Hui Li, Lin Guang Shao, Yuan Yuan Jiao

Applied Mechanics and Materials • 2014

To reduce the power loss during producing electricity and to improve the efficiency of electron transfer in microbial fuel cell (MFC), now current collector study provide a new direction lead to how to improve its performance. This study uses Titanium mesh (size in 0.45mm×20mesh) as Packing-Type MFC’s current collector, which contains 57.7% pure titanium. The mesh and wire diameter influence its transfer efficiency, that mesh number affects contact resistance while the wire diameter affects conduction resistance.

Bhavi Pandya, Latesh Chaudhari, Naresh R. Vaghela

Electrochem • 2025

The aim of this study was to enhance and maintain bioelectricity generation from distillery spent wash using a microbial fuel cell (MFC). Electrode materials play a critical role in the generation of bioelectricity in MFCs. Utilizing double oxidant-treated carbon felts in MFC applications increased current density to 749.56 mA/m2 and increased peak power density to 125.23 mW/m2. Electrochemical impedance spectroscopy (EIS) analysis further verified the improved electrocatalytic activity observed in the oxidized carbon felt, consistent with the findings from cyclic voltammetry (CV) and polarization curves, thereby confirming the enhanced performance of the oxidized carbon felt electrode. Overall, the study highlights the significance of electrode morphology and surface modifications in influencing microbial adhesion, electron transport, and the overall efficiency of fuel cells using distillery spent wash as a substrate.

Nicu Bizon, Phatiphat Thounthong

Mathematics • 2020

Two Hybrid Power System (HPS) topologies are proposed in this paper based on the Renewable Energy Sources (RESs) and a Fuel Cell (FC) system-based backup energy source. Photovoltaic arrays and wind turbines are modeled as RESs power flow. Hydrogen and air needed for FC stack to generate the power requested by the load are achieved through the Load-Following control loop. This control loop will regulate the fueling flow rate to load level. A real-time optimization strategy for RES/FC HPS based on Extremum Seeking Control will find the Maximum Efficiency Point or best fuel economy point by control of the boost converter. Therefore, two HPS configurations and associated strategies based on Load-Following and optimization loops of the fueling regulators were studied here and compared using the following performance indicators: the FC net power generated on the DC bus, the FC energy efficiency, the fuel consumption efficiency, and the total fuel consumption. An increase in the FC system’s electrical efficiency and fuel economy of up to 2% and 12% respectively has been obtained using the proposed optimization strategies compared with a baseline strategy.

Ramesh Kumar Tripathi, Jeetendra Prasad

INTERNATIONAL CONFERENCE ON POWER ELECTRONICS & SUSTAINABLE DEVELOPMENT (ICPESD) • 2022

Sediment microbial fuel cell (SMFC) generates a very low voltage which enables to power the electronics device. A power management system (PMS) has been implemented to extract energy from SMFC to provide power in a remote location. A Dc-Dc boost converter and a super capacitor are used in PMS. Eight SMFCs are implemented in the laboratory and are connected them in the series-parallel electrical connection. The energy obtained from stack SMFC is stored in the super capacitor. The energy stored in the super capacitor is applied to drive a Dc-Dc converter. The advantage of introducing the super capacitor in between the stack SMFC and the converter is that it provides a constant input voltage for the Dc-Dc converter. Two separate experiments are performed for the 6 V and 21.40 V. This PMS is able to drive a high voltage electronic device. The presented PMS system with SMFC is sustainable, self-powered, maintenance-free, and environment-friendly, which can be used in a remote location.

