Bioelectrochemistry (Amsterdam, Netherlands) • 2025

Microbial electrolysis cell (MEC) is an alternative to conventional sludge treatment process with great energy-recovery potential. However, hydrolysis is considered as a rate-limiting step in MEC. In this study, ozone (O 3 ) pretreatment was successfully applied to disintegrate sludge matrix and accelerate microbial electrolysis. At 100-250 mg·g -1 (O 3 /SS), rapid SCOD increment and SS reduction rates were observed with increased O 3 dosage. Afterwards, the mass transfer from gas to liquid was inhibited and oxidation reactions between O 3 and organics occurred, which resulted in a declining disintegration rate. At favorable dosage of 250 mg·g -1 (O 3 /SS), the degree of disintegration was 17 % and SS reduction reached 44.9 %. A lab-scale MEC experiment was performed by feeding ozonated sludge. Results showed that O 3 pretreatment yielded 8.3-times increment in biogas production rate. In addition, O 3 pretreatment improved the organics removal and bioelectrochemical efficiency during microbial electrolysis, achieving 74.50 % of VSS removal rate and 77.56 % of TCOD removal rate, with gas yield increased by 7.5 times and cathodic hydrogen recovery increased by 7.40 %. The FT-IR spectra indicated negligible difference between influent extracellular biological organic matter (EBOM) and effluent EBOM, which suggested the function of O 3 pretreatment was to accelerate microbial electrolysis reactions due to sludge disintegration. Furthermore, the ozonation pretreatment facilitated the enrichment of exoelectrogens and collaborative bacteria in MEC, collectively enhancing MEC performance. This study provides a theoretical reference for enhanced bioelectrochemical treatment of complex heterogeneous mixture with soluble/insoluble organic matters.

Bioresource technology • 2025

Ammonia nitrogen (NH 4 + -N) and sulfate (SO 4 2 - ) removal by Anaerobic ammonium oxidation (Anammox) and sulfate-reducing bacteria (SRB) was studied in dual-chamber microbial electrolysis cells (MECs). Appropriate anode potential stimulation promoted biofilm formation and enhanced extracellular polymeric substances fluorescence, facilitating electron transfer. The highest NH 4 + -N removal (81.1 %) was achieved at the anode potential of 0.6 V vs. Ag/AgCl after 50 days, coinciding with the increase in electroactive Candidatus_Brocadia from 1.1 % to 27.4 %. Simultaneously, SO 4 2 - removal reached 77.0 %, supported by cathodic biofilms dominated by SRB (Desulfofustis, Desulfomicrobium, and Desulfatirhabdium). Automated machine learning and principal co-ordinates analysis identified the anode potential as the key factor shaping microbial ecology. The appropriate anode potential (0.4-0.6 V vs. Ag/AgCl) promoted cathodic sulfidogenesis, indirectly enhancing electron flow and supporting Anammox process at the anode. These findings demonstrate that MECs hold great promise for simultaneously enhancing anaerobic ammonia oxidation bacteria and SRB activities, enabling efficient NH 4 + -N and SO 4 2 - removal.

Polymers • 2025

The increasing production of bioplastics worldwide requires sustainable end-of-life solutions to minimize the environmental burden. Anaerobic digestion (AD) has been recognized as a potential technology for valorizing waste and producing renewable energy. However, the inherent resistance of certain bioplastics to degradation under anaerobic conditions requires specific strategies for improvement. Thus, in this review, the anaerobic biodegradability of commonly used bioplastics such as polylactic acid (PLA), polyhydroxybutyrate (PHB), polybutylene adipate-co-terephthalate (PBAT), polybutylene succinate (PBS), polycaprolactone (PCL), and starch- and cellulose-based bioplastics are critically evaluated for various operational parameters, including the temperature, particle size, inoculum-to-substrate ratio (ISR) and polymer type. Special attention is given to process optimization strategies, including pretreatment techniques (mechanical, thermal, hydrothermal, chemical and enzymatic) and co-digestion with nutrient-rich organic substrates, such as food waste and sewage sludge. The combinations of these strategies used for improving hydrolysis kinetics, increasing the methane yield and stabilizing reactor performance are described. In addition, new technologies, such as hydrothermal pretreatment and microbial electrolysis cell-assisted AD, are also considered as prospective strategies for reducing the recalcitrant nature of some bioplastics. While various strategies have enhanced anaerobic degradability, a consistent performance across bioplastic types and operational settings remains a challenge. By integrating key recent findings and limitations alongside pretreatment and co-digestion strategies, this review offers new insights to facilitate the circular use of bioplastics in solid waste management systems.

Bioprocess and biosystems engineering • 2025

Electroplating wastewater, characterized by high concentrations of bivalent copper (Cu 2 ⁺) and nickel (Ni 2 ⁺), poses significant environmental and health risks. This study explores the potential of novel Enterococcus species AMZ3, AMZ8, and AMZ5 as biocatalysts in bioelectrochemical systems (BES) for the dual purpose of electricity generation and heavy metal recovery. The strains were isolated from microbial fuel cell (MFC) biofilms and evaluated in single-chamber MFCs and dual-compartment systems. A mixed culture of the strains outperformed individual species, achieving a peak power and current densities of 439.78 mW/m 2 and 5.31 A/m 2 , respectively. In addition, the system achieved a remarkable chemical oxygen demand removal efficiency of 94.6 ± 11.23% and a Coulombic efficiency of 33.7 ± 7.11%. Enhanced electrocatalytic activity in mixed-culture systems was attributed to synergistic microbial interactions, superior biofilm formation, and elevated extracellular polymeric substance protein content. Cyclic voltammetry and electrochemical impedance spectroscopy revealed reduced internal resistance and robust electron transfer pathways in the reactor containing the biofilms of the mixed Enterococcus species. Furthermore, BES with the mixed Enterococcus biofilms achieved copper and nickel removal efficiencies of 99.99 ± 0.01 and 99.96 ± 0.02%, respectively. The reduction and recovery of these metals occurred at the cathode, where copper was predominantly recovered as Cu 0 through bioelectrochemical reduction, while nickel was recovered as metallic Ni 0 through bioelectrochemical reduction, with surface-bound Ni 2 ⁺ also detected, likely formed post-deposition due to oxidative surface processes, as revealed by SEM-EDX, XRD, and XPS analyses. These findings establish the feasibility of mixed Enterococcus cultures in sustainable wastewater treatment, paving the way for scalable BES applications.

