Jing Li, Song Guo, W. Liang et al.

IEEE/ACM Transactions on Networking • 2024

The emerging digital twin technique enhances the network management efficiency and provides comprehensive insights on network performance, through mapping physical objects to their digital twins. The user satisfaction on digital twin-enabled service relies on the freshness of digital twin data, which is measured by the Age of Information (AoI). Due to long service delays, the use of the remote cloud for delay-sensitive service provisioning faces serious challenges. Mobile Edge Computing (MEC), as an ideal paradigm for delay-sensitive services, is able to realize real-time data communication between physical objects and their digital twins at the network edge. However, the mobility of physical objects and dynamics of user query arrivals make seamless service provisioning in MEC become challenging. In this paper, we investigate dynamic digital twin placements for improving user service satisfaction in MEC environments, by introducing a novel metric to measure user service satisfaction based on the AoI concept and formulating two user service satisfaction enhancement problems: the static and dynamic utility maximization problems under static and dynamic digital twin placement schemes. To this end, we first formulate an Integer Linear Programming (ILP) solution to the static utility maximization problem when the problem size is small; otherwise, we propose a performance-guaranteed approximation algorithm. We then propose an online algorithm with a provable competitive ratio for the dynamic utility maximization problem, by considering dynamic user query services. Finally, we evaluate the performance of the proposed algorithms via simulations. Simulation results demonstrate that the proposed algorithms outperform the comparison baseline algorithms, improving the algorithm performance by at least 10.7%, compared to the baseline algorithms.

Baogang Li, Wenjing Wu, Wei Zhao et al.

IEEE Transactions on Vehicular Technology • 2021

This article investigates how to exploit the cooperative mechanism between non-orthogonal multiple access (NOMA) user pairs to enhance the security of the mobile-edge computing (MEC) system. Considering the different delay requirements of Internet of Things (IoT) users, we propose a two-slot hybrid cooperative NOMA security (THCNS) scheme that utilizes the cooperative interference between NOMA user pairs to enhance the security of offloading. In the first time slot, the interference to the eavesdropper comes from the task signals (TSs) transmitted by the two users, while in the second time slot comes from jamming signal (JS) transmitted by the user who has completed the offloading tasks. The weighted sum secrecy outage probability (wSOP) and secrecy computation probability (SCP) are utilized to measure the security performance of users in the proposed scheme. To confirm the feasibility and applicability of the proposed scheme, we analyze the impact of some key parameters on users’ security, including the users’ local computation time and offloading time, transmit power, task allocation coefficients of two time slots. The analysis results indicate that the proposed scheme is more suitable for the case where the wiretap channel outperforms the main channel, and it can enhance the system security when selecting the optimal parameters. Finally, the numerical simulation results reveal how the analysis parameters affect the security performance of users and validate the theoretical analysis, it provides good insights about how to design parameters of IoT users to enhance their security performance in MEC system.

Michelle Outeda-García, Jorge Arca-Suárez, Emilio Lence et al.

Antimicrobial Agents and Chemotherapy • 2025

<jats:title>ABSTRACT</jats:title> <jats:sec> <jats:title/> <jats:p> Carbapenemase OXA-48 and its variants pose a serious threat to the development of effective treatments for bacterial infections. OXA-48-producing Enterobacterales are the most prevalent carbapenemase-producing bacteria in large parts of the world. Although these bacteria exhibit low-level carbapenem resistance <jats:italic>in vitro</jats:italic> , the infections they cause are challenging to treat with conventional therapies, owing to their spread and complex detection in clinical settings. However, numerous β-lactamase inhibitors (BLIs) are currently in the pipeline or late clinical stages. To assess the potential of these compounds, this study compared the efficacy against OXA-48 of novel β-lactamase inhibitors, specifically the 1,6-diazabicyclo[3,2,1]octanes (DBOs) avibactam, relebactam, zidebactam, nacubactam, and durlobactam, along with the cyclic and bicyclic boronates vaborbactam, taniborbactam, and xeruborbactam. The extensive kinetics assays identified xeruborbactam, taniborbactam, and durlobactam, together with the already established avibactam, as BLIs with superior biochemical performance. Susceptibility testing further validated these findings but also demonstrated significantly improved bacterial killing by the DBOs zidebactam, nacubactam, and durlobactam. On the other hand, binding studies demonstrated the superior inhibitory capacity of the BLIs durlobactam and xeruborbactam. Combinations, such as cefepime/zidebactam, meropenem/nacubactam, and sulbactam/durlobactam, show promising activity against OXA-48-producing Enterobacterales, while ceftazidime/avibactam, cefepime/taniborbactam, and meropenem/xeruborbactam combinations also appear highly active, largely due to the excellent kinetics of these new inhibitors. Overall, this comprehensive analysis provides important insights into the effectiveness of new BLIs against OXA-48-producing Enterobacterales, highlighting xeruborbactam, durlobactam, and avibactam as leading candidates. Additionally, BLIs like zidebactam, nacubactam, and taniborbactam also showed potential in addressing the clinical challenges posed by OXA-48-mediated antimicrobial resistance. </jats:p> </jats:sec>

Bo Dong, Yurong Li, Xinyue Li et al.

Journal of New Materials for Electrochemical Systems • 2022

<jats:p>Compared with a microbial fuel cell (MFC) of single flora, the MFC of mixed flora provide much better denitrification and electricity generation performance. Therefore, in-depth analysis of the kinetic features such as the structures of various types of microflora in MFCs is of important theoretical and practical significance. There is little existing research on the electricity generation and pollutant removal process of cathode microorganisms and the functions of microbial flora. To this end, this paper constructs an MFC anaerobic-aerobic coupled denitrification system and studies its performance enhancement method. First, the basic principle of MFC biological denitrification was expounded, the kinetics was introduced into the analysis of the reaction between the MFC microorganisms and pollutants, and the migration and transformation occurring in the reaction process and the mechanism of transformation speed changes were revealed. Then, the analysis and calculation methods for the electrochemical parameters and microbial diversity index in MFC were explained in detail, and the experimental results and analysis conclusions were given.</jats:p>

Rainer Kurz

Journal of Fuel Cell Science and Technology • 2005

<jats:p>A thermodynamic model for a gas turbine-fuel cell hybrid is created and described in the paper. The effects of gas turbine design parameters such as compressor pressure ratio, compressor efficiency, turbine efficiency, and mass flow are considered. The model allows to simulate the effects of fuel cell design parameters such as operating temperature, pressure, fuel utilization, and current density on the cycle efficiency. This paper discusses, based on a parametric study, optimum design parameters for a hybrid gas turbine. Because it is desirable to use existing gas turbine designs for the hybrids, the requirements for this hybridization are considered. Based on performance data for a typical 1600hp industrial single shaft gas turbine, a model to predict the off-design performance is developed. In the paper, two complementary studies are performed: The first study attempts to determine the range of cycle parameters that will lead to a reasonable cycle efficiency. Next, an existing gas turbine, that fits into the previously established range of parameters, will be studied in more detail. Conclusions from this paper include the feasibility of using existing gas turbine designs for the proposed cycle.</jats:p>

