Qian Sun, Zhiling Li, Wenzong Liu et al.

International Journal of Electrochemical Science • 2016

Recently, bioelectrochemical systems (BESs) were investigated for enhancing recalcitrant contamination reduction of recalcitrant contaminants. However, comprehensive evaluation of key operational parameters considering both performance and energy conservation were rarely concerned. In this study, impact of the initial concentration, applied voltage and co-substrates types were thoroughly investigated and evaluated for optimization of Alizarin Yellow R (AYR) decolorization. Increase of the initial AYR concentration would decrease decolorization efficiency (DE) and rate (k), while change of applied voltage showed the contrary trend. However, the low unit energy consumption (UEC) demanded the high initial concentration (1194 J-g-1 for 200 mg-L-1) and the low applied voltage (112.4 J-g-1 for 0.1 V). kAYR and kPPD fed with glucose were almost twice than acetate, while, UEC was close or lower (the initial AYR under 100 mg-L-1 or applied voltage under 0.3 V), which indicated the superior property of glucose as co-substrate than acetate. The modeling proposed the optimized initial AYR concentration, applied voltage to guarantee the highest decolorization rate and the lowest energy consumption. The study proposed the experimental basis and technique approach to guide the operational parameter for scale-up BES application.

Anthony J. Slate, Kathryn A. Whitehead, Dale A. C. Brownson et al.

Renewable and Sustainable Energy Reviews • 2018

Research into alternative renewable energy generation is a priority, due to the ever-increasing concern of climate change. Microbial fuel cells (MFCs) are one potential avenue to be explored, as a partial solution towards combating the over-reliance on fossil fuel based electricity. Limitations have slowed the advancement of MFC development, including low power generation, expensive electrode materials and the inability to scale up MFCs to industrially relevant capacities. However, utilisation of new advanced electrode-materials (i.e. 2D nanomaterials), has promise to advance the field of electromicrobiology. New electrode materials coupled with a more thorough understanding of the mechanisms in which electrogenic bacteria partake in electron transfer could dramatically increase power outputs, potentially reaching the upper extremities of theoretical limits. Continued research into both the electrochemistry and microbiology is of paramount importance in order to achieve industrial-scale development of MFCs. This review gives an overview of the current field and knowledge in regards to MFCs and discusses the known mechanisms underpinning MFC technology, which allows bacteria to facilitate in electron transfer processes. This review focusses specifically on enhancing the performance of MFCs, with the key intrinsic factor currently limiting power output from MFCs being the rate of electron transfer to/from the anode; the use of advanced carbon-based materials as electrode surfaces is discussed.

Wan-Ru Wen, Tianbiao Liu, Sheng-Qiang Fan et al.

Chemical Engineering Journal • 2025

Xin Sun, Xiaoshuai Wu, Zhuanzhuan Shi et al.

Journal of Power Sources • 2022

Abhilasha Singh Mathuriya

Environmental Technology • 2020

Bioelectrochemical systems such as microbial fuel cells are novel systems; those directly transform the chemical energy contained in organics of wastewater into electrical energy by the metabolic action of the microbial community. During the last two decades, bioelectrochemical systems astonishingly increased their wastewater treatment capabilities, sustainability, and power output. However, studies on scalable architectural designs of bioelectrochemical systems received less attention. Lower power yield and high cost are two major limitations for scaling up of bioelectrochemical systems. This study reports a low cost, scalable, air cathode bio-electrochemical reactor, constructed by adopting a trickling filtration approach (TrickBER) and operated in continuous mode. Various facets of construction, installation, and operation of TrickBER were investigated and optimized to achieve an efficient performance. TrickBER was found suitable in simultaneous electricity generation during continuous wastewater treatment and, in the future, could be used in small/cottage industries.

Yunxian Liu, Jie Zhou, Zekun Zhang et al.

Chemical Engineering Journal • 2025

Shanshan Chen, Xianyue Jing, Yongliang Yan et al.