Bioresource technology • 2025

Anaerobic digestion (AD) is widely used in waste treatment to produce clean energy such as biogas. However, the excessive ammonia produced during the AD process has a significant inhibitory effect on the microbial system. At present, strategies for alleviating ammonia inhibition have been studied. Among them, microbial electrolysis cell (MEC) emerged as a promising and effective approach in recent years. However, there is still a lack of systematic summary and comprehensive analysis of the mitigation mechanism. Here, ammonia inhibition mechanisms, mitigation mechanisms of MEC and the regulation of microorganisms were comprehensively reviewed. The results show that high ammonia MEC-AD system enhanced the expression of key proteins in hydrogenotrophic methanogens, and methane production shifted from acetoclastic pathway to the hydrogenotrophic pathway. NH 4 + is primarily oxidized at the anode through electrode-mediated pathways and microbial cooperation, enhancing anammox and denitrification gene abundance, promoting NH 4 + and NO 2 - conversion to nitrogen, thereby alleviating ammonia inhibition. This article provides a comparative assessment of MEC-AD and other technologies from the perspectives of technology, environmental sustainability, and economic feasibility. Supported by life cycle assessment, the MEC-AD system exhibits notable advantages in environmental and economic sustainability. However, mechanisms regulating substance conversion and enzyme activity are still unclear in MEC-AD system. In particular, the relationship between active functional microorganisms and their gene expression profiles. Overall, this paper presents the first systematic review of microbial metabolic regulation in high ammonia MEC-AD systems, providing a valuable framework for elucidating the mechanisms of MEC-AD technology alleviates ammonia inhibition. Abbreviations: AD, anaerobic digestion; FAN, free ammonia; VFA, volatile fatty acids; IET, interspecies electron transfer; EPS, extracellular polymeric substance; LCA, life cycle assessment; LCC, life cycle cost; AK, acetate kinase; AmtB, ammonium transfer protein; EAM, electroactive microorganisms; GHGs, greenhouse gas; MF, magnetic field-assistance; AS, air stripping; TAN, total ammonia nitrogen; CH 4 , methane; EET, extracellular electron transfer; DIET, direct interspecies electron transfer; C/N, carbon/nitrogen; MEC, microbial electrolysis cell; HM, hydrogenotrophic methanogenesis; H 4 MPT, tetrahydromethotrexate; ETS, electron transport system; AS, air stripping; SCOD, soluble chemical oxygen demand; CCC-MF, current-carrying-coil-based magnetic field.

Biosensors & bioelectronics • 2025

Acquiring weak electron signals from electroactive bacteria is critical for biosensing, wastewater treatment, and life science applications. However, current microbial electrochemical techniques are inefficient in capturing these signals at microscale. While organic electrochemical transistors can amplify signals exponentially, they lack an effective cathodic reaction to sustain electroactive bacterial dominant communities. Hence, a microbial electrochemical transistor is developed, integrating a microbial electrolytic cell with an organic electrochemical transistor by employing platinum source and drain electrodes. This design enables seamless incorporation of microbial electronic circuits into the ion gated circuits. Results demonstrate effective signal amplification of extracellular electrons generated by microbial gates within the device. The extracellular electron signals are successfully acquired across varying concentrations of organic matter, achieving a substantial signal amplification of ≈ 10 3 . The nonlinear relationship between biodegradable organic matter concentrations and device output signals is established. In continuous mode, a detection limit as low as 1 mgL -1 and a rapid response time of less than 60 s are achieved. This novel device facilitates efficient bacterial signal acquisitions on the microscale, bridges microbial electrochemistry with semiconductor physics, opening new avenues for bioelectronic systems in advancing extracellular electron transfer research, and promises in electroactive bacteria identification at even single-cell level.

Bioresource technology • 2025

Microbial electrolysis cells (MEC) supply electrons to sulfate-reducing bacteria (SRB) within cathode biofilms, however, these SRB exhibit heterogeneous spatial distributions due to varying competitiveness for electron utilization, which ultimately impacts sulfate removal efficiency. This study investigates the underlying mechanisms driving the evolution of this spatial heterogeneity within cathode biofilms and its subsequent influence on sulfate reduction performance by modulating the chemical oxygen demand-to-sulfate (C/S) ratio. When the C/S ratio decreased from 5 to 3, the sulfate removal rate increased by nearly 10 %. At C/S = 5, Bacteroidota and Desulfovibrio were the predominant groups. After the ratio decreased, Synergistota and Aminomonas became dominant. Concurrently, gene abundances associated with assimilatory sulfate reduction (ASR) also increased. Therefore, we conclude that decreasing the C/S from 5 to 3 promotes a more active bacterial region in the biofilm surface, leading to a more efficient spatial stratification of the microbial community and, consequently, improved MEC performance.

Bioresource technology • 2025

To achieve the simultaneous recycling of biogas slurry and anaerobic sludge, the sludge was used to synthesize sludge-based iron-carbon composite mediators (SICM), which were applied to enhance the performance of anaerobic digestion coupled with microbial electrolysis cell (AD-MEC) for biogas slurry degradation. By comparing four preparation methods, it was found that SICM oxygen-containing functional groups and different valence states of iron in SICM played active roles in facilitating electron transfer. Fe@C-B had the best performance of biogas slurry degradation, achieving a COD removal rate of 86.99 %. The methane yield for Fe@C was the greatest at 301.6 mL/gCOD. SICM enhanced AD-MEC performance through selective enrichment of key functional microorganisms such as Fastidiosipila, norank_f_Anaerolineaceae, Geobacter and Methanosaeta. This study demonstrated the feasibility of simultaneously converting biogas slurry into energy and recycling anaerobic sludge, also offering both theoretical and technical support for the sustainable development of biogas projects.

Bioresource technology • 2025

Although platinum-coated cathodes (Pt-C) are commonly applied in microbial electrolysis cell-anaerobic digestion (MEC-AD) systems for methanogenesis, they exhibit inherent biotoxicity. At 0.8 V, Pt-C achieved the highest methane yield (445.71 mL/gCOD), but overall enhancement remained limited. This treatment enhanced inter-biofilm electron transfer processes and electrolyte transport, particularly at cathodes, thereby stimulating quorum sensing, proteolysis, amino acid/peptide transport, and acidification of substrates. It promoted the proliferation of cathodic unclassified_f_Methanobacteriaceae and Geobacteraceae, upregulated hmd, acs and coo, which drove hydrogenotrophic methanogenesis, acetoclastic methanogenesis, and syntrophic acetate oxidation via direct interspecies electron transfer. Conversely, it inhibited formate and methylotrophic methanogenesis pathways and associated genes. Notably, methylotrophic methanogens, despite low abundance, had a disproportionately significant role in methane production. These findings underscore Pt's "double-edged sword" effect, revealing its complex, selective influence on microbial metabolism and methanogenic pathways in MEC-AD systems, providing novel mechanistic insights into optimizing CH 4 production.

Bioelectrochemistry (Amsterdam, Netherlands) • 2025

The increasing need for efficient nitrogen removal in wastewater treatment has driven interest in innovative biological and electrochemical approaches that can simultaneously address ammonium and nitrate contamination. This study explored the performance of simultaneous anodic ammonium oxidation and hydrogenotrophic denitrification in a single-chamber microbial electrolysis cell (MEC). Different operational conditions, including varying ammonia‑nitrogen/nitrate‑nitrogen ratios, were selected to evaluate the MEC's ability to promote anaerobic ammonium oxidation along with organic matter removal. The results demonstrated that the single-stage MEC achieved 57.8 % total nitrogen removal efficiency under an optimal condition where the influent contained only ammonium nitrogen at 200 mg/L with no added nitrate. Adding nitrate in the influent of the microbial electrolysis system decreased ammonium removal in all the operational conditions. Additionally, chemical oxygen demand (COD) destruction and methane production occurred uninterrupted throughout all experimental stages. Therefore, simultaneous methane production and nitrogen removal was realized in this study. The microbial electrolysis system achieved 97.3 ± 0.5 % nitrate removal, outperforming the hydrogenotrophic anaerobic digestion system. While no nitrite accumulation was observed in the systems, nitrous oxide emission occurred in all the operational conditions. A microbial community analysis showed that the anode of the MEC reactor was dominated by Pseudothauera and clostridium, which explained the denitrification performance by the MEC. This highlights the potential of bioelectrochemical systems for simultaneous ammonium and nitrate removal in a single-stage wastewater treatment process.