Θεόφιλος Καμπερίδης

• 2023

Η μικροβιακή κυψελίδα καυσίμου (MΚΚ) είναι ένα ηλεκτροχημικό σύστημα σχεδιασμένο για την επεξεργασία λυμάτων, με ταυτόχρονη παραγωγή ηλεκτρικού ρεύματος. Η χημική ενέργεια που περιέχεται σε ένα οργανικό απόβλητο μετατρέπεται σε ηλεκτρική ενέργεια μέσω ηλεκτροχημικά ενεργών μικροοργανισμών. Οι ΜΚΚ αποτελούνται από μια άνοδο όπου ο δότης ηλεκτρονίων (οργανικά λύματα) οξειδώνεται και μια κάθοδο όπου ένας δέκτης ηλεκτρονίων ανάγεται. Οι διατάξεις ΜΚΚ μπορούν να χωριστούν με βάση την παρουσία ενός θαλάμου καθόδου σε MFC διπλού θαλάμου και ενός θαλάμου. Σε αυτή την διατριβή, κατασκευάστηκαν και λειτουργήθηκαν ΜΚΚ ενός θαλάμου, τεσσάρων καθοδικών ηλεκτροδίων (αναγωγή οξυγόνου), χρησιμοποιώντας μια ποικιλία οικονομικά αποδοτικών υλικών. Αρχικά, διεξήχθησαν πειράματα χρησιμοποιώντας συνθετικό απόβλητο γλυκόζης, προκειμένου να συγκριθεί η απόδοση των διαφορετικών συνδυασμών υλικών. Η υψηλότερη πυκνότητα ισχύος που επιτεύχθηκε από μια ΜΚΚ ενός θαλάμου ήταν 14,2 W/m3, με κόκκους γραφίτη και μια ράβδο γραφίτη ως άνοδο και τέσσερα ηλεκτρόδια καθόδου (Plexiglas – Gore-Tex – MnO2). Αξιοσημείωτα αποτελέσματα λήφθηκαν από την ΜΚΚ που λειτούργησε με κεραμεικά ηλεκτρόδια καθόδου (Mullite – MnO2) και κόκκους γραφίτη με ράβδο γραφίτη ως άνοδο, με μέγιστη ισχύ 5,5 W/m3.Στη συνέχεια, οι κυψελίδες ενός θαλάμου που πέτυχαν την καλύτερη απόδοση όσον αφορά την πυκνότητα ρεύματος και την αποτελεσματική επεξεργασία των λυμάτων, λειτούργησαν με διαφορετικά υποστρώματα που προέρχονται από οικιακά απορρίμματα τροφίμων. Η επίδραση κάθε πρώτης ύλης στη λειτουργία των ΜΚΚ διερευνήθηκε, χρησιμοποιώντας εκχύλισμα FORBI (Βιομάζα υπολειμμάτων τροφίμων), συμπυκνωμένους ατμούς από αποξηραμένα οικιακά απορρίμματα τροφίμων (συμπύκνωμα), λύματα αντιδραστήρων αναερόβιας χώνευσης (εκροή) και ορό γάλακτος (που προέρχεται από διαδικασία σκοτεινής ζύμωσης). Οι ΜΚΚ ενός θαλάμου λειτούργησαν σε συνθήκες διαλείποντος έργου και συνεχούς λειτουργίας.Επιπλέον, χρησιμοποιήθηκαν ΜΚΚ διπλού θαλάμου για τη διερεύνηση της ανάκτησης βαρέων μετάλλων. Σε αυτή την εργασία εξετάστηκε η ενσωμάτωση της τεχνολογίας ΜΚΚ στην ανάκτηση βαρέων μετάλλων από φωτοβολταϊκά πάνελ (PVP) τέλους κύκλου ζωής (EoL). Μετά από μια προτεινόμενη διαδικασία ανακύκλωσης EoL PVP, η οποία περιελάμβανε μηχανική, θερμική και χημική επεξεργασία των PVP, δημιουργήθηκε ένα χημικό εκχύλισμα που περιέχει τα βαρέα μέταλλα της ηλιακής κυψέλης PVP / λεπτού υμενίου. Αρχικά δοκιμάστηκαν συνθετικά διαλύματα καθόδου που περιείχαν άργυρο και ίνδιο. Στη συνέχεια, το χημικό εκχύλισμα που προέρχεται από 2ης γενιάς EoL PVP χρησιμοποιήθηκε στην κάθοδο MFC, για τη μελέτη της ανάκτησης μετάλλων. Η ανάκτηση αργύρου ήταν υψηλή στις περιπτώσεις που μελετήθηκαν (>93%), με εναποθέσεις αργύρου στο ηλεκτρόδιο της καθόδου και ιζήματα στον θάλαμο της καθόδου. Επιπροσθέτως, η μέγιστη πυκνότητα ισχύος που λήφθηκε ήταν 0,8 W/m3 που αντιστοιχεί σε ρυθμό αναγωγής αργύρου 2,65 g Ag/h/m2. Η ανάκτηση του ινδίου έως και 96% επιτεύχθηκε κατά τη διάρκεια των πειραμάτων με συνθετικά λύματα με ινδίου, με μέγιστη πυκνότητα ισχύος 0,17 W/m3. Από την άλλη πλευρά, κατά την ανάκτηση ινδίου από το χημικό εκχύλισμα PVP EoL 2ης γενιάς, καταγράφηκε υψηλότερη ισχύς εξόδου (3,5 W/m3), με εναποθέσεις ινδίου (οξείδια) στο ηλεκτρόδιο της καθόδου, που αντιστοιχεί σε ανάκτηση 87%. Για να εξεταστεί περαιτέρω η απόδοση των ΜΚΚ αναπτύχθηκε ένα μοντέλο 2D που προσομοιώνει τη λειτουργία μιας MΚΚ διπλού θαλάμου. Η τεχνολογία ΜΚΚ διερευνήθηκε πειραματικά και υπολογιστικά προκειμένου να βελτιστοποιηθεί η απόδοση αυτού του ευεργετικού και φιλικού προς το περιβάλλον τρόπου επεξεργασίας των λυμάτων.

, Carlos Gallardo Bustos

• 2023

La escasez hídrica ha puesto en la mesa nuevos enfoques para la gestión del recurso hídrico, como los sistemas descentralizados que buscan la reutilización de aguas residuales a escala domiciliaria como las aguas grises. Sin embargo, las tecnologías de tratamiento de estas aguas descentralizadas aún deben responder a las nuevas escalas, a diferentes condiciones de operación, a los estándares de calidad y a la sustentabilidad energética. Los Sistemas Bioelectroquímicos, específicamente las Celdas de Combustible Microbioano son sistemas de tratamiento biológicos capaces de oxidar la materia orgánica (MO) disuelta al mismo tiempo que generan electricidad. Esta transformación de energía es debida a la capacidad de microorganismos electroquímicamente activos de transferir electrones metabólicos extracelularmente a un aceptor no soluble (e.g., electrodos). De esta forma, en un reactor bioelectroquímico (BER), el metabolismo de respiración de los microorganismos cambia, y no requieren aireación directa. A pesar de esto, la utilización de BERs combinados con sistemas de filtración de alta adsorción y con propiedades capacitivas como el carbón activado, no ha sido estudiado para el tratamiento directo de aguas grises. Este trabajo estudió el tratamiento de aguas grises sintéticas usando un nuevo BER (4L de capacidad de tratamiento, en duplicado (n=2)) con un diseño escalable y soporte de gránulos de carbón activado (GAC). El rendimiento del BER (i.e., pH, conductividad eléctrica, turbidez y demanda química de oxígeno disuelta de salida (DQOs)) es comparado con un biofiltro de GAC aireado equivalente (BF, n=2). Los reactores fueron operados por 503 días, midiendo la corriente generada por el BER y estudiando el desarrollo de biopelícula mediante microscopía electrónica de barrido y conteo celular con microscopía de epifluorescencia. BERs y BFs reportaron eficiencias de remoción de DQOs estadísticamente similares, superiores al 88% (con afluentes desde 180 a 580 mg/L). Al mismo tiempo, los BERs presentaron niveles de turbiedad efluente estadísticamente similares a los de BFs en un rango de 1.6 ± 1.2 a 4.1 ± 1.2 NTU (Nephelometric Turbidity Unit). Además, los BERs presentan una mayor cantidad de microrganismos sésiles en comparación con los BFs. El rendimiento eléctrico de los BERs con cátodo no aireado presentó un cambio de polarización del sistema junto a densidades de potencia promedio inestables de 44.2 ± 21.2 y 7.0 ± 7.4 mW/m3. En comparación, con cátodo aireado, las densidades de potencia promedio fueron estables con valores de 8.7 ± 1.7 y 8.2 ± 2.2 mW/m3, y con un 16% de aumento en operación de carga/descarga. Al mismo tiempo, los BERs fueron estables en la generación de corriente a pesar de no tener MO en el medio, sugiriendo que estos pueden aprovechar la MO adsorbida en los gránulos, obteniendo así una bio-regeneración de estos sin costos adicionales. En conclusión, los resultados mostraron que los BERs pueden proveer tasas de tratamiento elevadas con un consumo energético neto menor al de un biofiltro aireado convencional, operando de forma robusta y estable en el tiempo, pudiendo ofrecer un tratamiento sustentable para sistema descentralizados aprovechando la recuperación de energía directa, la señal eléctrica para monitoreo y una disminución de costos gracias a la bio-regeneración.

