique, A. S. Jatoi, M. Rajput et al.
IOP Conference Series: Materials Science and Engineering · 2018
Bio-electrochemical system for power generation getting attention due to utilization of waste material. Based on that study was made to convert sugar industry waste water for bio-electricity generation using double chamber microbial fuel cell. Different organic load in form of substrate concentration and parametric effect were tested to optimize the best condition for electricity generation. From 100g/l to 300g/l with step size 100g/l, for aeration rate from 100-250ml/min with step size 50ml/min, and for as pH from 4.5 to 6.5 with step size 0.5pH. The maximum power generation were observed at pH 6, aeration rate 200ml/min and organic load 200g/l about 820mA. Regarding above results that found favourable condition on environment as well as waste reduction.