Applied and Environmental Microbiology • 2020

Diazotrophs can produce bioavailable nitrogen from inert N 2 gas by bioelectrochemical nitrogen fixation ( e -BNF), which is emerging as an energy-saving and highly selective strategy for agriculture and industry. However, current e -BNF technology is impeded by requirements for NH 4 + assimilation inhibitors to facilitate intracellular ammonia secretion and precious metal catalysts to generate H 2 as the energy-carrying intermediate. Here, we initially demonstrate inhibitor- and catalystless extracellular NH 4 + production by the diazotroph Pseudomonas stutzeri A1501 using an electrode as the sole electron donor. Multiple lines of evidence revealed that P. stutzeri produced 2.32 ± 0.25 mg/liter extracellular NH 4 + at a poised potential of -0.3 V (versus standard hydrogen electrode [SHE]) without the addition of inhibitors or expensive catalysts. The electron uptake mechanism was attributed to the endogenous electron shuttle phenazine-1-carboxylic acid, which was excreted by P. stutzeri and mediated electron transfer from electrodes into cells to directly drive N 2 fixation. The faradaic efficiency was 20% ± 3%, which was 2 to 4 times that of previous e -BNF attempts using the H 2 -mediated pathway. This study reports a diazotroph capable of producing secretable NH 4 + via extracellular electron uptake, which has important implications for optimizing the performance of e -BNF systems and exploring the novel nitrogen-fixing mode of syntrophic microbial communities in the natural environment. IMPORTANCE Ammonia greatly affects global ecology, agriculture, and the food industry. Diazotrophs with an enhanced capacity of extracellular NH 4 + excretion have been proven to be more beneficial to the growth of microalgae and plants, whereas most previously reported diazotrophs produce intracellular organic nitrogen in the absence of chemical suppression and genetic manipulation. Here, we demonstrate that Pseudomonas stutzeri A1501 is capable of extracellular NH 4 + production without chemical suppression or genetic manipulation when the extracellular electrode is used as the sole electron donor. We also reveal the electron uptake pathway from the extracellular electron-donating partner to P. stutzeri A1501 via redox electron shuttle phenazines. Since both P. stutzeri A1501 and potential electron-donating partners (such as electroactive microbes and natural semiconductor minerals) are abundant in diverse soils and sediments, P. stutzeri A1501 has broader implications on the improvement of nitrogen fertilization in the natural environment.

Yuanming Li, Ke Feng, Chao Wu et al.

Chemosphere • 2021

Harshavardhan Mohan, Jeong‐Muk Lim, Min Cho et al.

Environmental Science and Pollution Research • 2019

You Wu, Hai–Liang Song, Yuan Pan et al.

Bioresource Technology • 2022

Clemens Bechinger, Roberto Di Leonardo, Hartmut Löwen et al.

Reviews of Modern Physics • 2016

This article reviews both experimental and theoretical advances in the field of active matter which consists of natural and artificial objects capable of self-propulsion. Prime examples of active particles are Brownian particles, biological or manmade microscopic and nanoscopic objects, that can propel themselfes by taking up energy from their environment and converting it into directed motion. The review provides a guided tour through the basic principles and fabrication of active particles and discusses also many interesting future directions these manmade micromachines and nanomachines could take as autonomous agents for healthcare, sustainability, and security applications.

Feng Fu, Chih‐Hung Wu, Fuying Li et al.

Energy Conversion and Management X • 2024

The microbial fuel cell (MFC), acknowledged as an innovative bioenergy conversion system, has attracted considerable attention in research. An MFC is a device that utilizes microorganisms to directly convert chemical energy present in organic compounds into electrical energy. This bioelectrochemical hybrid system functions not only as a power generation tool but also as an effective instrument for sewage treatment, incorporating nutrient recovery. Its noteworthy advantages encompass energy conservation, sludge reduction, and efficient energy conversion. This paper offers a comprehensive overview of recent cases that involve the synergistic treatment of MFC and traditional sewage treatment technologies. The integration of MFC with conventional sewage treatment processes has demonstrated greater efficiency compared to standalone MFC or traditional sewage treatment methods. This coupled system shows significant promise in converting waste into clean energy, optimizing resource utilization, and addressing the energy crisis. Significantly, the integration of MFC with anaerobic fermentation has attracted considerable attention owing to its distinctive advantages, positioning it as a potential future development trend. The paper concludes by analyzing the multifaceted benefits of this coupling system, providing valuable insights for future research on integrating MFC with other technologies.

