1
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Miksch S, Orellana LH, Oggerin de Orube M, Vidal-Melgosa S, Solanki V, Hehemann JH, Amann R, Knittel K. Taxonomic and functional stability overrules seasonality in polar benthic microbiomes. THE ISME JOURNAL 2024; 18:wrad005. [PMID: 38365229 PMCID: PMC10811738 DOI: 10.1093/ismejo/wrad005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 02/18/2024]
Abstract
Coastal shelf sediments are hot spots of organic matter mineralization. They receive up to 50% of primary production, which, in higher latitudes, is strongly seasonal. Polar and temperate benthic bacterial communities, however, show a stable composition based on comparative 16S rRNA gene sequencing despite different microbial activity levels. Here, we aimed to resolve this contradiction by identifying seasonal changes at the functional level, in particular with respect to algal polysaccharide degradation genes, by combining metagenomics, metatranscriptomics, and glycan analysis in sandy surface sediments from Isfjorden, Svalbard. Gene expressions of diverse carbohydrate-active enzymes changed between winter and spring. For example, β-1,3-glucosidases (e.g. GH30, GH17, GH16) degrading laminarin, an energy storage molecule of algae, were elevated in spring, while enzymes related to α-glucan degradation were expressed in both seasons with maxima in winter (e.g. GH63, GH13_18, and GH15). Also, the expression of GH23 involved in peptidoglycan degradation was prevalent, which is in line with recycling of bacterial biomass. Sugar extractions from bulk sediments were low in concentrations during winter but higher in spring samples, with glucose constituting the largest fraction of measured monosaccharides (84% ± 14%). In porewater, glycan concentrations were ~18-fold higher than in overlying seawater (1107 ± 484 vs. 62 ± 101 μg C l-1) and were depleted in glucose. Our data indicate that microbial communities in sandy sediments digest and transform labile parts of photosynthesis-derived particulate organic matter and likely release more stable, glucose-depleted residual glycans of unknown structures, quantities, and residence times into the ocean, thus modulating the glycan composition of marine coastal waters.
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Affiliation(s)
- Sebastian Miksch
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Luis H Orellana
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Monike Oggerin de Orube
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Silvia Vidal-Melgosa
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
- MARUM MPG Bridge Group Marine Glycobiology, Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
| | - Vipul Solanki
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Jan-Hendrik Hehemann
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
- MARUM MPG Bridge Group Marine Glycobiology, Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
| | - Rudolf Amann
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Katrin Knittel
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
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2
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Giljan G, Arnosti C, Kirstein IV, Amann R, Fuchs BM. Strong seasonal differences of bacterial polysaccharide utilization in the North Seas over an annual cycle. Environ Microbiol 2022; 24:2333-2347. [PMID: 35384240 DOI: 10.1111/1462-2920.15997] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 03/26/2022] [Accepted: 04/02/2022] [Indexed: 11/29/2022]
Abstract
Marine heterotrophic bacteria contribute considerably to global carbon cycling, in part by utilizing phytoplankton-derived polysaccharides. The patterns and rates of two different polysaccharide utilization modes - extracellular hydrolysis and selfish uptake - have previously been found to change during spring phytoplankton bloom events. Here we investigated seasonal changes in bacterial utilization of three polysaccharides, laminarin, xylan, and chondroitin sulfate. Strong seasonal differences were apparent in mode and speed of polysaccharide utilization, as well as in bacterial community compositions. Compared to the winter month of February, during the spring bloom in May, polysaccharide utilization was detected earlier in the incubations and a higher portion of all bacteria took up laminarin selfishly. Highest polysaccharide utilization was measured in June and September, mediated by bacterial communities that were significantly different from spring assemblages. Extensive selfish laminarin uptake, for example, was detectible within a few hours in June, while extracellular hydrolysis of chondroitin was dominant in September. In addition to the well-known Bacteroidota and Gammaproteobacteria clades, the numerically minor verrucomicrobial clade Pedosphaeraceae could be identified as a rapid laminarin utilizer. In summary, polysaccharide utilization proved highly variable over the seasons, both in mode and speed, and also by the bacterial clades involved. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Greta Giljan
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Carol Arnosti
- Department of Marine Sciences, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - Inga V Kirstein
- Alfred-Wegner-Institute Helmholtz-Center for Polar and Marine Research, Biological Station Helgoland, Helgoland, Germany
| | - Rudolf Amann
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Bernhard M Fuchs
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany
