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Imachi H, Nobu MK, Miyazaki M, Tasumi E, Saito Y, Sakai S, Ogawara M, Ohashi A, Takai K. Cultivation of previously uncultured microorganisms with a continuous-flow down-flow hanging sponge (DHS) bioreactor, using a syntrophic archaeon culture obtained from deep marine sediment as a case study. Nat Protoc 2022; 17:2784-2814. [PMID: 36104596 DOI: 10.1038/s41596-022-00735-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 06/14/2022] [Indexed: 11/09/2022]
Abstract
In microbiology, cultivation is a central approach for uncovering novel physiology, ecology, and evolution of microorganisms, but conventional methods have left many microorganisms found in nature uncultured. To overcome the limitations of traditional methods and culture indigenous microorganisms, we applied a two-stage approach: enrichment/activation of indigenous organisms by using a continuous-flow down-flow hanging sponge bioreactor and subsequent selective batch cultivation. Here, we provide a protocol for this bioreactor-mediated technique using activation of deep marine sediment microorganisms and downstream isolation of a syntrophic co-culture containing an archaeon closely related to the eukaryote ancestor (Candidatus Promethearchaeum syntrophicum strain MK-D1) as an example. Both stages can easily be tailored to target other environments and organisms by modifying the inoculum, feed solution/gases, attachment material and/or cultivation media. We anaerobically incubate polyurethane sponges inoculated with deep-sea methane seep sediment in a reactor at 10 °C and feed anaerobic artificial seawater medium and methane. Once phylogenetically diverse and metabolically active microorganisms are adapted to synthetic conditions in the reactor, we transition to growing community samples in glass tubes with the above medium, simple substrates and selective compounds (e.g., antibiotics). To accommodate for the slow growth anticipated for target organisms, primary cultures can be incubated for ≥6-12 months and analyzed for community composition even when no cell turbidity is observed. One casamino acid- and antibiotic-amended culture prepared in this way led to the enrichment of uncultured archaea. Through successive transfer in vitro combined with molecular growth monitoring, we successfully obtained the target archaeon with its partner methanogen as a pure syntrophic co-culture.
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Affiliation(s)
- Hiroyuki Imachi
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan.
| | - Masaru K Nobu
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
| | - Masayuki Miyazaki
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan.
| | - Eiji Tasumi
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
| | - Yumi Saito
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
| | - Sanae Sakai
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
| | - Miyuki Ogawara
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
| | - Akiyoshi Ohashi
- Department of Civil and Environmental Engineering, Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, Japan
| | - Ken Takai
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
- Section for Exploration of Life in Extreme Environments, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Sciences, Okazaki, Japan
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2
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Community Structure and Microbial Associations in Sediment-Free Methanotrophic Enrichment Cultures from a Marine Methane Seep. Appl Environ Microbiol 2022; 88:e0210921. [PMID: 35604226 DOI: 10.1128/aem.02109-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Syntrophic consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB) consume large amounts of methane and serve as the foundational microorganisms in marine methane seeps. Despite their importance in the carbon cycle, research on the physiology of ANME-SRB consortia has been hampered by the slow growth and complex physicochemical environment the consortia inhabit. Here, we report successful sediment-free enrichment of ANME-SRB consortia from deep-sea methane seep sediments in the Santa Monica Basin, California. Anoxic Percoll density gradients and size-selective filtration were used to separate ANME-SRB consortia from sediment particles and single cells to accelerate the cultivation process. Over a 3-year period, a subset of the sediment-associated ANME and SRB lineages, predominantly comprised of ANME-2a/2b ("Candidatus Methanocomedenaceae") and their syntrophic bacterial partners, SEEP-SRB1/2, adapted and grew under defined laboratory conditions. Metagenome-assembled genomes from several enrichments revealed that ANME-2a, SEEP-SRB1, and Methanococcoides in different enrichments from the same inoculum represented distinct species, whereas other coenriched microorganisms were closely related at the species level. This suggests that ANME, SRB, and Methanococcoides are more genetically diverse than other members in methane seeps. Flow cytometry sorting and sequencing of cell aggregates revealed that Methanococcoides, Anaerolineales, and SEEP-SRB1 were overrepresented in multiple ANME-2a cell aggregates relative to the bulk metagenomes, suggesting they were physically associated and possibly interacting. Overall, this study represents a successful case of selective cultivation of anaerobic slow-growing microorganisms from sediments based on their physical characteristics, introducing new opportunities for detailed genomic, physiological, biochemical, and ecological analyses. IMPORTANCE Biological anaerobic oxidation of methane (AOM) coupled with sulfate reduction represents a large methane sink in global ocean sediments. Methane consumption is carried out by syntrophic archaeal-bacterial consortia and fuels a unique ecosystem, yet the interactions in these slow-growing syntrophic consortia and with other associated community members remain poorly understood. The significance of this study is the establishment of sediment-free enrichment cultures of anaerobic methanotrophic archaea and sulfate-reducing bacteria performing AOM with sulfate using selective cultivation approaches based on size, density, and metabolism. By reconstructing microbial genomes and analyzing community composition of the enrichment cultures and cell aggregates, we shed light on the diversity of microorganisms physically associated with AOM consortia beyond the core syntrophic partners. These enrichment cultures offer simplified model systems to extend our understanding of the diversity of microbial interactions within marine methane seeps.