Min-Hua Cui, Dan Cui, Lei Gao et al.

Chemosphere • 2016

Wudneh Ayele Shewa, Jerald A. Lalman, Subba Rao Chaganti et al.

Energy • 2016

Linbin Hu, Yang Yang, Qian Fu et al.

Environmental Science & Technology • 2023

Three-dimensional porous materials have been demonstrated as the most successful bioelectrodes in bioelectrochemical systems due to their high specific surface area and abundant adhesion regions for electroactive bacteria. However, the pore clogging potentially limits the mass transfer process inside the electrode due to the unreasonable structure design and long-term operation. The investigation of mass transport behavior in the porous scaffolds is of great significance for designing the electrode structure and optimizing bioelectrochemical system performance. To in situ characterize the mass transport behavior in the orderly pore structure, model electrodes with 100 copper wires (10 × 10) are constructed to imitate a three-dimensional porous structure (pore size: ∼150 μm) commonly employed in bioelectrodes. The poor proton effective diffusion coefficient solidly demonstrates that the mass transport inside the three-dimensional porous electrode is critically inhibited, leading not only to a progressive change and sparse biomass in the biofilm development process but also to biofilm acidification due to serious proton accumulation. It finally results in sluggish bacterial metabolic activity and a decreased electrocatalytic capacity. The interior space of porous electrodes cannot be adequately utilized, resulting in the inability to fully exploit the advantages of their abundant surface area. Consequently, the construction of gradient porous electrodes with small inner and large outer pores to enhance mass transport is a feasible proposal for enhancing performance. The proposed methodology of establishing model electrodes combined with the in situ detection technique within porous electrodes is crucial for acquiring various types of physicochemical information inside the bioelectrode, such as biofilm growth situation, biochemical reaction conditions, as well as mass transfer characteristics. More importantly, the work provides a fundamental basis for designing highly efficient bioelectrodes.

Lin Su, Tao Yin, Hongxiu Du et al.

Bioelectrochemistry • 2020

John M. Pisciotta, James J Dolceamore

Journal of Microbial & Biochemical Technology • 2016

Chemical pollutants can adversely affect human and environmental health. In sediments, pollutants such as polycyclic aromatic hydrocarbons (PAHs), heavy metals and pesticides have the potential to exert an array of toxic effects on susceptible organisms. Certain chemicals including dichlorodiphenyltrichloroethane (DDT), various pharmaceuticals and endocrine disrupting agents (ex. nonylphenol) are recalcitrant in sediments, complicating removal. Agents such as dioxins bioaccumulate in plant and animal tissues used for human consumption. Traditional bioremediation employs applied or autochthonous organisms to breakdown or immobilize such environmental contaminants to less hazardous forms. Bacteria, fungi and phototrophs can be used as inexpensive, self-replicating catalysts to metabolize or otherwise neutralize pollutants. Bacteria are particularly useful since metabolically versatile representatives, including various Actinomycetes species, form spores, are resistant to multiple contaminants and survive over a wide range of environmental conditions. Unfortunately, conventional bioremediation suffers from certain drawbacks, like difficulties with subsurface process monitoring. These may be overcome using microbial bioelectrochemical systems (BESs). Recent studies demonstrate that BESs such as sediment Microbial Fuel Cells (sMFCs) can accelerate rates of bioremediation while coupling pollutant metabolism directly to the generation of renewable bio-electricity. BESs can further serve as sensitive pollutant biosensors for remote progress monitoring via existing wireless networks, facilitating bioremediation optimization. Here we review recent progress into conventional and bio-electrochemically mediated bioremediation technologies for common pollutants with a focus on recalcitrant organic pollutants of sediment. Emerging questions, opportunities and drawbacks pertaining to BES microbial technologies are highlighted. Use of BESs to remediate chemically diverse pollutants has proven effective; however, there remains a need to overcome limitations with BES process start up time, scale up and design, remote monitoring and the cost of BES electrodes and catalysts.