William J. Sembler, Sunil Kumar

Journal of Fuel Cell Science and Technology • 2011

<jats:p>To determine the effects of various parameters on the performance of a solid-oxide fuel cell (SOFC), a series of simulations was performed using computational fluid dynamics (CFD). The first step in this process was to create a three-dimensional CFD model of a specific single-cell SOFC for which experimental performance data had been published. The CFD simulation results developed using this baseline model were validated by comparing them to the experimental data. Numerous CFD simulations were then performed with various thermal conditions at the cell’s boundaries and with different fuel and air inlet temperatures. Simulations were also conducted with fuel utilization factors from 30% to 90% and air ratios from 2 to 6. As predicted by theory, conditions that resulted in higher cell temperatures or in lower air and fuel concentrations resulted in lower thermodynamically reversible voltages. However, the higher temperatures also reduced Ohmic losses and, when operating with low to moderate current densities, activation losses, which often caused the voltages actually being produced by the cell to increase. Additional simulations were performed during which air and fuel supply pressures were varied from 1 atm to 15 atm. Although the increased pressure resulted in higher cell voltages, this benefit was significantly reduced or eliminated when air- and fuel-compressor electrical loads were included. CFD simulations were also performed with counterflow, crossflow, and parallel-flow fuel-channel to air-channel configurations and with various flow-channel dimensions. The counterflow arrangement produced cell voltages that were equal to or slightly higher than the other configurations, and it resulted in a differential temperature across the electrolyte that was significantly less than that of the parallel-flow cell and was close to the maximum value in the crossflow cell, which limits stress caused by uneven thermal expansion. The use of wider ribs separating adjacent flow channels reduced the resistance to the electrical current conducted through the ribs. However, it also reduced the area over which incoming fuel and oxygen were in contact with the electrode surfaces and, consequently, impeded diffusion through the electrodes. Reducing flow-channel height reduced electrical resistance but increased the pressure drop within the channels. Plots of voltage versus current density, together with temperature and species distributions, were developed for the various simulations. Using these data, the effect of each change was determined and an optimum cell configuration was established. This process could be used by fuel cell designers to better predict the effect of various changes on fuel cell performance, thereby facilitating the design of more efficient cells.</jats:p>

Harmanjeet Shihn, Ramesh K. Shah

1st International Fuel Cell Science, Engineering and Technology Conference • 2003

<jats:p>This paper presents a framework for the system integration and optimization of a molten carbonate fuel cell (MCFC) working under stationary conditions using process integration. Here, the analysis is focused on two systems in terms of the efficiency and process requirements: (i) an MCFC system alone and (ii) an MCFC system integrated with the steam turbine cycle, now onwards referred to as fuel cell combined cycle system for electric power generation. In the first system, a steady state direct internal reforming MCFC system is being simulated using desulphurized natural gas. A heat exchanger network is developed using process integration so that a minimum amount of external thermal energy is provided to the fuel cell system for electric power generation. In the second analysis, a steam turbine system is added to the first (fuel cell) one to form a fuel cell combined cycle system. The procedure for developing a network of heat exchangers and proper integration of the steam turbine system with an optimized minimum temperature difference is discussed. The results of the study elucidate the advantages of properly designed fuel cell combined cycle system to reach power demand with 17% higher efficiency as compared with the system without a combined cycle.</jats:p>

Ling Jun Tan, Chen Yang, Nana Zhou

Journal of Fuel Cell Science and Technology • 2014

<jats:p>A hybrid system that combines a solid oxide fuel cell (SOFC) with a proton exchange membrane fuel cell (PEMFC) is presented in this paper. The SOFC stack acts as both an electricity producer and the fuel reformer for the PEMFC stack to generate additional power. A thermoeconomic model for the design optimization of a 220 kW SOFC-PEMFC hybrid system is developed in this work. Optimization of two objectives, i.e., the life cycle cost and the net electrical efficiency, are considered individually to find the optimum system configuration and component designs. Then, a multiparameter sensitivity analysis is performed to estimate the relative importance of the decision variables on the objectives. The optimization results indicate that the life cycle cost of the hybrid system is 3800–5,600 $/kW, and the maximum net electrical efficiency can reach around 63%, which is higher than an SOFC-only system, a reformer-PEMFC system, and an SOFC-gas turbine (GT) system with a similar output power. The sensitivity analysis shows that minimizing the size of the SOFC is most crucial to the system cost optimization. The hydrogen utilization factor in the SOFC is found to be sensitive to the net electrical efficiency.</jats:p>

Narelle K Bradford, L. Caffery, Anthony C. Smith

Rural and Remote Health • 2016

INTRODUCTION With the escalating costs of health care, issues with recruitment and retention of health practitioners in rural areas, and poor economies of scale, the question of delivering people to services or services to people is a dilemma for health authorities around the world. People living in rural areas have poorer health outcomes compared to their urban counterparts, and the problem of how to provide health care and deliver services in rural locations is an ongoing challenge. Telehealth services can efficiently and effectively improve access to healthcare for people living in rural and remote areas of Australia. However, telehealth services are not mainstream or routinely available in many rural and remote locations. The barriers to integration of telehealth into mainstream practice have been well described, but not the factors that may influence the success and sustainability of a service. Our aim was to collate, review and synthesise the available literature regarding telehealth services in rural and remote locations of Australia, and to identify the factors associated with their sustained success. METHODS A systematic literature review of peer-reviewed and grey literature was undertaken. Electronic databases were searched for potentially relevant articles. Reference lists of retrieved articles and the grey literature were also searched. Searches identified 970 potentially eligible articles published between 1988 and 2015. Studies and manuscripts of any type were included if they described telehealth services (store-and-forward or real-time videoconferencing) to provide clinical service or education and training related to health care in rural or remote locations of Australia. Data were extracted according to pre-defined criteria and checked for completeness and accuracy by a second reviewer. Any disagreements were resolved with discussion with a third researcher. All articles were appraised for quality and levels of evidence. Data were collated and grouped into categories including clinical speciality, disciplines involved, geographical location and the role of the service. Data relating to the success or sustainability of services were grouped thematically. RESULTS Inclusion criteria were met by 116 articles that described 72 discrete telehealth services. Telehealth services in rural and remote Australia are described and we have identified six key factors associated with the success and sustainability of services: vision, ownership, adaptability, economics, efficiency and equipment. CONCLUSIONS Telehealth has the potential to address many of the key challenges to providing health in Australia, with its substantial land area and widely dispersed population. This review collates information regarding the telehealth services in Australia and describes models of care and characteristics of successful and sustainable services. We identified a wide variety of telehealth services being provided in rural and remote areas of Australia. There is great potential to increase this number by scaling up and replicating successful services. This review provides information for policy makers, governments and public and private health services that wish to integrate telehealth into routine practice and for telehealth providers to enhance the sustainability of their service.

Phillip M. Hughes, Genevieve Verrastro, C. Fusco et al.