Amandeep Kaur, Jung Rae Kim, Iain Michie et al.

Biosensors & bioelectronics • 2013

Volatile fatty acid (VFA) concentration is one of the most important parameters for monitoring bio-processes such as anaerobic digestion and microbial fuel cells. In this study the correlation between VFA concentration and current/voltage responses and electrochemical properties by using the MFC technology was evaluated. The discrimination between different species of VFA by using two methods i.e., coulombic efficiency and cyclic voltammetry was investigated. Columbic efficiency gave a slow response of greater than 20h, particularly at concentration levels of 20mgl(-1). By using cyclic voltammetry to measure the oxidation peak at a consistent scan rate showed linear correlation to VFA concentration and peak current produced, up to <40mgl(-1)) in a rapid response time of 1-2min. The results presented showed good correlations between the individual VFA species concentration and charge, and also current generated. A MFC based biosensor array was produced capable of measuring individual acetate, propionate and butyrate concentrations with sensitivity down to 5mgl(-1) and up to 40mgl(-1).

Saikat Banerjee, Gymama Slaughter

Scientific reports • 2022

In this work, a low power microcontroller-based near field communication (NFC) interfaced with a flexible abiotic glucose hybrid fuel cell is designed to function as a battery-less glucose sensor. The abiotic glucose fuel cell is fabricated by depositing colloidal platinum (co-Pt) on the anodic region and silver oxide nanoparticles-multiwalled carbon nanotubes (Ag2O-MWCNTs) composite on the cathodic region. The electrochemical behavior is characterized using cyclic voltammetry and chronoamperometry. This glucose hybrid fuel cell generated an open circuit voltage of 0.46 V, short circuit current density of 0.444 mA/cm2, and maximum power density of 0.062 mW/cm2 at 0.26 V in the presence of 7 mM physiologic glucose. Upon device integration of the abiotic glucose hybrid fuel cell with the NFC module, the data from the glucose monitoring system is successfully transmitted to an android application for visualization at the user interface. The cell voltage correlated (r2 = 0.989) with glucose concentration (up to 19 mM) with a sensitivity of 13.9 mV/mM•cm2.

Carlos Sánchez, Paolo Dessì, Maeve Duffy et al.

Biosensors & bioelectronics • 2020

Microbial electrochemistry merges microbiology, electrochemistry and electronics to provide a set of technologies for environmental engineering applications. Understanding the electronic concepts is crucial for effectively adopting these systems, but the importance of electronic circuitry is often overlooked by microbial electrochemistry researchers. This review provides the background on the electronics and electrochemical concepts involved in the study of microorganisms interacting with electricity, and their applications in microbial electrochemical technology (MET). The potentiostat circuitry is described along with its working principles. Electrochemical analyses are presented together with the rational and parameters employed to study MET devices and electroactive microorganisms. Finally, future directions are delineated towards the adoption of MET, and the related electronics, in environmental engineering applications.

Hanan M Abd-Elmabood, Amany I Raafat, El-Sayed A Soliman et al.

Environmental technology • 2021

ABSTRACTThe present work focuses on the synthesis of a proton exchange membrane to be assembled in a microbial fuel cell (MFC) for simultaneous bioelectricity production and domestic wastewater treatment. The indigenous membrane was prepared by ionizing irradiation-induced graft copolymerization of glycidyl methacrylate (GMA) and vinyl acetate (VAc) onto low-density polyethylene and subsequently, the prepared grafted sheets were sulfonated via epoxy ring-opening of PGMA moieties. Parameters affecting the grafting degree were investigated and the prepared membranes were characterized by investigating their structural, thermal, mechanical, and electrical properties. Some physicochemical characteristics including ion exchange capacity, sulfonation density, and proton conductivity were also evaluated. The data confirmed the success of the preparation protocol to obtain a suitable membrane for the proposed application. Moreover, the performance of the assembled MFC was thoroughly investigated through the evaluation of its electrochemical behaviour including cyclic voltammetry, electrochemical impedance spectroscopy, columbic efficiency, and wastewater treatment capability. The sulfonated LDPE-g-P(GMA-co-VAc) membrane of 80% grafting degree shows substantial removal of chemical oxygen demand up to about 90% with columbic efficiency of 10.1%, columbic recovery of 8.7%, rate of energy harvest of 2.1 C/h and power density of 2.72 W m-2. However, the use of 10 mM of KMnO4 as electron acceptor drastically increase the harvested power density to reach 356.4 W m-2.