Hyeryeong Lee, Eun Mi Lee, Stacy Simai Reginald et al.

iScience • 2021

Oriented enzyme immobilization on electrodes is crucial for interfacial electrical coupling of direct electron transfer (DET)-based enzyme-electrode systems. As inorganic-binding peptides are introduced as molecular binders and enzyme-orienting agents, inorganic-binding peptide-fused enzymes should be designed and constructed to achieve efficient DET. In this study, it is aimed to compare the effects of various gold-binding peptides (GBPs) fused to enzymes on electrocatalytic activity, bioactivity, and material-binding behaviors. Here, GBPs with identical gold-binding properties but different amino acid sequences were fused to the FAD-dependent glucose dehydrogenase gamma-alpha complex (GDHγα) to generate four GDHγα variants. The structural, biochemical, mechanical, and bioelectrochemical properties of these GDHγα variants immobilized on electrode were determined by their fused GBPs. Our results confirmed that the GBP type is vital in the design, construction, and optimization of GBP-fused enzyme-modified electrodes for facile interfacial DET and practical DET-based enzyme-electrode systems.

Aylis Oner, Ensara Tufek, Irem Yezer et al.

Reactive and Functional Polymers • 2021

Álvaro Ramírez, Martı́n Muñoz, Ester López‐Fernández et al.

Current Opinion in Electrochemistry • 2024

The use of waste biomass as a precursor for carbon electrodes in electrochemical water treatment not only offers a resourceful solution to waste management challenges but also constitutes a substantial contribution to the circular economy. This paper critically reviews recent advancements in utilizing waste biomass derived carbon materials for electrochemical water treatment, focusing on applications like electrochemical advanced oxidation processes (e-AOPs) and capacitive deionization. The versatility of carbon materials, with characteristics such as extensive specific surface areas, high electrical conductivity, and tunable hydrophobicity, positions them as pivotal for various electrochemical applications. This short review extends to bioelectrochemical systems (BES), highlighting the potential of waste-derived carbon materials to enhance BES electrode efficiency while significantly reducing manufacturing costs. The comprehensive assessment of recent developments provides insights into strengths and weaknesses in the use of these materials and future research directions for optimizing electro/bioelectrochemical water treatment processes on a broader scale.

Nan Li, Shu Wang, Jingkun An et al.

The Science of The Total Environment • 2018

Abhilasha Singh Mathuriya, Moonmoon Hiloidhari, Pramod Gware et al.

Bioresource Technology • 2020

Olga El Kik, Geoffroy Lesage, François Zaviska et al.

Journal of environmental chemical engineering • 2024

Anaerobic membrane bioreactor (AnMBR) technology emerges as a groundbreaking solution for domestic wastewater treatment, offering high effluent quality and substantial potential for neutral or positive energy balances. This is achieved through the production of renewable methane biogas, concurrently reducing aeration and sludge handling costs. Despite these strides, fouling mitigation persists as a pivotal challenge, constituting a significant portion of membrane-based bioreactors energy requirements. In response, AnMBR technology has evolved through seamless integration with bioelectrochemical systems (BES), specifically microbial fuel and electrolysis cells. This integration aims to address fouling challenges while enhancing resource recovery from wastewater. In this context, the paper centers on key performance parameters, including removal efficiency, fouling mitigation strategies, and biogas generation, shedding light on the latest advancements in these integrated technologies. By scrutinizing recent progress, it identifies research gaps and needs, emphasizing potential optimizations such as integrating granular sludge or catalytic electrodes for micropollutant degradation. Overall, this review contributes to a deeper understanding and advocates for the broader application of the integrated AnMBR-BES approach, playing a pivotal role in advancing sustainable wastewater treatment.

Tian Li, Fan Chen, Qixing Zhou et al.