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3
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Miksch S, Meiners M, Meyerdierks A, Probandt D, Wegener G, Titschack J, Jensen MA, Ellrott A, Amann R, Knittel K. Bacterial communities in temperate and polar coastal sands are seasonally stable. ISME COMMUNICATIONS 2021; 1:29. [PMID: 36739458 PMCID: PMC9723697 DOI: 10.1038/s43705-021-00028-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 05/13/2021] [Accepted: 05/24/2021] [Indexed: 04/18/2023]
Abstract
Coastal sands are biocatalytic filters for dissolved and particulate organic matter of marine and terrestrial origin, thus, acting as centers of organic matter transformation. At high temporal resolution, we accessed the variability of benthic bacterial communities over two annual cycles at Helgoland (North Sea), and compared it with seasonality of communities in Isfjorden (Svalbard, 78°N) sediments, where primary production does not occur during winter. Benthic community structure remained stable in both, temperate and polar sediments on the level of cell counts and 16S rRNA-based taxonomy. Actinobacteriota of uncultured Actinomarinales and Microtrichales were a major group, with 8 ± 1% of total reads (Helgoland) and 31 ± 6% (Svalbard). Their high activity (frequency of dividing cells 28%) and in situ cell numbers of >10% of total microbes in Svalbard sediments, suggest Actinomarinales and Microtrichales as key heterotrophs for carbon mineralization. Even though Helgoland and Svalbard sampling sites showed no phytodetritus-driven changes of the benthic bacterial community structure, they harbored significantly different communities (p < 0.0001, r = 0.963). The temporal stability of benthic bacterial communities is in stark contrast to the dynamic succession typical of coastal waters, suggesting that pelagic and benthic bacterial communities respond to phytoplankton productivity very differently.
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Affiliation(s)
| | - Mirja Meiners
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | | | - David Probandt
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Gunter Wegener
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Jürgen Titschack
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Senckenberg am Meer, Wilhelmshaven, Germany
| | - Maria A Jensen
- UNIS, The University Centre in Svalbard, Longyearbyen, Norway
| | - Andreas Ellrott
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Rudolf Amann
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Katrin Knittel
- Max Planck Institute for Marine Microbiology, Bremen, Germany.
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4
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Walker AM, Leigh MB, Mincks SL. Patterns in Benthic Microbial Community Structure Across Environmental Gradients in the Beaufort Sea Shelf and Slope. Front Microbiol 2021; 12:581124. [PMID: 33584606 PMCID: PMC7876419 DOI: 10.3389/fmicb.2021.581124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 01/05/2021] [Indexed: 11/13/2022] Open
Abstract
The paradigm of tight pelagic-benthic coupling in the Arctic suggests that current and future fluctuations in sea ice, primary production, and riverine input resulting from global climate change will have major impacts on benthic ecosystems. To understand how these changes will affect benthic ecosystem function, we must characterize diversity, spatial distribution, and community composition for all faunal components. Bacteria and archaea link the biotic and abiotic realms, playing important roles in organic matter (OM) decomposition, biogeochemical cycling, and contaminant degradation, yet sediment microbial communities have rarely been examined in the North American Arctic. Shifts in microbial community structure and composition occur with shifts in OM inputs and contaminant exposure, with implications for shifts in ecological function. Furthermore, the characterization of benthic microbial communities provides a foundation from which to build focused experimental research. We assessed diversity and community structure of benthic prokaryotes in the upper 1 cm of sediments in the southern Beaufort Sea (United States and Canada), and investigated environmental correlates of prokaryotic community structure over a broad spatial scale (spanning 1,229 km) at depths ranging from 17 to 1,200 m. Based on hierarchical clustering, we identified four prokaryotic assemblages from the 85 samples analyzed. Two were largely delineated by the markedly different environmental conditions in shallow shelf vs. upper continental slope sediments. A third assemblage was mainly comprised of operational taxonomic units (OTUs) shared between the shallow shelf and upper slope assemblages. The fourth assemblage corresponded to sediments receiving heavier OM loading, likely resulting in a shallower anoxic layer. These sites may also harbor microbial mats and/or methane seeps. Substructure within these assemblages generally reflected turnover along a longitudinal gradient, which may be related to the quantity and composition of OM deposited to the seafloor; bathymetry and the Mackenzie River were the two major factors influencing prokaryote distribution on this scale. In a broader geographical context, differences in prokaryotic community structure between the Beaufort Sea and Norwegian Arctic suggest that benthic microbes may reflect regional differences in the hydrography, biogeochemistry, and bathymetry of Arctic shelf systems.
