Anand Parkash

Journal of Microbial & Biochemical Technology • 2016

The demands of energy in the world continue to accelerate and this triggers the global energy crisis and environmental Pollution. The reliance on fossil fuels (oil and gas) is unsustainable because of its finite, depleting supplies and impact on environment. As a result researchers are focusing on alternative, renewable and carbon neutral energy sources which are necessary for environmental and economic sustainability. MFC is a bioreactor that converts chemical energy present in the organic or inorganic compound substrates to electrical energy through catalytic reactions of microorganisms. Many substrates involve in generating electricity including carbohydrates, proteins, volatile acids, cellulose and wastewaters used as feed in MFC studies. MFC has a wide range of applications, including serving as household electrical generators and powering items such as small portable electronic devices boats, automobiles, electronics in space and self-feeding robots. The construction and analysis of MFCs requires knowledge at both scientific and engineering fields, ranging from microbiology and electrochemistry to materials and environmental engineering. We conclude that for further development of MFC technology a greater focus on the understanding of its components, microbial processes, factors of limitations and designs of the construction the in MFC systems is mandatory, in order to be simplified and large scale system developed; so that it will be cost-effective and to increase electricity production. This paper aimed to review on the current microbiology knowledge in electricity production, the materials and methods used to build the technology and the applications to MFC technology also highlighted.

Sikandar I. Mulla, Han Wang, Qian Sun et al.

Scientific Reports • 2016

Triclosan (TCS) is one of the most widespread emerging contaminants and has adverse impact on aquatic ecosystem, yet little is known about its complete biodegradation mechanism in bacteria. Sphingomonas sp, strain YL-JM2C, isolated from activated sludge of a wastewater treatment plant, was very effective on degrading TCS. Response surface methodology (RSM) was applied to optimize the conditions like temperature and pH. From RSM, the optimal TCS degradation conditions were found to be 30 °C and pH 7.0. Under optimal conditions, strain YL-JM2C completely mineralized TCS (5 mg L(-1)) within 72 h. Gas chromatography-mass spectrometry analysis revealed that 2,4-dichlorophenol, 2-chlorohydroquinone and hydroquinone are three main by-products of TCS. Furthermore, stable isotope experimental results revealed that the (13)C12-TCS was completely mineralized into CO2 and part of heavier carbon ((13)C) of labeled TCS was utilized by strain YL-JM2C to synthesize fatty acids (PLFAs). Cell surface hydrophobicity (CSH) and degradation test results suggested that the strain could enhance degradation capacity of TCS through increasing CSH. In addition, the bacterium also completely degraded spiked TCS (5 mg L(-1)) in wastewater collected from the wastewater treatment plant. Hence, these results suggest that the strain has potential to remediate TCS in the environment.

Kateryna Shchurska, Liudmyla Zubchenko, H. Sobczuk et al.

Innovative Biosystems and Bioengineering • 2019

Background. Microbial fuel cells are devices in which electricity is generated by microorganisms called exoelectrogens. During the process of anaerobic respiration exoelectrogens emit electrons outside the cell. These electrons can be transferred to the anode of biofuel cell via several different mechanisms. Electricity generation in microbial fuel cells depends primarily on the electrochemical activity of the exoelectrogens present in the anode space. Nowadays, the usage of microorganisms, immobilized as biofilms on the anode, is constantly increasing. Natural sources for exoelectrogens selection such as activated sludge, biofilter biofilms, sediments of seas and rivers have a very diverse microbial composition. Therefore, it is important to immobilize relatively deficient in natural sources exoelectrogens on the anode during the biofilm formation process. The main research areas are the development of a technique for obtaining of electroactive biofilms enriched with exoelectrogens along with reduction of the period of biofilm formation process.Objective. We set a goal to study the process of high exoelectrogenic biofilm formation basing on the combination of different methods of exoelectrogens isolation and immobilization at the anode of a microbial fuel cell.Methods. A three-stage technique was used to obtain a highly exoelectrogenic biofilm which, due to the combination of typical isolation and immobilization techniques of exoelectrogens, allows obtaining the biofilm in which the vast majority of microorganisms are exoelectrogens. In the first stage, a biofilter biofilm was used as a source of exoelectrogens. The biofilm formed in the first stage was used as an inoculum for the second stage of biofilm formation. During the second stage an additional selective factor (applied additional potential in the electrical circuit of the microbial fuel cell) was used. The third stage of biofilm formation was the isolation of exoelectrogens capable of reducing ferum (III) compounds from secondary biofilm with subsequent application of these cells as inoculum.Results. The usage of the proposed method allows obtaining of a biofilm enriched with exoelectrogenic bacteria. The maximum current density generated by the biofilm, obtained during the first stage, reaches 140 μA/cm2, during the second – 400 μA/cm2, during the third – 615 μA/cm2. The duration of biofilm formation at each stage was 110 h, 40 h, and 60 h, respectively.Conclusions. It has been proven that the duration of biofilm formation is reduced almost twice as a result of a combination of typical methods of isolation and immobilization of exoelectrogens; obtained biofilm has high electrochemical activity and properties similar to biofilm, formed by pure cultures of exoelectrogens.