Environmental Research • 2020

Rongxin Xia, Jun Cheng, Hui Li et al.

ACS Sustainable Chemistry & Engineering • 2022

An electromethanogenesis system incorporating CO2-reducing microorganisms and a cathode material offers a promising approach for CO2 fixation with improved thermodynamic efficiencies. However, low electron transfer rates at microorganism–cathode interfaces can limit CO2 conversion efficiency. A nanoarrays/bacteria hybrid system was proposed for bioelectrochemical reduction of CO2 to CH4. The hierarchical nanoarrays derived from metal–organic frameworks enhanced the CO2 conversion rate with the optimization of both a local electric field and Ni/Co dual metal active sites. Optimizing the electric field intensity (∼1.25-fold compared to bare CF) and introducing a heterojunction on the cathode material boosted the electron transfer and achieved a higher current density (maximum 10 A/m2) at −0.9 V (vs Ag/AgCl) for 9.6-fold CH4 production (697.9 mmol·day–1·m–2) compared to the control. The dual metal active sites provided extra electron shuttles from a cathode to a microorganism to boost the electron transfer for methane production with a thicker (∼1.3-fold) and enhanced conductive EPS production (∼1.68-fold). A decreased internal resistance, a reconstituted microbial community, and an enhanced methane production rate indicated an increase in the microbial electron transfer between Methanobacterium and Clostridia, resulting in a selective bioelectroreduction (84%) of CO2 to CH4. This study suggests that nanointerface engineering in electromethanogenesis systems can effectively regulate selective CO2 reduction for new generation biogas projects.

Wei Liu, Yundang Wu, Tongxu Liu et al.

Frontiers in Microbiology • 2019

The electron shuttling process has been recognized as an important microbial respiration process. Because the incubation temperature can influence both the reactivity of electron mediators and cell growth, it may also affect the electron-shuttle-mediated extracellular electron transfer (EET) process. Here, the effect of incubation temperature (22-38°C) was investigated in a bioelectrochemical system (BES) using Shewanella oneidensis MR-1 and 50 μM of 9,10-anthraquinone-2-sulfonate (AQS). We found that current generation increased as the temperature was increased from 22 to 34°C and then decreased sharply at 38°C. The biofilm biomass, as indicated by the total protein extracted from the electrode, increased as the temperature increased from 22 to 34°C and then decreased at 38°C, mirroring the current generation results. These results were further confirmed by increasing the temperature slowly, step-by-step, in a single BES with a constant biofilm biomass, suggesting that the EET rates could be substantially influenced by temperature, even with the same biofilm. The effects of temperature on the AQS bioreduction rate, c -type cytochrome ( c -Cyts)-bound-cofactor-mediated EET, the AQS mid-point potential, and the AQS diffusion coefficient were studied. From these results, we were able to conclude that temperature influenced the EET rates by changing the c -Cyts-bound-cofactor-mediated EET process and the AQS bioreduction rate, and that the change in biofilm formation was a dominant factor influencing the overall EET rates. These findings should contribute to the fundamental understanding of EET processes. Moreover, optimization of the operating parameters for current generation will be helpful for the practical application of bioelectrochemical techniques.

Huihui Zhou, Defeng Xing, Jun Ma et al.

Separation and Purification Technology • 2022

Bioelectrochemical anaerobic digestion (BEAD) is an attractive way to enhance biogas production in the anaerobic digestion process. Exploring cost-effective biocatalysts with remarkable catalytic ability is a pivotal issue for the industrial application of BEAD systems. In this study, intact anaerobic granular sludge (AGS) was employed as a biocatalyst in an attempt to achieve high-efficiency CH4 production via interactions between exoelectrogens and methanogens. The biogas production in the BEAD system was optimized by controlling the applied voltage (0, 0.6, 0.8, and 1 V) and acetate load (1000, 5000, and 10000 mg/L). The CH4 production rate increased with applied voltage and acetate loading, while the overall energy efficiency was the highest at an applied voltage of 0.8 V and an acetate load of 5000 mg/L. The BEAD system with AGS as the biocatalyst was also efficient for the degradation of highly concentrated organic waste, with an average methane production rate of 86.23 ± 7.12 L/m2/d and CH4 content as high as 88.87%. Microbial communities including organic-degrading bacteria and exoelectrogens (e.g., Syntrophomonas, Geobacter) and hydrogenotrophic methanogenic archaea (r.g., Methanobacterium) were enriched at the anode and the cathode, respectively. The AGS-based BEAD system represents a promising industrial application in biogas production.

