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Takahiro Yamashita, Hiroshi Yokoyama
Background: Metals are considered a suitable anode material for microbial fuel cells (MFCs) because of their high electrical conductivity. However, only a few types of metals have been used as anodes, and an extensive screening of metals has not yet been conducted. In this study, to develop a new metal anode for increased electricity generation in MFCs, 14 different metals (Al, Ti, Fe, Ni, Cu, Zn, Zr, Nb, Mo, Ag, In, Sn, Ta, and W) and 31 of their oxidized forms were comprehensively tested...
2018: Biotechnology for Biofuels
Ting Gao, Xian-Yang Shi
The present study investigated the endophytic bacterial communities in the seeds of mature, natural common reed (Phragmites australis) and narrowleaf cattail (Typha angustifolia L.). Additionally, seed endophytic bacterial communities were compared with rhizospheric and root endophytic bacterial communities using Illumina-based sequencing. Seed endophytic bacterial communities were dominated by Proteobacteria (reed, 41.24%; cattail, 45.51%), followed by Bacteroidetes (reed, 12.01%; cattail, 10.41%), Planctomycetes (reed, 10...
February 17, 2018: Archives of Microbiology
Bing Li, Wei-Min Wu, David B Watson, Erick Cardenas, Yuanqing Chao, D H Phillips, Tonia Mehlhorn, Kenneth Lowe, Shelly D Kelly, Pengsong Li, Huchun Tao, James M Tiedje, Craig S Criddle, Tong Zhang
A site in Oak Ridge, Tennessee, USA, has sediments that contain >3% iron oxides and is contaminated with uranium (U). The U(VI) was bioreduced to U(IV) and immobilized in situ through intermittent injections of ethanol. Then it was allowed to reoxidize via the invasion of low-pH (3.6-4.0), high-nitrate (up to 200 mM) groundwater back into the reduced zone for 1,383 days. To examine the biogeochemical response, high-throughput sequencing and network analysis were applied to characterize bacterial population shifts, as well as co-occurrence and co-exclusion patterns among microbial communities...
February 16, 2018: Applied and Environmental Microbiology
Atsushi Kouzuma, Shun'ichi Ishii, Kazuya Watanabe
In bioelectrochemical systems (BESs), electrons are transferred between electrochemically active microbes (EAMs) and conductive materials, such as electrodes, via extracellular electron transfer (EET) pathways, and electrons thus transferred stimulate intracellular catabolic reactions. Catabolic and EET pathways have extensively been studied for several model EAMs, such as Shewanella oneidensis MR-1 and Geobacter sulfurreducens PCA, whereas it is also important to understand the ecophysiology of EAMs in naturally occurring microbiomes, such as those in anode biofilms in microbial fuel cells treating wastewater...
January 31, 2018: Bioresource Technology
Youkang Zhao, Zhiling Li, Jincai Ma, Hui Yun, Mengyuan Qi, Xiaodan Ma, Hao Wang, Aijie Wang, Bin Liang
Bioelectroremediation is an efficient, sustainable, and environment-friendly remediation technology for the complexly contaminated sediments. Although various recalcitrant pollutants could be degraded in the electrode district, the degradation efficiency was generally confined by the low total organic carbon (TOC) content in the sediment. How to enhance the electroactive degraders' activity and efficiency remain poorly understood. Here we investigated the bioeletroremediation of a complexly contaminated river sediment with low TOC in a cylindric sediment microbial fuel cell stimulated by methanol...
February 3, 2018: Journal of Hazardous Materials
Hui Wan, Xiaoyun Yi, Xiaoping Liu, Chunhua Feng, Zhi Dang, Chaohai Wei
Applying an electric field to stimulate the microbial reductive dechlorination of polychlorinated biphenyls (PCBs) represents a promising approach for bioremediation of PCB-contaminated sites. This study aimed to demonstrate the biocathodic film-facilitated reduction of PCB 61 in a sediment-based bioelectrochemical reactor (BER) and, more importantly, the characterizations of electrode-microbe interaction from microbial and electrochemical perspectives particularly in a time-dependent manner. The application of a cathodic potential (-0...
February 2, 2018: Environmental Pollution
Léopold Mottet, Domitille Le Cornec, Jean-Marc Noël, Frédéric Kanoufi, Brigitte Delord, Philippe Poulin, Jérôme Bibette, Nicolas Bremond
Some bacteria can act as catalysts to oxidize (or reduce) organic or inorganic matter with the potential of generating electrical current. Despite their high value for sustainable energy, organic compound production and bioremediation, a tool to probe the natural biodiversity and to select most efficient microbes is still lacking. Compartmentalized cell culture is an ideal strategy for achieving such a goal but the appropriate compartment allowing cell growth and electron exchange must be tailored. Here, we develop a conductive composite hydrogel made of a double network of alginate and carbon nanotubes...