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3
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Lee SH, Kurade MB, Jeon BH, Kim J, Zheng Y, Salama ES. Water condition in biotrickling filtration for the efficient removal of gaseous contaminants. Crit Rev Biotechnol 2021; 41:1279-1296. [PMID: 34107840 DOI: 10.1080/07388551.2021.1917506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Biofiltration (BF) facilitates the removal of organic and inorganic compounds through microbial reactions. Water is one of the most important elements in biotrickling filters that provides moisture and nutrients to microbial biofilms. The maintenance of proper trickle watering is very critical in biotrickling filtration because the flow rate of the trickling water significantly influences contaminant removal, and its optimal control is associated with various physicochemical and biological mechanisms. The lack of water leads to the drying of the media, creating several issues, including the restricted absorption of hydrophilic contaminants and the inhibition of microbial activities, which ultimately deteriorates the overall contaminant removal efficiency (RE). Conversely, an excess of water limits the mass transfer of oxygen or hydrophobic gases. In-depth analysis is required to elucidate the role of trickle water in the overall performance of biotrickling filters. The processes involved in the treatment of various polluted gases under specific water conditions have been summarized in this study. Recent microscopic studies on biofilms were reviewed to explain the process by which water stress influences the biological mechanisms involved in the treatment of hydrophobic contaminated gases. In order to maintain an effective mass transfer, hydrodynamic and biofilm conditions, a coherent understanding of water stress and the development of extracellular polymeric substances (EPS) in biofilms is necessary. Future studies on the realistic local distribution of hydrodynamic patterns (trickle flow, water film thickness, and wet efficiency), integrated with biofilm distributions, should be conducted with respect to EPS development.
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Affiliation(s)
- Sang-Hun Lee
- Department of Environmental Science, Keimyung Unviersity, Daegu, South Korea
| | - Mayur B Kurade
- Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul, South Korea
| | - Byong-Hun Jeon
- Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul, South Korea
| | - Jungeun Kim
- Department of Environmental Science, Keimyung Unviersity, Daegu, South Korea
| | - Yuanzhang Zheng
- Department of Molecular Biology, School of Medicine Biochemistry, Indiana University, Indianapolis, IN, USA
| | - El-Sayed Salama
- Department of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, P. R. China
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4
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Dynamic modeling of anaerobic methane oxidation coupled to sulfate reduction: role of elemental sulfur as intermediate. Bioprocess Biosyst Eng 2021; 44:855-874. [PMID: 33566183 DOI: 10.1007/s00449-020-02495-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 12/07/2020] [Indexed: 10/22/2022]
Abstract
The process dynamics of anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SR), and the potential role of elemental sulfur as intermediate are presented in this paper. Thermodynamic screening and experimental evidence from the literature conclude that a prominent model to describe AOM-SR is based on the concept that anaerobic methane oxidation proceeds through the production of the intermediate elemental sulfur. Two microbial groups are involved in the process: (a) anaerobic methanotrophs (ANME-2) and (b) Desulfosarcina/Desulfococcus sulfur reducers cluster (DSS). In this work, a dynamic model was developed to explore the interactions between biotic and abiotic processes to simulate the microbial activity, the chemical composition and speciation of the liquid phase, and the gas phase composition in the reactor headspace. The model includes the microbial kinetics for the symbiotic growth of ANME-2 and DSS, mass transfer phenomena between the gas and liquid phase for methane, hydrogen sulfide, and carbon dioxide and acid-base reactions for bicarbonate, sulfide, and ammonium. A data set from batch experiments, running for 250 days in artificial seawater inoculated with sediment from Marine Lake Grevelingen (The Netherlands) was used to calibrate the model. The inherent characteristics of AOM-SR make the identification of the kinetic parameters difficult due to the high correlation between them. However, by meaningfully selecting a set of kinetic parameters, the model simulates successfully the experimental data for sulfate reduction and sulfide production. The model can be considered as the basic structure for simulating continuous flow three-phase engineered systems based on AOM-SR.
