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Velayudhan J, Subramanian S. A dual-chambered microbial fuel cell with manganese dioxide nano-structured cathode for wastewater treatment. NANOTECHNOLOGY 2024; 35:495404. [PMID: 39302178 DOI: 10.1088/1361-6528/ad7d7f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2024] [Accepted: 09/16/2024] [Indexed: 09/22/2024]
Abstract
Microbial fuel cells (MFCs) can generate electricity by breaking down organic molecules through sustainable bio-electrochemical processes and wastewater as an energy source. A novel approach to remediate wastewater containing selenite was studied utilizing a selenite-reducing mixed bacterial culture with a nano manganese oxide modified cathode in the MFCs. The modification enhanced electrochemical catalytic activity, extracellular electron transfer rate, chemical oxygen demand (COD) elimination efficiency, and coulombic efficiency. Scanning electron microscopy and energy dispersive x-rays analysis were used to examine a manganese dioxide-coated graphite cathode's surface morphology and chemical composition. The manganese dioxide-coated electrode generated up to 69% higher voltage with 150 ppm selenite concentration than the uncoated graphite electrode. The MFC removed up to 80% of the initial COD of 120 mg l-1and achieved a maximum power density of 1.51 W m-2. The study demonstrates that MFCs can effectively treat selenite-containing wastewater, and modifying the cathode can enhance energy production.
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Affiliation(s)
- Jayanthi Velayudhan
- Department of Biotechnology, School of biosciences and technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Sangeetha Subramanian
- Department of Biotechnology, School of biosciences and technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
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Asefaw BK, Walia N, Stroupe ME, Chen H, Tang Y. Unraveling mechanisms of selenium recovery by facultative anaerobic bacterium Azospira sp. A9D-23B in distinct reactor configurations. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024:10.1007/s11356-024-35140-6. [PMID: 39331294 DOI: 10.1007/s11356-024-35140-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Accepted: 09/21/2024] [Indexed: 09/28/2024]
Abstract
Microbial processes are crucial in the redox transformations of toxic selenium oxyanions. This study focused on isolating an efficient selenate-reducing strain, Azospira sp. A9D-23B, and evaluating its capability to recover extracellular selenium nanoparticles (SeNPs) from selenium-laden wastewater in different reactor setups. Analysis using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) revealed significantly higher extracellular SeNPs production (99%) on the biocathode of the bioelectrochemical (BEC) reactor compared to the conventional bioreactor (65%). Further investigations into the selenate reductase activity of strain A9D-23B revealed distinct mechanisms of selenate reduction in BEC and conventional bioreactor settings. Notably, selenate reductases associated with the outer membrane and periplasm displayed higher activity (18.31 ± 3.8 µmol/mg-min) on the BEC reactor's biocathode compared to the upflow anaerobic conventional bioreactor (3.24 ± 2.9 µmol/mg-min). Conversely, the selenate reductases associated with the inner membrane and cytoplasm exhibited lower activity (5.82 ± 2.2 µmol/mg-min) on the BEC reactor's biocathode compared to the conventional bioreactor (9.18 ± 1.6 µmol/mg-min). However, the comparable kinetic parameter ( K m ) across cellular fractions in both reactors suggest that SeNP localization was influenced by enzyme activity rather than selenate affinity. Overall, the mechanism involved in selenate reduction to SeNPs and the strain's efficiency in detoxifying selenate below levels regulated by the U.S. Environmental Protection Agency has broad implications for sustainable environmental remediation strategies.
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Affiliation(s)
- Benhur Kessete Asefaw
- Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, FL, 32310, USA
| | - Nidhi Walia
- Department of Biological Science, Florida State University, 91 Chieftain Way, Tallahassee, FL, 32306, USA
- Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL, 32306, USA
| | - Margaret Elizabeth Stroupe
- Department of Biological Science, Florida State University, 91 Chieftain Way, Tallahassee, FL, 32306, USA
- Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL, 32306, USA
| | - Huan Chen
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL, 32310, USA.
| | - Youneng Tang
- Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, FL, 32310, USA
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Lashani E, Moghimi H, J Turner R, Amoozegar MA. Selenite bioreduction by a consortium of halophilic/halotolerant bacteria and/or yeasts in saline media. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023:121948. [PMID: 37270053 DOI: 10.1016/j.envpol.2023.121948] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 05/18/2023] [Accepted: 05/31/2023] [Indexed: 06/05/2023]
Abstract
Selenium oxyanions are released into environments by natural and anthropogenic activities and are present in agricultural and glass manufacturing wastewater in several locations worldwide. Excessive amounts of this metalloid have adverse effects on the health of living organisms. Halophilic and halotolerant microorganisms were selected for selenium oxyanions remediation due to presence of significant amount of salt in selenium-containing wastewater. Effects of aeration, carbon sources, competitive electron acceptors, and reductase inhibitors were investigated on SeO32- bio-removal. Additionally, NO3--containing wastewater were exploited to investigate SeO32- remediation in synthetic agricultural effluents. The results showed that the SeO32- removal extent is maximum in aerobic conditions with succinate as a carbon source. SO42- and PO43- do not significantly interfere with SeO32- reduction, while WO42- and TeO32- decrease the SeO32- removal percentage (up to 35 and 37%, respectively). Furthermore, NO3- had an adverse effect on SeO32- biotransformation by our consortia. All consortia reduced SeO32- in synthetic agricultural wastewaters with a 45-53% removal within 120 h. This study suggests that consortia of halophilic/halotolerant bacteria and yeasts could be applied to treat SeO32--contaminated drainage water. In addition, sulphates, and phosphates do not interfere with selenite bioreduction by these consortia, which makes them suitable candidates for the bioremediation of selenium-containing wastewater.
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Affiliation(s)
- Elham Lashani
- Extremophiles Laboratory, Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Hamid Moghimi
- Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran.
| | - Raymond J Turner
- Microbial Biochemistry Laboratory, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada
| | - Mohammad Ali Amoozegar
- Extremophiles Laboratory, Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran
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Ostovar M, Saberi N, Ghiassi R. Selenium contamination in water; analytical and removal methods: a comprehensive review. SEP SCI TECHNOL 2022. [DOI: 10.1080/01496395.2022.2074861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Mojtaba Ostovar
- Faculty of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran
| | - Nima Saberi
- Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, ON, Canada
| | - Reza Ghiassi
- Water and Environmental Measurement and Monitoring Labour, School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran
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Ma S, Xu F, Qiu D, Fan S, Wang R, Li Y, Chen X. The occurrence, transformation and control of selenium in coal-fired power plants: Status quo and development. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2022; 72:131-146. [PMID: 34846276 DOI: 10.1080/10962247.2021.2010620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
As a trace element, selenium can cause serious harm to organisms when the concentration is too high. Coal-fired power plants are the main source of man-made selenium emissions. How to control the selenium pollution of coal-fired power plants to realize the renewable selenium and the sustainability of coal has not attracted enough attention from the whole world. This paper outlines the conversion and occurrence of selenium in coal-fired power plants. A small part of the selenium produced by combustion can be removed by selective catalytic reduction (SCR) and electrostatic precipitator (ESP) after the gas phase undergoes physical condensation and chemical adsorption to combine with the particulate matter in the flue gas.Because the chemical precipitation method has poor selenium removal effect, the remaining part enters the flue gas desulfurization absorption tower and can be enriched in the desulfurization slurry. The occurrence situation and conversion pathway of selenium in desulfurization slurry are introduced subsequently, the research progress of selenium removal from wet desulfurization wastewater is reviewed from three aspects: physics, biology and chemistry. We believe that the coupling application of oxidation-reduction potential (ORP) and pH can optimize selenium removal in the desulfurization system by improving the oxidation control. As a technology for wet desulfurization system to treat selenium pollution, it has a good development prospect in near future.Implications: Selenium is a trace element present in coal. It is not only of great significance to the life activities of organisms, but also a kind of rare resource. As the most important source of man-made emissions, coal-fired power plants will cause waste of selenium resources and selenium pollution in the surrounding environment. In this study, the occurrence, conversion and control of selenium in coal-fired power plants were systematically sorted out and analyzed. It is helpful for scholars to study the selenium transformation process more deeply. It is of great significance for policy formulation of recommended control technologies and emission limits. It is of great value for the formulation of recommended control technology and the in-depth study of the selenium transformation process.
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Affiliation(s)
- Shuangchen Ma
- Hebei Key Laboratory of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, People's Republic of China
- Moe Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing, People's Republic of China
| | - Fang Xu
- Hebei Key Laboratory of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, People's Republic of China
- Moe Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing, People's Republic of China
| | - Dao Qiu
- Department of Production and Technology, Huadian Xiangyang Electricity Supply Co, Ltd Huadian Xiangyang Electricity Supply Co, Ltd, Xiangyang, People's Republic of China
| | - Shuaijun Fan
- Hebei Key Laboratory of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, People's Republic of China
| | - Ruimin Wang
- Department of Production and Technology, Huadian Xiangyang Electricity Supply Co, Ltd Huadian Xiangyang Electricity Supply Co, Ltd, Xiangyang, People's Republic of China
| | - Yang Li
- Hebei Key Laboratory of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, People's Republic of China
| | - Xiangyang Chen
- Hebei Key Laboratory of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, People's Republic of China
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Tirumalai MR, Anane-Bediakoh D, Rajesh S, Fox GE. Net Charges of the Ribosomal Proteins of the S10 and spc Clusters of Halophiles Are Inversely Related to the Degree of Halotolerance. Microbiol Spectr 2021; 9:e0178221. [PMID: 34908470 PMCID: PMC8672879 DOI: 10.1128/spectrum.01782-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 11/24/2021] [Indexed: 11/20/2022] Open
Abstract
Net positive charge(s) on ribosomal proteins (r-proteins) have been reported to influence the assembly and folding of ribosomes. A high percentage of r-proteins from extremely halophilic archaea are known to be acidic or even negatively charged. Those proteins that remain positively charged are typically far less positively charged. Here, the analysis is extended to non-archaeal halophilic bacteria, eukaryotes, and halotolerant archaea. The net charges (pH 7.4) of the r-proteins that comprise the S10-spc operon/cluster from individual microbial and eukaryotic genomes were estimated and intercompared. It was observed that, as a general rule, the net charges of individual proteins remained mostly basic as the salt tolerance of the bacterial strains increased from 5 to 15%. The most striking exceptions were the extremely halophilic bacterial strains, Salinibacter ruber SD01, Acetohalobium arabaticum DSM 5501 and Selenihalanaerobacter shriftii ATCC BAA-73, which are reported to require a minimum of 18% to 21% salt for their growth. All three strains have higher numbers of acidic S10-spc cluster r-proteins than what is seen in the moderate halophiles or the halotolerant strains. Of the individual proteins, only uL2 never became acidic. uS14 and uL16 also seldom became acidic. The net negative charges on several of the S10-spc cluster r-proteins are a feature generally shared by all extremely halophilic archaea and bacteria. The S10-spc cluster r-proteins of halophilic fungi and algae (eukaryotes) were exceptions: these were positively charged despite the halophilicity of the organisms. IMPORTANCE The net charges (at pH 7.4) of the ribosomal proteins (r-proteins) that comprise the S10-spc cluster show an inverse relationship with the halophilicity/halotolerance levels in both bacteria and archaea. In non-halophilic bacteria, the S10-spc cluster r-proteins are generally basic (positively charged), while the rest of the proteomes in these strains are generally acidic. On the other hand, the whole proteomes of the extremely halophilic strains are overall negatively charged, including the S10-spc cluster r-proteins. Given that the distribution of charged residues in the ribosome exit tunnel influences cotranslational folding, the contrasting charges observed in the S10-spc cluster r-proteins have potential implications for the rate of passage of these proteins through the ribosomal exit tunnel. Furthermore, the universal protein uL2, which lies in the oldest part of the ribosome, is always positively charged irrespective of the strain/organism it belongs to. This has implications for its role in the prebiotic context.