Journal of hazardous materials • 2025

Constructed wetlands (CWs) are recognized as sustainable wastewater treatment systems. However, their efficiency in removing emerging contaminants such as antibiotics is restricted owing to inherent redox stratification and limited oxygen availability. Electrochemical technologies can effectively enhance antibiotic degradation via an optimized redox environment and increased electron transfer capacity. Nevertheless, the degradation mechanisms and pathways of antibiotics in different electrochemical CWs remain unclear. This study systematically compared the sulfamethoxazole (SMX) removal performance of three electrochemical CWs: microbial fuel cell CW (MFC-CW), micro-electrolysis CW (ME-CW), and electrolytic cell CW (EC-CW). Results demonstrated that SMX removal efficiency in electrochemical CWs increased by 18.6 %-33.4 % due to the synergistic effects of electrochemical oxidation, hydroxyl radical (·OH) oxidation, and microbial degradation. Notably, EC-CW showed a 33.4 % increase in the SMX removal efficiency and a 24.5 % decrease in antibiotic resistance gene (ARG) abundance. Further, it promoted the formation of low-toxicity transformation products, mitigating potential ecological risks. Direct current stimulation selectively enriched SMX-degrading bacteria (e.g., Proteobacteria) and non-ARG-associated microbial communities (e.g., Pseudomonas), effectively enhancing the microbial degradation process (which contributed 36.8 % to SMX degradation). This study provides a scalable and sustainable strategy for treating emerging contaminants in CWs.

Bioresource technology • 2025

The growing demand for sustainable wastewater valorization and renewable hydrogen energy has amplified the need for systems capable of recovering energy and producing hydrogen without external electricity input. In this study, ten single microbial fuel cells (MFC) were connected in parallel to enhance power generation, and the electricity produced was controlled using a power management system. The energy was then directly supplied to a microbial electrolysis cell (MEC) in real time and stored in a battery prior to the MEC operation. When directly connected, the MFC-MEC system achieved a hydrogen production rate of 0.08 m 3 /m 3 /d, while the battery-assisted mode reached 0.66 m 3 /m 3 /d, demonstrating an eight-fold increase. These findings demonstrate the feasibility of integrated MFC-MEC systems for self-powered hydrogen production, offering a potential pathway for transforming organic wastewater into hydrogen as a renewable energy carrier.

Bioelectrochemistry (Amsterdam, Netherlands) • 2025

Electroanalytical techniques can be used to provide new insights into the electrochemical response of microbial bioelectrodes with some limitations due to complex interphase biofilm-electrode. In this work, characterization techniques, including open-circuit voltage, cyclic voltammetry, and electrochemical impedance spectroscopy, were applied to the bioanode, while chronoamperometry was used for the MEC with nine combinations of applied voltage and biomass content for anodic biogas production. The open-circuit potential was characteristic of the bioanode at -0.4 V ± 0.02 V vs. Ag/AgCl; the cumulative charge evolution allowed differentiation of operation conditions, reaching a total charge between 30C and 170C. Three distinct profiles were found among the voltammograms including oxidation peaks, oxidation waves and no faradaic signals. The charge transfer resistance estimated via electrochemical impedance spectroscopy only allowed differentiation of the final from the initial conditions. A nonlinear correlation was found between electrochemical parameters and biogas volume and its composition. This work presents a method for the systematic electroanalysis of bioelectrodes and provides information on their behavior under different biomass and applied voltage conditions.

Food research international (Ottawa, Ont.) • 2025

S. aureus is a common foodborne pathogen that poses a great danger to the food industry and human health. Slightly acidic electrolytic water (SAEW) is characterized by strong antimicrobial effect and high potential for application. In this study, the effect of SAEW on the formation of VBNC state of S. aureus was systematically evaluated, and the differences in the formation of VBNC state of S. aureus in planktonic and biofilm states were also analyzed by flow cytometry. The results showed that treatment of S. aureus in planktonic and biofilm states with 0.8 mg/L SAEW resulted in complete loss of culturability at 2.5 h and 2.0 h, respectively, with 3.56 ± 0.28 % and 4.81 ± 0.13 % of cells formed VBNC state. And both states of VBNC S. aureus could be resuscitated, and the planktonic VBNC state S. aureus resuscitated faster. ATP concentration, ROS level and respiration intensity of different states of bacteria were examined, compared with uninduced bacteria, VBNC S. aureus showed increased ATP concentration and ROS level, and decreased catalase activity, esterase activity, and respiratory intensity. Meanwhile, the overall metabolic level of the biofilm VBNC state bacteria was lower than that of the planktonic VBNC state bacteria, and its ROS level was higher than that of the planktonic VBNC state bacteria. Gene expression was determined by RT-qPCR, and the results showed that the transcript levels of genes regulating N-acetylglucosamine metabolism were up-regulated and those related to lipid metabolism, antioxidant and respiratory metabolism were down-regulated in the VBNC state S. aureus. This study comprehensively evaluates the application effect of SAEW in the food industry to provide a scientific basis for its safe and effective use; deepens the understanding of the mechanism of the formation of VBNC states by bacteria in different states, and provides theoretical support for the control of VBNC bacteria.

Bioelectrochemistry (Amsterdam, Netherlands) • 2025

Microbial electrolysis cells (MECs) are promising for biohydrogen production from waste streams, yet their overall energy efficiency requires enhancement to be viable. This study, for the first time, utilized double-chamber MECs with graphite (Gr), ruthenium-coated graphite (Ru), and palladium-coated graphite (Pd) cathodes for biohydrogen production from potato processing wastewater under various applied voltages. The highest hydrogen evolution rate (HER) and energy efficiency (ηₑ) were achieved in the Ru reactor at 1.0 V, reaching 0.43 LH₂ L -1 d -1 and 106 %, respectively. These represent improvements of 81 % in HER and 33 % in ηₑ compared to the uncoated Gr reactor. The surface morphology of the Ru and Pd coated electrodes was characterized by SEM and XRD. Next-generation sequencing of the anode biofilm indicated a microbial community comprising polysaccharide-consuming bacteria, such as the phylum Bacteroidetes, and key exoelectrogens, including the genus Geobacter. An Artificial Neural Network (ANN) model (R 2  = 0.9432) was also developed to simulate HER performance, confirming high performance of Ru-coated cathode under various voltages. A techno-economic analysis (TEA) was conducted to assess the effect of cathode coating on the payback period. The analysis revealed that Pd and Ru coatings reduced the payback period by approximately 36 % and 34 %, respectively.

Bioelectrochemistry (Amsterdam, Netherlands) • 2025

This study delves deeply into the impact of different electrode materials on the redox properties of extracellular polymeric substances (EPS) within electroactive mixed microbial communities. The experimental results reveal that the redox properties of EPS exhibit significant variations depending on the electrode materials employed. Among them, the reactor (MEC-BTF3) utilizing dual carbon felts as the cathode and anode electrodes demonstrates the most outstanding degradation performance. Within a 96-h reaction period, the degradation efficiency of trichloroethylene (TCE) by this reactor reaches as high as 94.3 %. In-depth analysis indicates that the dual carbon electrodes possess a low charge transfer internal resistance, a characteristic that substantially enhances the electron transfer rate. Moreover, in the protein secondary structure of EPS, the β-sheet structure accounts for 40.0 % of the total amide I region. This structural feature effectively promotes the formation and stability of microbial aggregates. The important findings of this study not only facilitate a more profound understanding of the interaction mechanisms between electrode materials and EPS in electroactive microbial communities but also offer theoretical guidance for the development of more efficient and targeted bioelectrochemical system (BES).