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Affiliation(s)
- Alexis M Walker
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Mary Beth Leigh
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Sarah L Mincks
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, United States
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5
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Microbial Abundance and Enzyme Activity Patterns: Response to Changing Environmental Characteristics along a Transect in Kongsfjorden (Svalbard Islands). JOURNAL OF MARINE SCIENCE AND ENGINEERING 2020. [DOI: 10.3390/jmse8100824] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Svalbard archipelago is experiencing the effects of climate changes (i.e., glaciers’ thickness reduction and glacier front retreat), but how ice melting affects water biogeochemistry is still unknown. Microbial communities often act as environmental sentinels, modulating their distribution and activity in response to environmental variability. To assess microbial response to climate warming, within the ARctic: present Climatic change and pAst extreme events (ARCA) project, a survey was carried out along a transect in Konsfjorden from off-shore stations towards the Kronebreen glacier. Total bacterial abundance and the fraction of actively respiring cells (labelled by cyanotetrazolium chloride, CTC), cultivable heterotrophic bacterial abundance, and extracellular enzymatic activities (leucine aminopeptidase (LAP), beta-glucosidase (GLU), and alkaline phosphatase (AP)) were measured. In addition, water temperature, salinity, dissolved oxygen, turbidity, total suspended matter (TSM), particulate and chromophoric dissolved organic matter (CDOM), chlorophyll-a (Chl-a), and inorganic compounds were determined, in order to evaluate whether variations in microbial abundance and metabolism were related with changes in environmental variables. Colder waters at surface (3.5–5 m) depths and increased turbidity, TSM, and inorganic compounds found at some hydrological stations close to the glacier were signals of ice melting. CDOM absorption slope values (275–295 nm) varied from 0.0077 to 0.0109 nm−1, and total bacterial cell count and cultivable heterotrophic bacterial abundance were in the order of 106 cells/mL and 103 colony forming units/mL, respectively. Enzymatic rates <1.78, 1.25, and 0.25 nmol/L/h were recorded for AP, LAP, and GLU, respectively. Inorganic compounds, TSM, and turbidity correlated inversely with temperature; AP was significantly related with CDOM absorption spectra and heterotrophic bacteria (r = 0.59, 0.71, p < 0.05); and LAP with Chl-a, Particulate Organic Carbon (POC) and Particulate Organic Nitrogen (PON) (0.97, 0.780, 0.734, p < 0.01), suggesting that fresh material from ice melting stimulated the metabolism of the cultivable fraction.
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6
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Becker S, Tebben J, Coffinet S, Wiltshire K, Iversen MH, Harder T, Hinrichs KU, Hehemann JH. Laminarin is a major molecule in the marine carbon cycle. Proc Natl Acad Sci U S A 2020; 117:6599-6607. [PMID: 32170018 PMCID: PMC7104365 DOI: 10.1073/pnas.1917001117] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Marine microalgae sequester as much CO2 into carbohydrates as terrestrial plants. Polymeric carbohydrates (i.e., glycans) provide carbon for heterotrophic organisms and constitute a carbon sink in the global oceans. The quantitative contributions of different algal glycans to cycling and sequestration of carbon remain unknown, partly because of the analytical challenge to quantify glycans in complex biological matrices. Here, we quantified a glycan structural type using a recently developed biocatalytic strategy, which involves laminarinase enzymes that specifically cleave the algal glycan laminarin into readily analyzable fragments. We measured laminarin along transects in the Arctic, Atlantic, and Pacific oceans and during three time series in the North Sea. These data revealed a median of 26 ± 17% laminarin within the particulate organic carbon pool. The observed correlation between chlorophyll and laminarin suggests an annual production of algal laminarin of 12 ± 8 gigatons: that is, approximately three times the annual atmospheric carbon dioxide increase by fossil fuel burning. Moreover, our data revealed that laminarin accounted for up to 50% of organic carbon in sinking diatom-containing particles, thus substantially contributing to carbon export from surface waters. Spatially and temporally variable laminarin concentrations in the sunlit ocean are driven by light availability. Collectively, these observations highlight the prominent ecological role and biogeochemical function of laminarin in oceanic carbon export and energy flow to higher trophic levels.