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Affiliation(s)
- Madhan R. Tirumalai
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | | | - Sidharth Rajesh
- Clements High School (Class of 2023), Fort Bend Independent School District, Sugar Land, Texas, USA
| | - George E. Fox
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
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7
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Staicu LC, Barton LL. Selenium respiration in anaerobic bacteria: Does energy generation pay off? J Inorg Biochem 2021; 222:111509. [PMID: 34118782 DOI: 10.1016/j.jinorgbio.2021.111509] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/18/2021] [Accepted: 05/30/2021] [Indexed: 01/03/2023]
Abstract
Selenium (Se) respiration in bacteria was revealed for the first time at the end of 1980s. Although thermodynamically-favorable, energy-dense and documented in phylogenetically-diverse bacteria, this metabolic process appears to be accompanied by a number of challenges and numerous unanswered questions. Selenium oxyanions, SeO42- and SeO32-, are reduced to elemental Se (Se0) through anaerobic respiration, the end product being solid and displaying a considerable size (up to 500 nm) at the bacterial scale. Compared to other electron acceptors used in anaerobic respiration (e.g. N, S, Fe, Mn, and As), Se is one of the few elements whose end product is solid. Furthermore, unlike other known bacterial intracellular accumulations such as volutin (inorganic polyphosphate), S0, glycogen or magnetite, Se0 has not been shown to play a nutritional or ecological role for its host. In the context of anaerobic respiration of Se oxyanions, biogenic Se0 appears to be a by-product, a waste that needs proper handling, and this raises the question of the evolutionary implications of this process. Why would bacteria use a respiratory substrate that is useful, in the first place, and then highly detrimental? Interestingly, in certain artificial ecosystems (e.g. upflow bioreactors) Se0 might help bacterial cells to increase their density and buoyancy and thus avoid biomass wash-out, ensuring survival. This review article provides an in-depth analysis of selenium respiration (model selenium respiring bacteria, thermodynamics, respiratory enzymes, and genetic determinants), complemented by an extensive discussion about the evolutionary implications and the properties of biogenic Se0 using published and original/unpublished results.
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Affiliation(s)
- Lucian C Staicu
- Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Larry L Barton
- Department of Biology, University of New Mexico, MSCO3 2020, Albuquerque, NM 87131, USA
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Abstract
'There's antimony, arsenic, aluminum, selenium, and hydrogen, and oxygen, and nitrogen and rhenium'-so begins 'The Elements' song (https://www.youtube.com/watch?v=AcS3NOQnsQM), whereby Tom Lehrer (Fig. 1) assiduously deconstructed the many painstaking decades of research effort by scores of scientists in assembling the Periodic Table as primarily based upon the atomic numbers of the elements. Lehrer instead opted for his imaginative rhyme, with its musical meter purloined from the patter song of Major General Stanley ("I am the Very Model of a Modern Major General') as in the Gilbert and Sullivan's operetta 'The Pirates of Penzance'. By some coincidence, however, three of the four named in the first stanza are Group 15 and 16 elements with which I have considerable microbiological research experience. Only one is missing (tellurium). Hence, by futzing with Lehrer's 'libretto' to suit my own needs for this issue of FEMS, I would pose the following introductory re-rearrangement: 'There's antimony, arsenic, selenium, tellurium, and cadmium, and chromium, and calcium and curium'. While this may (or may not) sit well with Mr Lehrer, who at the time of this writing is still living, I hope it does not cause further discomfiture to the collective eternal peace of Professor Dimitri Mendeleev, Sir William Schwenk Gilbert and Sir Arthur Sullivan. Nonetheless, I will use this preface to take departure for the primary subject of this manuscript, namely our efforts on selenium, which is where it all got started.
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Affiliation(s)
- Ronald S Oremland
- Emeritus Senior Scientist, United States Geological Survey, Menlo Park, CA 94025, USA
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Wells M, Stolz JF. Microbial selenium metabolism: a brief history, biogeochemistry and ecophysiology. FEMS Microbiol Ecol 2020; 96:5921172. [DOI: 10.1093/femsec/fiaa209] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/08/2020] [Indexed: 01/02/2023] Open
Abstract
ABSTRACTSelenium is an essential trace element for organisms from all three domains of life. Microorganisms, in particular, mediate reductive transformations of selenium that govern the element's mobility and bioavailability in terrestrial and aquatic environments. Selenium metabolism is not just ubiquitous but an ancient feature of life likely extending back to the universal common ancestor of all cellular lineages. As with the sulfur biogeochemical cycle, reductive transformations of selenium serve two metabolic functions: assimilation into macromolecules and dissimilatory reduction during anaerobic respiration. This review begins with a historical overview of how research in both aspects of selenium metabolism has developed. We then provide an overview of the global selenium biogeochemical cycle, emphasizing the central role of microorganisms in the cycle. This serves as a basis for a robust discussion of current models for the evolution of the selenium biogeochemical cycle over geologic time, and how knowledge of the evolution and ecophysiology of selenium metabolism can enrich and refine these models. We conclude with a discussion of the ecophysiological function of selenium-respiring prokaryotes within the cycle, and the tantalizing possibility of oxidative selenium transformations during chemolithoautotrophic growth.
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Affiliation(s)
- Michael Wells
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA
| | - John F Stolz
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA
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Alqahtani MF, Bajracharya S, Katuri KP, Ali M, Ragab A, Michoud G, Daffonchio D, Saikaly PE. Enrichment of Marinobacter sp. and Halophilic Homoacetogens at the Biocathode of Microbial Electrosynthesis System Inoculated With Red Sea Brine Pool. Front Microbiol 2019; 10:2563. [PMID: 31787955 PMCID: PMC6855130 DOI: 10.3389/fmicb.2019.02563] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 10/23/2019] [Indexed: 11/13/2022] Open
Abstract
Homoacetogens are efficient CO2 fixing bacteria using H2 as electron donor to produce acetate. These organisms can be enriched at the biocathode of microbial electrosynthesis (MES) for electricity-driven CO2 reduction to acetate. Studies exploring homoacetogens in MES are mainly conducted using pure or mix-culture anaerobic inocula from samples with standard environmental conditions. Extreme marine environments host unique microbial communities including homoacetogens that may have unique capabilities due to their adaptation to harsh environmental conditions. Anaerobic deep-sea brine pools are hypersaline and metalliferous environments and homoacetogens can be expected to live in these environments due to their remarkable metabolic flexibility and energy-efficient biosynthesis. However, brine pools have never been explored as inocula for the enrichment of homacetogens in MES. Here we used the saline water from a Red Sea brine pool as inoculum for the enrichment of halophilic homoacetogens at the biocathode (-1 V vs. Ag/AgCl) of MES. Volatile fatty acids, especially acetate, along with hydrogen gas were produced in MES systems operated at 25 and 10% salinity. Acetate concentration increased when MES was operated at a lower salinity ∼3.5%, representing typical seawater salinity. Amplicon sequencing and genome-centric metagenomics of matured cathodic biofilm showed dominance of the genus Marinobacter and phylum Firmicutes at all tested salinities. Seventeen high-quality draft metagenome-assembled genomes (MAGs) were extracted from the biocathode samples. The recovered MAGs accounted for 87 ± 4% of the quality filtered sequence reads. Genome analysis of the MAGs suggested CO2 fixation via Wood-Ljundahl pathway by members of the phylum Firmicutes and the fixed CO2 was possibly utilized by Marinobacter sp. for growth by consuming O2 escaping from the anode to the cathode for respiration. The enrichment of Marinobacter sp. with homoacetogens was only possible because of the specific cathodic environment in MES. These findings suggest that in organic carbon-limited saline environments, Marinobacter spp. can live in consortia with CO2 fixing bacteria such as homoacetogens, which can provide them with fixed carbon as a source of carbon and energy.
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Affiliation(s)
- Manal F Alqahtani
- King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Biological and Environmental Science and Engineering Division, Thuwal, Saudi Arabia
| | - Suman Bajracharya
- King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Biological and Environmental Science and Engineering Division, Thuwal, Saudi Arabia
| | - Krishna P Katuri
- King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Biological and Environmental Science and Engineering Division, Thuwal, Saudi Arabia
| | - Muhammad Ali
- King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Biological and Environmental Science and Engineering Division, Thuwal, Saudi Arabia
| | - Ala'a Ragab
- King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Biological and Environmental Science and Engineering Division, Thuwal, Saudi Arabia
| | - Grégoire Michoud
- King Abdullah University of Science and Technology, Red Sea Research Center, Biological and Environmental Science and Engineering Division, Thuwal, Saudi Arabia
| | - Daniele Daffonchio
- King Abdullah University of Science and Technology, Red Sea Research Center, Biological and Environmental Science and Engineering Division, Thuwal, Saudi Arabia
| | - Pascal E Saikaly
- King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Biological and Environmental Science and Engineering Division, Thuwal, Saudi Arabia
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Zhang Y, Kuroda M, Nakatani Y, Soda S, Ike M. Removal of selenite from artificial wastewater with high salinity by activated sludge in aerobic sequencing batch reactors. J Biosci Bioeng 2019; 127:618-624. [DOI: 10.1016/j.jbiosc.2018.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 11/01/2018] [Accepted: 11/02/2018] [Indexed: 10/27/2022]
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12
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Zhang Y, Kuroda M, Arai S, Kato F, Inoue D, Ike M. Biological treatment of selenate-containing saline wastewater by activated sludge under oxygen-limiting conditions. WATER RESEARCH 2019; 154:327-335. [PMID: 30818098 DOI: 10.1016/j.watres.2019.01.059] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 06/09/2023]
Abstract
Selenium often coincides with high salinity in certain industrial wastewaters, which can be a limitation in the practical application of biological treatment. However, there are no studies on the biological treatment of selenate-containing saline wastewater. A sequencing batch reactor inoculated with activated sludge was applied to treat selenate in the presence of 3% (w/v) NaCl. Start-up of the sequencing batch reactor with a 7-day cycle duration and excessive acetate as the sole carbon source succeeded in removing above 98% and 72% soluble and solid selenium, respectively, under oxygen-limiting conditions. Further selenium removal experiments with a shorter cycle duration of 3 days and a stepwise decrease of acetate addition achieved soluble and total selenium removal efficiencies in most batches above 96% and 80%, respectively. Mass balance analysis revealed that selenate was converted into elemental selenium, most of which was accumulated in the sludge. Microscopic analyses also found that elemental selenium particles were primarily present as approximately 2 μm large rods, with some extremely large particles above 10 μm. Although the bacterial populations responsible for selenium removal, especially selenate reduction, could not be identified by microbial community analysis, this study reported for the first time that selenate could be biologically treated in the presence of considerable salinity, offering implications for the practical treatment of selenium in certain industrial wastewaters.