The Journal of Rural Health • 2021

Abstract Purpose Tracking changes in care utilization of medication for opioid use disorder (MOUD) services before, during, and after COVID‐19‐associated changes in policy and service delivery in a mixed rural and micropolitan setting. Methods Using a retrospective, open‐cohort design, we examined visit data of MOUD patients at a family medicine clinic across three identified periods: pre‐COVID, COVID transition, and COVID. Outcome measures include the number and type of visits (in‐person or telehealth), the number of new patients entering treatment, and the number of urine drug screens performed. Distance from patient residence to clinic was calculated to assess access to care in rural areas. Goodness‐of‐Fit Chi‐Square tests and ANOVAs were used to identify differences between time periods. Findings Total MOUD visits increased during COVID (436 pre vs. 581 post, p < 0.001), while overall new patient visits remained constant (33 pre vs. 29 post, p = 0.755). The clinic's overall catchment area increased in size, with new patients coming primarily from rural areas. Length of time between urine drug screens increased (21.1 days pre vs. 43.5 days post, p < 0.001). Conclusions The patterns of MOUD care utilization during this period demonstrate the effectiveness of telehealth in this area. Policy changes allowing for MOUD to be delivered via telehealth, waiving the need for in‐person initiation of MOUD, and increased Medicaid compensation for MOUD may play a valuable role in improving access to MOUD during the COVID‐19 pandemic and beyond.

Jamey J. Lister, P. J. Joudrey

The Journal of Rural Health • 2022

The drug overdose epidemic and Coronavirus Disease of 2019 (COVID-19) pandemic diminished the health of rural* communities in theUnited States, and their interaction had harmful synergistic effects. However, many rural residents mistrust public health interventions.1 We are health services researchers who grew up in the rural Midwest, with viewpoints informed by different disciplines (social work and general internal medicine). Over our lifetime, we witnessed the accumulation of mistrust of health care institutions among residents of our home communities. The issue of mistrust is so deep that friends, family, and community leaders question our expertise after relocating to academic jobs in urban communities. As such, we believe the only sustainableway to improve adoption of public health interventions in rural communities requires acknowledgment of the longstanding pattern of health care divestment in rural areas and creation of long-lasting partnerships between the health care system and rural communities. Conversely, solutions that seek to solve this issue with short-term remedies only represent a continuance of the norm, and in the eyes of rural residents, will be unlikely to dismantle mistrust that has grown over generations. To illustrate the impact of mistrust on health, we focus on how this issue affects 2 current public health interventions, medications for opioid use disorder (MOUD) (buprenorphine, methadone, and extended-release naltrexone) and COVID-19 vaccines, both of which reduce mortality and promote health. Leading health care institutions, like the Centers for Disease Control and Prevention2 and the Sub-

Xiaodong Zhao, Xiaorui Qin, Xiuqing Jing et al.

Biotechnology for Biofuels and Bioproducts • 0

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p>Soil microbial fuel cells (MFCs) can remove antibiotics and antibiotic resistance genes (ARGs) simultaneously, but their removal mechanism is unclear. In this study, metagenomic analysis was employed to reveal the functional genes involved in degradation, electron transfer and the nitrogen cycle in the soil MFC.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>The results showed that the soil MFC effectively removed tetracycline in the overlapping area of the cathode and anode, which was 64% higher than that of the control. The ARGs abundance increased by 14% after tetracycline was added (54% of the amplified ARGs belonged to efflux pump genes), while the abundance decreased by 17% in the soil MFC. Five potential degraders of tetracycline were identified, especially the species <jats:italic>Phenylobacterium zucineum,</jats:italic> which could secrete the 4-hydroxyacetophenone monooxygenase encoded by EC 1.14.13.84 to catalyse deacylation or decarboxylation. <jats:italic>Bacillus</jats:italic>, <jats:italic>Geobacter</jats:italic>, <jats:italic>Anaerolinea</jats:italic>, <jats:italic>Gemmatirosa kalamazoonesis</jats:italic> and <jats:italic>Steroidobacter denitrificans</jats:italic> since ubiquinone reductase (encoded by EC 1.6.5.3), succinate dehydrogenase (EC 1.3.5.1), Coenzyme Q-cytochrome c reductase (EC 1.10.2.2), cytochrome-c oxidase (EC 1.9.3.1) and electron transfer flavoprotein-ubiquinone oxidoreductase (EC 1.5.5.1) served as complexes I, II, III, IV and ubiquinone, respectively, to accelerate electron transfer. Additionally, nitrogen metabolism-related gene abundance increased by 16% to support the microbial efficacy in the soil MFC, and especially EC 1.7.5.1, and coding the mutual conversion between nitrite and nitrate was obviously improved.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The soil MFC promoted functional bacterial growth, increased functional gene abundance (including nitrogen cycling, electron transfer, and biodegradation), and facilitated antibiotic and ARG removal. Therefore, soil MFCs have expansive prospects in the remediation of antibiotic-contaminated soil. This study provides insight into the biodegradation mechanism at the gene level in soil bioelectrochemical remediation.</jats:p> </jats:sec>

A. Tunik, M. Tolstoy

IOP Conference Series: Materials Science and Engineering • 2017

A new type of a complex mobile independent power station developed in the Department of Engineering Communications and Life-Support Systems of Irkutsk National Research Technical University, is presented in this article. This station contains only solar panel, wind turbine, accumulator, diesel generator and microbial fuel cell for to produce electric energy, heat pump and solar collector to generate heat energy and also wastewater treatment plant and new complex control system. The complex mobile independent power station is intended for full power supply of a different kind of consumers located even in remote areas thus reducing their dependence from centralized energy supply systems, decrease the fossil fuel consumption, improve the environment of urban areas and solve the problems of the purification of industrial and municipal wastewater.

Egide Kalisa, S. Archer, Edward G. Nagato et al.

International Journal of Environmental Research and Public Health • 2019

Aerosolized particulate matter (PM) is a complex mixture that has been recognized as the greatest cause of premature human mortality in low- and middle-income countries. Its toxicity arises largely from its chemical and biological components. These include polycyclic aromatic hydrocarbons (PAHs) and their nitro-derivatives (NPAHs) as well as microorganisms. In Africa, fossil fuel combustion and biomass burning in urban settings are the major sources of human exposure to PM, yet data on the role of aerosols in disease association in Africa remains scarce. This review is the first to examine studies conducted in Africa on both PAHs/NPAHs and airborne microorganisms associated with PM. These studies demonstrate that PM exposure in Africa exceeds World Health Organization (WHO) safety limits and carcinogenic PAHs/NPAHs and pathogenic microorganisms are the major components of PM aerosols. The health impacts of PAHs/NPAHs and airborne microbial loadings in PM are reviewed. This will be important for future epidemiological evaluations and may contribute to the development of effective management strategies to improve ambient air quality in the African continent.