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Affiliation(s)
- Stefan Becker
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
- Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
| | - Jan Tebben
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany
| | - Sarah Coffinet
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
| | - Karen Wiltshire
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany
| | - Morten Hvitfeldt Iversen
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
| | - Tilmann Harder
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany
- Faculty of Biology and Chemistry, University of Bremen, 28359 Bremen, Germany
| | - Kai-Uwe Hinrichs
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
| | - Jan-Hendrik Hehemann
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany;
- Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
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7
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Mahmoudi N, Enke TN, Beaupré SR, Teske AP, Cordero OX, Pearson A. Illuminating microbial species‐specific effects on organic matter remineralization in marine sediments. Environ Microbiol 2019; 22:1734-1747. [DOI: 10.1111/1462-2920.14871] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/15/2019] [Accepted: 11/19/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Nagissa Mahmoudi
- Department of Earth and Planetary Sciences McGill University Montreal QC H3A 0E8
| | - Tim N. Enke
- Department of Civil and Environmental Engineering Massachusetts Institute of Technology (MIT) Cambridge Massachusetts 02139
| | - Steven R. Beaupré
- School of Marine and Atmospheric Sciences Stony Brook University Stony Brook New York 11794
| | - Andreas P. Teske
- Department of Marine Sciences University of North Carolina Chapel Hill North Carolina 27599
| | - Otto X. Cordero
- Department of Civil and Environmental Engineering Massachusetts Institute of Technology (MIT) Cambridge Massachusetts 02139
| | - Ann Pearson
- Department of Earth and Planetary Sciences Harvard University Cambridge Massachusetts 02138
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8
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Karrasch B, Horovitz O, Norf H, Hillel N, Hadas O, Beeri-Shlevin Y, Laronne JB. Quantitative ecotoxicological impacts of sewage treatment plant effluents on plankton productivity and assimilative capacity of rivers. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:24034-24049. [PMID: 31228068 DOI: 10.1007/s11356-019-04940-6] [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: 08/07/2018] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
Sewage treatment plants are sources of inorganic and organic matter as well as contaminants for the receiving watercourses. We analyzed the ecological consequences of such effluents by following a holistic and synecological ecotoxicological approach based on quantifying extracellular enzyme activities (EEA), primary production and bacterial cell, and biomass production rates. Samples were obtained at three locations at the Rivers Holtemme and Elbe, Germany and Lower Jordan River, Israel and West Bank, as well as from their adjacent sewage treatment plants. Blending river samples with sewage treatment plant effluents mainly resulted in a stimulation of EEAs, which was diminished in blends with 0.2-μm filtered sewage treatment plant effluents. Stimulation for primary production and bacterial cell and biomass production of River Holtemme and Elbe samples was observed, and inhibition of these rates for Lower Jordan River samples probably linked to generally high turbidity. The quantified bacterial biomass versus cell production rates showed almost unbalanced (≫ 1) growth. Very high biomass to cell production ratios were found for sewage and sewage-containing samples, which provides a semi-quantitative indicator function for high quantities of microbial easy utilizable dissolved organic matter as nutrition source. The presented approach enables the simultaneous quantification of inhibitory and stimulating toxic responses as well as supplying ecosystem-based data for policy decision-making, and for direct incorporation in models to derive management and remediation strategies.
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Affiliation(s)
- Bernhard Karrasch
- Department of River Ecology, Helmholtz Centre for Environmental Research - UFZ, Brückstraße 3a, 39114, Magdeburg, Germany.
| | - Omer Horovitz
- Department of Geography and Environmental Development, Ben-Gurion University of the Negev, 8410501, Beer Sheva, Israel
| | - Helge Norf
- Department of River Ecology, Helmholtz Centre for Environmental Research - UFZ, Brückstraße 3a, 39114, Magdeburg, Germany
| | - Noa Hillel
- Department of Geography and Environmental Development, Ben-Gurion University of the Negev, 8410501, Beer Sheva, Israel
| | - Ora Hadas
- Yigal Alon Kinneret Limnological Laboratory, Israel Oceanographic and Limnological Research, P.O.B. 447, 14950, Migdal, Israel
| | - Yaron Beeri-Shlevin
- Yigal Alon Kinneret Limnological Laboratory, Israel Oceanographic and Limnological Research, P.O.B. 447, 14950, Migdal, Israel
| | - Jonathan B Laronne
- Department of Geography and Environmental Development, Ben-Gurion University of the Negev, 8410501, Beer Sheva, Israel
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9
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Conte A, Papale M, Amalfitano S, Mikkonen A, Rizzo C, De Domenico E, Michaud L, Lo Giudice A. Bacterial community structure along the subtidal sandy sediment belt of a high Arctic fjord (Kongsfjorden, Svalbard Islands). THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 619-620:203-211. [PMID: 29149744 DOI: 10.1016/j.scitotenv.2017.11.077] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 11/07/2017] [Accepted: 11/07/2017] [Indexed: 06/07/2023]
Abstract
Open fjords are subject to contrasting environmental conditions, owing to meltwater glacial inputs, terrestrial runoff, and marine water mass exchanges, which are exacerbated by anthropogenic and climate perturbations. Following a slope-dependent water circulation, the subtidal sandy sediment belt regulates the convergent transport of nutrients downward the fjord depths, and the effective entrapment of suspended particles and microorganisms. In this study, we aimed at testing how glacial and seawater inputs may influence the bacterial community structure of subtidal sand deposits in the Kongsfjorden. Through total and viable cell counting and an amplicon sequencing approach, we found relevant differences in bacterial community structure along the glacio-marine sampling transect. Viable and high nucleic acid content (HNA) cells represented an important fraction of the total community, generally decreasing toward the glacier front. Besides the predominance of Alpha- and Gammaproteobacteria, Bacteroidetes, Firmicutes and Parcubacteria, the bacterial community structure was likely affected by the glacial activity in the inner fjord, with the occurrence of distinctive phylotypes belonging to Gemmatimonadates, Nitrospirae, Acidobacteria, and Chloroflexi. Overall, our outcomes highlighted that exploring the bacterial community distribution and structure can provide new insights into the active role of sand deposits in coastal cold environments.