Mohammed Sedki, Rabeay Y. A. Hassan, Silvana Andreescu et al.

Materials Science and Engineering C • 2019

Shun Che, Xun Guan, Roselyn Rodrigues et al.

Proceedings of the National Academy of Sciences • 2024

Per- and polyfluoroalkyl substances (PFAS), particularly the perfluorinated ones, are recalcitrant to biodegradation. By integrating an enrichment culture of reductive defluorination with biocompatible electrodes for the electrochemical process, a deeper defluorination of a C 6 -perfluorinated unsaturated PFAS was achieved compared to the biological or electrochemical system alone. Two synergies in the bioelectrochemical system were identified: i) The in-series microbial-electrochemical defluorination and ii) the electrochemically enabled microbial defluorination of intermediates. These synergies at the material-microbe interfaces surpassed the limitation of microbial defluorination and further turned the biotransformation end products into less fluorinated products, which could be less toxic and more biodegradable in the environment. This material-microbe hybrid system brings opportunities in the bioremediation of PFAS driven by renewable electricity and warrants future research on mechanistic understanding of defluorinating and electroactive microorganisms at the material-microbe interface for system optimizations.

Jiao Feng, Qiuhao Lu, Kang Li et al.

Frontiers in Bioengineering and Biotechnology • 2020

Microbial electrosynthesis (MES) or electro-fermentation (EF) is a promising microbial electrochemical technology for the synthesis of valuable chemicals or high-value fuels with aid of microbial cells as catalysts. By introducing electrical energy (current), fermentation environments can be altered or controlled in which the microbial cells are affected. The key role for electrical energy is to supply electrons to microbial metabolism. To realize electricity utility, a process termed inward extracellular electron transfer (EET) is necessary, and its efficiency is crucial to bioelectrochemical systems. The use of electron mediators was one of the main ways to realize electron transfer and improve EET efficiency. To break through some limitation of exogenous electron mediators, we introduced the phenazine-1-carboxylic acid (PCA) pathway from Pseudomonas aeruginosa PAO1 into Escherichia coli . The engineered E. coli facilitated reduction of fumarate by using PCA as endogenous electron mediator driven by electricity. Furthermore, the heterologously expressed PCA pathway in E. coli led to better EET efficiency and a strong metabolic shift to greater production of reduced metabolites, but lower biomass in the system. Then, we found that synthesis of adenosine triphosphate (ATP), as the "energy currency" in metabolism, was also affected. The reduction of menaquinon was demonstrated as one of the key reactions in self-excreted PCA-mediated succinate electrosynthesis. This study demonstrates the feasibility of electron transfer between the electrode and E. coli cells using heterologous self-excreted PCA as an electron transfer mediator in a bioelectrochemical system and lays a foundation for subsequent optimization.

Dmitry Pankratov, Jianming Zhao, Mohammed Ahmed Nur et al.

Electrochimica Acta • 2019

Franziska Enzmann, Markus Stöckl, Denise Gronemeier et al.

Engineering in Life Sciences • 2019

Cathode and catholyte are usually optimized to improve microbial electrosynthesis process, whereas the anodic counter reaction was not systematically investigated and optimized for these applications yet. Nevertheless, the anolyte and especially the anode material can limit the cathodic bioelectrochemical process. This paper compares for the first time the performance of different anode materials as counter electrodes for a cathodic bioelectrochemical process, the bioelectromethanogenesis. It was observed that depending on the anode material the cathodic methane production varies from 0.96 µmol/d with a carbon fabric anode to 25.44 µmol/d with a carbon felt anode of the same geometrical surface area. The used anolyte also affected the methane production rate at the cathode. Especially, the pH of the anolyte showed an impact on the system; an anolyte with pH 5 produced up to 2.0 times more methane compared to one with pH 8.5. The proton availability is discussed as one reason for this effect. Although some of the measured effects cannot be explained completely so far this study advises researchers to strongly consider the anode impact during process development and optimization of a cathodic bioelectrochemical synthesis process.