Applied biochemistry and biotechnology • 2025

Redox mediators (RMs) have been widely employed in bioelectrochemical systems to enhance electron transfer efficiency. However, systematic comparisons of RM-driven microbial selectivity and its direct correlation with methane production in microbial electrolysis cells (MECs) remain unexplored. This study investigates methane production in MECs using carbon felt (CF) electrodes modified with four RMs, i.e., neutral red (NR), anthraquinone-2,6-disulfonic acid disodium salt (AQDS), humic acid (HA), methyl viologen (MV), and the conductive polymer polyaniline (PANI). Cyclic voltammetry and electrochemical impedance spectroscopy revealed superior electrochemical activity for NR- and HA-modified electrodes (CF-NR, CF-HA) among the tests. CF-NR and CF-PANI demonstrated the highest biocompatibility, supporting 25% and 15% greater biofilm biomass than unmodified CF, respectively. Modified electrodes exhibited lower alpha diversity than CF, indicating enhanced selectivity in microbial enrichment. Overall, CF-HA achieved the highest methane yield (304.1 mL CH 4 /g COD), ~20% higher than the CF control. This study demonstrates that modification-specific microbial enrichment critically governs MEC performance, whereas the quantity of biomass adhesion to the electrode is not the determining factor.

World journal of microbiology & biotechnology • 2025

In this study, a two-chambered microbial electrolysis cell (MEC) was fabricated using a carbon cloth electrode, a Nafion-117 membrane, and Escherichia coli as the biocatalyst. The system treated sewage sludge with an initial chemical oxygen demand (COD) of 14,843 ± 350 mg/L, reducing it to approximately 170 ± 12 mg/L over the operational period. This configuration facilitated a significant increase in cell volume utilization of 89.5%, and achieved a maximum current production of 18.03 mA, along with hydrogen generation of 24.34 ± 1.3 mL at a biomass concentration of 13.5 ± 1.1 g/L. Cell growth contributed substantially to the degradation of organic matter, with sludge consumption reaching 12 g/L. The system produced an output voltage of 1.88934 ± 0.0091 V within 72 h and achieved the highest power density of 261,037 ± 1,245 mA/m 2 . The improved performance is attributed to the unique configuration of intermembranous live cells, highlighting the potential of biological electrocatalysts in advancing MEC technology. Further experiments demonstrated that when the initial COD load was 2,443 ± 175 mg/L, the MEC achieved a maximum COD removal efficiency of 98.5%. These findings emphasize the importance of optimizing sewage sludge substrate concentration to maximize power generation in MECs while simultaneously reducing the environmental burden of sludge biomass.

Bioresource technology • 2025

Volatile organic compounds (VOCs) severely impact human health and ecosystems, making effective removal technologies crucial. This study constructed a microbial electrolysis cell (MEC) using in situ synthesized nitrogen-doped carbon nanotube-modified carbon cloth (N-CNTs/CC) electrodes, which significantly enhanced VOCs degradation. N-CNTs reduced bioenergetic charge transfer impedance by 21.68 %, and their 3D conducting network, combined with electroactive microorganisms, promoted both direct and flavin-mediated indirect electron transfer. The system achieved 100 % removal of methyl methacrylate (MMA) within 6 h, 30.63 % higher than with carbon cloth electrodes. In mixed contaminants, MMA inhibited the degradation of other components. Meanwhile, selective enrichment of functional bacteria like Pseudomonas and Acinetobacter clarified microbial substrate response mechanisms. Cyclic voltammetry confirmed cytochrome-mediated direct electron transfer dominance. Under continuous flow with a 3-hour hydraulic retention time, complete MMA removal was achieved, showing strong engineering application potential. This study provides a theoretical basis for optimizing electrode strategies to advance energy-efficient waste treatment technologies.

Environmental research • 2025

Facing the issue of phosphorus (P) resource scarcity, microbial electrolysis cells (MECs) have garnered widespread attention from researchers due to their ability to recover P in the form of struvite without the need for external alkali addition. This study focuses on enhancing P recovery efficiency through modifying stainless steel mesh (SSM) cathodes with nickel-cobalt-tin (Ni-Co-Sn) composite materials and the circulation of catholyte in MECs. Results demonstrated that under optimal electrodeposition parameters (current density: 0.3 A/dm 2 , duration: 1800 s, temperature: 50 °C, and Ni:Co:Sn molar ion ratio of 2:1:0.5), the Ni-Co-Sn-SSM cathode system significantly reduced the charge transfer resistance of the original SSM, achieved a solution pH of 8.85 within 12 h, and exhibited exceptional P recovery efficiency of 87.5 %. In cyclic operation mode with controlled conditions, the P recovery efficiency reached 96.4 % within 8 h and attained near-complete recovery (99.9 %) after 12 h. The Ni-Co-Sn-SSM cathode enhances P recovery by maximizing hydrogen adsorption and desorption, increasing OH - generation, improving hydrogen evolution catalytic activity, and expanding the specific surface area to boost active sites and catholyte pH. Cathode modification and catholyte circulation significantly enhance P recovery, offering a sustainable solution for efficient P resource recycling.

Environmental monitoring and assessment • 2025

Anaerobic ammonium-oxidizing bacteria (AnAOB) present significant enrichment challenges due to slow growth kinetics and extended cultivation periods. This study employed single-chamber microbial electrolysis cells (MECs) to investigate substrate conversion rates, microbial community dynamics, and bacterial morphological adaptations in mixed consortia (incorporating nitrifiers, denitrifiers, and AnAOB) under varying applied voltages (0-1.2 V). Key results demonstrated that at 0.6 V, ammonium removal efficiency nearly doubled compared to the 0 V baseline, with AnAOB relative abundance increasing from 5.78 ± 0.38% to 12.34 ± 0.60% while denitrifiers decreased from 9.69 ± 1.33% to 2.84 ± 0.14%. Voltage escalation to 1.2 V induced proliferation of denitrifiers, which coexisted with AnAOB under carbon-limited conditions. During actual wastewater operation, ammonium degradation rates declined to 73% (Cycle 1) and 68% (Cycle 2), yet AnAOB maintained functional dominance at 12.56 ± 0.40% relative abundance. These findings provide valuable insights for AnAOB enrichment from complex communities, demonstrating voltage optimization's potential to enhance syntrophic interactions and intensify nitrogen removal pathways.