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Affiliation(s)
- Antonella Conte
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Maria Papale
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Stefano Amalfitano
- Water Research Institute, National Research Council (IRSA-CNR), Monterotondo, Rome, Italy
| | - Anu Mikkonen
- Department of Biological and Environmental Sciences, University of Jyvaskyla, Jyvaskyla, Finland
| | - Carmen Rizzo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Emilio De Domenico
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Luigi Michaud
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Angelina Lo Giudice
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy; Institute for the Coastal Marine Environment, National Research Council (IAMC-CNR), Messina, Italy.
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10
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Matos MN, Lozada M, Anselmino LE, Musumeci MA, Henrissat B, Jansson JK, Mac Cormack WP, Carroll J, Sjöling S, Lundgren L, Dionisi HM. Metagenomics unveils the attributes of the alginolytic guilds of sediments from four distant cold coastal environments. Environ Microbiol 2016; 18:4471-4484. [PMID: 27348213 DOI: 10.1111/1462-2920.13433] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 05/23/2016] [Indexed: 12/20/2022]
Abstract
Alginates are abundant polysaccharides in brown algae that constitute an important energy source for marine heterotrophic bacteria. Despite the key role of alginate degradation processes in the marine carbon cycle, little information is available on the bacterial populations involved in these processes. The aim of this work was to gain a better understanding of alginate utilization capabilities in cold coastal environments. Sediment metagenomes from four high-latitude regions of both Hemispheres were interrogated for alginate lyase gene homologue sequences and their genomic context. Sediments contained highly abundant and diverse bacterial assemblages with alginolytic potential, including members of Bacteroidetes and Proteobacteria, as well as several poorly characterized taxa. The microbial communities in Arctic and Antarctic sediments exhibited the most similar alginolytic profiles, whereas brackish sediments showed distinct structures with a higher proportion of novel genes. Examination of the gene neighbourhood of the alginate lyase homologues revealed distinct patterns depending on the potential lineage of the scaffolds, with evidence of evolutionary relationships among alginolytic gene clusters from Bacteroidetes and Proteobacteria. This information is relevant for understanding carbon fluxes in cold coastal environments and provides valuable information for the development of biotechnological applications from brown algae biomass.
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Affiliation(s)
- Marina N Matos
- Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn, U9120ACD, Argentina
| | - Mariana Lozada
- Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn, U9120ACD, Argentina
| | - Luciano E Anselmino
- Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn, U9120ACD, Argentina
| | - Matías A Musumeci
- Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn, U9120ACD, Argentina
| | - Bernard Henrissat
- Architecture et Fonction des Macromolécules Biologiques, CNRS, Aix-Marseille Université, Marseille, 13288, France.,INRA, USC 1408 AFMB, Marseille, F-13288, France.,Department of Biological Sciences, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
| | - Janet K Jansson
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Walter P Mac Cormack
- Instituto Antártico Argentino, Ciudad Autónoma de Buenos Aires, C1064ABR, Argentina.,Instituto Nanobiotec, CONICET - Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, C1113AAC, Argentina
| | - JoLynn Carroll
- Akvaplan-niva, Fram - High North Research Centre for Climate and the Environment, Tromsø, NO-9296, Norway.,CAGE - Centre for Arctic Gas Hydrate, Environment and Climate, UiT The Arctic University of Norway, Tromsø, N-9037, Norway
| | - Sara Sjöling
- School of Natural Sciences and Environmental Studies, Södertörn University, Huddinge, 141 89, Sweden
| | | | - Hebe M Dionisi
- Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn, U9120ACD, Argentina
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11
