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Lucie Semenec, Andrew E Laloo, Benjamin L Schulz, Ismael A Vergara, Philip L Bond, Ashley E Franks
Interspecies electron transfer (IET) occurs in many microbial communities, enabling extracellular electron exchange for syntrophic utilization of mixed resources. Various mechanisms of IET have been characterized including direct IET (DIET) and hydrogen IET (HIT) but their evolution throughout syntrophic adaptation has not been investigated through an omics approach. A syntrophic coculture of Geobacter sulfurreducens and Pseudomonas aeruginosa was established and evolved in restricted medium. The medium required cooperative metabolism due to preferential utilization of formate and fumarate by P...
October 3, 2017: Bioelectrochemistry
Matthew D Yates, Brian J Eddie, Nikolai Lebedev, Nicholas J Kotloski, Sarah M Strycharz-Glaven, Leonard M Tender
The ability of certain microorganisms to live in a multi-cell thick, electrode-grown biofilm by utilizing the electrode as a metabolic electron acceptor or donor requires electron transfer across cell membranes, through the biofilm, and across the biofilm/electrode interface. Even for the most studied system, anode-grown Geobacter sulfurreducens, the mechanisms underpinning each process and how they connect is largely unresolved. Here we report on G. sulfurreducens biofilms grown across the gap separating two electrodes by maintaining one electrode at 0...
September 18, 2017: Bioelectrochemistry
Yang-Guo Zhao, Yi Zhang, Zonglian She, Yue Shi, Min Wang, Mengchun Gao, Liang Guo
Performance of microbial fuel cells (MFCs) was monitored during the influent nutrient change from lactate to glucose/acetate/propionate and then to lactate. Meanwhile, anodic microbial communities were characterized by culture-independent molecular biotechnologies. Results showed MFC performance recovered rapidly when the lactate was replaced by one of its metabolic intermediates acetate, while it needed a longer time to recover if lactate substrate was converted to glucose/propionate or acetate to lactate...
September 1, 2017: Environmental Engineering Science
Xianbin Ying, Kun Guo, Wei Chen, Yuan Gu, Dongsheng Shen, Yuyang Zhou, Yuxiang Liang, Yanfeng Wang, Meizhen Wang, Huajun Feng
Both anode potentials and substrates can affect the process of biofilm formation in bioelectrochemical systems, but it is unclear who primarily determine the anode-respiring bacteria (ARB) community structure and composition. To address this issue, we divided microbial electrolysis cells (MECs) into groups, feeding them with different substrates and culturing them at various potentials. Non-turnover cyclic voltammetry indicated that the extracellular electron transfer components were uniform when feeding acetate, because the same oxidation peaks occurred at - 0...
September 25, 2017: Applied Microbiology and Biotechnology
Juan Chen, Pei-Fang Wang, Chao Wang, Jia-Jia Liu, Han Gao, Xun Wang
It is acknowledged that organohalide-respiring bacteria (OHRB) can degrade polybrominated diphenyl ethers (PBDEs); however, very little is known about the distribution of OHRB or their response to PBDE contamination in natural sediments. We collected sediments from 28 sampling sites in Taihu Lake, China, and investigated the spatial distribution and diversity of OHRB, and the relationships between the PBDE contamination levels and the PBDE removal potential. The abundances of five typical OHRB genera, namely Dehalobacter, Dehalococcoides, Dehalogenimonas, Desulfitobacterium, and Geobacter, ranged from 0...
September 21, 2017: Environmental Pollution
Kyle Michelson, Robert A Sanford, Albert J Valocchi, Charles J Werth
Members of the Geobacteraceae family are ubiquitous metal reducers that utilize conductive "nanowires" to reduce Mn(IV) and Fe(III) oxides in anaerobic sediments. However, it is not currently known if and to what extent the Mn(IV) and Fe(III) oxides in soil grains and low permeability sediments that are sequestered in pore spaces too small for cell passage can be reduced by long-range extracellular electron transport via Geobacter nanowires, and what mechanisms control this reduction. We developed a microfluidic reactor that physically separates Geobacter sulfurreducens from the Mn(IV) mineral birnessite by a 1...