Bioresources and bioprocessing • 2025

Volatile fatty acid (VFA) accumulation is a common issue that compromises the performance of biological hydrogen methanation systems (BHMs). This accumulation is often triggered by fluctuations in hydrogen supply, which can disrupt microbial activity and lead to system instability. To address this challenge, this study investigated the impact of employing a microbial electrolysis cell (MEC) in BHMs to mitigate system instability and acid build-up. As such, a conventional anaerobic digester (AD) and a microbial electrolysis cell, both supplemented with exogenous hydrogen, were evaluated for their performance in hydrogen methanation. The effect of exogenous hydrogen at high addition rates (> 4:1 CO 2 :H 2 molar ratio) under instantaneous and gradual injection modes was investigated. The results showed that the instantaneous addition of hydrogen resulted in the total failure of the anaerobic digestion system. Propionate accumulated in the system (> 2 g/L) and resulted in low pH (pH = 5.3). Methane production stopped, and the reactor never recovered from hydrogen shock. However, the microbial electrolysis system was able to withstand the instantaneous hydrogen addition and maintain normal operation under toxic hydrogen addition levels (> 4:1 CO 2 :H 2 molar ratio). Under the gradual injection mode, both MEC and AD reactors remained reasonably unaffected; even though the hydrogen injection exceeded the stoichiometric molar ratio. This study provides a new perspective on the application of MECs for reliable operation and storage of surplus renewable energy via biological hydrogen methanation.

Bioresource technology • 2025

Microbial electrolysis cells (MECs) offer a sustainable approach to producing hydrogen (H 2 ) from organic waste. However, industrialization of MECs is hindered by a low H 2 production rate (HPR), mainly due to inefficient mass transfer between microbes and electrodes. To overcome this limitation, efficient dual-chamber MEC reactor design and evaluation of various substrate applicability are essential. In this study, we investigated the potential of mixed fruit waste (MFW) as an MEC substrate and its impact on microbial community dynamics in a multi-stack MEC reactor designed for H 2 production. To enhance microbial utilization, MFW was pretreated with eco-friendly organic acids (i.e., citric acid), achieving a high carbohydrate extraction efficiency of 82 %. Physicochemical analyses of MFW before and after pretreatment confirmed effective hydrolysis. MEC operation with 25 % MFW extract achieved a high chemical oxygen demand (COD) removal efficiency of 77 % and a maximum current density of 0.71 A/m 2 (16.36 A/m 3 ). Organic components in the MFW extract, including 5-hydroxymethylfurfural (HMF) and furan derivatives, were completely decomposed during MEC operation. Notably, microbial community analysis revealed distinct spatial distributions across the anode's vertical positions. Fermentative bacteria predominated in the bottom section, while electroactive genera such as Geobacter and Comamonas dominated the top section, likely due to the upward flow and recirculation of the organic substrate introduced at the bottom. The proposed multi-stack MEC process enhanced substrate utilization and microbial symbiosis interactions, highlighting its potential for industrial-scale applications.

Bioresource technology • 2026

Microbial electrolytic cell (MEC) can achieve autotrophic nitrogen removal, which is a promising means for treating low C/N ammonium-rich wastewater. However, it still suffers from insufficient ammonium oxidation rate and low total nitrogen (TN) removal. This study optimized the autotrophic nitrogen removal performance of a single-chamber MEC reactor using carbon granule (CG) materials as the bioanode, combined with supercapacitor (SC) as power supply. In the anoxic anodic system with only ammonium as the electron donor, the CG-anode/SC-powered system achieved removal loads of 35.31 ± 4.89 and 27.44 ± 4.80 mg L -1 d -1 for NH 4 + -N and TN, respectively. This TN removal load was 7 and 5.8 times higher than those using carbon felt and carbon brush anodes, respectively, and 2.7 times higher than those using a direct current power supply. Microbial community composition and functional gene abundance analyses showed that the CG anode was occupied by microbes associated with the anaerobic ammonia oxidation (Candidatus_Kuenenia, Ignavibacterium, norank__c__SJA-28, and norank__f__A4b), combined with the key gene abundance increase of hzs and hdh in the anammox pathway. With the lower current and coulomb efficiency of the CG-anode/SC-powered system, it demonstrated that the mechanism on the enhanced nitrogen removal was the electrically driven anodic partial nitrification with electrode as electron acceptor for nitrite production in situ, and then combined with anammox for nitrogen removal. This study constructs a novel autotrophic nitrogen removal system combined with SC-MEC and anammox, providing a viable strategy for the treatment of low C/N ammonium-rich wastewater.

World journal of microbiology & biotechnology • 2025

The growing demand for freshwater, coupled with the increasing volume of industrial and municipal wastewater, has intensified the need for sustainable and eco-friendly reclamation strategies. Recent advancements in microbial biotechnology have emerged as promising tools for developing cost-effective, efficient, and environmentally sustainable wastewater treatment (WWT) strategies for reuse and safe disposal. This mini-review explores current innovations, such as microbial consortia, bioaugmentation, and the microalgae-bacteria nexus, which have shown promising results in nutrient removal, enhanced degradation of complex pollutants (including emerging contaminants), and biomass valorization. Moreover, bioelectrochemical systems, such as microbial fuel cells (MFC) and microbial electrolysis cells (MEC), have revolutionized WWT by facilitating pollutant degradation while simultaneously generating bioelectricity or biohydrogen. This article also critically examines the role of CRISPR-based tools and 'omics' approaches, which have enabled the development of novel microbial strains and degradative pathways, enhancing wastewater reclamation in challenging environments. Furthermore, advancements through the integration of multi-omics and artificial intelligence, digital twins, and Internet of Things (IoT) for microbial optimization and real-time process control are discussed. The review highlights the role of microbial systems in resource recovery, supporting a circular economy by transforming wastewater into valuable bioresources. Additionally, this review addresses the major challenges and proposes future research directions for effective wastewater treatment. The novelty of this manuscript is that no single review explores the cutting-edge microbial biotechnologies for wastewater reclamation, uniquely integrating CRISPR-Cas genome editing, multi-omics analyses, and artificial intelligence-driven optimization to advance pollutant degradation and real-time process control in one place. This study concludes that by implementing multi-omics and artificial intelligence (AI)-driven optimization process for wastewater treatment can be effective towards wastewater treatment while simultaneously minimizing the environmental pollution.

Bioresource technology • 2026

Methane production in microbial electrolysis cell-anaerobic digestion (MEC-AD) systems is limited by inefficient interfacial electron transfer (IET), which depends on the slow formation of a conductive microbial biofilm. In this study, a novel material with Fe (III) ions as the metal centers and the redox-active 2,5-dihydroxy-1,4-benzoquinone (dhbq) as the organic ligand (Fe@dhbq) was designed to act as an efficient "electron pool" that mediated electron transfer between the cathode and electroactive methanogens, which helped establish an efficient IET network by accelerating the maturation of electroactive biofilms. The results demonstrated that the electron transfer capacity of the CC/Fe@dhbq biofilm increased by an order of magnitude, and the current was 4.2 times higher than the control. Correspondingly, direct electron transfer (DET) pathway was formed to increase methane production by 35 %. This work provides a new strategy for enhancing methanogenesis via DET in electro-enhanced anaerobic digestion.