Falk Harnisch, Stefano Freguia

Chemistry, an Asian journal • 2012

Electroactive microbial biofilms and the microorganisms embedded therein are not only of crucial fundamental interest because they play an important role in redox cycles that occur in nature, they are also attracting increasing attention as key component of microbial bioelectrochemcial systems (BES). In these systems, interconversion of chemical and electrical energy and the associated exchange of electrons between living microbial cells and solid electrodes take place. The fascinating prospects and promise of BES technology have considerably increased the research on electroactive microbial biofilms over recent years. As a consequence, the research community is truly multifaceted, with backgrounds and interests ranging from molecular biology, via chemistry, to engineering. One of the most-important and most-widespread applied electrochemical techniques is cyclic voltammetry (CV). This Focus Review illustrates the power of this electrochemical technique and the versatility of the information that can be gained by its application for the electrochemical freshman. This Review will also pinpoint hurdles in using this technique, especially for the non-electrochemist, and the limitations of present models for data analysis. Because it aims to be a basic introduction, this Review will not discuss the latest intricacies in the field.

Michael Obermaier, Andreas Bauer, Mert Dalkilic et al.

Fuel Cells • 2021

Abstract Fuel cell performance and durability are highly dependent on water management, wherefore wettability properties of the cell's gas diffusion layer (GDL) are important. In this work, we implement a method to determine the GDL wetted surface area, which is based on capacitance measurements by cyclic voltammetry with a pH‐neutral, aqueous electrolyte, to an automotive size fuel cell failure analysis process and demonstrate its benefit. The electrolyte penetrates large pores of the GDL, wherefore, in contrast to the most conventional methods, also inner parts of the GDL are measured. Tenside concentration of the electrolyte and penetration time, polytetrafluoroethylene treatment of the GDL, and properties of the microporous layer highly influence the capacitance values. Thus, the method is sensitive to different GDL morphologies and surface modifications. Different degradation patterns for samples either artificially chemically and mechanically aged or after real‐operation (e.g., prototype vehicle) are detected by the method. For a comprehensive understanding, the obtained results are compared to ex situ degradation analysis data. A comparison to static contact angle measurements, being a state‐of‐the‐art method to determine GDL wettability, reveals a higher sensitivity of the introduced method to detect degradation, in particular, of chemically aged and real‐operation aged GDLs.

Carlos Quintero, Pooja Kesh, Padmaja Shastri et al.

ECS Meeting Abstracts • 2022

Renewable energy sources are required to lessen energy generation's reliance on fossil fuels. Microbial fuel cells (MFC) exploit microbial metabolic processes to oxidize organic matter to generate energy from wastewater; they serve as a low-cost, sustainable form of wastewater management. Despite the development of effective MFCs, low efficiency and power density have prevented their widespread adoption over traditional fuel cells. Modification of MFC electrodes has been investigated as a means to improve their limited power output. Here we assessed the MFC carbon cloth electrodes and compared them to a traditional glassy carbon, and clean carbon cloth. The electrochemical properties of the electrode surfaces were explored using a three electrode cell consisting of a platinum wire counter electrode and Ag/ AgCl/ 1M KCl reference electrode. Electrolyte dependent studies were conducted in phosphate buffered saline (PBS) in the presence of ferri/ferrocyanide. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) of the solution redox couple with various working electrode were performed in order to characterize electrode surface, prior, and post MFC use. The ultimate goal is to optimize the electrode surface chemistry to promote optimal MFC performance.

Agnieszka Cydzik-Kwiatkowska, Dawid Nosek

Energies • 2022

Michael Potter pioneered microbial fuel cell (MFC) technology in 1911 [...]

Xing Xie, Craig Criddle, Yi Cui

Energy & Environmental Science • 2014

Schematic of microbial bioelectrodes with different configurations.

N.T. Baker, L.L. Graham

Microbial Pathogenesis • 2010

Zhihao Yuan, Rajat Nag, Enda Cummins

Journal of Hazardous Materials • 2022

Microplastics (MPs) have been detected globally in the marine environment. MP polymers of various kinds have different toxicity potentials when decomposed into monomers. Also, the toxicity of MPs is influenced by the particle size distribution of MPs. Based on these parameters, a semi-quantitative risk assessment model has been developed in this study to rank MP polymers of potential health concern emerging from marine exposure pathways. A screening strategy was used to categorize three probability factors and two impact factors and calculate the final risk scores. Four different scenarios were assessed to investigate the influence of risk factors on the model output. The screening strategy prioritised PUR, PVC, PAN, ABS, PMMA, SAN, TPU, UP, PET, PS, and HDPE as the top-ranking polymers of concern (descending order). The sensitivity analysis revealed parameters that influenced the final risk score were hazard score based on monomer classification (RF5 coefficient +0.60)> particle size distribution of MPs (RF4 +0.54)> annual global waste generation (RF1 +0.52)> status of degradation in the marine environment (RF3 +0.32)> mean density of polymers (RF2 +0.16). The outcome of this study can inform the scientific community and the policymakers for better management of MPs where regulation and guidelines need to be considered.

Alessandra Cincinelli, Costanza Scopetani, David Chelazzi et al.

The Science of The Total Environment • 2020

Corina P. D. Brussaard, L. Peperzak, Siham Beggah et al.