October 2, 2017: Environmental Science & Technology
Eveline M van den Berg, Marina P Elisário, J Gijs Kuenen, Robbert Kleerebezem, Mark C M van Loosdrecht
Denitrification and dissimilatory reduction to ammonium (DNRA) are competing nitrate-reduction processes that entail important biogeochemical consequences for nitrogen retention/removal in natural and man-made ecosystems. The nature of the available carbon source and electron donor have been suggested to play an important role on the outcome of this microbial competition. In this study, the influence of lactate as fermentable carbon source on the competition for nitrate was investigated for varying ratios of lactate and nitrate in the influent (Lac/N ratio)...
2017: Frontiers in Microbiology
Kai Feng, Zhaojing Zhang, Weiwei Cai, Wenzong Liu, Meiying Xu, Huaqun Yin, Aijie Wang, Zhili He, Ye Deng
The relationship between biodiversity and ecosystem stability is poorly understood in microbial communities. Biofilm communities in small bioreactors called microbial electrolysis cells (MEC) contain moderate species numbers and easy tractable functional traits, thus providing an ideal platform for verifying ecological theories in microbial ecosystems. Here, we investigated the resilience of biofilm communities with a gradient of diversity, and explored the relationship between biodiversity and stability in response to a pH shock...
September 19, 2017: Molecular Ecology
Michiel H In 't Zandt, Sabrina Beckmann, Ruud Rijkers, Mike S M Jetten, Mike Manefield, Cornelia U Welte
Coal mining is responsible for 11% of total anthropogenic methane emission thereby contributing considerably to climate change. Attempts to harvest coalbed methane for energy production are challenged by relatively low methane concentrations. In this study, we investigated whether nutrient and acetate amendment of a non-producing sub-bituminous coal well could transform the system to a methane source. We tracked cell counts, methane production, acetate concentration and geochemical parameters for 25 months in one amended and one unamended coal well in Australia...
September 19, 2017: Microbial Biotechnology
Martin Culka, Simona G Huwiler, Matthias Boll, G Matthias Ullmann
Aromatic compounds are environmental pollutants with toxic and carcinogenic properties. Despite the stability of aromatic rings, bacteria are able to degrade the aromatic compounds into simple metabolites and use them as growth substrates under oxic or even under anoxic conditions. In anaerobic microorganisms, most monocyclic aromatic growth substrates are converted to the central intermediate benzoyl-coenzyme A, which is enzymatically reduced to cyclohexa-1,5-dienoyl-CoA. The strictly anaerobic bacterium Geobacter metallireducens uses the class II benzoyl-CoA reductase complex for this reaction...
October 3, 2017: Journal of the American Chemical Society
Hui Liu, Baogang Zhang, Heyang Yuan, Yutong Cheng, Song Wang, Zhen He
Vanadium (V) pollution in groundwater has posed serious risks to the environment and public health. Anaerobic microbial reduction can achieve efficient and cost-effective remediation of V(V) pollution, but its interactions with coexisting common electron acceptors such as NO3(-), Fe(3+), SO4(2-) and CO2 in groundwater remain unknown. In this study, the interactions between V(V) reduction and reduction of common electron acceptors were examined with revealing relevant microbial community and identifying dominant species...
September 12, 2017: Environmental Pollution
Simon Leitner, Harald Berger, Markus Gorfer, Thomas G Reichenauer, Andrea Watzinger
Reductive dechlorination performed by organohalide-respiring bacteria (OHRB) enables the complete detoxification of certain emerging groundwater pollutants such as perchloroethene (PCE). Environmental samples from a contaminated site incubated in a lab-scale microcosm (MC) study enable documentation of such reductive dechlorination processes. As compound-specific isotope analysis is used to monitor PCE degradation processes, nucleic acid analysis-like 16S-rDNA analysis-can be used to determine the key OHRB that are present...
September 15, 2017: Environmental Science and Pollution Research International
Jingxin Zhang, Liwei Mao, Le Zhang, Kai-Chee Loh, Yanjun Dai, Yen Wah Tong
Powdered activated carbon (AC) is commonly used as an effective additive to enhance anaerobic digestion (AD), but little is known about how the metabolic pathways resulting from adding AC change the microbial association network and enhance food waste treatment. In this work, the use of AC in an anaerobic digestion system for food waste was explored. Using bioinformatics analysis, taxonomic trees and the KEGG pathway analysis, changes in microbial network and biometabolic pathways were tracked. The overall effect of these changes were used to explain and validate improved digestion performance...