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Genome-Resolved Metagenomic Analysis Reveals Roles for Candidate Phyla and Other Microbial Community Members in Biogeochemical Transformations in Oil Reservoirs. mBio 2016; 7:e01669-15. [PMID: 26787827 PMCID: PMC4725000 DOI: 10.1128/mbio.01669-15] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Oil reservoirs are major sites of methane production and carbon turnover, processes with significant impacts on energy resources and global biogeochemical cycles. We applied a cultivation-independent genomic approach to define microbial community membership and predict roles for specific organisms in biogeochemical transformations in Alaska North Slope oil fields. Produced water samples were collected from six locations between 1,128 m (24 to 27°C) and 2,743 m (80 to 83°C) below the surface. Microbial community complexity decreased with increasing temperature, and the potential to degrade hydrocarbon compounds was most prevalent in the lower-temperature reservoirs. Sulfate availability, rather than sulfate reduction potential, seems to be the limiting factor for sulfide production in some of the reservoirs under investigation. Most microorganisms in the intermediate- and higher-temperature samples were related to previously studied methanogenic and nonmethanogenic archaea and thermophilic bacteria, but one candidate phylum bacterium, a member of the Acetothermia (OP1), was present in Kuparuk sample K3. The greatest numbers of candidate phyla were recovered from the mesothermic reservoir samples SB1 and SB2. We reconstructed a nearly complete genome for an organism from the candidate phylum Parcubacteria (OD1) that was abundant in sample SB1. Consistent with prior findings for members of this lineage, the OD1 genome is small, and metabolic predictions support an obligately anaerobic, fermentation-based lifestyle. At moderate abundance in samples SB1 and SB2 were members of bacteria from other candidate phyla, including Microgenomates (OP11), Atribacteria (OP9), candidate phyla TA06 and WS6, and Marinimicrobia (SAR406). The results presented here elucidate potential roles of organisms in oil reservoir biological processes. The activities of microorganisms in oil reservoirs impact petroleum resource quality and the global carbon cycle. We show that bacteria belonging to candidate phyla are present in some oil reservoirs and provide the first insights into their potential roles in biogeochemical processes based on several nearly complete genomes.
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Piquet AMT, Maat DS, Confurius-Guns V, Sintes E, Herndl GJ, van de Poll WH, Wiencke C, Buma AGJ, Bolhuis H. Springtime dynamics, productivity and activity of prokaryotes in two Arctic fjords. Polar Biol 2015. [DOI: 10.1007/s00300-015-1866-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Niches of two polysaccharide-degrading Polaribacter isolates from the North Sea during a spring diatom bloom. ISME JOURNAL 2014; 9:1410-22. [PMID: 25478683 DOI: 10.1038/ismej.2014.225] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 10/06/2014] [Accepted: 10/23/2014] [Indexed: 11/08/2022]
Abstract
Members of the flavobacterial genus Polaribacter thrive in response to North Sea spring phytoplankton blooms. We analyzed two respective Polaribacter species by whole genome sequencing, comparative genomics, substrate tests and proteomics. Both can degrade algal polysaccharides but occupy distinct niches. The liquid culture isolate Polaribacter sp. strain Hel1_33_49 has a 3.0-Mbp genome with an overall peptidase:CAZyme ratio of 1.37, four putative polysaccharide utilization loci (PULs) and features proteorhodopsin, whereas the agar plate isolate Polaribacter sp. strain Hel1_85 has a 3.9-Mbp genome with an even peptidase:CAZyme ratio, eight PULs, a mannitol dehydrogenase for decomposing algal mannitol-capped polysaccharides but no proteorhodopsin. Unlike other sequenced Polaribacter species, both isolates have larger sulfatase-rich PULs, supporting earlier assumptions that Polaribacter take part in the decomposition of sulfated polysaccharides. Both strains grow on algal laminarin and the sulfated polysaccharide chondroitin sulfate. For strain Hel1_33_49, we identified by proteomics (i) a laminarin-induced PUL, (ii) chondroitin sulfate-induced CAZymes and (iii) a chondroitin-induced operon that likely enables chondroitin sulfate recognition. These and other data suggest that strain Hel1_33_49 is a planktonic flavobacterium feeding on proteins and a small subset of algal polysaccharides, while the more versatile strain Hel1_85 can decompose a broader spectrum of polysaccharides and likely associates with algae.