Sagar Kumashi, Doohwan Jung, Jong-Seok Park et al.

IEEE Transactions on Biomedical Circuits and Systems • 2021

The paper presents a 256-pixel CMOS sensor array with in-pixel dual electrochemical and impedance detection modalities for rapid, multi-dimensional characterization of exoelectrogens. The CMOS IC has 16 parallel readout channels, allowing it to perform multiple measurements with a high throughput and enable the chip to handle different samples simultaneously. The chip contains a total of 2 × 256 working electrodes of size 44 μm × 52 μm, along with 16 reference electrodes of dimensions 56 μm × 399 μm and 32 counter electrodes of dimensions 399 μm × 106 μm, which together facilitate the high resolution screening of the test samples. The chip was fabricated in a standard 130nm BiCMOS process. The on-chip electrodes are subjected to additional fabrication processes, including a critical Al-etch step that ensures the excellent biocompatibility and long-term reliability of the CMOS sensor array in bio-environment. The electrochemical sensing modality is verified by detecting the electroactive analyte NaFeEDTA and the exoelectrogenic Shewanella oneidensis MR-1 bacteria, illustrating the chip's ability to quantify the generated electrochemical current and distinguish between different analyte concentrations. The impedance measurements with the HEK-293 cancer cells cultured on-chip successfully capture the cell-to-surface adhesion information between the electrodes and the cancer cells. The reported CMOS sensor array outperforms the conventional discrete setups for exoelectrogen characterization in terms of spatial resolution and speed, which demonstrates the chip's potential to radically accelerate synthetic biology engineering.

Keren Yanuka-Golub, Leah Reshef, Judith Rishpon et al.

Bioresource Technology • 2016

Yolina Hubenova, Eleonora Hubenova, Yordan Manasiev et al.

Microbiology Resource Announcements • 2022

Paenibacillus profundus YoMME was isolated from the anodic biofilm of a sediment microbial fuel cell and recognized as one of the few exoelectrogenic Gram-positive bacteria, capable of transferring electrons extracellularly. Here, we report its draft genome sequence. The genome project is deposited at DDBJ/ENA/GenBank under the accession number JAJNBZ000000000.

H. Abu Hassan, Lorenz Schulte-Illingheim, Bo Jin et al.

Procedia Engineering • 2016

The growing critical and toxic wastewater contamination problems seek various sustainable and environmental friendly treatment methods to be further investigated. 2,4-dichlorophenol (2,4-DCP) is one of the recalcitrant and hazardous contaminants normally found in industrial wastewater and in some cases in domestic wastewater as well. This study explored the capability of bacteria Bacillus subtilis to degrade the 2,4-DCP in a double chamber microbial fuel cell (MFC) system. The MFC enables the removal of contaminants by bacteria with concurrent electricity generation through electron transfer mechanisms. B. subtilis is found to be a good exoelectrogenic bacterium for generating an optimum potential of 95 mV with 12 mA/m2 current density in MFC. B. subtilis was able to degrade ∼60% of 2,4-DCP into acceptable simpler metabolites, thus could be further utilized in treating hazardous phenolic contaminants while generating electricity through benign and sustainable wastewater treatment method.

Nadali Alavi, Monireh Majlessi, Nazak Amanidaz et al.