Nature Communications • 2016

Marine environments are frequently exposed to oil spills as a result of transportation, oil drilling or fuel usage. Whereas large oil spills and their effects have been widely documented, more common and recurrent small spills typically escape attention. To fill this important gap in the assessment of oil-spill effects, we performed two independent supervised full sea releases of 5 m(3) of crude oil, complemented by on-board mesocosm studies and sampling of accidentally encountered slicks. Using rapid on-board biological assays, we detect high bioavailability and toxicity of dissolved and dispersed oil within 24 h after the spills, occurring fairly deep (8 m) below the slicks. Selective decline of marine plankton is observed, equally relevant for early stages of larger spills. Our results demonstrate that, contrary to common thinking, even small spills have immediate adverse biological effects and their recurrent nature is likely to affect marine ecosystem functioning.

Monika Novak Babič, Nina Gunde‐Cimerman, Márta Vargha et al.

International Journal of Environmental Research and Public Health • 2017

Microbiological drinking water safety is traditionally monitored mainly by bacterial parameters that indicate faecal contamination. These parameters correlate with gastro-intestinal illness, despite the fact that viral agents, resulting from faecal contamination, are usually the cause. This leaves behind microbes that can cause illness other than gastro-intestinal and several emerging pathogens, disregarding non-endemic microbial contaminants and those with recent pathogenic activity reported. This white paper focuses on one group of contaminants known to cause allergies, opportunistic infections and intoxications: Fungi. It presents a review on their occurrence, ecology and physiology. Additionally, factors contributing to their presence in water distribution systems, as well as their effect on water quality are discussed. Presence of opportunistic and pathogenic fungi in drinking water can pose a health risk to consumers due to daily contact with water, via several exposure points, such as drinking and showering. The clinical relevance and influence on human health of the most common fungal contaminants in drinking water is discussed. Our goal with this paper is to place fungal contaminants on the roadmap of evidence based and emerging threats for drinking water quality safety regulations.

Stilianos Louca, Florent Mazel, Michael Doebeli et al.

PLoS Biology • 2019

The global diversity of Bacteria and Archaea, the most ancient and most widespread forms of life on Earth, is a subject of intense controversy. This controversy stems largely from the fact that existing estimates are entirely based on theoretical models or extrapolations from small and biased data sets. Here, in an attempt to census the bulk of Earth's bacterial and archaeal ("prokaryotic") clades and to estimate their overall global richness, we analyzed over 1.7 billion 16S ribosomal RNA amplicon sequences in the V4 hypervariable region obtained from 492 studies worldwide, covering a multitude of environments and using multiple alternative primers. From this data set, we recovered 739,880 prokaryotic operational taxonomic units (OTUs, 16S-V4 gene clusters at 97% similarity), a commonly used measure of microbial richness. Using several statistical approaches, we estimate that there exist globally about 0.8-1.6 million prokaryotic OTUs, of which we recovered somewhere between 47%-96%, representing >99.98% of prokaryotic cells. Consistent with this conclusion, our data set independently "recaptured" 91%-93% of 16S sequences from multiple previous global surveys, including PCR-independent metagenomic surveys. The distribution of relative OTU abundances is consistent with a log-normal model commonly observed in larger organisms; the total number of OTUs predicted by this model is also consistent with our global richness estimates. By combining our estimates with the ratio of full-length versus partial-length (V4) sequence diversity in the SILVA sequence database, we further estimate that there exist about 2.2-4.3 million full-length OTUs worldwide. When restricting our analysis to the Americas, while controlling for the number of studies, we obtain similar richness estimates as for the global data set, suggesting that most OTUs are globally distributed. Qualitatively similar results are also obtained for other 16S similarity thresholds (90%, 95%, and 99%). Our estimates constrain the extent of a poorly quantified rare microbial biosphere and refute recent predictions that there exist trillions of prokaryotic OTUs.

Mélanie Beck, Anja Reckhardt, Julia Amelsberg et al.

Marine Chemistry • 2017

Jun-Jie Huang, Kailin Gao, Yang Lü et al.

Environmental Microbiome • 2023

This study revealed a collaborating sequential contribution of microbial taxa and functional genes in the decomposition of straw residues in a paddy soil. Firmicutes with the property of mobility, WLP and cellulose decomposition could be mostly involved in the initial breakdown of straw polymers, while Bacteroidota became abundant and possibly responsible for the decomposition of hemicellulosic polymers during the later stage.

Maïté S. Guignard, Andrew R. Leitch, Claudia Acquisti et al.

Frontiers in Ecology and Evolution • 2017

Nitrogen (N) and/or phosphorus (P) availability can limit growth of primary producers across most of the world’s aquatic and terrestrial ecosystems. These constraints are commonly overcome in agriculture by applying fertilizers to improve yields. However, excessive anthropogenic N and P inputs impact natural environments and have far-reaching ecological and evolutionary consequences, from individual species up to entire ecosystems. The extent to which global N and P cycles have been perturbed over the past century can be seen as a global fertilization experiment with significant redistribution of nutrients across different ecosystems. Here we explore the effects of N and P availability on stoichiometry and genomic traits of organisms, which, in turn, can influence: i) plant and animal abundances; ii) trophic interactions and population dynamics; and iii) ecosystem dynamics and productivity of agricultural crops. We articulate research priorities for a deeper understanding of how bioavailable N and P move through the environment and exert their ultimate impacts on biodiversity and ecosystem services.

Matthew A. Bowker, Sasha C. Reed, Fernando T. Maestre et al.

Plant and Soil • 2018

Sigrid Görgen, Karim Benzerara, Fériel Skouri‐Panet et al.