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Steen AD, Arnosti C. Picky, hungry eaters in the cold: persistent substrate selectivity among polar pelagic microbial communities. Front Microbiol 2014; 5:527. [PMID: 25339946 PMCID: PMC4189390 DOI: 10.3389/fmicb.2014.00527] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 09/22/2014] [Indexed: 11/13/2022] Open
Abstract
Polar pelagic microbial communities access a narrower range of polysaccharide substrates than communities at lower latitudes. For example, the glucose-containing polysaccharide pullulan is typically not hydrolyzed in fjord waters of Svalbard, even though pullulan is rapidly hydrolyzed in sediments from Svalbard fjords, other polysaccharides are hydrolyzed rapidly in Svalbard waters, and pullulan is hydrolyzed rapidly in temperate waters. The purpose of this study was to investigate potential factors preventing hydrolysis of pullulan in Svalbard fjord waters. To this end, in two separate years, water from Isfjorden, Svalbard, was amended with different carbon sources and/or additional nutrients in order to determine whether increasing the concentration of these potentially-limiting factors would lead to measurable enzymatic activity. Addition of nitrate, phosphate, glucose, or amino acids did not yield detectable pullulan hydrolysis. The only treatment that led to detectable pullulan hydrolysis was extended incubation after the addition of maltotriose (a subunit of pullulan, and potential inducer of pullulanase). In these fjords, the ability to enzymatically access pullulan is likely confined to numerically minor members of the pelagic microbial community. These results are consistent with the hypothesis that pelagic microbial communities at high latitudes exhibit streamlined functionality, focused on a narrower range of substrates, than their temperate counterparts.
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Affiliation(s)
- Andrew D Steen
- Department of Marine Sciences, University of North Carolina at Chapel Hill Chapel Hill, NC, USA ; Department of Earth and Planetary Sciences, University of Tennessee Knoxville, TN, USA
| | - Carol Arnosti
- Department of Marine Sciences, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
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Monier A, Findlay HS, Charvet S, Lovejoy C. Late winter under ice pelagic microbial communities in the high Arctic Ocean and the impact of short-term exposure to elevated CO2 levels. Front Microbiol 2014; 5:490. [PMID: 25324832 PMCID: PMC4179612 DOI: 10.3389/fmicb.2014.00490] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 09/01/2014] [Indexed: 11/13/2022] Open
Abstract
Polar Oceans are natural CO2 sinks because of the enhanced solubility of CO2 in cold water. The Arctic Ocean is at additional risk of accelerated ocean acidification (OA) because of freshwater inputs from sea ice and rivers, which influence the carbonate system. Winter conditions in the Arctic are of interest because of both cold temperatures and limited CO2 venting to the atmosphere when sea ice is present. Earlier OA experiments on Arctic microbial communities conducted in the absence of ice cover, hinted at shifts in taxa dominance and diversity under lowered pH. The Catlin Arctic Survey provided an opportunity to conduct in situ, under-ice, OA experiments during late Arctic winter. Seawater was collected from under the sea ice off Ellef Ringnes Island, and communities were exposed to three CO2 levels for 6 days. Phylogenetic diversity was greater in the attached fraction compared to the free-living fraction in situ, in the controls and in the treatments. The dominant taxa in all cases were Gammaproteobacteria but acidification had little effect compared to the effects of containment. Phylogenetic net relatedness indices suggested that acidification may have decreased the diversity within some bacterial orders, but overall there was no clear trend. Within the experimental communities, alkalinity best explained the variance among samples and replicates, suggesting subtle changes in the carbonate system need to be considered in such experiments. We conclude that under ice communities have the capacity to respond either by selection or phenotypic plasticity to heightened CO2 levels over the short term.
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Affiliation(s)
- Adam Monier
- Département de Biologie, Québec Océan and Institut de Biologie Intégrative et des Systèmes, Université Laval Québec, QC, Canada ; Takuvik Joint International Laboratory (CNRS UMI-3376), Université Laval Québec, QC, Canada
| | | | - Sophie Charvet
- Département de Biologie, Québec Océan and Institut de Biologie Intégrative et des Systèmes, Université Laval Québec, QC, Canada
| | - Connie Lovejoy
- Département de Biologie, Québec Océan and Institut de Biologie Intégrative et des Systèmes, Université Laval Québec, QC, Canada ; Takuvik Joint International Laboratory (CNRS UMI-3376), Université Laval Québec, QC, Canada
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Patterns of Microbially Driven Carbon Cycling in the Ocean: Links between Extracellular Enzymes and Microbial Communities. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/706082] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Heterotrophic microbial communities play a central role in the marine carbon cycle. They are active in nearly all known environments, from the surface to the deep ocean, in the sediments, and from the equator to the Poles. In order to process complex organic matter, these communities produce extracellular enzymes of the correct structural specificity to hydrolyze substrates to sizes sufficiently small for uptake. Extracellular enzymatic hydrolysis thus initiates heterotrophic carbon cycling. Our knowledge of the enzymatic capabilities of microbial communities in the ocean is still underdeveloped. Recent studies, however, suggest that there may be large-scale patterns of enzymatic function in the ocean, patterns of community function that may be connected to emerging patterns of microbial community composition. Here I review some of these large-scale contrasts in microbial enzyme activities, between high-latitude and temperate surface ocean waters, contrasts between inshore and offshore waters, changes with depth gradients in the ocean, and contrasts between the water column and underlying sediments. These contrasting patterns are set in the context of recent studies of microbial communities and patterns of microbial biogeography. Focusing on microbial community function as well as composition and potential should yield clearer understanding of the factors driving carbon cycling in the ocean.