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Affiliation(s)
- Yuanyuan Zhang
- Division of Sustainable Energy and Environmental Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Masashi Kuroda
- Division of Sustainable Energy and Environmental Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Shunsuke Arai
- Nippon Steel & Sumitomo Metal Corporation, 20-1 Shintomi, Futtu, Chiba, 293-8511, Japan
| | - Fumitaka Kato
- Nippon Steel & Sumitomo Metal Corporation, 20-1 Shintomi, Futtu, Chiba, 293-8511, Japan
| | - Daisuke Inoue
- Division of Sustainable Energy and Environmental Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Michihiko Ike
- Division of Sustainable Energy and Environmental Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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13
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Respiratory Selenite Reductase from Bacillus selenitireducens Strain MLS10. J Bacteriol 2019; 201:JB.00614-18. [PMID: 30642986 DOI: 10.1128/jb.00614-18] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/03/2019] [Indexed: 11/20/2022] Open
Abstract
The putative respiratory selenite [Se(IV)] reductase (Srr) from Bacillus selenitireducens MLS10 has been identified through a polyphasic approach involving genomics, proteomics, and enzymology. Nondenaturing gel assays were used to identify Srr in cell fractions, and the active band was shown to contain a single protein of 80 kDa. The protein was identified through liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a homolog of the catalytic subunit of polysulfide reductase (PsrA). It was found to be encoded as part of an operon that contains six genes that we designated srrE, srrA, srrB, srrC, srrD, and srrF SrrA is the catalytic subunit (80 kDa), with a twin-arginine translocation (TAT) leader sequence indicative of a periplasmic protein and one putative 4Fe-4S binding site. SrrB is a small subunit (17 kDa) with four putative 4Fe-4S binding sites, SrrC (43 kDa) is an anchoring subunit, and SrrD (24 kDa) is a chaperon protein. Both SrrE (38 kDa) and SrrF (45 kDa) were annotated as rhodanese domain-containing proteins. Phylogenetic analysis revealed that SrrA belonged to the PsrA/PhsA clade but that it did not define a distinct subgroup, based on the putative homologs that were subsequently identified from other known selenite-respiring bacteria (e.g., Desulfurispirillum indicum and Pyrobaculum aerophilum). The enzyme appeared to be specific for Se(IV), showing no activity with selenate, arsenate, or thiosulfate, with a Km of 145 ± 53 μM, a V max of 23 ± 2.5 μM min-1, and a k cat of 23 ± 2.68 s-1 These results further our understanding of the mechanisms of selenium biotransformation and its biogeochemical cycle.IMPORTANCE Selenium is an essential element for life, with Se(IV) reduction a key step in its biogeochemical cycle. This report identifies for the first time a dissimilatory Se(IV) reductase, Srr, from a known selenite-respiring bacterium, the haloalkalophilic Bacillus selenitireducens strain MLS10. The work extends the versatility of the complex iron-sulfur molybdoenzyme (CISM) superfamily in electron transfer involving chalcogen substrates with different redox potentials. Further, it underscores the importance of biochemical and enzymological approaches in establishing the functionality of these enzymes.
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Eswayah AS, Smith TJ, Scheinost AC, Hondow N, Gardiner PHE. Microbial transformations of selenite by methane-oxidizing bacteria. Appl Microbiol Biotechnol 2017. [PMID: 28646447 PMCID: PMC5554269 DOI: 10.1007/s00253-017-8380-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Methane-oxidizing bacteria are well known for their role in the global methane cycle and their potential for microbial transformation of wide range of hydrocarbon and chlorinated hydrocarbon pollution. Recently, it has also emerged that methane-oxidizing bacteria interact with inorganic pollutants in the environment. Here, we report what we believe to be the first study of the interaction of pure strains of methane-oxidizing bacteria with selenite. Results indicate that the commonly used laboratory model strains of methane-oxidizing bacteria, Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b, are both able to reduce the toxic selenite (SeO32−) but not selenate (SeO42−) to red spherical nanoparticulate elemental selenium (Se0), which was characterized via energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The cultures also produced volatile selenium-containing species, which suggests that both strains may have an additional activity that can transform either Se0 or selenite into volatile methylated forms of selenium. Transmission electron microscopy (TEM) measurements and experiments with the cell fractions cytoplasm, cell wall and cell membrane show that the nanoparticles are formed mainly on the cell wall. Collectively, these results are promising for the use of methane-oxidizing bacteria for bioremediation or suggest possible uses in the production of selenium nanoparticles for biotechnology.
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Affiliation(s)
- Abdurrahman S Eswayah
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, UK
- Biotechnology Research Centre, Tripoli, Libya
| | - Thomas J Smith
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, UK
| | - Andreas C Scheinost
- The Rossendorf Beamline at ESRF, F-38043, Grenoble, France
- Institute of Resource Ecology, Helmholtz Zentrum Dresden Rossendorf, D-01328, Dresden, Germany
| | - Nicole Hondow
- School of Chemical and Process Engineering, University of Leeds, Leeds, UK
| | - Philip H E Gardiner
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, UK.
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Louie TS, Giovannelli D, Yee N, Narasingarao P, Starovoytov V, Göker M, Klenk HP, Lang E, Kyrpides NC, Woyke T, Bini E, Häggblom MM. High-quality draft genome sequence of Sedimenticola selenatireducens strain AK4OH1 T, a gammaproteobacterium isolated from estuarine sediment. Stand Genomic Sci 2016; 11:66. [PMID: 27721915 PMCID: PMC5052931 DOI: 10.1186/s40793-016-0191-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 08/31/2016] [Indexed: 11/10/2022] Open
Abstract
Sedimenticola selenatireducens strain AK4OH1T (= DSM 17993T = ATCC BAA-1233T) is a microaerophilic bacterium isolated from sediment from the Arthur Kill intertidal strait between New Jersey and Staten Island, NY. S. selenatireducens is Gram-negative and belongs to the Gammaproteobacteria. Strain AK4OH1T was the first representative of its genus to be isolated for its unique coupling of the oxidation of aromatic acids to the respiration of selenate. It is a versatile heterotroph and can use a variety of carbon compounds, but can also grow lithoautotrophically under hypoxic and anaerobic conditions. The draft genome comprises 4,588,530 bp and 4276 predicted protein-coding genes including genes for the anaerobic degradation of 4-hydroxybenzoate and benzoate. Here we report the main features of the genome of S. selenatireducens strain AK4OH1T.
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Affiliation(s)
- Tiffany S Louie
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ USA
| | - Donato Giovannelli
- Institute of Earth, Ocean, and Atmospheric Science, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ USA ; Institute of Marine Science, ISMAR, National Research Council of Italy, CNR, Ancona, Italy ; Institute for Advanced Studies, Program in Interdisciplinary Studies, Princeton, NJ USA
| | - Nathan Yee
- Department of Environmental Sciences, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ USA
| | - Priya Narasingarao
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ USA
| | - Valentin Starovoytov
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ USA
| | - Markus Göker
- Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Hans-Peter Klenk
- Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany ; Newcastle University, School of Biology, Newcastle upon Tyne, UK
| | - Elke Lang
- Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Nikos C Kyrpides
- Department of Energy Joint Genome Institute, Genome Biology Program, Walnut Creek, CA USA ; Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Tanja Woyke
- Department of Energy Joint Genome Institute, Genome Biology Program, Walnut Creek, CA USA
| | - Elisabetta Bini
- Pharmacy Practice and Administration, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ USA ; Present address: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN USA
| | - Max M Häggblom
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ USA
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Oren A. Glycerol metabolism in hypersaline environments. Environ Microbiol 2016; 19:851-863. [DOI: 10.1111/1462-2920.13493] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 08/05/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Aharon Oren
- The Institute of Life Sciences, The Hebrew University of Jerusalem, The Edmond J. Safra Campus; Jerusalem 91904 Israel
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Microbial Transformations of Selenium Species of Relevance to Bioremediation. Appl Environ Microbiol 2016; 82:4848-59. [PMID: 27260359 DOI: 10.1128/aem.00877-16] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Selenium species, particularly the oxyanions selenite (SeO3 (2-)) and selenate (SeO4 (2-)), are significant pollutants in the environment that leach from rocks and are released by anthropogenic activities. Selenium is also an essential micronutrient for organisms across the tree of life, including microorganisms and human beings, particularly because of its presence in the 21st genetically encoded amino acid, selenocysteine. Environmental microorganisms are known to be capable of a range of transformations of selenium species, including reduction, methylation, oxidation, and demethylation. Assimilatory reduction of selenium species is necessary for the synthesis of selenoproteins. Dissimilatory reduction of selenate is known to support the anaerobic respiration of a number of microorganisms, and the dissimilatory reduction of soluble selenate and selenite to nanoparticulate elemental selenium greatly reduces the toxicity and bioavailability of selenium and has a major role in bioremediation and potentially in the production of selenium nanospheres for technological applications. Also, microbial methylation after reduction of Se oxyanions is another potentially effective detoxification process if limitations with low reaction rates and capture of the volatile methylated selenium species can be overcome. This review discusses microbial transformations of different forms of Se in an environmental context, with special emphasis on bioremediation of Se pollution.
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Heavy metal resistance in halophilicBacteriaandArchaea. FEMS Microbiol Lett 2016; 363:fnw146. [DOI: 10.1093/femsle/fnw146] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2016] [Indexed: 12/25/2022] Open
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Tan LC, Nancharaiah YV, van Hullebusch ED, Lens PNL. Selenium: environmental significance, pollution, and biological treatment technologies. Biotechnol Adv 2016; 34:886-907. [PMID: 27235190 DOI: 10.1016/j.biotechadv.2016.05.005] [Citation(s) in RCA: 220] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 04/26/2016] [Accepted: 05/21/2016] [Indexed: 10/21/2022]
Abstract
Selenium is an essential trace element needed for all living organisms. Despite its essentiality, selenium is a potential toxic element to natural ecosystems due to its bioaccumulation potential. Though selenium is found naturally in the earth's crust, especially in carbonate rocks and volcanic and sedimentary soils, about 40% of the selenium emissions to atmospheric and aquatic environments are caused by various industrial activities such as mining-related operations. In recent years, advances in water quality and pollution monitoring have shown that selenium is a contaminant of potential environmental concern. This has practical implications on industry to achieve the stringent selenium regulatory discharge limit of 5μgSeL(-1) for selenium containing wastewaters set by the United States Environmental Protection Agency. Over the last few decades, various technologies have been developed for the treatment of selenium-containing wastewaters. Biological selenium reduction has emerged as the leading technology for removing selenium from wastewaters since it offers a cheaper alternative compared to physico-chemical treatments and is suitable for treating dilute and variable selenium-laden wastewaters. Moreover, biological treatment has the advantage of forming elemental selenium nanospheres which exhibit unique optical and spectral properties for various industrial applications, i.e. medical, electrical, and manufacturing processes. However, despite the advances in biotechnology employing selenium reduction, there are still several challenges, particularly in achieving stringent discharge limits, the long-term stability of biogenic selenium and predicting the fate of bioreduced selenium in the environment. This review highlights the significance of selenium in the environment, health, and industry and biotechnological advances made in the treatment of selenium contaminated wastewaters. The challenges and future perspectives are overviewed considering recent biotechnological advances in the management of these selenium-laden wastewaters.
