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Iron reducing bacteria

Raquel Rose Silva Correia, Jean Remy Davée Guimarães
Recent studies have shown Hg methylation in mangrove sediments, however, little is known about the different microorganism consortia involved. We investigated the participation of prokaryotes in general, iron-reducing bacteria-IRB, sulfate-reducing bacteria-SRB, methanogens and fungi in Hg methylation and sulfate reduction rates (SRR) in mangrove sediments using iron amendments for IRB and specific inhibitors for the other microorganisms. Sediment samples were collected from two mangrove zones, tidal flat and mangrove forest (named root sediments)...
October 14, 2016: Chemosphere
Grace E Schwartz, Lauren K Redfern, Kaoru Ikuma, Claudia K Gunsch, Laura S Ruhl, Avner Vengosh, Heileen Hsu-Kim
Mercury (Hg) associated with coal ash is an environmental concern, particularly if the release of coal ash to the environment is associated with the conversion of inorganic Hg to methylmercury (MeHg), a bioaccumulative form of Hg that is produced by anaerobic microorganisms. In this study, sediment slurry microcosm experiments were performed to understand how spilled coal ash might influence MeHg production in anaerobic sediments of an aquatic ecosystem. Two coal ash types were used: (1) a weathered coal ash; and (2) a freshly collected, unweathered fly ash that was relatively enriched in sulfate and Hg compared to the weathered ash...
October 5, 2016: Environmental Science. Processes & Impacts
Ning Wang, Xi-Mei Xue, Albert L Juhasz, Zhi-Zhou Chang, Hong-Bo Li
Previous studies have shown that biochar enhances microbial reduction of iron (Fe) oxyhydroxide under anaerobic incubation. However, there is a lack of data on its influence on arsenic (As) release from As-contaminated paddy soils. In this study, paddy soil slurries (120 mg As kg(-1)) were incubated under anaerobic conditions for 60 days with and without the addition of biochar (3%, w/w) prepared from rice straw at 500 °C. Arsenic release, Fe reduction, and As fractionation were determined at 1, 10, 20, 30, and 60 d, while Illumina sequencing and real-time PCR were used to characterize changes in soil microbial community structure and As transformation function genes...
October 6, 2016: Environmental Pollution
Pamela Vazquez-Gutierrez, Tomas de Wouters, Julia Werder, Christophe Chassard, Christophe Lacroix
The gut microbiota plays an important role in host health, in particular by its barrier effect and competition with exogenous pathogenic bacteria. In the present study, the competition of Bifidobacterium pseudolongum PV8-2 (Bp PV8-2) and Bifidobacterium kashiwanohense PV20-2 (Bk PV20-2), isolated from anemic infant gut microbiota and selected for their high iron sequestration properties, was investigated against Salmonella Typhimurium (S. Typhi) and Escherichia coli O157:H45 (EHEC) by using co-culture tests and assays with intestinal cell lines...
2016: Frontiers in Microbiology
Amanda M Achberger, Brent C Christner, Alexander B Michaud, John C Priscu, Mark L Skidmore, Trista J Vick-Majors
Subglacial Lake Whillans (SLW) is located beneath ∼800 m of ice on the Whillans Ice Stream in West Antarctica and was sampled in January of 2013, providing the first opportunity to directly examine water and sediments from an Antarctic subglacial lake. To minimize the introduction of surface contaminants to SLW during its exploration, an access borehole was created using a microbiologically clean hot water drill designed to reduce the number and viability of microorganisms in the drilling water. Analysis of 16S rRNA genes (rDNA) amplified from samples of the drilling and borehole water allowed an evaluation of the efficacy of this approach and enabled a confident assessment of the SLW ecosystem inhabitants...
2016: Frontiers in Microbiology
Barbara Casentini, Fabiano Teo Falcione, Stefano Amalfitano, Stefano Fazi, Simona Rossetti
Different countries in Europe still suffer of elevated arsenic (As) concentration in groundwaters used for human consumption. In the case of households not connected to the distribution system, decentralized water supply systems, such as Point of Use (POU) and Point of Entry (POE), offer a direct benefit for the consumers. Field scale ex-situ treatment systems based on metallic iron (ZVI) are already available for the production of reduced volumes of drinking water in remote areas (village scale). To address drinking water needs at larger scale, we designed a pilot unit able to produce an elevated daily volume of water for human consumption...