J. Vázquez-Castillo, A. Castillo-Atoche, J. Estrada-López et al.

IEEE Transactions on Instrumentation and Measurement • 2022

In this article, a Kalman framework is proposed for dynamic energy-saving in wireless sensor networks used to monitor urban noise pollution. The energy-saving framework implements a dynamic power management strategy (DPMS) with the Kalman algorithm that varies the sensor node’s sleep period according to the measured noise levels. An Internet-of-Things (IoT) edge-based self-sustaining long-range (LoRa) network is developed and used for ubiquitous monitoring and analysis of urban noise pollution. The network consists of a star topology with six LoRa battery-free wireless sensing nodes deployed in Mérida city downtown, each node powered by a green facade structure consisting of an array of plant-microbial fuel cells (P-MFC). The sensor node’s prototype was implemented following Mexican regulations, transmitting the data packets with the open frequency band of 915 MHz, and monitoring the LoRa network from a web page. Experimental results prove a sustainable operation with a green facade P–MFC array power generation of 112.1 mW with an open-circuit voltage of 2.7 V and a short-circuit current of 180 mA. The sensor node’s average power consumption is 11.2 mW; therefore, sufficient energy is generated for continuous monitoring. The efficient Kalman DPMS is also tested with the urban noise measurement estimation and adjusting the sleep period only if the urban measurement state estimation is above the threshold normativity. The system’s low-power consumption allows to perform 70 continuous LoRa transmissions even when the energy harvester source is absent, and the power capacity of the green facade restores a supercapacitor full charge after only 4 min of a LoRa transmission. A 23.6% of energy was saved with Kalman DPMS in comparison with a continuous measurement system of 10-min uniform-sleep period.

A. Abdel Azim, R. Bellini, A. Vizzarro et al.

Recycling • 2023

E-materials become e-waste once they have been discarded without the intent of reuse. Due to its rich content of metals, among which many are Critical Raw Materials (CRMs), e-waste can be considered an urban mine to exploit and valorise. Common metal refining is performed by energy-intensive processes frequently based on the use of fossil fuel. Bio-metallurgy is a promising alternative for e-waste valorisation based on biological routes of specialised microorganisms able to leach solid-containing metals. Because of the physiology of these microorganisms, microbial leaching can be economically feasible, besides being an environmentally sustainable process. Like Bacteria and Fungi, Archaea are also capable of metal leaching activity, though their potential is underestimated. Among them, the extremophiles are the most studied and applied in the field of metal recovery, while mesophilic species are less common but still of high interest. Here we provide the state of industrial application of bio-metallurgy and report on the state of the art of Archaea exploitation in metal recovery from e-waste. Moreover, we give a special highlight to methanogenic archaea, which are able to convert CO2 into methane in order to highlight the potential for the valorisation of CO2-rich industrial streams generated by key processes (i.e., anaerobic digestion, concrete, and steel production) in CH4 for gas grid distribution, while making metals content in e-waste available again as raw material.

Z. Borjas, J. M. Ortiz, A. Aldaz et al.

Energies • 2015

Microbial electrochemical technologies (METs) constitute the core of a number of emerging technologies with a high potential for treating urban wastewater due to a fascinating reaction mechanism—the electron transfer between bacteria and electrodes to transform metabolism into electrical current. In the current work, we focus on the model electroactive microorganism Geobacter sulfurreducens to explore both the design of new start-up procedures and electrochemical operations. Our chemostat-grown plug and play cells, were able to reduce the start-up period by 20-fold while enhancing chemical oxygen demand (COD) removal by more than 6-fold during this period. Moreover, a filter-press based bioreactor was successfully tested for both acetate-supplemented synthetic wastewater and real urban wastewater. This proof-of-concept pre-pilot treatment included a microbial electrolysis cell (MEC) followed in time by a microbial fuel cell (MFC) to finally generate electrical current of ca. 20 A·m−2 with a power of 10 W·m−2 while removing 42 g COD day−1·m−2. The effective removal of acetate suggests a potential use of this modular technology for treating acetogenic wastewater where Geobacter sulfurreducens outcompetes other organisms.

Chennappa Gurikar, H.B. Vandana, B. Netravati et al.

Journal of Pure and Applied Microbiology • 2021

Microbial Fuel Cells (MFCs) are the device that involves bacteria and organic matter, to generate electrical current via bacterial metabolism from a wide range of organic and inorganic substrates. MFCs are novel bioreactors, that convert chemical energy into electrochemical energy through bio-catalysis of various wastes (agriculture, food, households, food processing industries) using microorganisms. MFC is a promising approach that offers direct, clean, green energy generation, ease of waste recyclability, and by-product utilization of different sources. In recent, MFCs research advances related to electrode development and utilization of suitable different rural and urban wastes is a significant interest in the MFC application. Hence in a large-scale application, the MFC concept is one of the effective technologies for the management of different wastes and is simultaneously used for electricity generation to cater to the energy demand in rural or remote areas that are not linked to the electric grid. MFCs help reduce the global energy crisis and reduce the pressure on non-renewable energy resources.

A. Capodaglio, D. Molognoni, Enrico Dallago et al.

The Scientific World Journal • 2013

Application of microbial fuel cells (MFCs) to wastewater treatment for direct recovery of electric energy appears to provide a potentially attractive alternative to traditional treatment processes, in an optic of costs reduction, and tapping of sustainable energy sources that characterizes current trends in technology. This work focuses on a laboratory-scale, air-cathode, and single-chamber MFC, with internal volume of 6.9 L, operating in batch mode. The MFC was fed with different types of substrates. This study evaluates the MFC behaviour, in terms of organic matter removal efficiency, which reached 86% (on average) with a hydraulic retention time of 150 hours. The MFC produced an average power density of 13.2 mW/m3, with a Coulombic efficiency ranging from 0.8 to 1.9%. The amount of data collected allowed an accurate analysis of the repeatability of MFC electrochemical behaviour, with regards to both COD removal kinetics and electric energy production.

Jui-Sheng Chou, Tsung-Chi Cheng, Chi‐Yun Liu et al.

International Journal of Energy Research • 2022

Plant microbial fuel cells (PMFCs) are an emergent green‐energy technology that continuously converts solar energy into electricity. Placing PMFCs on the roofs of urban buildings can help to create green urban environments even as they generate power. The power generation performance of PMFCs is affected by a range of environmental factors, so their power generation capacity is difficult to estimate. To develop an artificial intelligence model to forecast PMFC power generation accurately, relevant results obtained using shallow and deep learning techniques are compared for the first time. Once deep learning techniques had been identified as superior for this purpose, they were used with a bio‐inspired optimization algorithm to dynamically setting the model hyperparameters. The developed model can also be applied to estimate the power generation capacity of PMFC devices in the future. The model was trained using data collected from sensors in a site experiment that was carried out using PMFCs embedded with Chinese pennisetumin (Pennisetum alopecuroides), narrowleaf cattail (Typha angustifolia), dwarf rotala (Rotala rotundifolia), and no plant as a control group. The original data of device parameters, environmental parameters, and the measured power generation of PMFCs in numerical form were applied to train shallow learning and time‐series deep learning models. Meanwhile, the state‐of‐the‐art sliding window technique was used to establish a numerical matrix, which was converted into a 2D image‐like format to represent inputs for deep convolutional neural network (CNN) models. The accuracy in predicting the power generation capacity of PMFC devices showed that EfficientNet, an advanced type of CNN, was the best model among the shallow and deep learning techniques. These analytical results demonstrate the superior performance of deep CNNs in learning image features and their consequent suitability for constructing PMFC power generation forecasting models. To enhance the generalization performance of CNN, a newly developed bio‐inspired optimization algorithm, jellyfish search (JS), was incorporated into this model to determine the optimal hyperparameters, yielding the hybrid JSCNN model. This investigation revealed that the JS optimization algorithm can find better values of hyperparameters of the CNN and stabilize model accuracy. Notably, once the optimal hyperparameters have been obtained using JS, the computation time of the hybrid JSCNN model is shorter than that of the generic CNN model, supporting the need to determine the appropriate hyperparameter values in deep learning. This study is the first to use its particular setup and to offer its particular precautions; it therefore contributes to the body of domain knowledge and practicality of sustainable PMFCs.