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Affiliation(s)
- Lea Chua Tan
- UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands.
| | - Yarlagadda V Nancharaiah
- Biofouling and Biofilm Process Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre Kalpakkam, 603102 Tamil Nadu, India.
| | - Eric D van Hullebusch
- Université Paris-Est, Laboratoire Géomatériaux et Environnement (EA 4508), UPEM, 77454 Marne-la-Vallée, France.
| | - Piet N L Lens
- UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands; Department of Chemistry and Bioengineering, Tampere University of Technology, P.O-Box 541, Tampere, Finland.
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Gonzalez-Gil G, Lens PNL, Saikaly PE. Selenite Reduction by Anaerobic Microbial Aggregates: Microbial Community Structure, and Proteins Associated to the Produced Selenium Spheres. Front Microbiol 2016; 7:571. [PMID: 27199909 PMCID: PMC4844624 DOI: 10.3389/fmicb.2016.00571] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 04/05/2016] [Indexed: 12/22/2022] Open
Abstract
Certain types of anaerobic granular sludge, which consists of microbial aggregates, can reduce selenium oxyanions. To envisage strategies for removing those oxyanions from wastewater and recovering the produced elemental selenium (Se(0)), insights into the microbial community structure and synthesis of Se(0) within these microbial aggregates are required. High-throughput sequencing showed that Veillonellaceae (c.a. 20%) and Pseudomonadaceae (c.a.10%) were the most abundant microbial phylotypes in selenite reducing microbial aggregates. The majority of the Pseudomonadaceae sequences were affiliated to the genus Pseudomonas. A distinct outer layer (∼200 μm) of selenium deposits indicated that bioreduction occurred in the outer zone of the microbial aggregates. In that outer layer, SEM analysis showed abundant intracellular and extracellular Se(0) (nano)spheres, with some cells having high numbers of intracellular Se(0) spheres. Electron tomography showed that microbial cells can harbor a single large intracellular sphere that stretches the cell body. The Se(0) spheres produced by the microorganisms were capped with organic material. X-ray photoelectron spectroscopy (XPS) analysis of extracted Se(0) spheres, combined with a mathematical approach to analyzing XPS spectra from biological origin, indicated that proteins and lipids were components of the capping material associated to the Se(0) spheres. The most abundant proteins associated to the spheres were identified by proteomic analysis. Most of the proteins or peptide sequences capping the Se(0) spheres were identified as periplasmic outer membrane porins and as the cytoplasmic elongation factor Tu protein, suggesting an intracellular formation of the Se(0) spheres. In view of these and previous findings, a schematic model for the synthesis of Se(0) spheres by the microorganisms inhabiting the granular sludge is proposed.
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Affiliation(s)
- Graciela Gonzalez-Gil
- Division of Biological and Environmental Sciences and Engineering, Water Desalination and Reuse Center, King Abdullah University of Science and TechnologyThuwal, Saudi Arabia; Department of Environmental Engineering and Water Technology, UNESCO-IHE Institute for Water EducationDelft, Netherlands
| | - Piet N L Lens
- Department of Environmental Engineering and Water Technology, UNESCO-IHE Institute for Water Education Delft, Netherlands
| | - Pascal E Saikaly
- Division of Biological and Environmental Sciences and Engineering, Water Desalination and Reuse Center, King Abdullah University of Science and Technology Thuwal, Saudi Arabia
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Maltman C, Walter G, Yurkov V. A Diverse Community of Metal(loid) Oxide Respiring Bacteria Is Associated with Tube Worms in the Vicinity of the Juan de Fuca Ridge Black Smoker Field. PLoS One 2016; 11:e0149812. [PMID: 26914590 PMCID: PMC4767881 DOI: 10.1371/journal.pone.0149812] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 02/04/2016] [Indexed: 01/24/2023] Open
Abstract
Epibiotic bacteria associated with tube worms living in the vicinity of deep sea hydrothermal vents of the Juan de Fuca Ridge in the Pacific Ocean were investigated for the ability to respire anaerobically on tellurite, tellurate, selenite, selenate, metavanadate and orthovanadate as terminal electron acceptors. Out of 107 isolates tested, 106 were capable of respiration on one or more of these oxides, indicating that metal(loid) oxide based respiration is not only much more prevalent in nature than is generally believed, but also is an important mode of energy generation in the habitat. Partial 16S rRNA gene sequencing revealed the bacterial community to be rich and highly diverse, containing many potentially new species. Furthermore, it appears that the worms not only possess a close symbiotic relationship with chemolithotrophic sulfide-oxidizing bacteria, but also with the metal(loid) oxide transformers. Possibly they protect the worms through reduction of the toxic compounds that would otherwise be harmful to the host.
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Affiliation(s)
- Chris Maltman
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Graham Walter
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Vladimir Yurkov
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
- * E-mail:
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22
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Winters YD, Lowenstein TK, Timofeeff MN. Starvation-Survival in Haloarchaea. Life (Basel) 2015; 5:1587-609. [PMID: 26569313 PMCID: PMC4695838 DOI: 10.3390/life5041587] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/09/2015] [Accepted: 10/23/2015] [Indexed: 11/16/2022] Open
Abstract
Recent studies claiming to revive ancient microorganisms trapped in fluid inclusions in halite have warranted an investigation of long-term microbial persistence. While starvation-survival is widely reported for bacteria, it is less well known for halophilic archaea-microorganisms likely to be trapped in ancient salt crystals. To better understand microbial survival in fluid inclusions in ancient evaporites, laboratory experiments were designed to simulate growth of halophilic archaea under media-rich conditions, complete nutrient deprivation, and a controlled substrate condition (glycerol-rich) and record their responses. Haloarchaea used for this work included Hbt. salinarum and isolate DV582A-1 (genus Haloterrigena) sub-cultured from 34 kyear Death Valley salt. Hbt. salinarum and DV582A-1 reacted to nutrient limitation with morphological and population changes. Starved populations increased and most cells converted from rods to small cocci within 56 days of nutrient deprivation. The exact timing of starvation adaptations and the physical transformations differed between species, populations of the same species, and cells of the same population. This is the first study to report the timing of starvation strategies for Hbt. salinarum and DV582A-1. The morphological states in these experiments may allow differentiation between cells trapped with adequate nutrients (represented here by early stages in nutrient-rich media) from cells trapped without nutrients (represented here by experimental starvation) in ancient salt. The hypothesis that glycerol, leaked from Dunaliella, provides nutrients for the survival of haloarchaea trapped in fluid inclusions in ancient halite, is also tested. Hbt. salinarum and DV582A-1 were exposed to a mixture of lysed and intact Dunaliella for 56 days. The ability of these organisms to utilize glycerol from Dunaliella cells was assessed by documenting population growth, cell length, and cell morphology. Hbt. salinarum and DV582A-1 experienced size reductions and shape transitions from rods to cocci. In the short-term, these trends more closely resembled the response of these organisms to starvation conditions than to nutrient-rich media. Results from this experiment reproduced the physical state of cells (small cocci) in ancient halite where prokaryotes co-exist with single-celled algae. We conclude that glycerol is not the limiting factor in the survival of haloarchaea for thousands of years in fluid inclusions in halite.
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Microbial Diversity in Engineered Haloalkaline Environments Shaped by Shared Geochemical Drivers Observed in Natural Analogues. Appl Environ Microbiol 2015; 81:5026-36. [PMID: 25979895 DOI: 10.1128/aem.01238-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 05/12/2015] [Indexed: 01/17/2023] Open
Abstract
Microbial communities in engineered terrestrial haloalkaline environments have been poorly characterized relative to their natural counterparts and are geologically recent in formation, offering opportunities to explore microbial diversity and assembly in dynamic, geochemically comparable contexts. In this study, the microbial community structure and geochemical characteristics of three geographically dispersed bauxite residue environments along a remediation gradient were assessed and subsequently compared with other engineered and natural haloalkaline systems. In bauxite residues, bacterial communities were similar at the phylum level (dominated by Proteobacteria and Firmicutes) to those found in soda lakes, oil sands tailings, and nuclear wastes; however, they differed at lower taxonomic levels, with only 23% of operational taxonomic units (OTUs) shared with other haloalkaline environments. Although being less diverse than natural analogues, bauxite residue harbored substantial novel bacterial taxa, with 90% of OTUs nonmatchable to cultured representative sequences. Fungal communities were dominated by Ascomycota and Basidiomycota, consistent with previous studies of hypersaline environments, and also harbored substantial novel (73% of OTUs) taxa. In bauxite residues, community structure was clearly linked to geochemical and physical environmental parameters, with 84% of variation in bacterial and 73% of variation in fungal community structures explained by environmental parameters. The major driver of bacterial community structure (salinity) was consistent across natural and engineered environments; however, drivers differed for fungal community structure between natural (pH) and engineered (total alkalinity) environments. This study demonstrates that both engineered and natural terrestrial haloalkaline environments host substantial repositories of microbial diversity, which are strongly shaped by geochemical drivers.
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Abstract
In nature, selenium is actively cycled between oxic and anoxic habitats, and this cycle plays an important role in carbon and nitrogen mineralization through bacterial anaerobic respiration. Selenium-respiring bacteria (SeRB) are found in geographically diverse, pristine or contaminated environments and play a pivotal role in the selenium cycle. Unlike its structural analogues oxygen and sulfur, the chalcogen selenium and its microbial cycling have received much less attention by the scientific community. This review focuses on microorganisms that use selenate and selenite as terminal electron acceptors, in parallel to the well-studied sulfate-reducing bacteria. It overviews the significant advancements made in recent years on the role of SeRB in the biological selenium cycle and their ecological role, phylogenetic characterization, and metabolism, as well as selenium biomineralization mechanisms and environmental biotechnological applications.