Yuanyao Ye, Wenshan Guo, Huu Hao Ngo et al.

The Science of The Total Environment • 2024

In recent years, biofuel production has attracted considerable attention, especially given the increasing worldwide demand for energy and emissions of greenhouse gases that threaten this planet. In this case, one possible solution is to convert biomass into green and sustainable biofuel, which can enhance the bioeconomy and contribute to sustainable economic development goals. Due to being in large quantities and containing high organic content, various biomass sources such as food waste, textile waste, microalgal waste, agricultural waste and sewage sludge have gained significant attention for biofuel production. Also, biofuel production technologies, including thermochemical processing, anaerobic digestion, fermentation and bioelectrochemical systems, have been extensively reported, which can achieve waste valorization through producing biofuels and re-utilizing wastes. Nevertheless, the commercial feasibility of biofuel production is still being determined, and it is unclear whether biofuel can compete equally with other existing fuels in the market. The concept of a circular economy in biofuel production can promote the environmentally friendly and sustainable valorization of biomass waste. This review comprehensively discusses the state-of-the-art production of biofuel from various biomass sources and the bioeconomy perspectives associated with it. Biofuel production is evaluated within the framework of the bioeconomy. Further perspectives on possible integration approaches to maximizing waste utilization for biofuel production are discussed, and what this could mean for the circular economy. More research related to pretreatment and machine learning of biofuel production should be conducted to optimize the biofuel production process, increase the biofuel yield and make the biofuel prices competitive.

Nidaa S. Herzallh, Yifat Cohen, Dina Mukha et al.

Biosensors and Bioelectronics • 2020

Man Tung Wong, Danhui Cheng, Ri Wang et al.

Enzyme and Microbial Technology • 2016

Deping Li, Wenbo Guo, Ying Zhai et al.

Environmental Pollution • 2023

G. Contreras, Johanna Thomsen, Marc Pfitzer et al.

Current Research in Biotechnology • 2022

Methanogenic archaea play an important role in the global carbon cycle, as they catalyze the final step in anaerobic biomass decomposition to generate methane. This physiological trait has attracted much attention for the production of biogenic methane with methanogenic archaea as an alternative to fossil natural gas. Considerable progress has been made on the bioprocessing aspects for this purpose, and bioelectrochemical systems are considered to further optimize cost-effectiveness. Genetic tools for mesophilic methanogenic archaea are long available; however, more sophisticated methodology is still in its infancy. Thus, there is a requirement to develop further genetic tools. Moreover, biotechnologically relevant species are becoming genetically accessible only recently. However, the production of value-added products, such as isoprene, with methanogenic archaea has been demonstrated at low levels. In this perspective article, we discuss some of the recent developments on bioprocessing and genetic engineering strategies and provide a brief perspective on the biotechnological prospects of methanogenic archaea.

Byung Chul Kim, Gahyun Baek, Changman Kim et al.

ACS ES&T Engineering • 2024

Extracellular electron transport (EET) is a biological process where microorganisms can donate electrons from the interior of their cells to external electron acceptors or act as electron acceptors to receive electrons from external sources and electrodes. This process often occurs in the surrounding environment or within biofilms, enabling the redox reactions essential for energy metabolism. This review evaluates the latest developments in electron transfer (EET) research in environmental biotechnology, showcasing its varied applications across bioelectrochemical systems (BES), including microbial fuel cells and microbial electrosynthesis for CO2 upcycling, as well as its utilization in non-BES such as anaerobic digestion and bioleaching for useful resource recovery. The review emphasizes the interdisciplinary approach of EET research, merging microbiology, chemistry, environmental engineering, material science, and system control engineering. This paper provides insights into the performance optimization of EET and the outlook for future industrial and commercial applications. The review also explores the potential applications of EET to mitigate global and environmental challenges, offering innovative biotechnological solutions that pave the way for a sustainable circular bioeconomy.