Liesje De Schamphelaire, Korneel Rabaey, Pascal Boeckx et al.

Microbial Biotechnology • 2008

<jats:title>Summary</jats:title><jats:p>The benefits of sediment microbial fuel cells (SMFCs) go beyond energy generation for low‐power applications. Aside from producing electrical energy, SMFCs can enhance the oxidation of reduced compounds at the anode, thus bringing about the removal of excessive or unwanted reducing equivalents from submerged soils. Moreover, an SMFC could be applied to control redox‐dependent processes in sediment layers. Several cathodic reactions that may drive these sediment oxidation reactions are examined. Special attention is given to two biologically mediated cathodic reactions, respectively employing an oxygen reduction and a manganese cycle. Both reactions imply a low cost and a high electrode potential and are of interest for reactor‐type MFCs as well as for SMFCs.</jats:p>

RR Rudenko, EE Vasilevich, GO Zhdanova et al.

International Journal of Engineering &amp; Technology • 0

<jats:p>The possibility of using urban sewage sludge from the silt areas of the sewage treatment facilities of the left bank of Irkutsk as a substratum in microbial fuel cells (MFС) was studied. The characteristics of voltage and current intensity generated by the microbiological preparation "Doctor Robik 109" in MFC without taking into account and taking into account the resistance of the external electric circuit are obtained. It is shown that sewage sludge with the addition of peptone and acetate (without the introduction of microorganisms-bioagents) is also capable of generating electricity. Presumably, this is due to the presence in the sewage sludge of a large number of microorganisms and their spores. An increase in the total microbial number in the investigated wastewater sediments supports the above hypothesis. The carried out researches testify to the prospects of using MFC for municipal sewage sludge utilization.  </jats:p>

Que Vo Nguyen Xuan, Hoang Dung Nguyen, Nguyen Xuan Phuong Vo et al.

Nature-Based Solutions for Urban Sustainability • 2025

<jats:title>Abstract</jats:title> <jats:p>A plant–microbial fuel cell (PMFC) is a derived technology of microbial fuel cell technology that integrates plant photosynthesis and rhizosphere microbial metabolism for bioelectricity generation and organic pollutant treatment. With living plants as a structural component, PMFCs can also function as green roofs. Integration of PMFCs in a green roof is a new and innovative approach that has huge scope for sustainable development in urban areas, particularly with tropical climates. Solving of bottlenecks in system configuration and operational optimization are both essential for successful implementation and performance of PMFC–green roofs. Adaptive features of PMFC–green roofs in tropical urban regions include intensive and natural growth media, regular watering with supplementary wastewater sources, and diverse plant adaptation with superior resistance to strong irradiation and toxic pollutants in wastewaters. These critical issues determine the plant vitality and plant–microbe interactions. Plant species adopting C4 carbon fixation and crassulacean acid metabolism are prioritized to achieve high day and night transpiration rates, photosynthetic efficiency, and tolerance capacity to harsh tropical rooftop conditions. Runoff contamination and management of end-of-life disposals are specific concerns to ensure public safety and the full assessment of wastewater amended PMFC–green roofs in tropical urban regions. This chapter describes the working principles underlying PMFC technology and its possibility to integrate into tropical rooftops for a simultaneous wastewater treatment. This chapter also highlights challenges that need to be overcome for large-scale applications of PMFC–green roofs in tropical urban regions.</jats:p>

K. Rabaey

Microbiology Australia • 2009

Wastewater, whether it is domestic or industrial, represents a great opportunity to recover water, energy or chemicals, and nutrients. Today, wastewater treatment is energy-consuming, and does not recover the resources from the wastewater. Bioelectrochemical systems (BESs), which have recently been developed, allow for adequate harvesting of the energy or for the production of high quality chemicals. In this article, the basic principles and opportunities of BESs in the context of wastewater treatment are explained.

Emre Oguz Koroglu, B. Özkaya, A. Çetinkaya

International Journal of Energy Science • 2014

Microbial fuel cells (MFCs) are bioelectrochemical systems which enable the conversion of chemical energy directly into electrical energy with microorganism. Studies focused on using organic materials of waste to increase power production performance. In this study, two different MFC reactors were investigated to produce electricity using domestic wastewater. The highest current and power density were 1385 mA/m 2 and 16 mW/m 2 at Ti-TiO2/Nafion combination with 78% COD removal. Ti-TiO2/CMI7000 assemblies generated 750 mA/m2 of current densities and 5 mW/m2 of power density and HRT of 1 day was found favorable for MFC system.

Juliette Monetti, P. Ledezma, Bernardino Virdis et al.

ACS Omega • 2019

Removal and recovery of nutrients from waste streams is essential to avoid depletion of finite resources and further disruption of the nutrient cycles. Bioelectrochemical systems (BESs) are gaining interest because of their ability to recover nutrients through ion migration across membranes at a low energy demand. This work assesses the feasibility of the concept of nutrient bio-electroconcentration from domestic wastewater, which is a widely available source of nutrients in ionic form, collected via sewer networks and easily accessible at centralized wastewater treatment plants. Here, we demonstrate the limits of a three-chamber BES for the recovery of nutrients from domestic wastewater. Because of low ionic conductivity, the measured current densities did not exceed 2 A m, with corresponding limited nutrient ion recoveries. Moreover, in a 3D electrode, forcing higher current densities through potentiostatic control leads to higher Ohmic losses, resulting in anode potential profiles and runaway currents and potentials, with consequent unwanted water oxidation and disintegration of the graphite electrode. At the current density of 1.9 A m, N removal efficiency of 48.1% was obtained at the anode. However, calcium and magnesium salts precipitated on the anion-exchange membrane, putatively lowering its permselectivity and allowing for migration of cations through it. This phenomenon resulted in low N and K recovery efficiencies (12.0 and 11.5%, respectively), whereas P was not recovered because of precipitation of salts in the concentrate chamber.