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Affiliation(s)
- Y V Nancharaiah
- Environmental Engineering and Water Technology Department, UNESCO-IHE Institute for Water Education, Delft, The Netherlands Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam, Tamil Nadu, India
| | - P N L Lens
- Environmental Engineering and Water Technology Department, UNESCO-IHE Institute for Water Education, Delft, The Netherlands
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Kalishwaralal K, Jeyabharathi S, Sundar K, Muthukumaran A. A novel one-pot green synthesis of selenium nanoparticles and evaluation of its toxicity in zebrafish embryos. ARTIFICIAL CELLS NANOMEDICINE AND BIOTECHNOLOGY 2014; 44:471-7. [DOI: 10.3109/21691401.2014.962744] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Cluff MA, Hartsock A, MacRae JD, Carter K, Mouser PJ. Temporal changes in microbial ecology and geochemistry in produced water from hydraulically fractured Marcellus shale gas wells. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:6508-17. [PMID: 24803059 DOI: 10.1021/es501173p] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Microorganisms play several important roles in unconventional gas recovery, from biodegradation of hydrocarbons to souring of wells and corrosion of equipment. During and after the hydraulic fracturing process, microorganisms are subjected to harsh physicochemical conditions within the kilometer-deep hydrocarbon-bearing shale, including high pressures, elevated temperatures, exposure to chemical additives and biocides, and brine-level salinities. A portion of the injected fluid returns to the surface and may be reused in other fracturing operations, a process that can enrich for certain taxa. This study tracked microbial community dynamics using pyrotag sequencing of 16S rRNA genes in water samples from three hydraulically fractured Marcellus shale wells in Pennsylvania, USA over a 328-day period. There was a reduction in microbial richness and diversity after fracturing, with the lowest diversity at 49 days. Thirty-one taxa dominated injected, flowback, and produced water communities, which took on distinct signatures as injected carbon and electron acceptors were attenuated within the shale. The majority (>90%) of the community in flowback and produced fluids was related to halotolerant bacteria associated with fermentation, hydrocarbon oxidation, and sulfur-cycling metabolisms, including heterotrophic genera Halolactibacillus, Vibrio, Marinobacter, Halanaerobium, and Halomonas, and autotrophs belonging to Arcobacter. Sequences related to halotolerant methanogenic genera Methanohalophilus and Methanolobus were detected at low abundance (<2%) in produced waters several months after hydraulic fracturing. Five taxa were strong indicators of later produced fluids. These results provide insight into the temporal trajectory of subsurface microbial communities after "fracking" and have important implications for the enrichment of microbes potentially detrimental to well infrastructure and natural gas fouling during this process.
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Affiliation(s)
- Maryam A Cluff
- Department of Civil, Environmental and Geodetic Engineering, Ohio State University , Columbus, Ohio 43210, United States
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Lai CY, Yang X, Tang Y, Rittmann BE, Zhao HP. Nitrate shaped the selenate-reducing microbial community in a hydrogen-based biofilm reactor. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:3395-3402. [PMID: 24579788 DOI: 10.1021/es4053939] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
To study the effect of nitrate (NO3(-)) on selenate (SeO4(2-)) reduction, we tested a H2-based biofilm with a range of influent NO3(-) loadings. When SeO4(2-) was the only electron acceptor (stage 1), 40% of the influent SeO4(2-) was reduced to insoluble elemental selenium (Se(0)). SeO4(2-) reduction was dramatically inhibited when NO3(-) was added at a surface loading larger than 1.14 g of N m(-2) day(-1), when H2 delivery became limiting and only 80% of the input NO3(-) was reduced (stage 2). In stage 3, when NO3(-) was again removed from the influent, SeO4(2-) reduction was re-established and increased to 60% conversion to Se(0). SeO4(2-) reduction remained stable at 60% in stages 4 and 5, when the NO3(-) surface loading was re-introduced at ≤ 0.53 g of N m(-2) day(-1), allowing for complete NO3(-) reduction. The selenate-reducing microbial community was significantly reshaped by the high NO3(-) surface loading in stage 2, and it remained stable through stages 3-5. In particular, the abundance of α-Proteobacteria decreased from 30% in stage 1 to less than 10% of total bacteria in stage 2. β-Proteobacteria, which represented about 55% of total bacteria in the biofilm in stage 1, increased to more than 90% of phylotypes in stage 2. Hydrogenophaga, an autotrophic denitrifier, was positively correlated with NO3(-) flux. Thus, introducing a NO3(-) loading high enough to cause H2 limitation and suppress SeO4(2-) reduction had a long-lasting effect on the microbial community structure, which was confirmed by principal coordinate analysis, although SeO4(2-) reduction remained intact.
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Affiliation(s)
- Chun-Yu Lai
- Ministry of Education, Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University , Hangzhou 310029, People's Republic of China
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Buchs B, Evangelou MWH, Winkel LHE, Lenz M. Colloidal properties of nanoparticular biogenic selenium govern environmental fate and bioremediation effectiveness. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:2401-2407. [PMID: 23363320 DOI: 10.1021/es304940s] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Microbial selenium (Se) bioremediation is based on conversion of water soluble, toxic Se oxyanions to water insoluble, elemental Se. Formed biogenic elemental Se is of nanometer size, hampering straightforward separation from the aqueous phase. This study represents the first systematic investigation on colloidal properties of pure biogenic Se suspensions, linking electrophoretic mobility (ζ-potential) to column settling behavior. It was demonstrated that circumneutral pH, commonly applied in bioremediation, is not appropriate for gravitational separation due to the negative ζ-potential preventing agglomeration. Mono/di/trivalent counter cations and acidity (protons) were used to screen efficiently the intrinsic negative charge of biogenic Se suspensions at circumneutral pH. Fast settling was induced by La(3+) addition in the micromolar range (86.2 ± 3.5% within 0.5 h), whereas considerably higher concentrations were needed when Ca(2+) or Na(+) was used. Colloidal stability was furthermore studied in different model waters. It was demonstrated that surface waters as such represent a fragile system regarding colloidal stability of biogenic Se suspensions (ζ-potential ∼ -30 mV), whereas dissolved organic matter increases colloidal stability. In marine waters, biogenic Se is colloidally destabilized and is thus expected to settle, representing a potential sink for Se during transport in the aquatic environment.
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Affiliation(s)
- Benjamin Buchs
- Institute for Ecopreneurship, University of Applied Sciences and Arts Northwestern Switzerland (FHNW) , School of Life Sciences, Gründenstrasse 40, 4132 Muttenz, Switzerland
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Polyextremophiles and the Constraints for Terrestrial Habitability. CELLULAR ORIGIN, LIFE IN EXTREME HABITATS AND ASTROBIOLOGY 2013. [DOI: 10.1007/978-94-007-6488-0_1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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30
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Zhilina TN, Zavarzina DG, Panteleeva AN, Osipov GA, Kostrikina NA, Tourova TP, Zavarzin GA. Fuchsiella alkaliacetigena gen. nov., sp. nov., an alkaliphilic, lithoautotrophic homoacetogen from a soda lake. Int J Syst Evol Microbiol 2012; 62:1666-1673. [DOI: 10.1099/ijs.0.034363-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The first alkaliphilic obligately anaerobic hydrogenotrophic homoacetogenic bacterium, strain Z-7100T, was isolated from sediments of the soda-depositing soda lake Tanatar III (Altay, Russia). Cells were thin, flexible rods, motile, Gram-negative and spore-forming. The organism was an obligate alkaliphile, growing at pH 8.5 to 10.5, with optimum growth at pH 8.8–9.3, and it grew in soda brines containing 1.9–4.7 M total Na+ (optimum at 2.8–3.3 M). It exhibited an obligate dependence upon sodium carbonate but not upon chloride ions with an NaCl range for growth of 0–14 % (w/v) and an optimum at 7.0–8.5 % (w/v). The isolate was mesophilic and grew at temperatures from 25 to 45 °C, with an optimum at 40 °C. An H2+CO2 mixture, ethanol, pyruvate and lactate were utilized with the formation of acetate as the sole metabolic product. Carbohydrates and amino acids did not support growth. The isolate had a respiratory type of metabolism, reducing
NO
3
–
, SeO4
2− or anthraquinone-2,6-disulfonate (as electron acceptors with ethanol as an electron donor). It was able to grow chemolithotrophically on H2+CO2 in medium supplemented with a vitamin solution only. The major cellular fatty acids were the saturated fatty acids anteiso-C15, C14 : 0 and C16 : 0 and the aldehydes C16, C14 and anteiso-C15. The DNA G+C content of the isolate was 32.0 mol%. 16S rRNA gene sequence analysis showed that strain Z-7100T is a member of the order
Halanaerobiales
and represents a new branch within the family
Halobacteroidaceae
, clustering with the type strain of
Selenihalanaerobacter shriftii
(92.9 % gene sequence similarity). On the basis of its physiological characteristics and phylogenetic position, the isolate is considered to represent a novel species in a new genus within the family
Halobacteroidaceae
. The name Fuchsiella alkaliacetigena gen. nov., sp. nov. is proposed. The type strain of the type species is Z-7100T ( = DSM 24880T = VKM B-2667T).
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Affiliation(s)
- Tatyana N. Zhilina
- Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, Moscow 117312, Russia
| | - Daria G. Zavarzina
- Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, Moscow 117312, Russia
| | - Angela N. Panteleeva
- Bioengineering Center, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/1, Moscow 117312, Russia
| | - Georgy A. Osipov
- Bakulev Center for Cardiovascular Surgery, Russian Academy of Medical Sciences, Rublevskoe shosse, Moscow 135, Russia
| | - Nadezhda A. Kostrikina
- Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, Moscow 117312, Russia
| | - Tatyana P. Tourova
- Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, Moscow 117312, Russia
| | - Georgy A. Zavarzin
- Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, Moscow 117312, Russia
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Desulfohalophilus alkaliarsenatis gen. nov., sp. nov., an extremely halophilic sulfate- and arsenate-respiring bacterium from Searles Lake, California. Extremophiles 2012; 16:727-42. [PMID: 22744231 PMCID: PMC3432211 DOI: 10.1007/s00792-012-0468-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 06/14/2012] [Indexed: 12/03/2022]
Abstract
A haloalkaliphilic sulfate-respiring bacterium, strain SLSR-1, was isolated from a lactate-fed stable enrichment culture originally obtained from the extreme environment of Searles Lake, California. The isolate proved capable of growth via sulfate-reduction over a broad range of salinities (125–330 g/L), although growth was slowest at salt-saturation. Strain SLSR-1 was also capable of growth via dissimilatory arsenate-reduction and displayed an even broader range of salinity tolerance (50–330 g/L) when grown under these conditions. Strain SLSR-1 could also grow via dissimilatory nitrate reduction to ammonia. Growth experiments in the presence of high borate concentrations indicated a greater sensitivity of sulfate-reduction than arsenate-respiration to this naturally abundant anion in Searles Lake. Strain SLSR-1 contained genes involved in both sulfate-reduction (dsrAB) and arsenate respiration (arrA). Amplicons of 16S rRNA gene sequences obtained from DNA extracted from Searles Lake sediment revealed the presence of close relatives of strain SLSR-1 as part of the flora of this ecosystem despite the fact that sulfate-reduction activity could not be detected in situ. We conclude that strain SLSR-1 can only achieve growth via arsenate-reduction under the current chemical conditions prevalent at Searles Lake. Strain SLSR-1 is a deltaproteobacterium in the family Desulfohalobiacea of anaerobic, haloalkaliphilic bacteria, for which we propose the name Desulfohalophilus alkaliarsenatis gen. nov., sp. nov.