Journal of environmental management • 2026

Addressing the challenges of unstable activity in microbial sulfate-reducing bacteria (SRB) and the need for further recovery of sulfate reduction products, this study employed iron-carbon (Fe-C) micro-electrolysis to enhance microbial sulfate reduction (MSR) and achieve sulfur resource recovery. By comparing the synergistic effects of iron (Fe), carbon (C), and Fe/C composite systems with a polyvinyl alcohol-sodium alginate (PVA-SA) immobilization system, the key mechanisms were elucidated. The optimized Fe-C system (Fe/C mass ratio 2:1, 6 g Fe/L: 3 g C/L) reduced sulfate from 1000 mg/L to 362.9 mg/L within 5 d, while minimizing sulfide accumulation to 48.6 mg/L via in-situ generation of iron sulfides (FeS). X-ray photoelectron spectroscopy (XPS) confirmed FeS formation, validating direct sulfur recovery. Micro-electrolysis selectively enriched completely oxidizing sulfate-reducing bacteria (SRB), particularly Desulfococcus (relative abundance: 10.5 % in Fe-C group vs. 3.7 % in control), enhancing metabolic efficiency. PVA-SA hydrogel immobilization significantly improved microbial stress resistance, manifested as increased cell viability (1.21 × control) and stabilized extracellular polymeric substances (EPS). This alleviated Fe 3+ cytotoxicity and maintained reducing conditions (ORP stabilized below -200 mV). Under the optimal Fe/C ratio, electron transfer system activity (ETSA) reached its maximum (1.4 × control). The research demonstrates that Fe-C micro-electrolysis combined with PVA-SA immobilization establishes an efficient platform for sulfate removal and sulfur resource recovery, providing a sustainable strategy for treating sulfate-laden wastewater.

Bioresource technology • 2026

Zero-gap microbial electrolysis cells (MECs) have demonstrated large current and hydrogen production rates from defined substrates in synthetic media, but operation with real waste streams has yet to be proved. This study evaluated the performance and 30-days stability of zero-gap MECs operated with effluent from a single-stage anaerobic digester. The system achieved a maximum current density of 8.8 ± 0.3 A/m 2 with a hydrogen production rate of 32 ± 6 L/L-d, and during 30 days of continuous operation, sustained an average current density of 7 ± 2 A/m 2 and a hydrogen production rate of 20.8 ± 0.2 L/L-d. Carbonate precipitation was identified as a major challenge to long-term stability, and mild acid washing effectively mitigated its adverse effects. The low buffer capacity of the effluent was primarily limiting performance. These findings underscore the significant impact of wastewater chemistry on MEC operation and validate the feasibility of utilizing real waste streams as viable feedstocks for biohydrogen production in zero-gap configurations.

Bioresource technology • 2026

This study presents an integrated approach combining microbial electrolysis cells (MECs) with three external ammonium extraction systems, Gas Diffuser (GD), Stripping Column (SP) and Thermally Assisted Stripping (SP + T), to enhance nitrogen removal and recovery from high-strength wastewater. Among the configurations, MECs operated at 0.75 V and integrated with SP + T achieved the highest performances, with current density of 8.8 A m -2 , ammonium removal and recovery rates reaching 69.8 and 37.9 gN m -2  d -1 , Faradaic efficiency of 74.9 % and specific energy consumption for ammonium recovery of 3.3 kWh kg -1 N. The SP + T system boosted ammonia volatilization at the catholyte and accelerated ammonium transport across the cation exchange membrane, leading to improved removal and recovery performance. Concurrently, H 2 generation reached 1557.6 L H 2  m -3  d -1 with specific energy consumption of 31.4 kWh kg -1 H 2 . These results highlight that coupling MEC and SP + T is a promising configuration for efficient nitrogen recovery and renewable hydrogen generation, while demonstrating MECs as a sustainable technology for wastewater treatment and resource recovery. STRUCTURED ABSTRACT: The study presents a novel approach for enhancing nitrogen recovery from wastewater using MECs integrated with different ammonium stripping systems. By evaluating three configurations, gas diffuser (GD), ambient-temperature stripping (SP) and thermally assisted MEC stripping system (SP + T), this work systematically investigates how operational strategies affect the performance of nitrogen removal and recovery. Key performance indicators such as current density, Faradaic efficiency, specific energy consumption and hydrogen production are quantified and compared as well. Furthermore, organic removal rates, percentage and energy efficiency of organic matter treatment in the anode are also assessed. The findings described highlight the importance of optimizing operational parameters such as temperature and contact surface to maximize ammonium recovery in MECs. The SP + T approach is relevant for bioelectrochemical and wastewater treatment systems aiming to optimize nitrogen management and valorization. Furthermore, the study includes a comprehensive energy analysis and contextualizes the results with respect to conventional ammonia production technologies such as the Haber-Bosch process, among others. Thus, these results are of relevance to the fields of wastewater treatment, nutrient recovery, energy/hydrogen production, environmental biotechnology and circular economy, offering a scalable and energy-efficient solution for nutrient valorization.

Scientific reports • 2026

The transition to a hydrogen-based energy system requires safe and efficient large-scale storage solutions. Underground hydrogen storage (UHS) has emerged as a promising candidate, but the effectiveness and long-term security of UHS depend on a fundamental understanding of hydrogen transport mechanisms in subsurface environments. Among these, hydrogen diffusion into formation water plays a key role in governing mass loss, geochemical reactions, and microbial activity. This study presents a combined experimental and mathematical approach to quantify hydrogen diffusion in distilled water and brine at temperatures of 30 °C, 45 °C, and 60 °C, and pressures near 6.5 MPa. A new formulation is proposed that accounts for non-constant gas compressibility and enables systematic identification of the initial non-diffusive regime in pressure-time data. The methodology was validated by measuring the diffusion coefficient of CO₂ in distilled water, giving values consistent with those reported in the literature. Experimental results showed that hydrogen diffusion coefficients increase with temperature, from 3.6[Formula: see text]0.4 × 10⁻⁹ m²/s at 30 °C to 6.1[Formula: see text]0.3 × 10⁻⁹ m²/s at 60 °C. An additional series of tests on brine demonstrated that increasing salinity from 0 to 10,000 ppm of NaCl salt reduces the hydrogen diffusion coefficient to 5.[Formula: see text]0.2 × 10⁻⁹ m²/s at 60 °C. This methodology offers a robust framework for characterizing gas diffusion in aqueous systems, providing critical input not only for modeling hydrogen behavior in geological storage formations but also for optimizing hydrogen production via water electrolysis and its utilization in fuel cells.

ACS sustainable chemistry & engineering • 2026

Microbial electromethanogenesis (EM) presents a promising pathway for sustainable biogas upgrading, but accurately predicting its performance is challenging due to complex, nonlinear process dynamics. Here, we systematically compared seven supervised machine learning (ML) algorithms, including one-dimensional convolutional neural network (1D-CNN), multilayer perceptron (MLP), gradient boosting regressor (GBR), adaptive boosting regressor (AdaBoost), stacking regressors, and K-nearest neighbors (kNN), for their predictive biomethane production capabilities using experimental data from EM bioelectrochemical systems (EM-BESs). The data set encompassed operational parameters such as optical density (OD 600 ), pH, electrical conductivity (EC, mS/cm), average applied current (A m -2 ), and CO 2 availability (mol). After hyperparameter optimization, the 1D-CNN model exhibited superior predictive performance ( R 2 = 0.934), significantly outperforming traditional ML methods. To move beyond prediction and uncover mechanistic insights, a feature importance analysis was conducted on the CNN model using SHapley Additive exPlanations (SHAP). The analysis revealed that average current, OD 600 , and pH were the most influential features in biomethane production, confirming that the model learned relationships grounded in fundamental bioelectrochemical principles. The SHAP analysis also identified complex, nonmonotonic effects of other variables, providing deeper process understanding. This study not only demonstrates the promising ability of ML, especially deep learning architectures, to advance EM optimization but also provides mechanistic insights into the factors governing bioelectrochemical methanogenesis. These findings are broadly applicable to analogous BESs, particularly microbial electrosynthesis (i.e., commodity chemical) and microbial electrolysis cells (i.e., biohydrogen), offering potential for enhancing system performance through data-driven operational control across sustainable biotechnology applications.

