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Paul Kavanagh, Catherine H Botting, Partha S Jana, Donal Leech, Florence Abram
Geobacter sulfurreducens is a dissimilatory metal-reducing bacterium capable of forming thick electron-conducting biofilms on solid electrodes. Here, we employ for the first time comparative proteomics to identify key physiological changes involved in G. sulfurreducens adaptation from fumarate-respiring planktonic cells to electron-conducting biofilms. Increased levels of proteins involved in outer membrane biogenesis, cell motility and secretion are expressed in biofilms. Of particular importance to the electron-conducting biofilms are proteins associated with secretion systems of Type I, II, V and Type IV pili...
October 10, 2016: Journal of Proteome Research
Yan Dang, Yuqing Lei, Zhao Liu, Yiting Xue, Dezhi Sun, Li-Ying Wang, Dawn E Holmes
A considerable amount of leachate with high fulvic acid (FA) content is generated during the municipal solid waste (MSW) incineration process. This incineration leachate is usually processed by downstream bio-methanogenic treatment. However, few studies have examined the impact that these compounds have on methanogenesis and how they are degraded and transformed during the treatment process. In this study, a laboratory-scale expanded granular sludge bed (EGSB) reactor was operated with MSW incineration leachate containing various concentrations of FA (1500 mg/L to 8000 mg/L) provided as the influent...
September 23, 2016: Water Research
Milán Farkas, Sándor Szoboszlay, Tibor Benedek, Fruzsina Révész, Péter Gábor Veres, Balázs Kriszt, András Táncsics
Dissimilatory iron-reducing bacteria are commonly found in microbial communities of aromatic hydrocarbon-contaminated subsurface environments where they often play key role in the degradation of the contaminants. The Siklós benzene, toluene, ethylbenzene, and xylene (BTEX)-contaminated area is one of the best characterized petroleum hydrocarbon-contaminated sites of Hungary. Continuous monitoring of the microbial community in the center of the contaminant plume indicated the presence of an emerging Geobacter population and a Rhodoferax phylotype highly associated with aromatic hydrocarbon-contaminated subsurface environments...
September 28, 2016: Folia Microbiologica
Hui Yun, Deyong Kong, Bin Liang, Minhua Cui, Zhiling Li, Aijie Wang
Chloramphenicol (CAP) is a frequently detected environmental pollutant. In this study, an electroactive biofilm for CAP reduction was established by initially in the anode and then inverting to the cathode. The established biocathode could enhance the reduction of CAP to the nitro-group reduced CAP (AMCl2) and further dechlorinated form (AMCl), both had lost the antibacterial activity. The phylogenetic diversity of the acclimated biofilm was decreased after the polar inversion. Proportions of functional bacterial genera, including Geobacter, Desulfovibrio and Pseudomonas responsible for the bidirectional electron transfer and nitroaromatics reduction, had increased 28%, 104% and 43% in the cathode...
December 2016: Bioresource Technology
Toshiyuki Ueki, Kelly P Nevin, Trevor L Woodard, Derek R Lovley
Physiological studies and biotechnology applications of Geobacter species have been limited by a lack of genetic tools. Therefore, potential additional molecular strategies for controlling metabolism were explored. When the gene for citrate synthase, or acetyl-CoA transferase, was placed under the control of a LacI/IPTG regulator/inducer system, cells grew on acetate only in the presence of IPTG. The TetR/AT system could also be used to control citrate synthase gene expression and acetate metabolism. A strain that required IPTG for growth on D-lactate was constructed by placing the gene for D-lactate dehydrogenase under the control of the LacI/IPTG system...
November 2016: Journal of Industrial Microbiology & Biotechnology
T P Delforno, D Y Okada, C V Faria, M B A Varesche
The objective of this study was to evaluate the removal of linear alkylbenzene sulfonate (LAS) associated with Fe(III) supplementation using an expanded granular sludge bed (EGSB) reactor. The reactor was inoculated with a granular sludge and fed with synthetic wastewater containing a specific LAS load rate (SLLR) of 1.5 mg gVS(-1) d(-1) (∼16.4 mgLAS L(-1) influent) and supplied with 7276 μMol L(-1) of Fe(III). The biomasses from the inoculum and at the end of the EGSB-Fe operation (127 days) were characterized using 16S rRNA Ion Tag sequencing...