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Mishra RR, Prajapati S, Das J, Dangar TK, Das N, Thatoi H. Reduction of selenite to red elemental selenium by moderately halotolerant Bacillus megaterium strains isolated from Bhitarkanika mangrove soil and characterization of reduced product. CHEMOSPHERE 2011; 84:1231-7. [PMID: 21664643 DOI: 10.1016/j.chemosphere.2011.05.025] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2011] [Revised: 05/10/2011] [Accepted: 05/10/2011] [Indexed: 05/13/2023]
Abstract
Two Gram (+) bacterial strains, BSB6 and BSB12, showing resistance and potential for Se(IV) reduction among 26 moderately halotolerant isolates from the Bhitarkanika mangrove soil were characterized by biochemical and 16S rDNA sequence analyses. Both of them were strictly aerobic and able to grow in a wide range of pH (4-11), temperature (4-40°C) and salt concentration (4-12%) having an optimum growth at 37°C, pH ∼7.5 and 7% salt (NaCl). The biochemical characteristics and 16S rDNA sequence analysis of BSB6 and BSB12 showed the closest phylogenetic similarity with the species Bacillus megaterium. Both the strains effectively reduced Se(IV) and complete reduction of selenite (up to 0.25 mM) was achieved within 40 h. SEM with energy dispersive X-ray and TEM analyses revealed the formation of nano size spherical selenium particles in and around the bacterial cells which were also supported by the confocal micrograph study. The UV-Vis diffuse reflectance spectra and XRD of selenium precipitates revealed that the selenium particles are in the nanometric range and crystalline in nature. These bacterial strains may be exploited further for bioremediation process of Se(IV) at relatively high salt concentrations and green synthesis of selenium nanoparticles.
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Affiliation(s)
- Rashmi Ranjan Mishra
- Department of Biotechnology, North Orissa University, Takatapur, Baripada 757 003, Orissa, India
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Sorokin DY, Detkova EN, Muyzer G. Sulfur-dependent respiration under extremely haloalkaline conditions in soda lake 'acetogens' and the description of Natroniella sulfidigena sp. nov. FEMS Microbiol Lett 2011; 319:88-95. [PMID: 21438913 DOI: 10.1111/j.1574-6968.2011.02272.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Microbial sulfidogenesis is the main dissimilatory anaerobic process in anoxic sediments of extremely haloalkaline soda lakes. In soda lakes with a salinity >2 M of the total Na(+) sulfate reduction is depressed, while thiosulfate- and sulfur-dependent sulfidogenesis may still be very active. Anaerobic enrichments at pH 10 and a salinity of 2-4 M total Na(+) from sediments of hypersaline soda lakes with thiosulfate and elemental sulfur as electron acceptors and simple nonfermentable electron donors resulted in the isolation of two groups of haloalkaliphilic bacteria capable of dissimilatory sulfidogenesis. Both were closely related to obligately heterotrophic fermentative homoacetogens from soda lakes. The salt-tolerant alkaliphilic thiosulfate-reducing isolates were identified as representatives of Tindallia magadiensis, while the extremely natronophilic obligate sulfur/polysulfide-respiring strains belonged to the genus Natroniella and are proposed here as a novel species Natroniella sulfidigena. Despite the close phylogenetic relation to Natroniella acetigena, it drastically differed from the type strain phenotypically (chemolithoautotrophic and acetate-dependent sulfur respiration, absence of acetate as the final metabolic product). Apparently, in the absence of specialized respiratory sulfidogens, primarily fermentative bacteria that are well adapted to extreme salinity may take over an uncharacteristic ecological function. This finding, once again, exemplifies the importance of isolation and phenotypic investigation of pure cultures.
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Affiliation(s)
- Dimitry Y Sorokin
- Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia.
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34
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Rauschenbach I, Yee N, Häggblom MM, Bini E. Energy metabolism and multiple respiratory pathways revealed by genome sequencing ofDesulfurispirillum indicumstrain S5. Environ Microbiol 2011; 13:1611-21. [DOI: 10.1111/j.1462-2920.2011.02473.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Rauschenbach I, Narasingarao P, Häggblom MM. Desulfurispirillum indicum sp. nov., a selenate- and selenite-respiring bacterium isolated from an estuarine canal. Int J Syst Evol Microbiol 2011; 61:654-658. [DOI: 10.1099/ijs.0.022392-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Strain S5T, a novel bacterium that was isolated for its capability to respire selenate to elemental selenium, is described. In addition to selenate respiration, it was also capable of dissimilatory selenite, arsenate and nitrate reduction with short-chain organic acids such as pyruvate, lactate and acetate as the carbon sources and electron donors. The isolate was unable to grow fermentatively. Strain S5T was isolated from sediment of an estuarine canal in Chennai, India. Phylogenetic analysis of the 16S rRNA gene of this novel isolate revealed that it belonged to the family Chrysiogenaceae with sequence similarities of 92 and 98 %, respectively, with the type strains of Chrysiogenes arsenatis and Desulfurispirillum alkaliphilum, its closest known relatives. Strain S5T and D. alkaliphilum were closely related in terms of their 16S rRNA gene phylogeny; however, they varied greatly in their genomic DNA G+C content (56 mol% versus 45 mol%) and cellular fatty acid compositions, as well as in many metabolic capabilities. Strain S5T represents a novel species for which the name Desulfurispirillum indicum sp. nov. is proposed; the type strain is S5T (=DSM 22839T =ATCC BAA-1389T).
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Affiliation(s)
- Ines Rauschenbach
- Rutgers University, Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, 76 Lipman Drive, New Brunswick, NJ 08901, USA
| | - Priya Narasingarao
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093, USA
| | - Max M. Häggblom
- Rutgers University, Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, 76 Lipman Drive, New Brunswick, NJ 08901, USA
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Sakaguchi T, Nakano T, Kimura Y, Nogami S, Kubo I, Morita Y. Development of a genetic transfer system in selenate-respiring bacterium Citrobacter sp. strain JSA which was isolated from natural freshwater sediment. J Biosci Bioeng 2011; 111:443-7. [PMID: 21215694 DOI: 10.1016/j.jbiosc.2010.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 10/25/2010] [Accepted: 12/01/2010] [Indexed: 11/16/2022]
Abstract
Conjugative mating between the selenate-reducing bacterium Citrobacter sp. strain JSA and Escherichia coli S17-1 harboring the broad-host-range plasmid pKT230 or pKT240 (IncQ) allowed genetic transfer to strain JSA at a maximum frequency of 2.5×10(-5) (pKT230) and 5.1×10(-6) (pKT240) per recipient JSA cell. Kanamycin-resistant (selection marker of pKT230 and pKT240) transconjugants were routinely obtained with this method, and we confirmed that both vectors were also successfully transferred and replicated in strain JSA without alteration of the replicon. Furthermore, an electroporation method has also allowed transformation of JSA at a frequency of 10(-7) to 10(-6) transformants per μg vector DNA (per recipient cell), and PCR and hybridization analyses revealed that pKT230 and pKT240 are stably maintained in transformed JSA cells. These results indicated that both InQ plasmids can be used as vectors for gene transfer to selenate-reducing strain JSA. This is the first study to demonstrate an effective method for genetic transfer in a selenate-reducing Citrobacter bacterium and will aid in the elucidation of the selenium oxyanion reduction mechanism in this genus of environmental selenate-respiring isolates.
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Affiliation(s)
- Toshifumi Sakaguchi
- Department of Environmental Sciences, Prefectural University of Hiroshima, Hiroshima 727-0023, Japan.
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37
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Abstract
Life at high salt concentrations is energetically expensive. The upper salt concentration limit at which different dissimilatory processes occur in nature appears to be determined to a large extent by bioenergetic constraints. The main factors that determine whether a certain type of microorganism can make a living at high salt are the amount of energy generated during its dissimilatory metabolism and the mode of osmotic adaptation used. I here review new data, both from field observations and from the characterization of cultures of new types of prokaryotes growing at high salt concentrations, to evaluate to what extent the theories formulated 12 years ago are still valid, need to be refined, or should be refuted on the basis of the novel information collected. Most data agree well with the earlier theories. Some new observations, however, are not easily explained: the properties of Natranaerobius and other haloalkaliphilic thermophilic fermentative anaerobes, growth of the sulfate-reducing Desulfosalsimonas propionicica with complete oxidation of propionate and Desulfovermiculus halophilus with complete oxidation of butyrate, growth of lactate-oxidizing sulfate reducers related to Desulfonatronovibrio at 346 g l(-1) salts at pH 9.8, and occurrence of methane oxidation in the anaerobic layers of Big Soda Lake and Mono Lake.
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Affiliation(s)
- Aharon Oren
- Department of Plant and Environmental Sciences, Institute of Life Sciences, and Moshe Shilo Minerva Center for Marine Biogeochemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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38
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Kivistö AT, Karp MT. Halophilic anaerobic fermentative bacteria. J Biotechnol 2010; 152:114-24. [PMID: 20804793 DOI: 10.1016/j.jbiotec.2010.08.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 08/17/2010] [Accepted: 08/23/2010] [Indexed: 10/19/2022]
Abstract
In hypersaline environments bacteria are exposed to a high osmotic pressure caused by the surrounding high salt concentrations. Halophilic microorganisms have specific strategies for balancing the osmotic pressure and surviving in these extreme conditions. Halophilic fermentative bacteria form taxonomically and phylogenetically a coherent group mainly belonging to the order Halanaerobiales. In this review, halophilic anaerobic fermentative bacteria in terms of taxonomy and phylogeny, special characteristics, survival strategies, and potential for biotechnological applications in a wide variety of branches, such as production of hydrogen, are discussed.
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Affiliation(s)
- Anniina T Kivistö
- Tampere University of Technology, Department of Chemistry and Bioengineering, Tampere, Finland.
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Sorokin DY, Rusanov II, Pimenov NV, Tourova TP, Abbas B, Muyzer G. Sulfidogenesis under extremely haloalkaline conditions in soda lakes of Kulunda Steppe (Altai, Russia). FEMS Microbiol Ecol 2010; 73:278-90. [PMID: 20500526 DOI: 10.1111/j.1574-6941.2010.00901.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Sulfidogenic activity (SA) in anoxic sediments of several soda lakes with variable salinity in south Kulunda Steppe (Altai, Russia) has been investigated. The study included in situ measurements of sulfate reduction rates and laboratory experiments with sediment slurries in which sulfate, thiosulfate or elemental sulfur were used as electron acceptors. Despite the extreme conditions (high salt concentrations and high pH), the SA values were relatively high (ranging from 0.02 to 1.20 micromol HS(-) cm(-3) h(-1)), and only hampered under salt-saturated conditions. The highest SA was observed with elemental sulfur, followed by thiosulfate, while the lowest SA was determined in the presence of sulfate. Of all the electron donors tested, the addition of formate resulted in the highest SA with all three sulfur electron acceptors. Surprisingly, hydrogen as an electron donor had very little effect. Acetate was utilized as an electron donor only under sulfur-reducing conditions. Indigenous populations of sulfidogens in soda lake sediments showed an obligately alkaliphilic pH response of SA, showing a pattern that corresponded well to the in situ pH conditions. Sulfate reduction was much more susceptible to salt inhibition than thiosulfate and sulfur reduction. Microbiological investigations indicated that sulfate-reducing bacteria belonging to the orders Desulfovibrionales and Desulfobacterales could very likely be responsible for the SA with sulfate and thiosulfate as electron acceptors at moderate salt concentrations. Sulfur reduction at moderate salinity was carried out by a specialized group of haloalkaliphilic sulfur-reducing bacteria that utilize volatile fatty acids. In saturated soda brine, extremely natronophilic representatives of the order Halanaerobiales were responsible for the sulfur-dependent respiration.