Discover Materials • 2020

Abstract Although biomineralization of CaCO 3 is widespread in Bacteria and Archaea, the molecular mechanisms involved in this process remain less known than those used by Eukaryotes. A better understanding of these mechanisms is crucial for a broad diversity of studies including those (i) aiming at assessing the role of bacteria in the geochemical cycles of Ca and C, (ii) investigating the process of fossilization, and (iii) engineering applications using bacterially mediated CaCO 3 mineralization. Different types of bacterially-mediated mineralization modes have been distinguished depending on whether they are influenced (by extracellular organic molecules), induced (by metabolic activity) or controlled (by specific genes). In the first two types, mineralization is usually extracellular, while it is intracellular for the two ascertained cases of controlled bacterial mineralization. In this review, we list a large number of cases illustrating the three different modes of bacterially-mediated CaCO 3 mineralization. Overall, this shows the broad diversity of metabolic pathways, organic molecules and thereby microorganisms that can biomineralize CaCO 3 . Providing an improved understanding of the mechanisms involved and a good knowledge of the molecular drivers of carbonatogenesis, the increasing number of (meta)-omics studies may help in the future to estimate the significance of bacterially mediated CaCO 3 mineralization.

Stephanie Dutkiewicz, Anna E. Hickman, Oliver Jahn et al.

Nature Communications • 2019

Monitoring changes in marine phytoplankton is important as they form the foundation of the marine food web and are crucial in the carbon cycle. Often Chlorophyll-a (Chl-a) is used to track changes in phytoplankton, since there are global, regular satellite-derived estimates. However, satellite sensors do not measure Chl-a directly. Instead, Chl-a is estimated from remote sensing reflectance (R RS ): the ratio of upwelling radiance to the downwelling irradiance at the ocean's surface. Using a model, we show that R RS in the blue-green spectrum is likely to have a stronger and earlier climate-change-driven signal than Chl-a. This is because R RS has lower natural variability and integrates not only changes to in-water Chl-a, but also alterations in other optically important constituents. Phytoplankton community structure, which strongly affects ocean optics, is likely to show one of the clearest and most rapid signatures of changes to the base of the marine ecosystem.

Annika Vaksmaa, Simon Guerrero-Cruz, Pooja Ghosh et al.

Frontiers in Marine Science • 2023

Advancements in chemical, medical, cosmetic, and plastic producing industries have improved agricultural yields, health and human life in general. As a negative consequence, a plethora of chemicals are intentionally and unintentionally released to terrestrial and aquatic environments with sometimes devastating effects for entire ecosystems. One mitigation strategy to counteract this pollution is bioremediation. Bioremediation is an umbrella term for biologically mediated processes during which an undesired compound is transformed, degraded, sequestered and/or entirely removed from the ecosystem. Organisms across all domains of life may mediate bioremediation; yet, fungi are particularly promising candidates. They possess metabolic capabilities to break down complex molecules which make fungi the ultimate degraders of recalcitrant organic matter in nature. Bioremediation by fungi, also termed mycoremediation, has been more frequently investigated in terrestrial than aquatic ecosystems, although fungi also thrive in lacustrine and marine environments. Here, we focus on mycoremediation of emerging pollutants in aquatic environments. In this context, we draw parallels between terrestrial and aquatic fungal taxa, and their role in mycoremediation. We discuss the ability of fungi to break-down (i) pesticides, (ii) pharmaceuticals and personal care products, (iii) plastics, both conventional types and (iv) bioplastics, and fungal role, (v) mitigation of heavy metal pollution. Furthermore, we (vi) discuss possible mycoremediation strategies in applied settings and highlight novel enzyme based mycoremediation strategies.

Alain Prinzhofer, Isabelle Moretti, J.B.L. Françolin et al.

International Journal of Hydrogen Energy • 2019

Alexander T. Demetillo, Michelle V. Japitana, Evelyn B. Taboada

Sustainable Environment Research • 2019

In this paper, a low cost, real-time water quality monitoring system which can be applied in remote rivers, lakes, coastal areas and other water bodies is presented. The main hardware of the system consists of off-the-shelf electrochemical sensors, a microcontroller, a wireless communication system and the customized buoy. It detects water temperature, dissolved oxygen and pH in a pre-programmed time interval. The developed prototype disseminates the gathered information in graphical and tabular formats through a customized web-based portal and preregistered mobile phones to better serve relevant end-users. To check the system effectivity, the buoy’s stability in harsh environmental conditions, system energy consumption, data transmission efficiency and web-based display of information were carefully evaluated. The experimental results prove that the system has great prospect and can be practically used for environmental monitoring by providing stakeholders with relevant and timely information for sound decision making.

Bai-Lu Tang, Jie Yang, Xiu‐Lan Chen et al.

Nature Communications • 2020

Predator-prey interactions play important roles in the cycling of marine organic matter. Here we show that a Gram-negative bacterium isolated from marine sediments (Pseudoalteromonas sp. strain CF6-2) can kill Gram-positive bacteria of diverse peptidoglycan (PG) chemotypes by secreting the metalloprotease pseudoalterin. Secretion of the enzyme requires a Type II secretion system. Pseudoalterin binds to the glycan strands of Gram positive bacterial PG and degrades the PG peptide chains, leading to cell death. The released nutrients, including PG-derived D-amino acids, can then be utilized by strain CF6-2 for growth. Pseudoalterin synthesis is induced by PG degradation products such as glycine and glycine-rich oligopeptides. Genes encoding putative pseudoalterin-like proteins are found in many other marine bacteria. This study reveals a new microbial interaction in the ocean.

Vahid Vajihinejad, Sarang P. Gumfekar, Behnaz Bazoubandi et al.