Bioresource technology • 2026

Microbial upcycling of heavy metal wastewater into catalysts offers a sustainable solution for antibiotic degradation, yet traditional synthesis is hindered by severe metal toxicity and complexation issues. To address these challenges, a stepwise biosynthesis strategy was developed using Shewanella oneidensis MR-1 to fabricate copper-manganese bimetallic sulfide (bio-CuMnSs) from heavy metal-laden wastewater. Unlike the one-step method, this strategy maintained high cell viability, enabling the efficient production of uniform nanoparticles. The bio-CuMnS (Cu/Mn molar ratio of 2:1) significantly outperformed its chemically synthesized counterpart, achieving 96 % degradation of tetracycline hydrochloride (TCH, 20 mg/L) within 60 min via peroxymonosulfate (PMS) activation. Mechanistic investigations revealed that the degradation was predominantly driven by surface-bound radicals (HO • /SO 4 •- ) confined by biogenic functional groups, with supplementary contributions from singlet oxygen ( 1 O 2 ). A distinct bimetal-sulfur synergy was confirmed, where intermediate-valence sulfur species (S 2 2- , S n 2- , and S 0 ) served as internal electron donors to drive the cooperative regeneration of Cu(I) and Mn(II) active sites, thereby sustaining PMS activation. The bio-CuMnS/PMS system maintained high efficiency over a broad pH range (5-11), in complex water matrices, and for different tetracycline antibiotics. Furthermore, the catalyst derived from real electroplating wastewater exhibited performance comparable to that from laboratory precursors, confirming the feasibility of simultaneous heavy metal valorization and antibiotic wastewater treatment.

Bioresource technology • 2026

Stable NO 2 - supply and low-temperature inhibition represent two major bottlenecks for anaerobic ammonia oxidation (anammox) in mainstream wastewater treatment. It was reported that applied electric fields enable anaerobic ammonium-oxidizing bacteria (AnAOB) to directly oxidize NH 4 + to N 2 . Whereas, low-temperature inhibition primarily stems from impaired electron transfer and subsequent metabolic suppression. Enhancing these processes through applied potential and conductive materials offers a strategy for this study. A single-chamber microbial electrolysis cell with 0.6 V anodic potential and 10 mg L -1 reduced graphene oxide (RGO) was developed. Results showed that the system achieved nitrogen removal rates of 7.4 ± 0.5g N m -3 d -1 and 74.2 ± 4.8 mg N m -2 d -1 at 10°C. NH 4 + -N and total nitrogen removal efficiencies increased by 116.6% and 147.0%, respectively. The applied potential upregulated pili/cytochrome expression, while the RGO network provided a low-resistance conductive matrix. As a result, synergic system effectively intensified electron transfer, which increased anode current density by 1.9-fold and reduced resistance by 67.7%, supporting both conventional anammox via enhanced nitritation and the electric-anammox pathway. Furthermore, it also promoted the enrichment functional genes, such as hzs and hdh (107.6%-238.1%), and enhanced cold adaptation marked by increased in extracellular proteins and polysaccharides (44.8%-18.9%). This work demonstrates coordinated electron transfer enhancement and metabolic activation through potential-RGO integration provides an innovative solution for energy-efficient nitrogen removal in cold-region wastewater treatment.

Bioprocess and biosystems engineering • 2026

Microbial bioelectrochemical technologies rely on the development of biofilms on electrode surfaces; therefore, a high surface area in packed anodes is advantageous for their performance. In addition, bioelectrochemical reactors (BERs) for hydrogen production require low-cost installation materials to enable large-scale implementation. In this study, a one-liter BER was constructed using 0.38 L of carbon felt as a packed bioanode, 0.65 L of compost leachate as the electrolyte, and a stainless-steel mesh cathode. The reactor was operated under an anode potential of 0.05 V vs. Ag/AgCl (KCl, 3.5 M) in batch cycles of 24 h each. After medium replacement, the maximum accumulated gas volume reached 2.37 L, corresponding to a production rate of 7.38 m⁻ 3 gas m⁻ 3 packed reactor d⁻ 1 . The cathode potential varied over time, leading to fluctuations in energy efficiency, which exceeded 100%. Average energy, cathode and coulombic efficiencies over eight operational cycles were 124 ± 64%, 118 ± 56%, and 120 ± 61%, respectively. The gas yield obtained from compost leachate in the BER was within the upper range of productivity reported for microbial electrolysis cells. This work demonstrates a sustainable alternative for BER installation and operation and proposes a monitoring strategy to track energy efficiency during hydrogen production.

Bioresource technology • 2026

Anaerobic ammonium oxidation (Anammox) provides a low-carbon pathway for nitrogen removal, yet its reliance on nitrite (NO 2 - -N) constrains large-scale application. Emerging evidence indicates that Anammox bacteria (AnAOB) can oxidize ammonium (NH 4 + -N) through extracellular electron transfer (EET) without NO 2 - -N. However, the long-term stability of this process in mixed communities remains unresolved. Here, microbial electrolysis cells were operated for 260 days to investigate how anodic potential and conductive carrier regulate EET-dependent Anammox. A threshold potential of 0.4-0.6 V (vs. SHE) enabled NO 2 - -N-free NH 4 + -N removal of 103.61 ± 9.22 mg N·L -1 ·d -1 (approximately 2.5-fold higher than highly enriched communities) via a hydroxylamine oxidoreductase-mediated pathway. The conductive carrier increased electron flux 4.9-fold, enhanced protein secretion, and stabilized biofilms. High potential combined with conductive carrier enriched electroactive AnAOB (Candidatus Kuenenia, Candidatus Brocadia) and induced a shift from NO 2 - -N-dependent to EET-dependent metabolism. These findings demonstrate sustained long-term EET-dependent Anammox and inform scalable, carbon-free nitrogen removal.

Water research • 2026

Microbial electrolysis cells (MECs) can produce green hydrogen while removing organic contaminants from liquid waste streams by leveraging the metabolic activity of electroactive microorganisms. Despite their potential in a sustainable, circular economy, large-scale MECs that can treat relevant volumes of wastewater have failed to deliver performance proportional to their lab-scale counterparts. The reason behind this lower performance at scale remains unclear. In this study, we developed a combined electrochemistry-, hydrodynamic-, and microbial ecology-informed framework to analyze and optimize MEC performance during scale-up, enabling accurate quantification of major limitations and the identification of strategies to overcome them, ultimately facilitating equivalent performance at scale. Applying this framework to the scale-up of a zero-gap MEC from 9 cm 2 electrode area to 100 cm 2 electrode area, resulted in similar maximum current densities in a 100 cm 2 MEC (21.7 ± 1.1 A/m 2 ) compared to a 9 cm 2 system (25.1 ± 2.7 A/m 2 ), as well as equivalent hydrogen production rates of 69.3 L/L-d (100 cm 2 ) and 67.7 ± 2.4 L/L-d (9 cm 2 ). COMSOL flow dynamics simulations were used to scale up the reactor configuration without negatively affecting electrolyte velocity and distribution in the cell, minimizing the increase in internal resistances during scale-up (11.7 ± 0.5 mΩm 2 at 9 cm 2 ; 19.7 ± 1.3 mΩm 2 at 100 cm 2 ). Microbial community structures were assessed at both scales using high-throughput sequencing, highlighting the differences of populations across electrode dimensions and operational parameters. The framework presented here accelerates the development of effective strategies toward the scale-up of MECs by furthering the understanding of how electrochemical, hydrodynamic, and microbial ecology parameters change as the reactor dimension is increased. Ultimately, this approach contributes to advancing electrochemical biotechnology toward practical deployment in energy-efficient wastewater treatment systems.