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Carrier V, Svenning MM, Gründger F, Niemann H, Dessandier PA, Panieri G, Kalenitchenko D. The Impact of Methane on Microbial Communities at Marine Arctic Gas Hydrate Bearing Sediment. Front Microbiol 2020; 11:1932. [PMID: 33071992 PMCID: PMC7541813 DOI: 10.3389/fmicb.2020.01932] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/22/2020] [Indexed: 01/26/2023] Open
Abstract
Cold seeps are characterized by high biomass, which is supported by the microbial oxidation of the available methane by capable microorganisms. The carbon is subsequently transferred to higher trophic levels. South of Svalbard, five geological mounds shaped by the formation of methane gas hydrates, have been recently located. Methane gas seeping activity has been observed on four of them, and flares were primarily concentrated at their summits. At three of these mounds, and along a distance gradient from their summit to their outskirt, we investigated the eukaryotic and prokaryotic biodiversity linked to 16S and 18S rDNA. Here we show that local methane seepage and other environmental conditions did affect the microbial community structure and composition. We could not demonstrate a community gradient from the summit to the edge of the mounds. Instead, a similar community structure in any methane-rich sediments could be retrieved at any location on these mounds. The oxidation of methane was largely driven by anaerobic methanotrophic Archaea-1 (ANME-1) and the communities also hosted high relative abundances of sulfate reducing bacterial groups although none demonstrated a clear co-occurrence with the predominance of ANME-1. Additional common taxa were observed and their abundances were likely benefiting from the end products of methane oxidation. Among these were sulfide-oxidizing Campilobacterota, organic matter degraders, such as Bathyarchaeota, Woesearchaeota, or thermoplasmatales marine benthic group D, and heterotrophic ciliates and Cercozoa.
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Affiliation(s)
- Vincent Carrier
- Department of Arctic and Marine Biology, The Arctic University of Norway, Tromsø, Norway.,Centre for Arctic Gas Hydrate, Environment and Climate, The Arctic University of Norway, Tromsø, Norway
| | - Mette M Svenning
- Department of Arctic and Marine Biology, The Arctic University of Norway, Tromsø, Norway.,Centre for Arctic Gas Hydrate, Environment and Climate, The Arctic University of Norway, Tromsø, Norway
| | - Friederike Gründger
- Department of Bioscience, Arctic Research Centre, Aarhus University, Aarhus, Denmark
| | - Helge Niemann
- Centre for Arctic Gas Hydrate, Environment and Climate, The Arctic University of Norway, Tromsø, Norway.,Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research, and Utrecht University, Den Burg, Netherlands.,Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, Netherlands
| | - Pierre-Antoine Dessandier
- Centre for Arctic Gas Hydrate, Environment and Climate, The Arctic University of Norway, Tromsø, Norway
| | - Giuliana Panieri
- Centre for Arctic Gas Hydrate, Environment and Climate, The Arctic University of Norway, Tromsø, Norway
| | - Dimitri Kalenitchenko
- Centre for Arctic Gas Hydrate, Environment and Climate, The Arctic University of Norway, Tromsø, Norway
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6
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Klasek S, Torres ME, Bartlett DH, Tyler M, Hong W, Colwell F. Microbial communities from Arctic marine sediments respond slowly to methane addition during
ex situ
enrichments. Environ Microbiol 2020; 22:1829-1846. [DOI: 10.1111/1462-2920.14895] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 11/11/2019] [Accepted: 11/30/2019] [Indexed: 11/27/2022]
Affiliation(s)
- Scott Klasek
- Department of Microbiology Oregon State University Corvallis Oregon USA
| | - Marta E. Torres
- College of Earth, Ocean, and Atmospheric Sciences Oregon State University Corvallis Oregon USA
| | - Douglas H. Bartlett
- Marine Biology Research Division, Scripps Institution of Oceanography University of California San Diego California 92093‐0202 USA
| | - Madeline Tyler
- Department of Microbiology Oregon State University Corvallis Oregon USA
| | - Wei‐Li Hong
- Centre for Arctic Gas Hydrate, Environment and Climate (CAGE), Department of Geosciences UiT The Arctic University of Norway N‐9037 Tromsø Norway