MethodsX • 2022

Many researchers are interested in utilizing renewable and sustainable energy made by exoelectrogenic bacteria during electrodialysis for the separation of minerals and organic matters from aqueous environments. The aim of this study was to develop a novel thermophilic fermenter and dual anion exchange membrane bioelectrochemical system for separating biohydrogen production inhibitors from the thermophilic fermenter and thereby increasing biological and cathodic hydrogen production by food waste and wastewater.•Using this innovative system the biohydrogen production inhibitors were separated and nutrients (for example ammonium), alkalinity, buffering capacity and pH were preserved in the bioreactor at the same time, led to higher biological and cathodic hydrogen production.

Tanya Tschirhart, Eunkyoung Kim, Ryan T. McKay et al.

Nature Communications • 2017

The ability to interconvert information between electronic and ionic modalities has transformed our ability to record and actuate biological function. Synthetic biology offers the potential to expand communication 'bandwidth' by using biomolecules and providing electrochemical access to redox-based cell signals and behaviours. While engineered cells have transmitted molecular information to electronic devices, the potential for bidirectional communication stands largely untapped. Here we present a simple electrogenetic device that uses redox biomolecules to carry electronic information to engineered bacterial cells in order to control transcription from a simple synthetic gene circuit. Electronic actuation of the native transcriptional regulator SoxR and transcription from the PsoxS promoter allows cell response that is quick, reversible and dependent on the amplitude and frequency of the imposed electronic signals. Further, induction of bacterial motility and population based cell-to-cell communication demonstrates the versatility of our approach and potential to drive intricate biological behaviours.

Bhawna Bisht, Jerin James, Waseem Ahmad et al.

Chemical Engineering Journal • 2025

Kingsley Nwagu, I. A. Ekpo, Benjamin Ekaluo et al.

Microbiology and Biotechnology Letters • 2019

In this study we attempted to screen bacteria and fungi that generate electricity while treating wastewater using optimized double-chamber microbial fuel cell (MFC) system parameters. Optimization was carried out for five best exoelectrogenic isolates (two bacteria and three fungi) at pH values of 6.0, 7.5, 8.5, and 9.5, and temperatures of 30, 35, 40, and 45; the generated power densities were measured using a digital multimeter (DT9205A). The isolates were identified using molecular characterization, followed by the phylogenetic analysis of isolates with known exoelectrogenic microorganisms. The bacterium, Proteus species, N6 (KX548358.1) and fungus, Candida parapsilosis, S10 (KX548360) produced the highest power densities of 1.59 and 1.55 W/m 2 (at a pH of 8.5 and temperatures of 35 and 40) within 24 h, respectively. Other fungi-Clavispora lusitaniae, S9 (KX548359.1) at 40, Clavispora lusitaniae, S14 (KX548361.1) at 35-and bacterium-Providencia species, N4 (KX548357.1) at 40-produced power densities of 1.51, 1.46, and 1.44 W/m 2 , respectively within 24 h. The MFCs achieved higher power densities at a pH of 8.5, temperature of 40 within 24 h. The bacterial isolates have a close evolutionary relationship with other known exoelectrogenic microorganisms. These findings helped us determine the optimal pH, temperature, evolutionary relationship, and exoelectrogenic fungal species other than bacteria that enhance MFC performance.

Eduardo Leiva, Enzo Leiva-Aravena, Carolina Rodríguez et al.

The Science of The Total Environment • 2018

C. Li, Tao Li, Fengquan Li et al.

Electroanalysis • 2025

Sediment microbial fuel cells (SMFCs) offer a promising approach for in situ and online pH monitoring, and enhancing their sensitivity is critical for promoting practical application. In this study, the sensors with different anode areas (4, 18, and 81 cm 2 ) and external resistance (50, 1 k, 20 kΩ, and open‐circuit) were constructed in flooded soil. Buffer solutions with pH values ranging from 2.2 to 11.8 were added to the surface of the cathode to simulate acidic and alkaline contaminations. Results showed that the addition of acidic buffer solutions triggered voltage peaks whereas alkaline solutions caused voltage drops. The highest sensitivity was observed with a 20 kΩ resistor and a larger anode area than 4 cm 2 . The two‐way ANOVA confirmed that the factors of the anode area and external resistance were significant ( p < 0.001) for the sensitivity. The repeated contaminations did not alter pH value of soil where the anode was buried, and electrogenic bacteria were enriched on the anode after the operation of the SMFC sensors. As external resistance increases, the relative abundance of exoelectrogenic bacteria‐associated genera (EB‐genera) to total bacteria progressively decreased. Clostridium , Thermincola , Anaeromyxobacter , Acinetobacter , and Desulfitobacterium were the most abundant EB‐genera on the anode.