Han Gao, Y. Scherson, G. Wells

Environ. Sci.: Processes Impacts • 2014

Conventional biological wastewater treatment processes are energy-intensive endeavors that yield little or no recovered resources and often require significant external chemical inputs. However, with embedded energy in both organic carbon and nutrients (N, P), wastewater has the potential for substantial energy recovery from a low-value (or no-value) feedstock. A paradigm shift is thus now underway that is transforming our understanding of necessary energy inputs, and potential energy or resource outputs, from wastewater treatment, and energy neutral or even energy positive treatment is increasingly emphasized in practice. As two energy sources in domestic wastewater, we argue that the most suitable way to maximize energy recovery from wastewater treatment is to separate carbon and nutrient (particularly N) removal processes. Innovative anaerobic treatment technologies and bioelectrochemical processes are now being developed as high efficiency methods for energy recovery from waste COD. Recently, energy savings or even generation from N removal has become a hotspot of research and development activity, and nitritation-anammox, the newly developed CANDO process, and microalgae cultivation are considered promising techniques. In this paper, we critically review these five emerging low energy or energy positive bioprocesses for sustainable wastewater treatment, with a particular focus on energy optimization in management of nitrogenous oxygen demand. Taken together, these technologies are now charting a path towards to a new paradigm of resource and energy recovery from wastewater.

A. S. Mathuriya, Shashank Bajpai, S. Giri

Journal of Biochemical Technology • 2015

Microbial fuel cells are the bioelectrochemical systems which convert chemical energy of chemical compounds into electricity by catalytic aid of microorganisms. Plant microbial fuel cells are the fuel cells which apply plants in any way to assist electricity generation. In present study, a house plant Epipremnum aureum was used in cathodic chamber of two chamber microbial fuel cell designed to treat wastewater. The performance of plant microbial fuel cell was compared with conventional microbial fuel cell. E. aureum efficiently provided oxygen in cathode chamber and t he resulting plant microbial fuel cell system showed remarkable performance during sunlight. Present system shows an alternative of mechanical aeration or mediator in cathodic chamber. Normal 0 false false false EN-IN X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

A. Escapa, M. San-Martín, A. Morán

Frontiers in Energy Research • 2014

Globally, large amounts of electrical energy are spent every year for domestic wastewater (dWW) treatment. In the future, energy prices are expected to rise as the demand for energy resources increases and fossil fuel reserves become depleted. By using appropriate technologies, the potential chemical energy contained in the organic compounds present in dWWs might help to improve the energy and economic balance of dWW treatment plants. Bioelectrochemical Systems (BESs) in general and microbial electrolysis cells (MECs) in particular represent an emerging technology capable of harvesting part of this energy. This study offers an overview of the potential of using MEC technology in dWW treatment plants (dWWTPs) to reduce the energy bill. It begins with a brief account of the basics of BESs, followed by an examination of how MECs can be integrated in dWW treatment plants (dWWTPs), identifying scaling-up bottlenecks and estimating potential energy savings. A simplified analysis showed that the use of MEC technology may help to reduce up to ~20% the energy consumption in a conventional dWWTP. The study concludes with a discussion of the future perspectives of MEC technology for dWW treatment. The growing rates of municipal water and wastewater treatment markets in Europe offer excellent business prospects and it is expected that the first generation of MECs could be ready within 1-4 years. However, before MEC technology may achieve practical implementation in dWWTPs, it needs not only to overcome important techno-economic challenges, but also to compete with other energy-producing technologies.

I. Vasiliadou, A. Berná, Carlos Manchon et al.

Frontiers in Energy Research • 2018

Domestic and industrial wastewaters contain organic substrates and nutrients that can be recovered instead of being dissipated by emerging efficient technologies. The aim of this study was to promote bio-hydrogen production and carbon fixation using a mixed culture of purple phototrophic bacteria (PPB) that use infrared radiation in presence or absence of an electrode as electron donor. In order to evaluate the hydrogen production under electrode-free conditions, batch experiments were conducted using different nitrogen (NH4Cl, Na-glutamate, N2 gas) and carbon sources (malic-, butyric-, acetic- acids) under various COD:N ratios. Results suggested that the efficiency of PPB to produce biogenic H2 was highly dependent on the substrates used. The maximum hydrogen production (H2_max, 423 mLH2/L) and production rate (H2_rate, 2.71 mLH2/Lh) were achieved using malic acid and Na-glutamate at a COD:N ratio of 100:15. Under these optimum conditions, a significant fixation of nitrogen in form of single-cell proteins (874.4 mg/L) was also detected. Under bio-electrochemical conditions using a H-cell bio-electrochemical device, the PPB were grown planktonic in the bio-cathode chamber with the optimum substrate ratio of malic acid and Na-glutamate. A redox potential of -0.5 V (vs Ag/AgCl) under bio-electrochemical conditions produced comparable amounts of bio-hydrogen but significantly negligible traces of CO2 as compared to the biological system (11.8 mLCO2/L). This suggests that PPB can interact with the cathode to extract electrons for further CO2 re-fixation (coming from the TCA cycle) into the Calvin cycle, thereby improving the C usage. It has also been observed during cyclic voltammograms that a redox potential of -0.8 V favours considerably the electrons consumption by the PPB culture, suggesting that the PPB can use these electrons to increase the biohydrogen production. These results are expected to prove the feasibility of stimulating PPB through bio-electrochemical processes in the production of H2 from wastewater resources, which is a field of special novelty and still unexplored.

N'dah Joel Koffi, S. Okabe

SSRN Electronic Journal • 2022

Performances of anodic ammonia oxidation have been investigated for various bioelectrochemical systems at a wide range of poised anodic potentials in the literature. The effect of poised cathodic potential on ammonium nitrogen (NH4+-N) and total nitrogen (TN, sum of NH4+-N, NO2--N, and NO3--N) removal from domestic wastewater by single chamber air-cathode microbial fuel cells (MFCs) was investigated. Poising the air-cathode potential at + 0.7 V vs. SHE significantly increased current generation (from 11 ± 1 mA to 22.8 ± 5 mA) and oxygen permeation into the MFC through the air-cathode (from 75.4 ± 1.2 g-O2/m3/d to 151 ± 3.7 g-O2/m3/d), which consequently resulted in a high NH4+-N removal rate of 150 ± 13 g-NH4+-N/m3/d and TN removal rate of 63 ± 16 g-TN/m3/d. These high NH4+-N and TN removal rates could be attributed to the enhancement of dual respiratory pathways: the electrode-assisted anodic and aerobic NH4+ oxidation.