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Affiliation(s)
- Dimitry Y Sorokin
- Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia.
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40
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Srivastava D, Madamwar D, Subramanian RB. Pentavalent arsenate reductase activity in cytosolic fractions of Pseudomonas sp., isolated from arsenic-contaminated sites of Tezpur, Assam. Appl Biochem Biotechnol 2009; 162:766-79. [PMID: 19950002 DOI: 10.1007/s12010-009-8852-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 11/03/2009] [Indexed: 11/30/2022]
Abstract
Pentavalent arsenate reductase activity was localized and characterized in vitro in the cytosolic fraction of a newly isolated bacterial strain from arsenic-contaminated sites. The bacterium was gram negative, rod-shaped, nonmotile, non-spore-forming, and noncapsulated, and the strain was identified as Pseudomonas sp. DRBS1 following biochemical and molecular approaches. The strain Pseudomonas sp. DRBS1 exhibited enzymatic machinery for reduction of arsenate(V) to arsenite(III). The suspended culture of the bacterium reduced more than 97% of As(V) (40-100 mM) to As(III) in 48 h. The growth rate and total cellular yield decreased in the presence of higher concentration of arsenate. The suspended culture repeatedly reduced 10 mM As(V) within 5 h up to five consecutive inputs. The cell-free extracts reduced 86% of 100 microM As(V) in 40 min. The specific activity of arsenate reductase enzyme in the presence of 100 microM arsenate is 6.68 micromol/min per milligram protein. The arsenate reductase activity is maximum at 30 degrees C and at pH 5.2. The arsenate reductase activity increased in the presence of electron donors like citrate, glucose, and galactose and metal ions like Cd(+2), Cu(+2), Ca(+2), and Fe(+2). Selenate as an electron donor also supports the growth of strain DRBS1 and significantly increased the arsenate reduction.
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Affiliation(s)
- Deepti Srivastava
- BRD School of Biosciences, Sardar Patel Maidan, Sardar Patel University, Satellite Campus, Vadtal Road, Vallabh Vidyanagar 388 120, Post Box No. 39, Gujarat, India
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41
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Sakaguchi T, Kato M, Kuriyama N, Niiyama H, Hamada S, Morita Y, Tamiya E. Conjugal Transformation and Transposon and Chemical Mutagenesis of Gram-Negative Selenate-Respiring Citrobacter sp. Strain JSA. Curr Microbiol 2009; 59:88-94. [DOI: 10.1007/s00284-009-9406-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 03/19/2009] [Accepted: 03/23/2009] [Indexed: 11/29/2022]
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Ecophysiology of "Halarsenatibacter silvermanii" strain SLAS-1T, gen. nov., sp. nov., a facultative chemoautotrophic arsenate respirer from salt-saturated Searles Lake, California. Appl Environ Microbiol 2009; 75:1950-60. [PMID: 19218420 DOI: 10.1128/aem.02614-08] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Searles Lake occupies a closed basin harboring salt-saturated, alkaline brines that have exceptionally high concentrations of arsenic oxyanions. Strain SLAS-1(T) was previously isolated from Searles Lake (R. S. Oremland, T. R. Kulp, J. Switzer Blum, S. E. Hoeft, S. Baesman, L. G. Miller, and J. F. Stolz, Science 308:1305-1308, 2005). We now describe this extremophile with regard to its substrate affinities, its unusual mode of motility, sequenced arrABD gene cluster, cell envelope lipids, and its phylogenetic alignment within the order Halanaerobacteriales, assigning it the name "Halarsenatibacter silvermanii" strain SLAS-1(T). We also report on the substrate dynamics of an anaerobic enrichment culture obtained from Searles Lake that grows under conditions of salt saturation and whose members include a novel sulfate reducer of the order Desulfovibriales, the archaeon Halorhabdus utahensis, as well as a close homolog of strain SLAS-1(T).
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43
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Navarro JB, Moser DP, Flores A, Ross C, Rosen MR, Dong H, Zhang G, Hedlund BP. Bacterial succession within an ephemeral hypereutrophic Mojave Desert playa Lake. MICROBIAL ECOLOGY 2009; 57:307-320. [PMID: 18758846 DOI: 10.1007/s00248-008-9426-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Accepted: 07/03/2008] [Indexed: 05/26/2023]
Abstract
Ephemerally wet playas are conspicuous features of arid landscapes worldwide; however, they have not been well studied as habitats for microorganisms. We tracked the geochemistry and microbial community in Silver Lake playa, California, over one flooding/desiccation cycle following the unusually wet winter of 2004-2005. Over the course of the study, total dissolved solids increased by approximately 10-fold and pH increased by nearly one unit. As the lake contracted and temperatures increased over the summer, a moderately dense planktonic population of approximately 1x10(6) cells ml(-1) of culturable heterotrophs was replaced by a dense population of more than 1x10(9) cells ml(-1), which appears to be the highest concentration of culturable planktonic heterotrophs reported in any natural aquatic ecosystem. This correlated with a dramatic depletion of nitrate as well as changes in the microbial community, as assessed by small subunit ribosomal RNA gene sequencing of bacterial isolates and uncultivated clones. Isolates from the early-phase flooded playa were primarily Actinobacteria, Firmicutes, and Bacteroidetes, yet clone libraries were dominated by Betaproteobacteria and yet uncultivated Actinobacteria. Isolates from the late-flooded phase ecosystem were predominantly Proteobacteria, particularly alkalitolerant isolates of Rhodobaca, Porphyrobacter, Hydrogenophaga, Alishwenella, and relatives of Thauera; however, clone libraries were composed almost entirely of Synechococcus (Cyanobacteria). A sample taken after the playa surface was completely desiccated contained diverse culturable Actinobacteria typically isolated from soils. In total, 205 isolates and 166 clones represented 82 and 44 species-level groups, respectively, including a wide diversity of Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Gemmatimonadetes, Acidobacteria, and Cyanobacteria.
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Affiliation(s)
- Jason B Navarro
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
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44
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Oren A. Microbial life at high salt concentrations: phylogenetic and metabolic diversity. SALINE SYSTEMS 2008; 4:2. [PMID: 18412960 PMCID: PMC2329653 DOI: 10.1186/1746-1448-4-2] [Citation(s) in RCA: 476] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 04/15/2008] [Indexed: 12/04/2022]
Abstract
Halophiles are found in all three domains of life. Within the Bacteria we know halophiles within the phyla Cyanobacteria, Proteobacteria, Firmicutes, Actinobacteria, Spirochaetes, and Bacteroidetes. Within the Archaea the most salt-requiring microorganisms are found in the class Halobacteria. Halobacterium and most of its relatives require over 100–150 g/l salt for growth and structural stability. Also within the order Methanococci we encounter halophilic species. Halophiles and non-halophilic relatives are often found together in the phylogenetic tree, and many genera, families and orders have representatives with greatly different salt requirement and tolerance. A few phylogenetically coherent groups consist of halophiles only: the order Halobacteriales, family Halobacteriaceae (Euryarchaeota) and the anaerobic fermentative bacteria of the order Halanaerobiales (Firmicutes). The family Halomonadaceae (Gammaproteobacteria) almost exclusively contains halophiles. Halophilic microorganisms use two strategies to balance their cytoplasm osmotically with their medium. The first involves accumulation of molar concentrations of KCl. This strategy requires adaptation of the intracellular enzymatic machinery, as proteins should maintain their proper conformation and activity at near-saturating salt concentrations. The proteome of such organisms is highly acidic, and most proteins denature when suspended in low salt. Such microorganisms generally cannot survive in low salt media. The second strategy is to exclude salt from the cytoplasm and to synthesize and/or accumulate organic 'compatible' solutes that do not interfere with enzymatic activity. Few adaptations of the cells' proteome are needed, and organisms using the 'organic-solutes-in strategy' often adapt to a surprisingly broad salt concentration range. Most halophilic Bacteria, but also the halophilic methanogenic Archaea use such organic solutes. A variety of such solutes are known, including glycine betaine, ectoine and other amino acid derivatives, sugars and sugar alcohols. The 'high-salt-in strategy' is not limited to the Halobacteriaceae. The Halanaerobiales (Firmicutes) also accumulate salt rather than organic solutes. A third, phylogenetically unrelated organism accumulates KCl: the red extremely halophilic Salinibacter (Bacteroidetes), recently isolated from saltern crystallizer brines. Analysis of its genome showed many points of resemblance with the Halobacteriaceae, probably resulting from extensive horizontal gene transfer. The case of Salinibacter shows that more unusual types of halophiles may be waiting to be discovered.
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Affiliation(s)
- Aharon Oren
- Department of Plant and Environmental Sciences, Hebrew University of Jerusalem, Jerusalem, Israel.
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Narasingarao P, Häggblom MM. Identification of anaerobic selenate-respiring bacteria from aquatic sediments. Appl Environ Microbiol 2007; 73:3519-27. [PMID: 17435005 PMCID: PMC1932684 DOI: 10.1128/aem.02737-06] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The diversity population of microorganisms with the capability to use selenate as a terminal electron acceptor, reducing it to selenite and elemental selenium by the process known as dissimilatory selenate reduction, is largely unknown. The overall objective of this study was to gain an in-depth understanding of anaerobic biotransformation of selenium in the environment, particularly anaerobic respiration, and to characterize the microorganisms catalyzing this process. Here, we demonstrate the isolation and characterization of four novel anaerobic dissimilatory selenate-respiring bacteria enriched from a variety of sources, including sediments from three different water bodies in Chennai, India, and a tidal estuary in New Jersey. Strains S5 and S7 from India, strain KM from the Meadowlands, NJ, and strain pn1, categorized as a laboratory contaminant, were all phylogenetically distinct, belonging to various phyla in the bacterial domain. The 16S rRNA gene sequence shows that strain S5 constitutes a new genus belonging to Chrysiogenetes, while strain S7 belongs to the Deferribacteres, with greater than 98% 16S rRNA gene similarity to Geovibrio ferrireducens. Strain KM is related to Malonomonas rubra, Pelobacter acidigallici, and Desulfuromusa spp., with 96 to 97% 16S rRNA gene similarity. Strain pn1 is 99% similar to Pseudomonas stutzeri. Strains S5, S7, and KM are obligately anaerobic selenate-respiring microorganisms, while strain pn1 is facultatively anaerobic. Besides respiring selenate, all these strains also respire nitrate.