December 1, 2016: Journal of Environmental Management
Joana Madjarov, Anna Prokhorova, Thorsten Messinger, Johannes Gescher, Sven Kerzenmacher
In this study, different inoculation strategies for continuously operated microbial anodes are analyzed and compared. After 20daysof operation with municipal wastewater anodes pre-incubated with a biofilm of the exoelectrogenic species Geobacter and Shewanella showed current densities of (65±8) μA/cm(2). This is comparable to the current densities of non-inoculated anodes and anodes inoculated with sewage sludge. Analysis of the barcoded pre-grown multispecies biofilms reveal that 99% of the original biofilm was detached after 20daysof operation with municipal wastewater...
December 2016: Bioresource Technology
Zhengsheng Yu, Zhili He, Xuanyu Tao, Jizhong Zhou, Yunfeng Yang, Mengxin Zhao, Xiaowei Zhang, Zhe Zheng, Tong Yuan, Pu Liu, Yong Chen, Virgo Nolan, Xiangkai Li
The Lanzhou reach of the Yellow River, located at the upstream of Lanzhou, has been contaminated by heavy metals and polycyclic aromatic hydrocarbons over a long-time. We hypothesized that indigenous microbial communities would remediate those contaminants and some unique populations could play an important role in this process. In this study, we investigated the sediment microbial community structure and function from the Lanzhou reach. Sediment samples were collected from two nearby sites (site A and site B) in the Lanzhou reach along the Yellow River...
September 16, 2016: Ecotoxicology
Zheng Chen, Yuanpeng Wang, Xiuli Jiang, Dun Fu, Dong Xia, Haitao Wang, Guowen Dong, Qingbiao Li
Microbially-mediated arsenic (As) metabolism and iron (Fe) bioreduction from sediments play crucial roles in global As/Fe cycle, and their mobilization is associated with the various effects within the alliance of "mediator-bacteria-DOM (Dissolved Organic Matter)". The gradient levels (0.05, 0.10 and 1.00mM) of sodium anthraquinone-2,6-disulphonate (AQDS) as a mediator were investigated for their impact on reductive dissolution of As(V) and Fe(III) from arsenic-rich sediment. For the overall performance of AQDS-mediated reductive dissolution on As(V) and Fe(III), a more positive effect resulting from 0...
September 8, 2016: Science of the Total Environment
Joana M Dantas, Telma Simões, Leonor Morgado, Clara Caciones, Ana P Fernandes, Marta A Silva, Marta Bruix, P Raj Pokkuluri, Carlos A Salgueiro
A family of triheme cytochromes from Geobacter sulfurreducens plays an important role in extracellular electron transfer. In addition to their role in electron transfer pathways, two members of this family (PpcA and PpcD) were also found to be able to couple e(-)/H(+) transfer through the redox Bohr effect observed in the physiological pH range, a feature not observed for cytochromes PpcB and PpcE. In attempting to understand the molecular control of the redox Bohr effect in this family of cytochromes, which is highly homologous both in amino acid sequence and structures, it was observed that residue 6 is a conserved leucine in PpcA and PpcD, whereas in the other two characterized members (PpcB and PpcE) the equivalent residue is a phenylalanine...
October 6, 2016: Journal of Physical Chemistry. B
Jianchao Zhang, Yahai Lu
Syntrophic methanogenesis is an essential link in the global carbon cycle and a key bioprocess for the disposal of organic waste and production of biogas. Recent studies suggest direct interspecies electron transfer (DIET) is involved in electron exchange in methanogenesis occurring in paddy soils, anaerobic digesters, and specific co-cultures with Geobacter. In this study, we evaluate the possible involvement of DIET in the syntrophic oxidation of butyrate in the enrichments from two lake sediments (an urban lake and a natural lake)...
2016: Frontiers in Microbiology
Yiran Dong, Robert A Sanford, Maxim I Boyanov, Kenneth M Kemner, Theodore M Flynn, Edward J O'Loughlin, Yun-Juan Chang, Randall A Locke, Joseph R Weber, Sheila M Egan, Roderick I Mackie, Isaac Cann, Bruce W Fouke
: A novel halophilic and metal-reducing bacterium, Orenia metallireducens strain Z6, was isolated from briny groundwater extracted from a 2.02 km-deep borehole in the Illinois Basin, IL. This organism shared 96% 16S rRNA gene similarity with Orenia marismortui but demonstrated physiological properties previously unknown for this genus. In addition to exhibiting a fermentative metabolism typical of the genus Orenia, strain Z6 reduces various metal oxides [Fe(III), Mn(IV), Co(III), and Cr(VI)], using H2 as the electron donor...