September 12, 2017: Scientific Reports
David Jf Walker, Ramesh Y Adhikari, Dawn E Holmes, Joy E Ward, Trevor L Woodard, Kelly P Nevin, Derek R Lovley
The possibility that bacteria other than Geobacter species might contain genes for electrically conductive pili (e-pili) was investigated by heterologously expressing pilin genes of interest in Geobacter sulfurreducens. Strains of G. sulfurreducens producing high current densities, which are only possible with e-pili, were obtained with pilin genes from Flexistipes sinusarabici, Calditerrivibrio nitroreducens and Desulfurivibrio alkaliphilus. The conductance of pili from these strains was comparable to native G...
September 5, 2017: ISME Journal
Shaomei He, Roman A Barco, David Emerson, Eric E Roden
Extracellular electron transfer (EET) is recognized as a key biochemical process in circumneutral pH Fe(II)-oxidizing bacteria (FeOB). In this study, we searched for candidate EET genes in 73 neutrophilic FeOB genomes, among which 43 genomes are complete or close-to-complete and the rest have estimated genome completeness ranging from 5 to 91%. These neutrophilic FeOB span members of the microaerophilic, anaerobic phototrophic, and anaerobic nitrate-reducing FeOB groups. We found that many microaerophilic and several anaerobic FeOB possess homologs of Cyc2, an outer membrane cytochrome c originally identified in Acidithiobacillus ferrooxidans...
2017: Frontiers in Microbiology
Shusi Liu, Yixin Lu, Chen Yang, Chuanping Liu, Lin Ma, Zhi Dang
Biochar was carbon-rich and generated by high-temperature pyrolysis of biomass under oxygen-limited conditions. Due to the limitations of surface functional groups and the weakness of surface activity in the field of environmental remediation, the raw biochar frequently was chemically modified to improve its properties with a new performance. In this study, a kind of high-efficiency and low-cost amino biochar modified by nano zero-valent iron (ABC/NZVI) was synthesized and applied to paddy soil contaminated with arsenic (As)...
September 2, 2017: Environmental Science and Pollution Research International
Lean Zhou, Tian Li, Jingkun An, Chengmei Liao, Nan Li, Xin Wang
Electroactive biofilms (EABs) generated from mixed inocula are attractive due to their unique direct extracellular electron transfer abilities and potential use in water pollution control. In this study, for the first time, we identified a chemical that can be used for EAB regulation (both inhibition and promotion). We confirmed that tobramycin, an antibiotic previously demonstrated to inhibit the activity of EABs, is an agonist of EAB formation at subminimal inhibitory concentrations (sub-MICs). Compared to the control, at tobramycin concentrations of 0...
November 15, 2017: Water Research
N A D Ho, S Babel, F Kurisu
Bioelectrochemical reactors using AMI-7001S and CMI-7000S membranes were investigated for silver recovery and power generation. High silver removal (83.73-92.50%) and columbic efficiency (11.50-19.89%) were obtained in CMI-based reactor after 24h, although, some diffusion of Ag(+) ions was observed. In contrast, substrate loss was found in AMI-based reactor, which caused low overall performance. At an initial Ag(+) concentration 2000mg/L, a maximum power density of 5396mW/m(3) and 3385mW/m(3) were obtained in CMI and AMI-based reactor, respectively...
November 2017: Bioresource Technology
Lizhen Xing, Shuo Yang, Qidong Yin, Sihuang Xie, Peter James Strong, Guangxue Wu
In this study, the effects of four types of organic compounds (tryptone, acetate/propionate, glucose and ethanol) on methanogenesis, electron transfer processes and microbial community structure were examined. When tryptone and acetate/propionate were used, the dominant methanogenic pathway was aceticlastic methanogenesis and Methanosarcina was the most abundant methanogen. When glucose or ethanol were provided as the external carbon source, the aceticlastic and hydrogenotrophic pathways were utilised simultaneously, and Methanosarcina and Methanobacterium were enriched...
November 2017: Bioresource Technology
Bo Ye, Haiping Luo, Yaobin Lu, Guangli Liu, Renduo Zhang, Xiao Li
The aim of this study was to improve performance of the microbial electrolysis desalination and chemical-production cell (MEDCC) using enlarged anode and high applied voltages. MEDCCs with anode lengths of 9 and 48cm (i.e., the 9cm-anode MEDCC and 48cm-anode MEDCC, respectively) were tested under different voltages (1.2-3.0V). Our results demonstrated for the first time that the MEDCC could maintain high performance even under the applied voltage higher than that for water dissociation (i.e., 1.8V). Under the applied voltage of 2...
November 2017: Bioresource Technology
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