February 2, 2018: Soft Matter
Francesca Berini, Marko Verce, Luka Ausec, Elena Rosini, Fabio Tonin, Loredano Pollegioni, Ines Mandić-Mulec
Bioinformatics has revealed the presence of putative laccase genes in diverse bacteria, including extremophiles, autotrophs, and, interestingly, anaerobes. Integrity of laccase genes in anaerobes has been questioned, since laccases oxidize a variety of compounds using molecular oxygen as the electron acceptor. The genome of the anaerobe Geobacter metallireducens GS-15 contains five genes for laccase-like multicopper oxidases. In order to show whether one of the predicted genes encodes a functional laccase, the protein encoded by GMET_RS10855 was heterologously expressed in Escherichia coli cells...
January 29, 2018: Applied Microbiology and Biotechnology
Kei Suzuki, Yutaka Kato, Arashi Yui, Shuji Yamamoto, Syota Ando, Owen Rubaba, Yosuke Tashiro, Hiroyuki Futamata
We investigated how bacterial communities adapted to external resistances and exhibited the performance of electricity production in microbial fuel cells (MFCs) with external resistance of 10 Ω (LR-MFC) and 1000 Ω (HR-MFC). The HR-MFC exhibited better performance than the LR-MFC. The power densities of the LR-MFC and the HR-MFC were 5.2 ± 1.6 mW m-2 and 28 ± 9.6 mW m-2 after day 197, respectively. Low-scan cyclic voltammetry analyses indicated that the onset potential of the HR-MFC was more negative than that of the LR-MFC, suggesting that the higher external resistance led to enrichment of the highly current producing bacteria on the anode surface...
January 16, 2018: Journal of Bioscience and Bioengineering
Rhiannon C G Creasey, A Bernardus Mostert, Tuan Nguyen, Bernardino Virdis, Stefano Freguia, Bronwyn Laycock
Electron transfer is central to cellular life, from photosynthesis to respiration. In the case of anaerobic respiration, some microbes have extracellular appendages that can be utilised to transport electrons over great distances. Two model organisms heavily studied in this arena are Shewanella oneidensis and Geobacter sulfurreducens. There is some debate over how, in particular, the Geobacter sulfurreducens nanowires (formed from pilin nanofilaments) are capable of achieving the impressive feats of natural conductivity that they display...
January 18, 2018: Acta Biomaterialia
Rong Yu, Richard G Andrachek, Leo G Lehmicke, David L Freedman
Biostimulation was identified as a potential technology to treat a fractured sandstone aquifer contaminated with trichloroethene (TCE) and cis-1,2-dichloroethene (cis-DCE). Most of the mass of TCE and cis-DCE resides within the rock matrix and strategies to restore groundwater to pre-existing conditions are severely limited by back diffusion. A microcosm study using crushed rock and groundwater from the site was performed to assess biostimulation and natural attenuation. Lactate, hydrogen release compound® (HRC), and emulsified vegetable oil (EVO) significantly increased the rate of TCE reduction to cis-DCE...
January 16, 2018: Science of the Total Environment
Jianchao Zhang, Xingxuan Xia, Siliang Li, Wei Ran
Carboxylated multiwalled carbon nanotubes (MWCNTs-COOH) have become a growing concern in terms of their fate and toxicity in aqueous environments. Methane (CH4) is a major product of organic matter degradation in waterlogged environments. In this study, we determined the effect of MWCNTs-COOH on the production of CH4 from propionate oxidation in paddy soil enrichments. The results showed that the methanogenesis from propionate degradation was accelerated in the presence of MWCNTs-COOH. In addition, the rates of CH4 production and propionate degradation increased with increasing concentrations of MWCNTs-COOH...
2018: PeerJ
Brittany D Bennett, Kaitlyn E Redford, Jeffrey A Gralnick
The transport of metals into and out of cells is necessary for the maintenance of appropriate intracellular concentrations. Metals are needed for incorporation into metalloproteins but become toxic at higher concentrations. Many metal transport proteins have been discovered in bacteria, including the Mg2+ transporter-E (MgtE) family of passive Mg2+/Co2+ cation-selective channels. Low sequence identity exists between members of the MgtE family, indicating that substrate specificity may differ among MgtE transporters...