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MESH Headings
- Bacteria, Anaerobic/classification
- Bacteria, Anaerobic/isolation & purification
- Bacteria, Anaerobic/metabolism
- Bacteria, Anaerobic/ultrastructure
- Bacterial Typing Techniques
- Carbon/metabolism
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- Fermentation
- Genes, rRNA/genetics
- Geologic Sediments/microbiology
- India
- Microscopy, Electron, Transmission
- Molecular Sequence Data
- New Jersey
- Oxidation-Reduction
- Phylogeny
- RNA, Bacterial/genetics
- RNA, Ribosomal, 16S/genetics
- Seawater/microbiology
- Selenic Acid
- Selenium Compounds/metabolism
- Sequence Analysis, DNA
- Sequence Homology, Nucleic Acid
- Sodium Selenite/metabolism
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Affiliation(s)
- Priya Narasingarao
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
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Nakagawa T, Iino T, Suzuki KI, Harayama S. Ferrimonas futtsuensis sp. nov. and Ferrimonas kyonanensis sp. nov., selenate-reducing bacteria belonging to the Gammaproteobacteria isolated from Tokyo Bay. Int J Syst Evol Microbiol 2007; 56:2639-2645. [PMID: 17082404 DOI: 10.1099/ijs.0.64399-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two novel mesophilic, facultatively anaerobic, selenate-reducing bacteria, designated strains FUT3661T and Asr22-7T, were isolated from a sediment sample and the alimentary tract of littleneck clams, respectively. Both sources of the samples were collected from the coast of Tokyo Bay, Japan. Cells were Gram-negative rods and motile by means of a polar flagellum. The strains reduced selenate to elemental selenium (Se0) and also reduced iron(III) oxyhydroxide, iron(III) citrate, arsenate, manganese(IV) oxide, elemental sulfur and oxygen and used lactate, pyruvate, yeast extract, tryptone and Casamino acids as electron donors and carbon sources. The strains contained both menaquinone (MK-7) and ubiquinones (Q-7 and Q-8) as isoprenoid quinones. The major fatty acids were C16:0 and C16:1omega9c. The G+C content of the genomic DNA was 58.1 mol% for strain FUT3661T and 57.2 mol% for strain Asr22-7T. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strains were related to members of the genus Ferrimonas (<94.0% similarities), although the two novel strains formed a separate lineage. 16S rRNA gene sequence similarity between strains FUT3661T and Asr22-7T was 96%. On the basis of this polyphasic analysis, it was concluded that strains FUT3661T and Asr22-7T represent two novel species within the genus Ferrimonas, for which the names Ferrimonas futtsuensis sp. nov. (type strain FUT3661T=NBRC 101558T=DSM 18154T) and Ferrimonas kyonanensis sp. nov. (type strain Asr22-7T=NBRC 101286T=DSM 18153T) are proposed.
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Affiliation(s)
- Tatsunori Nakagawa
- NITE Biological Resource Center, National Institute of Technology and Evaluation (NITE), Kazusakamatari 2-5-8, Kisarazu, Chiba 292-0818, Japan
| | - Takao Iino
- NITE Biological Resource Center, National Institute of Technology and Evaluation (NITE), Kazusakamatari 2-5-8, Kisarazu, Chiba 292-0818, Japan
| | - Ken-Ichiro Suzuki
- NITE Biological Resource Center, National Institute of Technology and Evaluation (NITE), Kazusakamatari 2-5-8, Kisarazu, Chiba 292-0818, Japan
| | - Shigeaki Harayama
- NITE Biological Resource Center, National Institute of Technology and Evaluation (NITE), Kazusakamatari 2-5-8, Kisarazu, Chiba 292-0818, Japan
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Jiang H, Dong H, Zhang G, Yu B, Chapman LR, Fields MW. Microbial diversity in water and sediment of Lake Chaka, an athalassohaline lake in northwestern China. Appl Environ Microbiol 2006; 72:3832-45. [PMID: 16751487 PMCID: PMC1489620 DOI: 10.1128/aem.02869-05] [Citation(s) in RCA: 238] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We employed culture-dependent and -independent techniques to study microbial diversity in Lake Chaka, a unique hypersaline lake (32.5% salinity) in northwest China. It is situated at 3,214 m above sea level in a dry climate. The average water depth is 2 to 3 cm. Halophilic isolates were obtained from the lake water, and halotolerant isolates were obtained from the shallow sediment. The isolates exhibited resistance to UV and gamma radiation. Microbial abundance in the sediments ranged from 10(8) cells/g at the water-sediment interface to 10(7) cells/g at a sediment depth of 42 cm. A major change in the bacterial community composition was observed across the interface. In the lake water, clone sequences affiliated with the Bacteroidetes were the most abundant, whereas in the sediments, sequences related to low G+C gram-positive bacteria were predominant. A similar change was also present in the archaeal community. While all archaeal clone sequences in the lake water belonged to the Halobacteriales, the majority of the sequences in the sediments were related to those previously obtained from methanogenic soils and sediments. The observed changes in the microbial community structure across the water-sediment interface were correlated with a decrease in salinity from the lake water (32.5%) to the sediments (approximately 4%). Across the interface, the redox state also changed from oxic to anoxic and may also have contributed to the observed shift in the microbial community.
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Affiliation(s)
- Hongchen Jiang
- Department of Geology, Miami University, Oxford, OH 45056, USA
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Narasingarao P, Häggblom MM. Sedimenticola selenatireducens, gen. nov., sp. nov., an anaerobic selenate-respiring bacterium isolated from estuarine sediment. Syst Appl Microbiol 2006; 29:382-8. [PMID: 16427757 DOI: 10.1016/j.syapm.2005.12.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Indexed: 11/23/2022]
Abstract
The respiration of selenate, as a terminal electron acceptor has been known for over a decade, but the microorganisms involved in this respiration are largely unknown. Here we characterize a novel selenate-respiring bacterium, strain AK4OH1, isolated from an estuarine sediment enrichment culture. Strain AK4OH1 has the unique capability to oxidize aromatic acids, such as benzoate, 4-hydroxybenzoate and 3-hydroxybenzoate, coupled to selenate respiration. This novel respiratory coupling has not been described before. Reduction of selenate is followed by stoichiometric accumulation of selenite. The strain grows in agar shake tubes forming bright red colonies due to precipitation of elemental selenium. Strain AK4OH1 is a strictly anaerobic bacterium, which can also respire nitrate and nitrite via denitrification. Analysis of the 16S rRNA gene sequence shows that this strain clusters with another selenate-reducing bacterium and a (per) chlorate reducing bacterium, within the Gammaproteobacteria, along with symbionts of bivalves and tubeworms. Based on its unique physiological capabilities and its 16S rRNA gene sequence phylogeny, we classify this strain AK4OH1 as a new genus and species with the proposed name Sedimenticola selenatireducens.
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Affiliation(s)
- Priya Narasingarao
- Department of Biochemistry and Microbiology, Biotechnology Center for Agriculture and the Environment, Cook College, Rutgers, State University of New Jersey, 76 Lipman Drive, New Brunswick, NJ 08901-8525, USA
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Weldon JM, MacRae JD. Correlations between arsenic in Maine groundwater and microbial populations as determined by fluorescence in situ hybridization. CHEMOSPHERE 2006; 63:440-8. [PMID: 16310822 DOI: 10.1016/j.chemosphere.2005.08.061] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Revised: 08/12/2005] [Accepted: 08/16/2005] [Indexed: 05/05/2023]
Abstract
Arsenic is known to cause serious health effects when consumed in drinking water. In the state of Maine, approximately half of the population relies on private groundwater wells for their drinking water. Of those wells, as many as 13% may contain arsenic levels above the current EPA maximum contaminant level of 10 microgl(-1). Microorganisms can potentially contribute to arsenic release into groundwater through several mechanisms. Some can reduce arsenate to arsenite, which is more toxic and may be more mobile. Sulfurospirillum species NP4, which was isolated from well water, respires arsenate and could act in this way. Microorganisms can also act indirectly by reducing bedrock surface coatings, such as iron oxyhydroxides, that adsorb arsenic in the groundwater environment. The genus Geobacter contains many species that are capable of iron reduction that could play a role in the indirect release of arsenic into groundwater. Water samples from Northport, ME and the Branch Lake region of Ellsworth, ME, which both have elevated groundwater arsenic levels, have been probed using fluorescence in situ hybridization (FISH), to determine the percentage of the population that is NP4 and the percentage that are Geobacter species. Geobacter abundance correlates well with the total arsenic concentration indicating that indirect mechanisms could be important in releasing arsenic. NP4 appears to be reducing arsenate since its prevalence correlates well with arsenite, the end product of arsenate respiration.
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Affiliation(s)
- Jennifer M Weldon
- Department of Civil and Environmental Engineering, University of Maine at Orono, 5711 Boardman Hall, 04469-5711, USA
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50
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Dong H, Zhang G, Jiang H, Yu B, Chapman LR, Lucas CR, Fields MW. Microbial diversity in sediments of saline Qinghai Lake, China: linking geochemical controls to microbial ecology. MICROBIAL ECOLOGY 2006; 51:65-82. [PMID: 16400537 DOI: 10.1007/s00248-005-0228-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2004] [Accepted: 03/27/2005] [Indexed: 05/06/2023]
Abstract
Saline lakes at high altitudes represent an important and extreme microbial ecosystem, yet little is known about microbial diversity in such environments. The objective of this study was to examine the change of microbial diversity from the bottom of the lake to sediments of 40 cm in depth in a core from Qinghai Lake. The lake is saline (12.5 g/L salinity) and alkaline (pH 9.4) and is located on the Qinghai-Tibetan Plateau at an altitude of 3196 m above sea level. Pore water chemistry of the core revealed low concentrations of sulfate and iron (<1 mM), but high concentrations of acetate (40-70 mM) and dissolved organic carbon (1596-5443 mg/L). Total organic carbon and total nitrogen contents in the sediments were approximately 2 and <0.5%, respectively. Acridine orange direct count data indicated that cell numbers decreased from 4 x 10(9) cells/g at the water-sediment interface to 6 x 10(7) cells/g wet sediment at the 40-cm depth. This change in biomass was positively correlated with acetate concentration in pore water. Phospholipid fatty acid (PLFA) community structure analyses determined decrease in the proportion of the Proteobacteria and increase in the Firmicutes with increased depth. Characterization of small subunit (SSU) rRNA genes amplified from the sediments indicated a shift in the bacterial community with depth. Whereas the alpha-, beta-, and gamma-Proteobacteria and the Cytophaga/Flavobacterium/Bacteroides (CFB) were dominant at the water-sediment interface, low G + C gram-positive bacteria (a subgroup of Firmicutes) became the predominant group in the anoxic sediments. Both PLFA and the sequence data showed similar trend. The Proteobacteria, CFB, and gram-positive bacteria are present in other saline lakes, but the presence of Actinobacteria and Acidobacteria/Holophaga in significant proportions in the Qinghai Lake sediments appears to be unique. The archaeal diversity was much lower, and clone sequences could be grouped in the Euryarchaeota and Crenarchaeota domains. The archaeal clones were not related to any known cultures but to sequences previously found in methane-rich sediments. Acetate-utilizing methanogens were isolated from sediment incubations, and alpha- and gamma-proteobacterial isolates were obtained from a water sample from the lake-bottom (23 m). Our data collectively showed that the observed diversity and shift in the community structure with depth was correlated with geochemical parameters (the redox state and availability of electron acceptor and donor). Heterotrophic methanogenesis is possibly adominant metabolic process in the Qinghai Lake sediments. These results reinforce the importance of geochemical controls on microbial ecology in saline and alkaline lake environments.
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Affiliation(s)
- Hailiang Dong
- Department of Geology, Miami University, Oxford, OH 45056, USA.
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