Yufeng Jiang, Baogang Zhang, Chao He et al.

Water Research • 2018

Amjad Ali, Khulood Fahad Alabbosh, Ahmad Naveed et al.

ACS Omega • 2022

Terpolymerizations of newly synthesized ethylene (E), vinylcyclohexene (VCH), and 1-hexene were carried out with symmetrical metallocene catalysts rac -Me 2 Si(2-Me-4-Ph-Ind) 2 ZrCl 2 (catalyst A) and rac -Et(Ind) 2 ZrCl 2 (catalyst B). X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), high-temperature gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR) spectroscopy were used to evaluate the behavior and microstructure of the polymers. The activity of catalyst B was 1.49 × 10 6 gm/mmol Mt ·h), with a T m of 73.45 (°C) and Δ H m of 43.19 (J/g), while catalyst A produced first higher 1-hexene, 19.6 mol %, and VCH contents with a narrow molecular weight distribution (MWD). In previous reports, ethylene propylene monomer dienes (EPDM) had a low content and were used for dielectric and insulating properties with nanomaterials. Second, this paper presents a kind of elastomeric polymers based on E/1-hexene and VCH with a high dielectric constant ( k = 6-4) and mechanical properties. In addition, low dielectric loss suggests the suitable application potential of these polymeric materials for the fabrications of capacitors. Also, this work reveals that these polymers can be a better candidate for high-voltage electrical insulation due to their enhanced dielectric, mechanical, and thermal characteristics. To examine the insulating property, the interface characteristics of the polymer were evaluated using electrochemical impedance spectroscopy (EIS) with a frequency range of 1 × 10 5 -0.01 Hz and an amplitude of 5.0 mV. EIS is an effective method to investigate the polymers' interfacial electron transfer characteristics. The EIS Nyquist plot showed high Warburg impedance features in the low-frequency domain with straight lines without a semicircle, suggesting that the property of the polymer owing to the high electrical resistance and poor conductivity for ionic kinetics in the electrolyte may have surpassed that of the semicircle. Although the slope of low frequencies in polymers holding potent exoelectrogenic bacteria ( Shewanella oneidensis MR-1) as a charge carrier in the electrolyte could significantly reduce the Warburg resistance, it still could not improve the conductivity, which demonstrated that the external charge supply could not alter the insulating property in the used polymers.

Jihun Park, Jinsu Kim, Hyungmin Choi et al.

Process Safety and Environmental Protection • 2024

Guillaume Pillot, Eléonore Frouin, Emilie Pasero et al.

Bioresource Technology • 2018

Henan Li, Weihua He, Youpeng Qu et al.

Journal of Power Sources • 2017

Vajihe Yousefi, Davod Mohebbi‐Kalhori, Abdolreza Samimi

International Journal of Hydrogen Energy • 2019

Yang Wu, Linda Liang, Chen Zhou et al.

ACS ES&T Water • 2023

Bioelectrochemical systems (BES) can recover energy from organic-bearing waste streams, but their use has been stymied by poor electron transfer from the cathode. Redox-active electron shuttles could stimulate electron transfer provided that they are compatible with the exoelectrogenic bacteria. This work evaluated melanin-modified carboxylated graphene (M/CG) as a novel cathode catalyst in a microbial fuel cell. Biogenic melanin catalysts (i.e., bio-M/CG) significantly increased bioelectricity production due to its abundant pyrrole N, which lowered charge-transfer resistance and, thus, promoted the cathodic oxygen–reduction reaction (ORR). The high content of pyrrole N in the bio-M/CG catalyst also enriched exoelectrogens, such as Azospirillum, Chryseobacterium, and Azoarcus, which accounted for over 50% of the total abundance of bacteria in biofilms on the anode. Moreover, the functional genes of key enzymes involved in microbial electron transfer (MET) were increased by the bio-M/CG catalyst. These data confirm that the bio-M/CG catalyst improved the bioelectrochemical performance via synergetic promotion of cathodic ORR and microbial electron transfer, thus providing a new alternative for advancing BES technology. This work highlights the potential application of melanin in enhancing cathodic oxygen–reduction reaction kinetics and improving microbial electron transfer in BES. This study emphasizes the promising application of melanin in enhancing the ORR kinetics and improving MET in BES, offering exciting prospects for future sustainable and environmentally friendly applications.