September 28, 2016: Water Research
Jayeeta Sarkar, Sufia K Kazy, Abhishek Gupta, Avishek Dutta, Balaram Mohapatra, Ajoy Roy, Paramita Bera, Adinpunya Mitra, Pinaki Sar
Nutrient deficiency severely impairs the catabolic activity of indigenous microorganisms in hydrocarbon rich environments (HREs) and limits the rate of intrinsic bioremediation. The present study aimed to characterize the microbial community in refinery waste and evaluate the scope for biostimulation based in situ bioremediation. Samples recovered from the wastewater lagoon of Guwahati refinery revealed a hydrocarbon enriched [high total petroleum hydrocarbon (TPH)], oxygen-, moisture-limited, reducing environment...
2016: Frontiers in Microbiology
Christopher T Lefèvre, Paul A Howse, Marian L Schmidt, Monique Sabaty, Nicolas Menguy, George W Luther, Dennis A Bazylinski
Although dissimilatory sulfate-reducing bacteria (SRB) are generally described as strictly anaerobic organisms with regard to growth, several reports have shown that some SRB, particularly Desulfovibrio species, are quite resistant to O2 . For example, SRB remain viable in many aerobic environments while some even reduce O2 to H2 O. However, reproducible aerobic growth of SRB has not been unequivocally documented. Desulfovibrio magneticus is a SRB that is also a magnetotactic bacterium (MTB). MTB biomineralize magnetosomes which are intracellular, membrane-bounded, magnetic iron mineral crystals...
October 4, 2016: Environmental Microbiology Reports
Jiaojiao Niu, Jie Deng, Yunhua Xiao, Zhili He, Xian Zhang, J D Van Nostrand, Yili Liang, Ye Deng, Xueduan Liu, Huaqun Yin
Bioleaching has been employed commercially to recover metals from low grade ores, but the production efficiency remains to be improved due to limited understanding of the system. This study examined the shift of microbial communities and S&Fe cycling in three subsystems within a copper ore bioleaching system: leaching heap (LH), leaching solution (LS) and sediment under LS. Results showed that both LH and LS had higher relative abundance of S and Fe oxidizing bacteria, while S and Fe reducing bacteria were more abundant in the Sediment...
October 4, 2016: Scientific Reports
Antonio Velasco, Arturo Aburto-Medina, Esmaeil Shahsavari, Sergio Revah, Irmene Ortiz
Abiotic and biotic processes can be used to remediate DDX (DDT, DDD, DDE, and DDNS) contaminated soils; these processes can be fostered using specific carbon-amendments to stimulate particular soil indigenous microbial communities to improve rates or extent of degradation. In this study, toluene and glycerol were evaluated as cosubstrates under aerobic and anoxic conditions to determine the degradation efficiencies of DDX and to elucidate possible degradation mechanisms. Slurry microcosms experiments were performed during 60 days using pretreated soil with zero-valent iron (ZVI)...
September 22, 2016: Journal of Hazardous Materials
Masaki Serata, Mayumi Kiwaki, Tohru Iino
Lactic acid bacteria have a variety of mechanisms for tolerance to oxygen and reactive oxygen species, and these mechanisms differ among species. Lactobacillus casei strain Shirota grows well under aerobic conditions, indicating that the various systems involved in oxidative stress resistance function in this strain. To elucidate the mechanism of oxidative stress resistance in L. casei strain Shirota, we examined the transcriptome response to oxygen or hydrogen peroxide exposure. We then focused on an uncharacterized gene that was found to be up-regulated by both oxygen and hydrogen peroxide stress; we named the gene hprA1 (hydrogen peroxide resistance gene)...
September 29, 2016: Microbiology
Teresa Fresno, Eduardo Moreno-Jiménez, Jesús M Peñalosa
The efficiency of combining iron sulfate and organic amendments (paper mill sludge, olive mill waste compost and olive tree pruning biochar) for the remediation of an As- and Cu-contaminated soil was evaluated. Changes in As and Cu fractionation and solubility due to the application of the amendments was explored by leachate analysis, single and sequential extractions. Also, the effects on Arrhenatherum elatius growth, germination of Lactuca sativa and toxicity to the bacteria Vibrio fischeri were assessed...