Kathryne C. Ford, Michaela A. TerAvest

Applied and Environmental Microbiology • 2023

Extracellular electron transfer is a process by which bacterial cells can exchange electrons with a redox-active material located outside of the cell. In Shewanella oneidensis , this process is natively used to facilitate respiration using extracellular electron acceptors such as Fe(III) or an anode. Previously, it was demonstrated that this process can be used to drive the microbial electrosynthesis (MES) of 2,3-butanediol (2,3-BDO) in S. oneidensis exogenously expressing butanediol dehydrogenase (BDH). Electrons taken into the cell from a cathode are used to generate NADH, which in turn is used to reduce acetoin to 2,3-BDO via BDH. However, generating NADH via electron uptake from a cathode is energetically unfavorable, so NADH dehydrogenases couple the reaction to proton motive force. We therefore need to maintain the proton gradient across the membrane to sustain NADH production. This work explores accomplishing this task by bidirectional electron transfer, where electrons provided by the cathode go to both NADH formation and oxygen (O 2 ) reduction by oxidases. We show that oxidases use trace dissolved oxygen in a microaerobic bioelectrical chemical system (BES), and the translocation of protons across the membrane during O 2 reduction supports 2,3-BDO generation. Interestingly, this process is inhibited by high levels of dissolved oxygen in this system. In an aerated BES, O 2 molecules react with the strong reductant (cathode) to form reactive oxygen species, resulting in cell death.IMPORTANCEMicrobial electrosynthesis (MES) is increasingly employed for the generation of specialty chemicals, such as biofuels, bioplastics, and cancer therapeutics. For these systems to be viable for industrial scale-up, it is important to understand the energetic requirements of the bacteria to mitigate unnecessary costs. This work demonstrates sustained production of an industrially relevant chemical driven by a cathode. Additionally, it optimizes a previously published system by removing any requirement for phototrophic energy, thereby removing the additional cost of providing a light source. We also demonstrate the severe impact of oxygen intrusion into bioelectrochemical systems, offering insight to future researchers aiming to work in an anaerobic environment. These studies provide insight into both the thermodynamics of electrosynthesis and the importance of the bioelectrochemical systems' design.

Georgy Givirovskiy, Vesa Ruuskanen, Leo S. Ojala et al.

Heliyon • 2019

Hydrogen-oxidizing bacteria (HOB) have been shown to be promising micro-organisms for the reduction of carbon dioxide to a wide range of value-added products in bioelectrochemical systems with in situ water electrolysis of the cultivation medium, also known as a hybrid biological-inorganic systems (HBI). However, scaling up of this process requires overcoming the inherent constraints of the low energy efficiency partly associated with the pH-neutral electrolyte with low conductivity. Most of the research in the field is concentrated on the bacterial cultivation, whereas the analysis and evaluation of the electrode material performance have received little attention in the literature so far. Therefore, in the present work, in situ electrolysis of a pH-neutral medium for HOB cultivation was performed with different combinations of electrode materials. Besides conventional electrode types, electrodes with coatings made of earth-abundant cobalt and a nickel-iron alloy, known for their catalytic activity for the kinetically sluggish oxygen evolution reaction (OER), were prepared and tested as potential substitutes for catalysts made of precious metals. The cultivation of HOB with in situ water electrolysis has been successfully tested in a small scale electrobioreactor in order to support the experimental results. A simplified water electrolysis model was developed and applied to evaluate the current-voltage characteristics of an bioelectrochemical system prototype. Application of the developed model allows quantitative evaluation and comparison of reversible, ohmic, and activation overvoltages of different electrode sets. The modeling results were found to agree well with the experimental data. The developed model and the data gathered can be applied to further investigation, simulation, and optimization of HBI systems.