Cheng Chen, Mingzhuang Sun, Ziwei Liu et al.

Water Research • 2020

Shici Zhang, Xizhong Bao, Fangping Wan et al.

Journal of Renewable and Sustainable Energy • 2018

Microbial fuel cells (MFCs) could achieve both sewage treatment and power generation, and an appropriate cathode material with a suitable structure could improve the MFC performance. The three-dimensional (3D) cage-shape materials derived from loofah sponge, as activated carbon fibers with high strength, were first utilized in the single-chamber air-cathode MFC (loofah sponge activated carbon fibers (LSACF)-MFC). In this study, the maximum compressive strength of LSACF as high as 202.4 kPa was achieved when the activated temperature and time were 750 °C and 60 min, respectively. Under such conditions, the 3D morphological characteristic and relatively large Brunauer-Emmett-Teller (BET) specific surface area (422.5 m2/g) were indicated to facilitate the attachment of exoelectrogenic bacteria and decrease the internal resistance of the MFC system. According to the polarization and power density curve, the internal resistance was 420 Ω, and meanwhile, the maximum power density of 4083 mW/m3 was achieved. These results suggest that this LSACF with high strength has great potential for the MFC application.

Lang Zhou, Bing Lu, Mo Li et al.

Fuel • 2024

Chenhui Yang, Hüsnü Aslan, Peng Zhang et al.

Nature Communications • 2020

Bioelectricity generation, by Shewanella oneidensis (S. oneidensis) MR-1, has become particularly alluring, thanks to its extraordinary prospects for energy production, pollution treatment, and biosynthesis. Attempts to improve its technological output by modification of S. oneidensis MR-1 remains complicated, expensive and inefficient. Herein, we report on the augmentation of S. oneidensis MR-1 with carbon dots (CDs). The CDs-fed cells show accelerated extracellular electron transfer and metabolic rate, with increased intracellular charge, higher adenosine triphosphate level, quicker substrate consumption and more abundant extracellular secretion. Meanwhile, the CDs promote cellular adhesion, electronegativity, and biofilm formation. In bioelectrical systems the CDs-fed cells increase the maximum current value, 7.34 fold, and power output, 6.46 fold. The enhancement efficacy is found to be strongly dependent on the surface charge of the CDs. This work demonstrates a simple, cost-effective and efficient route to improve bioelectricity generation of S. oneidensis MR-1, holding promise in all relevant technologies.

Thanh H. Trinh, Yoshimitsu Uemura, Nga T.T. Tran

Journal of the Japan Institute of Energy • 2019

The use of exoelectrogenic bacteria to produce electricity has attracted much attention recently. One of the applications of this kind of bacteria is microbial fuel cell (MFC). This current study aims to investigate the effects of duration and wavelength of light radiation on agar salt-bridge MFC performance via bacteria in terms of electricity voltage and power density. Activated sludge was used as an inoculum of the MFC. The experiments were conducted under two radiation modes, i.e., normal solar radiation and full-time radiation by artificial lamps: fluorescent and LED lamps. The LED lamps include red (632 nm), yellow (594 nm), green (515 nm), and blue (463 nm). The results showed that the full-time radiation enhanced the electricity generation a little more than normal solar radiation. Among the colors, yellow LED gave the highest power density than others with less chronological fluctuations.

Bahareh Asefi, Shiue-Lin Li, Henry A. Moreno et al.

Process Safety and Environmental Protection • 2019

Peixian Yang, Giin-Yu Amy Tan, Muhammad Aslam et al.