January 12, 2018: Applied and Environmental Microbiology
Yaping Zhang, Guanqun Li, Jing Wen, Yangao Xu, Jian Sun, Xun-An Ning, Xingwen Lu, Yujie Wang, Zuoyi Yang, Yong Yuan
Heavy metals play an important role in the conductivity of solution, power generation and activity of microorganisms in bioelectrochemical systems (BESs). However, effect of heavy metal on the process of exoelectrogenesis metabolism and extracellular electron transfer of electrochemically active biofilms (EABs) was poorly understood. Herein, we investigated the impact of Cu2+ at gradually increasing concentration on the morphological and electrochemical performance and bacterial communities of anodic biofilms in mixed-culture BESs...
January 5, 2018: Chemosphere
Nina Ponomarenko, Jens Niklas, Phani Raj Pokkuluri, Oleg G Poluektov, David Michael Tiede
Periplasmic cytochrome A (PpcA) is a representative of a broad class of multi-heme cytochromes functioning as protein "nanowires" for storage and extracellular transfer of multiple electrons in the δ-proteobacterium Geobacter sulfurreducens. PpcA contains three bis-His coordinated hemes held in a spatial arrangement that is highly conserved among the multi-heme cytochromes c3 and c7 families, carries low potential hemes and is notable for having one of the lowest number of amino acids utilized to maintain a characteristic protein fold and site specific heme function...
January 3, 2018: Biochemistry
Nicole L Ing, Tyler D Nusca, Allon I Hochbaum
Correction for 'Geobacter sulfurreducens pili support ohmic electronic conduction in aqueous solution' by Nicole L. Ing et al., Phys. Chem. Chem. Phys., 2017, 19, 21791-21799.
December 13, 2017: Physical Chemistry Chemical Physics: PCCP
Pablo Ledezma, Yang Lu, Stefano Freguia
Electrochemical activity in bacteria has been observed in numerous environments and conditions. However, enrichments in circumneutral freshwater media where acetate is the main electron donor seem to invariably lead to the dominance of Geobacter spp. Here we report on an electroactive bacterial consortium which was enriched on acetate as electron donor, but in a medium which reproduces hydrolysed urine (high pH, high salinity and high free ammonia). The consortium was found to be free of Geobacter species, whereas a previously undescribed community dominated by species closely related to Pseudomonas and Desulfuromonas was established...
December 4, 2017: FEMS Microbiology Letters
Bineyam Mezgebe, George A Sorial, E Sahle-Demessie, Ashraf Aly Hassan, Jingrang Lu
The objective of this research was to evaluate the biodegradation of chloroform by using biotrickling filter (BTF) and determining the dominant bacteria responsible for the degradation. The research was conducted in three phases under anaerobic condition, namely, in the presence of co-metabolite (Phase I), in the presence of co-metabolite and surfactant (Phase II) and in the presence of surfactant but no co-metabolite (Phase III). The results showed that the presence of ethanol as a co-metabolite provided 49% removal efficiency...
November 1, 2017: Water, Air, and Soil Pollution
Jan Němeček, Jana Steinová, Roman Špánek, Tomáš Pluhař, Petr Pokorný, Petra Najmanová, Vladislav Knytl, Miroslav Černík
In situ bioremediation (ISB) using reductive dechlorination is a widely accepted but relatively slow approach compared to other technologies for the treatment of groundwater contaminated by chlorinated ethenes (CVOCs). Due to the known positive kinetic effect on microbial metabolism, thermal enhancement may be a viable means of accelerating ISB. We tested thermally enhanced ISB in aquifers situated in sandy saprolite and underlying fractured granite. The system comprised pumping, heating and subsequent injection of contaminated groundwater aiming at an aquifer temperature of 20-30°C...
December 7, 2017: Science of the Total Environment
Soroush Saheb-Alam, Abhijeet Singh, Malte Hermansson, Frank Persson, Anna Schnürer, Britt-Marie Wilén, Oskar Modin
The enrichment of CO2-reducing microbial bio-cathodes is challenging. Previous research has shown that a promising approach could be to first enrich bio-anodes and then lower the potential so the electrodes are converted into bio-cathodes. However, the effect of such a transition on the microbial community on the electrode has not been studied. The goal of this study was, thus, to compare the start-up of bio-cathodes from pre-enriched anodes with direct start-up from bare electrodes and to investigate changes in microbial community composition...
December 8, 2017: Applied and Environmental Microbiology
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