Marshall D. McDaniel, L. Tiemann, A. S. Grandy

Ecological Applications • 2014

Our increasing dependence on a small number of agricultural crops, such as corn, is leading to reductions in agricultural biodiversity. Reductions in the number of crops in rotation or the replacement of rotations by monocultures are responsible for this loss of biodiversity. The belowground implications of simplifying agricultural plant communities remain unresolved; however, agroecosystem sustainability will be severely compromised if reductions in biodiversity reduce soil C and N concentrations, alter microbial communities, and degrade soil ecosystem functions as reported in natural communities. We conducted a meta-analysis of 122 studies to examine crop rotation effects on total soil C and N concentrations, and the faster cycling microbial biomass C and N pools that play key roles in soil nutrient cycling and physical processes such as aggregate formation. We specifically examined how rotation crop type and management practices influence C and N dynamics in different climates and soil types. We found that adding one or more crops in rotation to a monoculture increased total soil C by 3.6% and total N by 5.3%, but when rotations included a cover crop (i.e., crops that are not harvested but produced to enrich the soil and capture inorganic N), total C increased by 8.5% and total N 12.8%. Rotations substantially increased the soil microbial biomass C (20.7%) and N (26.1%) pools, and these overwhelming effects on microbial biomass were not moderated by crop type or management practices. Crop rotations, especially those that include cover crops, sustain soil quality and productivity by enhancing soil C, N, and microbial biomass, making them a cornerstone for sustainable agroecosystems.

Xiancan Zhu, Luying Sun, F. Song et al.

European Journal of Soil Science • 2018

Sustainable agricultural management practices improve soil processes, prevent soil erosion and consequently enhance crop productivity. The integrated agricultural practice (IP) developed in northeast China, by altering row spacing of planting, adopting no‐tillage and returning all crop residues, showed great benefit in sustaining crop yield. However, its effect on the soil microbiome remains largely elusive. This study evaluated the effect of 12‐year integrated agricultural practice on the structure and activity of the soil microbial community at different soil depths in China's Mollisols zone. The experiment consisted of integrated agricultural practice and conventional practice (CP) treatments in a split‐plot arrangement. The soil microbial community was characterized by MiSeq sequencing. The results showed that agricultural practices affected 12 phyla, 24 classes, 32 orders and 75 families in the bacterial community and one phyla, four classes, 12 orders and 18 families in the fungal community. Integrated agricultural practice resulted in greater bacterial richness and diversity, and increased the relative abundances of Actinobacteria, Gemmatimonadetes, Verrucomicrobia and Ascomycota, but reduced Bacteroidetes, Firmicutes and Basidiomycota in the dominant bacterial and fungal phyla. These findings suggested that integrated agricultural practice modified the soil physiochemical properties and consequently altered microbial community structure and diversity, which in turn affected soil microbial biomass and enzyme activities. These changes under integrated agricultural practice could have contributed to the enhanced crop yield, suggesting that IP is a sustainable agricultural practice.

Qian Zhang, Junjun Wu, Fan Yang et al.

Scientific Reports • 2016

The effect of agricultural land use change on soil microbial community composition and biomass remains a widely debated topic. Here, we investigated soil microbial community composition and biomass [e.g., bacteria (B), fungi (F), Arbuscular mycorrhizal fungi (AMF) and Actinomycete (ACT)] using phospholipid fatty acids (PLFAs) analysis, and basal microbial respiration in afforested, cropland and adjacent uncultivated soils in central China. We also investigated soil organic carbon and nitrogen (SOC and SON), labile carbon and nitrogen (LC and LN), recalcitrant carbon and nitrogen (RC and RN), pH, moisture, and temperature. Afforestation averaged higher microbial PLFA biomass compared with cropland and uncultivated soils with higher values in top soils than deep soils. The microbial PLFA biomass was strongly correlated with SON and LC. Higher SOC, SON, LC, LN, moisture and lower pH in afforested soils could be explained approximately 87.3% of total variation of higher total PLFAs. Afforestation also enhanced the F: B ratios compared with cropland. The basal microbial respiration was higher while the basal microbial respiration on a per-unit-PLFA basis was lower in afforested land than adjacent cropland and uncultivated land, suggesting afforestation may increase soil C utilization efficiency and decrease respiration loss in afforested soils.

Amir Khan, Ajay Veer Singh, S. Gautam et al.

Frontiers in Plant Science • 2023

Addressing the pressing issues of increased food demand, declining crop productivity under varying agroclimatic conditions, and the deteriorating soil health resulting from the overuse of agricultural chemicals, requires innovative and effective strategies for the present era. Microbial bioformulation technology is a revolutionary, and eco-friendly alternative to agrochemicals that paves the way for sustainable agriculture. This technology harnesses the power of potential microbial strains and their cell-free filtrate possessing specific properties, such as phosphorus, potassium, and zinc solubilization, nitrogen fixation, siderophore production, and pathogen protection. The application of microbial bioformulations offers several remarkable advantages, including its sustainable nature, plant probiotic properties, and long-term viability, positioning it as a promising technology for the future of agriculture. To maintain the survival and viability of microbial strains, diverse carrier materials are employed to provide essential nourishment and support. Various carrier materials with their unique pros and cons are available, and choosing the most appropriate one is a key consideration, as it substantially extends the shelf life of microbial cells and maintains the overall quality of the bioinoculants. An exemplary modern bioformulation technology involves immobilizing microbial cells and utilizing cell-free filters to preserve the efficacy of bioinoculants, showcasing cutting-edge progress in this field. Moreover, the effective delivery of bioformulations in agricultural fields is another critical aspect to improve their overall efficiency. Proper and suitable application of microbial formulations is essential to boost soil fertility, preserve the soil’s microbial ecology, enhance soil nutrition, and support crop physiological and biochemical processes, leading to increased yields in a sustainable manner while reducing reliance on expensive and toxic agrochemicals. This manuscript centers on exploring microbial bioformulations and their carrier materials, providing insights into the selection criteria, the development process of bioformulations, precautions, and best practices for various agricultural lands. The potential of bioformulations in promoting plant growth and defense against pathogens and diseases, while addressing biosafety concerns, is also a focal point of this study.

M. Glodowska, M. Woźniak

Agricultural Sciences • 2019

For a constantly growing human population, healthy and productive soil is critical for sustainable delivery of agricultural products. The soil microorganisms play a crucial role in soil structure and functioning. They are responsible for soil formation, ecosystem biogeochemistry, cycling of nutrients and degradation of plant residues and xenobiotics. Certain agricultural treatments, such as fertilizers and pesticides applications, crop rotation, or soil amendment addition, influence the composition, abundance and function of bacteria and fungi in the soil ecosystems. Some of these practices have rather negative effects; others can help soil microorganisms by creating a friendlier habitat or providing nutrients. The changes in microbial community structure cannot be fully captured with traditional methods that are limited only to culturable organisms, which represent less than 1% of the whole population. The use of new molecular techniques such as metagenomics offers the possibility to better understand how agriculture affects soil microbiota. Therefore, the main goal of this review is to discuss how common farming practices influence microbial activity in the soil, with a special focus on pesticides, fertilizers, heavy metals and crop rotation. Furthermore, potential practices to mitigate the negative effects of some treatments are suggested and treatments that can beneficially influence soil microbiota are pointed out. Finally, application of metagenomics technique in agriculture and perspectives of developing efficient molecular tools in order to assess soil condition in the context of microbial activities are underlined.

Maëlle Deshoux, S. Sadet-Bourgeteau, Solène Gentil et al.