Scientific Reports • 2019

In a staged anaerobic fluidized-bed ceramic membrane bioreactor, metagenomic and metatranscriptomic analyses were performed to decipher the microbial interactions on the granular activated carbon. Metagenome bins, representing the predominating microbes in the bioreactor: syntrophic propionate-oxidizing bacteria (SPOB), acetoclastic Methanothrix concilii, and exoelectrogenic Geobacter lovleyi, were successfully recovered for the reconstruction and analysis of metabolic pathways involved in the transformation of fatty acids to methane. In particular, SPOB degraded propionate into acetate, which was further converted into methane and CO 2 by M. concilii via the acetoclastic methanogenesis. Concurrently, G. lovleyi oxidized acetate into CO 2 , releasing electrons into the extracellular environment. By accepting these electrons through direct interspecies electron transfer (DIET), M. concilii was capable of performing CO 2 reduction for further methane formation. Most notably, an alternative RuBisCO-mediated CO 2 reduction (the reductive hexulose-phosphate (RHP) pathway) is transcriptionally-active in M. concilii. This RHP pathway enables M. concilii dominance and energy gain by carbon fixation and methanogenesis, respectively via a methyl-H 4 MPT intermediate, constituting the third methanogenesis route. The complete acetate reduction (2 mole methane formation/1 mole acetate consumption), coupling of acetoclastic methanogenesis and two CO 2 reduction pathways, are thermodynamically favorable even under very low substrate condition (down to to 10 -5 M level). Such tight interactions via both mediated and direct interspecies electron transfer (MIET and DIET), induced by the conductive GAC promote the overall efficiency of bioenergy processes.

Yuta Yoshimura, Kazunori Nakashima, Masaji Kato et al.

ACS Omega • 2018

Single-chamber microbial fuel cells (MFCs) were constructed using rice bran (carbon source) and pond bottom mud (microbial source). The total electric charge obtained in the MFC combining rice bran with pond bottom mud was four times higher than that in MFC using only rice bran. Phylogenetic analyses revealed dominant growth of fermentative bacteria such as Bacteroides and Clostridium species, and exoelectrogenic Geobacter species in the anode biofilms, suggesting that mutualism of these bacteria is a key factor for effective electricity generation in the MFC. Furthermore, rice bran, consisting of persistent polysaccharide, was pretreated by the hydrodynamic cavitation system to improve the digestibility and enhance the efficiency in MFC, resulting in 26% increase in the total production of electricity.

Rong‐Bin Song, Yichao Wu, Zong‐Qiong Lin et al.

Angewandte Chemie International Edition • 2017

Coating individual bacterial cells with conjugated polymers to endow them with more functionalities is highly desirable. Here, we developed an in situ polymerization method to coat polypyrrole on the surface of individual Shewanella oneidensis MR-1, Escherichia coli, Ochrobacterium anthropic or Streptococcus thermophilus. All of these as-coated cells from different bacterial species displayed enhanced conductivities without affecting viability, suggesting the generality of our coating method. Because of their excellent conductivity, we employed polypyrrole-coated Shewanella oneidensis MR-1 as an anode in microbial fuel cells (MFCs) and found that not only direct contact-based extracellular electron transfer is dramatically enhanced, but also the viability of bacterial cells in MFCs is improved. Our results indicate that coating individual bacteria with conjugated polymers could be a promising strategy to enhance their performance or enrich them with more functionalities.

Lei Cheng, Di Min, Dongfeng Liu et al.

Biosensors and Bioelectronics • 2020

Hoang-Uyen-Dung Nguyen, Dang‐Trang Nguyen, Kozo Taguchi

Biochemical Engineering Journal • 2022

Márcia S. S. Santos, L. Peixoto, Kashif Mushtaq et al.

Journal of Energy Storage • 2021

Hossein Shamsaldini Lory, Moj Khaleghi, Mohammad Reza Miroliaei et al.

Emergent Materials • 2024

Heejung Jung, Gahyun Baek, Changsoo Lee

Chemical Engineering Journal • 2020

Li‐Zhi Huang, Yifeng Zhang, Xin‐Ming Hu et al.

Electrochimica Acta • 2018

Anna Joicy, Hwijin Seo, Myoung-Eun Lee et al.

International Journal of Hydrogen Energy • 2022

Ryo Inaba, Misa Nagoya, Atsushi Kouzuma et al.