November 1, 2016: Applied and Environmental Microbiology
André Baudler, Markus Langner, Camilla Rohr, Andreas Greiner, Uwe Schröder
In this publication, we propose metal-polymer hybrid materials as a novel platform for the development of 3 D anode materials for bioelectrochemical systems, such as microbial fuel cells. Extremely low gravimetric density, high porosity, high electric conductivity, and distinct elastic properties are characteristics that are superior for bioelectrochemical applications. As a proof of concept, we investigated copper-melamine foams (Cu-MF) based on a commercially available, open cell melamine foam. With a low amount of copper (16...
August 22, 2016: ChemSusChem
Paul G Koster van Groos, Daniel I Kaplan, Hyun-Shik Chang, John C Seaman, Dien Li, Aaron D Peacock, Kirk G Scheckel, Peter R Jaffé
Small-scale continuous flow wetland mesocosms (∼0.8 L) were used to evaluate how plant roots under different iron loadings affect uranium (U) mobility. When significant concentrations of ferrous iron (Fe) were present at circumneutral pH values, U concentrations in root exposed sediments were an order of magnitude greater than concentrations in root excluded sediments. Micro X-ray absorption near-edge structure (μ-XANES) spectroscopy indicated that U was associated with the plant roots primarily as U(VI) or U(V), with limited evidence of U(IV)...
November 2016: Chemosphere
Xia Lu, Yurong Liu, Alexander Johs, Linduo Zhao, Tieshan Wang, Ziming Yang, Hui Lin, Dwayne A Elias, Eric M Pierce, Liyuan Liang, Tamar Barkay, Baohua Gu
No abstract text is available yet for this article.
September 6, 2016: Environmental Science & Technology
Olof Regnell
No abstract text is available yet for this article.
September 6, 2016: Environmental Science & Technology
Kenneth H Nealson, Annette R Rowe
Electromicrobiology is a subdiscipline of microbiology that involves extracellular electron transfer (EET) to (or from) insoluble electron active redox compounds located outside the outer membrane of the cell. These interactions can often be studied using electrochemical techniques which have provided novel insights into microbial physiology in recent years. The mechanisms (and variations) of outward EET are well understood for two model systems, Shewanella and Geobacter, both of which employ multihaem cytochromes to provide an electron conduit to the cell exterior...
September 2016: Microbial Biotechnology
Guo-Wei Zhou, Xiao-Ru Yang, Hu Li, Christopher W Marshall, Bang-Xiao Zheng, Yu Yan, Jian-Qiang Su, Yong-Guan Zhu
Anaerobic ammonium oxidation coupled to iron(III) reduction, termed Feammox, is a newly discovered nitrogen cycling process. However, little is known about the roles of electron shuttles in the Feammox reactions. In this study, two forms of Fe(III) (oxyhydr)oxide ferrihydrite (ex situ ferrihydrite and in situ ferrihydrite) were used in dissimilatory Fe(III) reduction (DIR) enrichments from paddy soil. Evidence for Feammox in DIR enrichments was demonstrated using the (15)N-isotope tracing technique. The extent and rate of both the (30)N2-(29)N2 and Fe(II) formation were enhanced when amended with electron shuttles (either 9,10-anthraquinone-2,6-disulfonate (AQDS) or biochar) and further simulated when these two shuttling compounds were combined...
September 6, 2016: Environmental Science & Technology
James M Byrne, Gerrit van der Laan, Adriana I Figueroa, Odeta Qafoku, Chongmin Wang, Carolyn I Pearce, Michael Jackson, Joshua Feinberg, Kevin M Rosso, Andreas Kappler
The ability for magnetite to act as a recyclable electron donor and acceptor for Fe-metabolizing bacteria has recently been shown. However, it remains poorly understood whether microbe-mineral interfacial electron transfer processes are limited by the redox capacity of the magnetite surface or that of whole particles. Here we examine this issue for the phototrophic Fe(II)-oxidizing bacteria Rhodopseudomonas palustris TIE-1 and the Fe(III)-reducing bacteria Geobacter sulfurreducens, comparing magnetite nanoparticles (d ≈ 12 nm) against microparticles (d ≈ 100-200 nm)...
2016: Scientific Reports
Qian Liu, Zhiyong Jason Ren, Cong Huang, Bingfeng Liu, Nanqi Ren, Defeng Xing
BACKGROUND: Biohythane is a new and high-value transportation fuel present as a mixture of biomethane and biohydrogen. It has been produced from different organic matters using anaerobic digestion. Bioenergy can be recovered from waste activated sludge through methane production during anaerobic digestion, but energy yield is often insufficient to sludge disposal. Microbial electrolysis cell (MEC) is also a promising approach for bioenergy recovery and waste sludge disposal as higher energy efficiency and biogas production...
2016: Biotechnology for Biofuels
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