Macromolecular Materials and Engineering • 2018

Abstract Water soluble polymer flocculants are important constituents of solid–liquid separation units for the treatment of a variety of process‐affected effluents. The systematic development of a flocculant relies on a good understanding of flocculation process, polymer synthesis, polymer characterization, and, not the least, flocculation performance assessment as desired for a particular treatment process, all of which are essential to establish meaningful relationships between flocculant microstructure and flocculation efficiency. The aim of this article is to communicate the bigger picture of this research area to the readers. The recent advances in the application of bio/natural, synthetic, and stimuli‐responsive flocculants are reviewed. Then, the basic polymer reaction engineering tools to control the microstructure of flocculants are provided and the techniques for the quantification of flocculant microstructure are concisely discussed. This is followed by a review of the methods used for the characterization of particle‐polymer force measurement, and flocculation/dewatering assessment with attention to the characterization of aggregate structures.

Catarina Cúcio, Aschwin H. Engelen, Rodrigo Costa et al.

Frontiers in Microbiology • 2016

Seagrasses are marine flowering plants growing in soft-body sediments of intertidal and shallow sub-tidal zones. They play an important role in coastal ecosystems by stabilizing sediments, providing food and shelter for animals, and recycling nutrients. Like other plants, seagrasses live intimately with both beneficial and unfavorable microorganisms. Although much is known about the microbiomes of terrestrial plants, little is known about the microbiomes of seagrasses. Here we present the results of a detailed study on the rhizosphere microbiome of seagrass species across the North-eastern Atlantic Ocean: Zostera marina, Zostera noltii, and Cymodocea nodosa. High-resolution amplicon sequencing of 16S rRNA genes showed that the rhizobiomes were significantly different from the bacterial communities of surrounding bulk sediment and seawater. Although we found no significant differences between the rhizobiomes of different seagrass species within the same region, those of seagrasses in different geographical locations differed strongly. These results strongly suggest that the seagrass rhizobiomes are shaped by plant metabolism, but not coevolved with their host. The core rhizobiome of seagrasses includes mostly bacteria involved in the sulfur cycle, thereby highlighting the importance of sulfur-related processes in seagrass ecosystems.

Olivia E. Mosley, Emilie Gios, Murray E. Close et al.

The ISME Journal • 2022

The nitrogen cycle plays a major role in aquatic nitrogen transformations, including in the terrestrial subsurface. However, the variety of transformations remains understudied. To determine how nitrogen cycling microorganisms respond to different aquifer chemistries, we sampled groundwater with varying nutrient and oxygen contents. Genes and transcripts involved in major nitrogen-cycling pathways were quantified from 55 and 26 sites, respectively, and metagenomes and metatranscriptomes were analyzed from a subset of oxic and dysoxic sites (0.3-1.1 mg/L bulk dissolved oxygen). Nitrogen-cycling mechanisms (e.g. ammonia oxidation, denitrification, dissimilatory nitrate reduction to ammonium) were prevalent and highly redundant, regardless of site-specific physicochemistry or nitrate availability, and present in 40% of reconstructed genomes, suggesting that nitrogen cycling is a core function of aquifer communities. Transcriptional activity for nitrification, denitrification, nitrite-dependent anaerobic methane oxidation and anaerobic ammonia oxidation (anammox) occurred simultaneously in oxic and dysoxic groundwater, indicating the availability of oxic-anoxic interfaces. Concurrent activity by these microorganisms indicates potential synergisms through metabolite exchange across these interfaces (e.g. nitrite and oxygen). Fragmented denitrification pathway encoding and transcription was widespread among groundwater bacteria, although a considerable proportion of associated transcriptional activity was driven by complete denitrifiers, especially under dysoxic conditions. Despite large differences in transcription, the capacity for the final steps of denitrification was largely invariant to aquifer conditions, and most genes and transcripts encoding N 2 O reductases were the atypical Sec-dependant type, suggesting energy-efficiency prioritization. Results provide insights into the capacity for cooperative relationships in groundwater communities, and the richness and complexity of metabolic mechanisms leading to the loss of fixed nitrogen.

Jinkiat Chew, Longlong Zhu, Shaun Nielsen et al.

The Science of The Total Environment • 2020

Biochar-based compound fertilizers (BCF) and amendments have proven to enhance crop yields and modify soil properties (pH, nutrients, organic matter, structure etc.) and are now in commercial production in China. While there is a good understanding of the changes in soil properties following biochar addition, the interactions within the rhizosphere remain largely unstudied, with benefits to yield observed beyond the changes in soil properties alone. We investigated the rhizosphere interactions following the addition of an activated wheat straw BCF at an application rates of 0.25% (g·g - 1 soil), which could potentially explain the increase of plant biomass (by 67%), herbage N (by 40%) and P (by 46%) uptake in the rice plants grown in the BCF-treated soil, compared to the rice plants grown in the soil with conventional fertilizer alone. Examination of the roots revealed that micron and submicron-sized biochar were embedded in the plaque layer. BCF increased soil Eh by 85 mV and increased the potential difference between the rhizosphere soil and the root membrane by 65 mV. This increased potential difference lowered the free energy required for root nutrient accumulation, potentially explaining greater plant nutrient content and biomass. We also demonstrate an increased abundance of plant-growth promoting bacteria and fungi in the rhizosphere. We suggest that the redox properties of the biochar cause major changes in electron status of rhizosphere soils that drive the observed agronomic benefits.

Sian F. Henley, Emma L. Cavan, Sarah E. Fawcett et al.