Applied and Environmental Microbiology • 2019

Conductive nanomaterials have been reported to accelerate methanogenesis by promoting direct interspecies electron transfer (DIET), while their effects seem to vary depending on operational conditions. The present study examined the effects of magnetite nanoparticles (MNPs) on methanogenesis from acetate by soil-derived anaerobic cultures under continuous agitation. We found that MNPs accelerated methanogenesis in agitated cultures, as has been observed previously for static cultures. Metabarcoding of 16S rRNA gene amplicons showed that Methanosarcina substantially increased in the presence of MNPs, while DIET-related Geobacter did not occur. Metagenomic and metatranscriptomic analyses confirmed the predominance of Methanosarcina in MNP-supplemented agitated cultures. In addition, genes coding for acetoclastic methanogenesis, but not those for hydrogenotrophic methanogenesis, were abundantly expressed in the dominant Methanosarcina in the presence of MNPs. These results suggest that MNPs stimulate acetoclastic methanogenesis under continuous agitation. IMPORTANCE Previous studies have shown that conductive nanoparticles, such as MNPs, accelerate methanogenesis and suggested that MNPs facilitate DIET between exoelectrogenic bacteria and methanogenic archaea. In these methanogens, electrons thus obtained are considered to be used for hydrogenotrophic methanogenesis. However, the present work provides evidence that shows that MNPs accelerate DIET-independent acetoclastic methanogenesis under continuous agitation. Since most of previous studies have examined effects of MNPs in static or weakly agitated methanogenic cultures, results obtained in the present work suggest that hydraulic conditions definitively determine how MNPs accelerate methanogenesis. In addition, the knowledge obtained in this study is useful for engineers operating stirred-tank anaerobic digesters, since we show that MNPs accelerate methanogenesis under continuous agitation.

Shahirah Raiyan Saleh, Nur Kamilah Binti Abd Jalil, Umi Aisah Asli et al.

Jurnal Kejuruteraan • 2019

Soil Microbial Fuel Cell (SMFC) is a device that using bacteria in soils as a biocatalyst. These bacteria, called exoelectrogenic bacteria are oxidizing organic substrates to release electrons, which then harvested in an external circuit to produce bioelectricity. Despite all the potential, the bioelectricity production from soils is still low and its relation with SMFC conditions is uncertain. Hence, the main objective in this study is to enhance and stabilize the bioelectricity production of SMFC by additional glucose, nutrient broth and Escherichia coli (E. coli) as exoelectrogenic bacteria. A number of factors of SMFC performance were first identified to be preliminary investigated, that is the type of electrode, water addition to soil and distance between anode to cathode. It has been established in this study to use SMFC with the configuration of 9.5 cm in diameter and 15 cm height of the plastic container, with the 12 cm distance between carbon felt of anode and cathode. The electricity produced was measured by using a multimeter in term of voltage reading (mV). From this study, the highest bioelectricity produced was obtained from SMFC using nutrient broth with a maximum voltage of 700 mV. It has found that the additional E. coli bacteria did not increase the bioelectricity production. The use of E. coli needed to be combined with nutrient broth in order to achieve high and stable bioelectricity. It can be suggested that the indigenous bacteria that exist in the soils possibly played the role in producing bioelectricity.

Anouer Kebir, L. A. Woodward, Ouassima Akhrif

Renewable Energy • 2018

Vajihe Yousefi, Davod Mohebbi‐Kalhori, Abdolreza Samimi

SHILAP Revista de lepidopterología • 2019

The effect of the thickness of ceramic membrane on the productivity of microbial fuel cells (MFCs) was investigated with respect to the electricity generation and domestic wastewater treatment efficiencies. The thickest ceramic membrane (9 mm) gained the highest coulombic efficiency (27.58±4.2 %), voltage (681.15±33.1 mV), and current and power densities (447.11±21.37 mA/m2, 63.82±10.42 mW/m2) compared to the 6- and 3-mm thick separators. The results of electrochemical impedance spectroscopy (EIS) analysis were investigated to identify the internal resistance constituents by proposing the appropriate equivalent electrical circuit. The Gerischer element was modeled as the coupled reaction, and diffusion in the porous carbon electrodes and the constant phase element was assimilated into the electrical double-layer capacitance. The thickest ceramic (9 mm) was found to have the largest ohmic resistance; however, owing to its superior barrier capability, it provided more anoxic conditions for better accommodation of exoelectrogenic bacteria in the anode chamber. Therefore, lower charge transfer, fewer diffusional impedances, and higher rates of anodic reactions were achieved. Excessive oxygen and substrate crossover through the thinner ceramics (of 6 and 3 mm) resulted in the suppressed development of anaerobic anodic biofilm and the accomplishment of aerobic substrate respiration without electricity generation.