Veterinary and animal science • 2026

Livestock production significantly contributes to global greenhouse gas (GHG) emissions, particularly methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂), posing challenges to climate change mitigation and environmental sustainability. This review explores advanced, system-wide approaches to reduce emissions from livestock systems while enhancing productivity, resilience, and resource efficiency. It covers short-term mitigation strategies such as dietary interventions-including methane inhibitors, microbial modulators, and natural compounds-that target enteric fermentation. Long-term solutions involve genetic and breeding innovations, such as microbiome-genome interaction analyses, CRISPR-based editing, and low-methane phenotyping, supported by genomic selection and precision phenotyping tools. The review also assesses advanced manure management technologies like anaerobic digesters and nutrient recovery systems, and examines precision livestock farming tools, including real-time sensors, machine learning models, UAVs, and IoT-based monitoring systems. Emerging digital tools, blockchain, augmented reality, and AI-assisted diagnostics are highlighted for enhancing traceability and decision-making. The potential of integrated energy systems, such as microbial fuel cells, hydrogen electrolysis, algae-based bioenergy, and thermal gasification, is discussed alongside traditional renewables, enabling livestock farms to become clean energy hubs. Circularity is emphasized through silvopasture, algal bioremediation, insect bioconversion, and integrated crop-livestock systems. Environmental assessment tools and the socio-political dimensions of technology adoption, including policy, education, and farmer behavior, are also considered. Future research directions, such as atmospheric methane oxidation, 4D-printed feed additives, and quantum modeling, are proposed. Overall, the review calls for a transdisciplinary, integrated approach to transform livestock systems into climate-smart, low-emission food production networks.

iScience • 2026

Specialized cytochrome protein complexes conduct electrons across cell membranes in electrogenic bacteria, which enables these microbes to be harnessed for applications in electrical generation, biosensing, and microbial electrosynthesis. Here, we engineer the surface-exposed MtrC subunit from the MtrCAB complex of Shewanella oneidensis to enable selective cell attachment to functional materials, including electrodes for improved bioelectricity production. Incorporating a SpyTag bioconjugation domain on MtrC enables specific covalent attachment of SpyCatcher-fused proteins to MtrCAB on S. oneidensis and Escherichia coli . Importantly, the MtrC modification does not disrupt electron export, offering opportunities to interface cells with electronic materials. In the second approach, incorporating a graphite binding sequence on MtrC improves S. oneidensis attachment to graphite electrodes, yielding 30% greater current production in a microbial electrolysis cell compared to a variant expressing unmodified MtrC. An engineerable platform on the surface of electrogenic cells creates numerous opportunities for biotic-abiotic interface manipulation.

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Research Square • 2026

Abstract Rapid expansion of battery-power-driven technologies in electric vehicles, autonomous systems, aerospace platforms, defensesystems and medical devices has strengthened the demand of energy storage systems for safe, reliable and fault-tolerantoperations. Lithium-ion batteries with high energy density and competent electrochemical properties, are characteristicallyvulnerable which leads to cell level degradation, imbalance, and even failure. Battery Packs of large scale are composed ofseveral cells (hundreds or thousands). The failure of a single cell in the large scale battery packs can significantly result indegradation of performance of the system. And in extreme cases it could also lead to the shutdown of complete system. Thepaper presents a comprehensive modeling of the battery module by incorporating redundant cell switching mechanism thatwhich provides a simulation framework which can act as an intelligent fault tolerant battery module using MATLAB and Simulink.The battery module of the battery pack is designed in such a way that it consists two primary cells and a redundant cell whichare interconnected and are controlled by switching network comprising nine electronically controlled switches. The controlalgorithm implemented to monitor the cell voltage, current, State of Charge (SOC) continuously and dynamically reconfiguresthe topology if the module considering the primary cell voltage reaching the predefined threshold value. The modular designenables scalable integration of such multiple modules to form a complete battery pack, offering enhanced reliability, faultisolation, and maintainability. The system proposed is validated in the simulation environment in detail and is followed bythe incorporation of cell balancing hence by demonstrating the suitability for applying in the advanced battery managementsystems where safety-critical applications play a vital role.

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Applied and Environmental Microbiology • 2026

ABSTRACT Antibiotic contamination from biogenic waste in agricultural soils poses a significant threat to soil health and crop productivity. We investigated the effect of antibiotics on the soil microbial community, antibiotic resistance genes, and mobile genetic elements (MGEs) and plant productivity in a 6-week greenhouse trial. Here, Spinacia oleracea (spinach) and Raphanus sativus (radish) were grown from seeds, and a mix of five antibiotics, namely sulfamethoxazole, trimethoprim, enrofloxacin, clarithromycin, and chlortetracycline, was added to the soil at concentrations of 0, 0.1, 1, and 10 mg kg −1 soil dry weight (c0, c0.1, c1, and c10, respectively). Overall, we found that the antibiotic treatments significantly impacted prokaryotic α-diversity and prokaryotic and fungal β-diversity. The relative abundance of human and plant pathogens did not increase under antibiotic exposure, but there was a significant reduction in plant growth-promoting bacteria. Moreover, the c10 treatment significantly increased the abundance of MGE intI1, indicative of horizontal gene transfer and sulfonamide resistance gene sul1, and significantly lowered radish biomass and nitrogen uptake, while spinach biomass and nitrogen uptake were unaffected. In summary, our study showed that antibiotic exposure significantly changed prokaryotic community diversity, while fungi remained largely unaffected. The reduction of plant growth-promoting bacteria may have a significant impact on soil nutrient cycling and crop productivity, but more research is needed to understand the long-term impact of these co-applied antibiotics on food production. Additionally, more studies are needed to understand the effect of antibiotics on realistic, field-scale conditions to fully understand the impact on environmental and human health. IMPORTANCE Agricultural soils are frequently contaminated with complex mixtures of antibiotics from various biogenic sources, yet we lack a clear understanding of their specific ecological impact. While many studies investigate antibiotics, they are often studied in pollution sources like manure, which contain confounding factors like heavy metals. To provide a mechanistic understanding of antibiotic-specific responses, we investigated the effects of a complex, five-antibiotic mixture on the soil-plant system, independent of other contaminants. As expected, antibiotics reduced prokaryotic diversity and increased the abundance of some genes related to antibiotic resistance. Additionally, antibiotic exposure reduced plant growth-promoting bacteria, which may have subsequent detrimental effects on plant and soil health. Moreover, we found that antibiotic exposure can reduce plant biomass and nitrogen uptake, but this is highly plant dependent. This research highlights the critical need to monitor antibiotic pollution due to its potential detrimental effect on plant health and alterations to the soil microbiome.