| | - Frederick Colwell
- Department of Microbiology Oregon State University Corvallis Oregon USA
- College of Earth, Ocean, and Atmospheric Sciences Oregon State University Corvallis Oregon USA
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Cassarini C, Rene ER, Bhattarai S, Vogt C, Musat N, Lens PNL. Anaerobic methane oxidation coupled to sulfate reduction in a biotrickling filter: Reactor performance and microbial community analysis. CHEMOSPHERE 2019; 236:124290. [PMID: 31310977 DOI: 10.1016/j.chemosphere.2019.07.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 06/28/2019] [Accepted: 07/02/2019] [Indexed: 06/10/2023]
Abstract
The aim of this work was to evaluate the performance of a biotrickling filter (BTF) packed with polyurethane foam and pall rings for the enrichment of microorganisms mediating anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SR) by activity tests and microbial community analysis. A BTF was inoculated with microorganisms from a known AOM active deep sea sediment collected at a depth of 528 m below the sea level (Alpha Mound, Gulf of Cadiz). The microbial community analysis was performed by catalyzed reporter deposition - fluorescence in situ hybridization (CARD-FISH) and 16S rRNA sequence analysis. The AOM occurrence and rates in the BTF were assessed by performing batch activity assays using 13C-labelled methane (13CH4). After an estimated start-up time of ∼20 days, AOM rates of ∼0.3 mmol l-1 day-1 were observed in the BTF, values almost 20 times higher than previously reported in a polyurethane foam packed BTF. The microbial community consisted mainly of anaerobic methanotrophs (ANME-2, 22% of the total number of cells) and sulfate reducing bacteria (SRB, 47% of the total number of cells). This study showed that the BTF is a suitable reactor configuration for the enrichment of microbial communities involved in AOM coupled to SR at ambient pressure and temperature with a relatively short start-up time.
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Affiliation(s)
- Chiara Cassarini
- UNESCO-IHE, Institute for Water Education, P. O. Box 3015, 2601, DA, Delft, the Netherlands; National University of Ireland Galway, University Road, Galway, H91 TK33, Ireland.
| | - Eldon R Rene
- UNESCO-IHE, Institute for Water Education, P. O. Box 3015, 2601, DA, Delft, the Netherlands
| | - Susma Bhattarai
- UNESCO-IHE, Institute for Water Education, P. O. Box 3015, 2601, DA, Delft, the Netherlands
| | - Carsten Vogt
- Helmholtz-Centre for Environmental Research - UFZ, Department of Isotope Biogeochemistry, Permoser Strasse 15, 04318, Leipzig, Germany
| | - Niculina Musat
- Helmholtz-Centre for Environmental Research - UFZ, Department of Isotope Biogeochemistry, Permoser Strasse 15, 04318, Leipzig, Germany
| | - Piet N L Lens
- UNESCO-IHE, Institute for Water Education, P. O. Box 3015, 2601, DA, Delft, the Netherlands; National University of Ireland Galway, University Road, Galway, H91 TK33, Ireland
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8
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Panchavinin S, Tobino T, Hara-Yamamura H, Matsuura N, Honda R. Candidates of quorum sensing bacteria in activated sludge associated with N-acyl homoserine lactones. CHEMOSPHERE 2019; 236:124292. [PMID: 31310968 DOI: 10.1016/j.chemosphere.2019.07.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 06/21/2019] [Accepted: 07/02/2019] [Indexed: 06/10/2023]
Abstract
This study aimed to explore candidates of microbial groups which is associated with quorum sensing in activated sludge. Activated sludge samples were collected from three wastewater treatment plants (WWTP) to analyze N-acyl homoserine lactone (AHL) by Fourier-transform mass spectrometry (FTMS) and 16S rRNA-based microbial community. Among activated sludge samples taken at 3 WWTPs in different seasons, 2 AHL species of N-3-hydroxyoctanoyl-l-homoserine lactone and N-3-hydroxydecanoyl-l-homoserine lactone were detected in the range of ranged of 0.1 ng/L to 1.6 ng/L. The detected AHL species were not dependent on treatment systems nor seasons. From microbial community analysis, population abundance of one strain in Verrucomicrobia and two strains in Holophagaceae had high correlation with AHL concentration in activated sludge. Comamonadaceae had also moderately correlated population with AHL concentrations among quorum sensing bacteria reported previously.