SSRN Electronic Journal • 2023

Changes in soil microbial communities may impact soil fertility and stability because microbial communities are key to soil functioning by supporting soil ecological quality and agricultural production. The effects of soil amendment with biochar on soil microbial communities are widely documented but studies highlighted a high degree of variability in their responses following biochar application. The multiple conditions under which they were conducted (experimental designs, application rates, soil types, biochar properties) make it difficult to identify general trends. This supports the need to better determine the conditions of biochar production and application that promote soil microbial communities. In this context, we performed the first ever meta-analysis of the biochar effects on soil microbial biomass and diversity (prokaryotes and fungi) based on high-throughput sequencing data. The majority of the 181 selected publications were conducted in China and evaluated the short-term impact (<3 months) of biochar. We demonstrated that a large panel of variables corresponding to biochar properties, soil characteristics, farming practices or experimental conditions, can affect the effects of biochar on soil microbial characteristics. Using a variance partitioning approach, we showed that responses of soil microbial biomass and prokaryotic diversity were highly dependent on biochar properties. They were influenced by pyrolysis temperature, biochar pH, application rate and feedstock type, as wood-derived biochars have particular physico-chemical properties (high C:N ratio, low nutrient content, large pores size) compared to non-wood-derived biochars. Fungal community data was more heterogenous and scarcer than prokaryote data (30 publications). Fungal diversity indices were rather dependent on soil properties: they were higher in medium-textured soils, with low pH but high soil organic carbon. Altogether, this meta-analysis illustrates the need for long-term field studies in European agricultural context for documenting responses of soil microbial communities to biochar application under diverse conditions combining biochar types, soil properties and conditions of use.

Jing Li, Xueping Wu, M. Gebremikael et al.

PLOS ONE • 2018

Microbial mechanisms associated with soil organic carbon (SOC) decomposition are poorly understood. We aim to determine the effects of inorganic and organic fertilizers on soil labile carbon (C) pools, microbial community structure and C mineralization rate under an intensive wheat-maize double cropping system in Northern China. Soil samples in 0–10 cm layer were collected from a nine-year field trial involved four treatments: no fertilizer, CK; nitrogen (N) and phosphorus (P) fertilizers, NP; maize straw combined with NP fertilizers, NPS; and manure plus straw and NP fertilizers, NPSM. Soil samples were analyzed to determine labile C pools (including dissolved organic C, DOC; light free organic C, LFOC; and microbial biomass C, MBC), microbial community composition (using phospholipid fatty acid (PLFA) profiles) and SOC mineralization rate (from a 124-day incubation experiment). This study demonstrated that the application of chemical fertilizers (NP) alone did not alter labile C fractions, soil microbial communities and SOC mineralization rate from those observed in the CK treatment. Whereas the use of straw in conjunction with chemical fertilizers (NPS) became an additional labile substrate supply that decreased C limitation, stimulated growth of all PLFA-related microbial communities, and resulted in 53% higher cumulative mineralization of C compared to that of CK. The SOC and its labile fractions explained 78.7% of the variance of microbial community structure. Further addition of manure on the top of straw in the NPSM treatment did not significantly increase microbial community abundances, but it did alter microbial community structure by increasing G+/G- ratio compared to that of NPS. The cumulative mineralization of C was 85% higher under NPSM fertilization compared to that of CK. Particularly, the NPSM treatment increased the mineralization rate of the resistant pool. This has to be carefully taken into account when setting realistic and effective goals for long-term soil C stabilization.

Fenghua Wang, Shuaimin Chen, Yuying Wang et al.

Frontiers in Microbiology • 2018

The continuous use of nitrogen (N) fertilizers to increase soil fertility and crop productivity often results in unexpected environmental effects and N losses through biological processes, such as nitrification and denitrification. In this study, multidisciplinary approaches were employed to assess the effects of N fertilization in a long-term (~20 years) field experiment in which a fertilizer gradient (0, 200, 400, and 600 kg N ha−1 yr−1) was applied in a winter wheat-summer maize rotation cropping system in the North China Plain, one of the most intensive agricultural regions in China. The potential nitrification/denitrification rates, bacterial community structure, and abundances of functional microbial communities involved in key processes of the N cycle were assessed during both the summer maize (SM) and winter wheat (WW) seasons. Long-term N fertilization resulted in a decrease in soil pH and an increase in soil organic matter (OM), total N and total carbon concentrations. Potential nitrification/denitrification and the abundances of corresponding functional N cycling genes were positively correlated with the fertilization intensity. High-throughput sequencing of the 16S rRNA gene revealed that the increased fertilization intensity caused a significant decrease of bacterial diversity in SM season, while changed the microbial community composition such as increasing the Bacteroidetes abundance and decreasing Acidobacteria abundance in both SM and WW seasons. The alteration of soil properties markedly correlated with the variation in microbial structure, as soil pH and OM were the most predominant factors affecting the microbial structure in the SM and WW seasons, respectively. Furthermore, consistently with the results of functional gene quantification, functional prediction of microbial communities based on 16S rRNA sequence data also revealed that the abundances of the key nitrificaiton/denitrification groups were elevated by long-term N inputs. Taken together, our results suggested that soil microbial community shifted consistently in both SM and WW seasons toward a higher proportion of N-cycle microbes and exhibited higher N turnover activities in response to long-term elevated N fertilizer. These findings provided new insights into the molecular mechanisms responsible for N loss in intensively N fertilized agricultural ecosystems.

Marie Simonin, Amélie A. M. Cantarel, A. Crouzet et al.

Frontiers in Microbiology • 2018

Metal-oxide nanoparticles (NPs) such as copper oxide (CuO) NPs offer promising perspectives for the development of novel agro-chemical formulations of pesticides and fertilizers. However, their potential impact on agro-ecosystem functioning still remains to be investigated. Here, we assessed the impact of CuO-NPs (0.1, 1, and 100 mg/kg dry soil) on soil microbial activities involved in the carbon and nitrogen cycles in five contrasting agricultural soils in a microcosm experiment over 90 days. Additionally, in a pot experiment, we evaluated the influence of plant presence on the toxicity of CuO-NPs on soil microbial activities. CuO-NPs caused significant reductions of the three microbial activities measured (denitrification, nitrification, and soil respiration) at 100 mg/kg dry soil, but the low concentrations (0.1 and 1 mg/kg) had limited effects. We observed that denitrification was the most sensitive microbial activity to CuO-NPs in most soil types, while soil respiration and nitrification were mainly impacted in coarse soils with low organic matter content. Additionally, large decreases in heterotrophic microbial activities were observed in soils planted with wheat, even at 1 mg/kg for soil substrate-induced respiration, indicating that plant presence did not mitigate or compensate CuO-NP toxicity for microorganisms. These two experiments show that CuO-NPs can have detrimental effects on microbial activities in soils with contrasting physicochemical properties and previously exposed to various agricultural practices. Moreover, we observed that the negative effects of CuO-NPs increased over time, indicating that short-term studies (hours, days) may underestimate the risks posed by these contaminants in soils.