December 2016: Chemosphere
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
Andrew H Knoll, Kristin D Bergmann, Justin V Strauss
Microfossils, stromatolites, preserved lipids and biologically informative isotopic ratios provide a substantial record of bacterial diversity and biogeochemical cycles in Proterozoic (2500-541 Ma) oceans that can be interpreted, at least broadly, in terms of present-day organisms and metabolic processes. Archean (more than 2500 Ma) sedimentary rocks add at least a billion years to the recorded history of life, with sedimentological and biogeochemical evidence for life at 3500 Ma, and possibly earlier; phylogenetic and functional details, however, are limited...
November 5, 2016: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Ian T Cadby, Susan A Ibrahim, Matthew Faulkner, David J Lee, Douglas Browning, Stephen J Busby, Andrew L Lovering, Melanie R Stapleton, Jeffrey Green, Jeffrey A Cole
In silico analyses identified a Crp/Fnr family transcription factor (HcpR) in sulfate-reducing bacteria that controls expression of the hcp gene, which encodes the hybrid cluster protein and contributes to nitrosative stress responses. There is only one hcpR gene in the model sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough, but two copies in D. desulfuricans 27774, which can use nitrate as an alternative electron acceptor to sulfate. Structures of the D. desulfuricans hcpR1, hcpR2 and hcp operons are reported...
September 27, 2016: Molecular Microbiology
Yankai Xie, Haoran Dong, Guangming Zeng, Lin Tang, Zhao Jiang, Cong Zhang, Junmin Deng, Lihua Zhang, Yi Zhang
Nanoscale zero-valent iron (NZVI) particles, applied for in-situ subsurface remediation, are inevitable to interact with various microbes in the remediation sites directly or indirectly. This review summarizes their interactions, including the effects of NZVI on microbial activity and growth, the synergistic effect of NZVI and microbes on the contaminant removal, and the effects of microbes on the aging of NZVI. NZVI could exert either inhibitive or stimulative effects on the growth of microbes. The mechanisms of NZVI cytotoxicity (i...
September 14, 2016: Journal of Hazardous Materials
Zheyun Zhang, Hee Sun Moon, Satish C B Myneni, Peter R Jaffé
Microbial redox transformations of arsenic (As) are coupled to dissimilatory iron and sulfate reduction in the wetlands, however, the processes involved are complex and poorly defined. In this study, we investigated the effect of dissimilatory iron and sulfate reduction on As dynamics in the wetland rhizosphere and its bioaccumulation in plants using greenhouse mesocosms. Results show that high Fe (50μM ferrihydrite/g solid medium) and SO4(2-) (5mM) treatments are most favorable for As sequestration in the presence of wetland plants (Scirpus actus), probably because root exudates facilitate the microbial reduction of Fe(III), SO4(2-), and As(V) to sequester As(III) by incorporation into iron sulfides and/or plant uptake...
June 14, 2016: Journal of Hazardous Materials
Nadine Lehnen, Hannah K Marchant, Anne Schwedt, Jana Milucka, Christian Lott, Miriam Weber, Julien Dekaezemacker, Brandon K B Seah, Philipp F Hach, Wiebke Mohr, Marcel M M Kuypers
Seagrass meadows of Posidonia oceanica represent hotspots of productivity in the oligotrophic Mediterranean Sea. The lack of dissolved inorganic nitrogen (DIN) in the seawater suggests that the N-demand of these meadows might be in part supported by microbial dinitrogen (N2) fixation. However, currently there are no direct N2 fixation measurements available for this productive marine macrophyte. Here we investigated N2 fixation activity associated with P. oceanica leaf, rhizome and root pieces. In 15N2 incubations, the roots exhibited highest rates of N2 fixation...
October 2016: Systematic and Applied Microbiology
María Guadalupe Almazán-Torres, Eduardo Ordóñez-Regil, Ana Carolina Ruiz-Fernández
The uranium (U) and plutonium (Pu) content with depth in a sediment core collected in the continental shelf off the mouth of the Santiago River in the Mexican Pacific was studied to evaluate the contamination effects of the effluent of the Santiago-Lerma River as it moves into the sea. The large mass of terrestrial detritus delivered by the river influences the physicochemical and geochemical processes in the seafloor. Abnormal concentrations of U and Pu in sediments were examined as indicative of the effects of anoxic conditions...
November 2016: Journal of Environmental Radioactivity
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
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