Frontiers in Marine Science • 2020

The Southern Ocean plays a critical role in regulating global climate as a major sink for atmospheric carbon dioxide (CO2), and in global ocean biogeochemistry by supplying nutrients to the global thermocline, thereby influencing global primary production and carbon export. Biogeochemical processes within the Southern Ocean regulate regional primary production and biological carbon uptake, primarily through iron supply, and support ecosystem functioning over a range of spatial and temporal scales. Here we assimilate existing knowledge and present new data to examine the biogeochemical cycles of iron, carbon and major nutrients, their key drivers and their responses to, and roles in, contemporary climate and environmental change. Projected increases in iron supply, coupled with increases in light availability to phytoplankton through increased near-surface stratification and longer ice-free periods, are very likely to increase primary production and carbon export around Antarctica. Biological carbon uptake is likely to increase for the Southern Ocean as a whole, whilst there is greater uncertainty around projections of primary production in the Sub-Antarctic and basin-wide changes in phytoplankton species composition, as well as their biogeochemical consequences. Phytoplankton, zooplankton, higher trophic level organisms and microbial communities are strongly influenced by Southern Ocean biogeochemistry, in particular through nutrient supply and ocean acidification. In turn, these organisms exert important controls on biogeochemistry through carbon storage and export, nutrient recycling and redistribution, and benthic-pelagic coupling. The key processes described in this paper are summarised in the graphical abstract. Climate-mediated changes in Southern Ocean biogeochemistry over the coming decades are very likely to impact primary production, sea-air CO2 exchange and ecosystem functioning within and beyond this vast and critically important ocean region.

Will Steffen, Reinhold Leinfelder, Jan Zalasiewicz et al.

Earth s Future • 2016

Abstract Stratigraphy provides insights into the evolution and dynamics of the Earth System over its long history. With recent developments in Earth System science, changes in Earth System dynamics can now be observed directly and projected into the near future. An integration of the two approaches provides powerful insights into the nature and significance of contemporary changes to Earth. From both perspectives, the Earth has been pushed out of the Holocene Epoch by human activities, with the mid‐20th century a strong candidate for the start date of the Anthropocene, the proposed new epoch in Earth history. Here we explore two contrasting scenarios for the future of the Anthropocene, recognizing that the Earth System has already undergone a substantial transition away from the Holocene state. A rapid shift of societies toward the UN Sustainable Development Goals could stabilize the Earth System in a state with more intense interglacial conditions than in the late Quaternary climate regime and with little further biospheric change. In contrast, a continuation of the present Anthropocene trajectory of growing human pressures will likely lead to biotic impoverishment and a much warmer climate with a significant loss of polar ice.

Julie A. Hope, David M. Paterson, Simon F. Thrush

Journal of Ecology • 2019

Abstract Sediment dwelling, microscopic primary producers, that occupy sediments in the photic zone, are commonly referred to as microphytobenthos (MPB). The MPB are essential components of soft‐sediment systems, but are often overlooked when assessing coastal ecosystem functionality and service delivery. The MPB are involved in several complex interactions and feedback that underpin the delivery of vital ecosystem services. MPB profoundly influence the flow and cycling of carbon and nutrients, such as nitrogen, directly and indirectly underpinning highly productive shallow water marine food webs. The MPB can also stabilize sediments through the formation of biofilms, and significantly improve water quality by mediating the benthic–pelagic coupling of nutrients, sediment and pollutants. The functional role of the MPB is compromised by increasing anthropogenic pressures such as nutrient enrichment, sedimentation, herbicides and emerging contaminants such as microplastic pollution. However, MPB are extremely good at buffering the effects of these land‐sourced stressors at the interface between land and sea. Synthesis . Society often appreciates the final provisioning of goods and services from our coastal marine environments. However, provisioning services are only possible due to the multitude of supporting and regulating services that underpin them. Microphytobenthos (MPB) are central to benthic ecological networks, and contribute to ecosystem service delivery through various pathways. Understanding the critical role of MPB in complex networks is therefore essential to appreciate their importance in ecosystem function and service delivery into the future.

Verena B. Heuer, Fumio Inagaki, Yuki Morono et al.

Science • 2020

Microorganisms in marine subsurface sediments substantially contribute to global biomass. Sediments warmer than 40°C account for roughly half the marine sediment volume, but the processes mediated by microbial populations in these hard-to-access environments are poorly understood. We investigated microbial life in up to 1.2-kilometer-deep and up to 120°C hot sediments in the Nankai Trough subduction zone. Above 45°C, concentrations of vegetative cells drop two orders of magnitude and endospores become more than 6000 times more abundant than vegetative cells. Methane is biologically produced and oxidized until sediments reach 80° to 85°C. In 100° to 120°C sediments, isotopic evidence and increased cell concentrations demonstrate the activity of acetate-degrading hyperthermophiles. Above 45°C, populated zones alternate with zones up to 192 meters thick where microbes were undetectable.

Chuanlun Zhang, Hongyue Dang, Farooq Azam et al.

National Science Review • 2018

ABSTRACT Carbon is a keystone element in global biogeochemical cycles. It plays a fundamental role in biotic and abiotic processes in the ocean, which intertwine to mediate the chemistry and redox status of carbon in the ocean and the atmosphere. The interactions between abiotic and biogenic carbon (e.g. CO2, CaCO3, organic matter) in the ocean are complex, and there is a half-century-old enigma about the existence of a huge reservoir of recalcitrant dissolved organic carbon (RDOC) that equates to the magnitude of the pool of atmospheric CO2. The concepts of the biological carbon pump (BCP) and the microbial loop (ML) shaped our understanding of the marine carbon cycle. The more recent concept of the microbial carbon pump (MCP), which is closely connected to those of the BCP and the ML, explicitly considers the significance of the ocean's RDOC reservoir and provides a mechanistic framework for the exploration of its formation and persistence. Understanding of the MCP has benefited from advanced ‘omics’ and novel research in biological oceanography and microbial biogeochemistry. The need to predict the ocean's response to climate change makes an integrative understanding of the BCP, ML and MCP a high priority. In this review, we summarize and discuss progress since the proposal of the MCP in 2010 and formulate research questions for the future.