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Affiliation(s)
- Smarch Panchavinin
- Department of Environmental Design, Graduate School of Natural Science and Technology, Kanazawa University, Ishikawa, 920-1192, Japan.
| | - Tomohiro Tobino
- Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, 113-8657, Japan.
| | - Hiroe Hara-Yamamura
- Research Center for Sustainable Energy and Technology, Kanazawa University, Ishikawa, 920-1192, Japan.
| | - Norihisa Matsuura
- Faculty of Geosciences and Civil Engineering, Kanazawa University, Ishikawa, 920-1192, Japan
| | - Ryo Honda
- Faculty of Geosciences and Civil Engineering, Kanazawa University, Ishikawa, 920-1192, Japan.
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Bhattarai S, Cassarini C, Lens PNL. Physiology and Distribution of Archaeal Methanotrophs That Couple Anaerobic Oxidation of Methane with Sulfate Reduction. Microbiol Mol Biol Rev 2019; 83:e00074-18. [PMID: 31366606 PMCID: PMC6710461 DOI: 10.1128/mmbr.00074-18] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In marine anaerobic environments, methane is oxidized where sulfate-rich seawater meets biogenic or thermogenic methane. In those niches, a few phylogenetically distinct microbial types, i.e., anaerobic methanotrophs (ANME), are able to grow through anaerobic oxidation of methane (AOM). Due to the relevance of methane in the global carbon cycle, ANME have drawn the attention of a broad scientific community for 4 decades. This review presents and discusses the microbiology and physiology of ANME up to the recent discoveries, revealing novel physiological types of anaerobic methane oxidizers which challenge the view of obligate syntrophy for AOM. An overview of the drivers shaping the distribution of ANME in different marine habitats, from cold seep sediments to hydrothermal vents, is given. Multivariate analyses of the abundance of ANME in various habitats identify a distribution of distinct ANME types driven by the mode of methane transport. Intriguingly, ANME have not yet been cultivated in pure culture, despite intense attempts. Further advances in understanding this microbial process are hampered by insufficient amounts of enriched cultures. This review discusses the advantages, limitations, and potential improvements for ANME laboratory-based cultivation systems.
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Affiliation(s)
- S Bhattarai
- UNESCO-IHE, Institute for Water Education, Delft, The Netherlands
| | - C Cassarini
- UNESCO-IHE, Institute for Water Education, Delft, The Netherlands
- National University of Ireland Galway, Galway, Ireland
| | - P N L Lens
- UNESCO-IHE, Institute for Water Education, Delft, The Netherlands
- National University of Ireland Galway, Galway, Ireland
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Eregowda T, Rene ER, Lens PNL. Bioreduction of selenate in an anaerobic biotrickling filter using methanol as electron donor. CHEMOSPHERE 2019; 225:406-413. [PMID: 30884302 DOI: 10.1016/j.chemosphere.2019.02.158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 02/22/2019] [Accepted: 02/23/2019] [Indexed: 06/09/2023]
Abstract
The anaerobic bioreduction of selenate, fed in step (up to 60 mg.L-1) or continuous (∼7 mg.L-1) trickling mode, in the presence of gas-phase methanol (4.3-50 g m-3.h-1) was evaluated in a biotrickling filter (BTF). During the 48 d of step-feed and 41 d of continuous-feed operations, average selenate removal efficiencies (RE) > 90% and ∼68% was achieved, corresponding to a selenate reduction rate of, respectively, 7.3 and 4.5 mg.L-1.d-1. During the entire period of BTF operation, 65.6% of the total Se fed as SeO42- was recovered. Concerning gas-phase methanol, the maximum elimination capacity (ECmax) was 46.4 g m-3.h-1, with a RE > 80%. Methanol was mainly utilized for acetogenesis and converted to volatile fatty acids (VFA) in the liquid-phase. Up to 5000 mg.L-1 of methanol and 800 mg.L-1 of acetate accumulated in the trickling liquid of the BTF.
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Affiliation(s)
- Tejaswini Eregowda
- UNESCO-IHE, Institute for Water Education, P. O. Box 3015, 2601 DA Delft, the Netherlands
| | - Eldon R Rene
- UNESCO-IHE, Institute for Water Education, P. O. Box 3015, 2601 DA Delft, the Netherlands.
| | - Piet N L Lens
- UNESCO-IHE, Institute for Water Education, P. O. Box 3015, 2601 DA Delft, the Netherlands; National University of Ireland Galway, University Road, Galway H91 TK33, Ireland
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