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Seasonal changes in substrate utilization patterns by bacterioplankton in the Amundsen Gulf (western Arctic). Polar Biol 2014. [DOI: 10.1007/s00300-014-1523-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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D'Ambrosio L, Ziervogel K, MacGregor B, Teske A, Arnosti C. Composition and enzymatic function of particle-associated and free-living bacteria: a coastal/offshore comparison. ISME JOURNAL 2014; 8:2167-79. [PMID: 24763371 DOI: 10.1038/ismej.2014.67] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 03/19/2014] [Accepted: 03/23/2014] [Indexed: 11/09/2022]
Abstract
We compared the function and composition of free-living and particle-associated microbial communities at an inshore site in coastal North Carolina and across a depth profile on the Blake Ridge (offshore). Hydrolysis rates of six different polysaccharide substrates were compared for particle-associated (>3 μm) and free-living (<3 to 0.2 μm) microbial communities. The 16S rRNA- and rDNA-based clone libraries were produced from the same filters used to measure hydrolysis rates. Particle-associated and free-living communities resembled one another; they also showed similar enzymatic hydrolysis rates and substrate preferences. All six polysaccharides were hydrolyzed inshore. Offshore, only a subset was hydrolyzed in surface water and at depths of 146 and 505 m; just three polysaccharides were hydrolyzed at 505 m. The spectrum of bacterial taxa changed more subtly between inshore and offshore surface waters, but changed greatly with depth offshore. None of the OTUs occurred at all sites: 27 out of the 28 major OTUs defined in this study were found either exclusively in a surface or in a mid-depth/bottom water sample. This distinction was evident with both 16S rRNA and rDNA analyses. At the offshore site, despite the low community overlap, bacterial communities maintained a degree of functional redundancy on the whole bacterial community level with respect to hydrolysis of high-molecular-weight substrates.
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Affiliation(s)
- Lindsay D'Ambrosio
- Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kai Ziervogel
- Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Barbara MacGregor
- Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Andreas Teske
- Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Carol Arnosti
- Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Verrucomicrobia are candidates for polysaccharide-degrading bacterioplankton in an arctic fjord of Svalbard. Appl Environ Microbiol 2014; 80:3749-56. [PMID: 24727271 DOI: 10.1128/aem.00899-14] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Arctic marine bacterial communities, members of the phylum Verrucomicrobia are consistently detected, although not typically abundant, in 16S rRNA gene clone libraries and pyrotag surveys of the marine water column and in sediments. In an Arctic fjord (Smeerenburgfjord) of Svalbard, members of the Verrucomicrobia, together with Flavobacteria and smaller proportions of Alpha- and Gammaproteobacteria, constituted the most frequently detected bacterioplankton community members in 16S rRNA gene-based clone library analyses of the water column. Parallel measurements in the water column of the activities of six endo-acting polysaccharide hydrolases showed that chondroitin sulfate, laminarin, and xylan hydrolysis accounted for most of the activity. Several Verrucomicrobia water column phylotypes were affiliated with previously sequenced, glycoside hydrolase-rich genomes of individual Verrucomicrobia cells that bound fluorescently labeled laminarin and xylan and therefore constituted candidates for laminarin and xylan hydrolysis. In sediments, the bacterial community was dominated by different lineages of Verrucomicrobia, Bacteroidetes, and Proteobacteria but also included members of multiple phylum-level lineages not observed in the water column. This community hydrolyzed laminarin, xylan, chondroitin sulfate, and three additional polysaccharide substrates at high rates. Comparisons with data from the same fjord in the previous summer showed that the bacterial community in Smeerenburgfjord changed in composition, most conspicuously in the changing detection frequency of Verrucomicrobia in the water column. Nonetheless, in both years the community hydrolyzed the same polysaccharide substrates.
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Polysaccharides and proteins added to flowing drinking water at microgram-per-liter levels promote the formation of biofilms predominated by bacteroidetes and proteobacteria. Appl Environ Microbiol 2014; 80:2360-71. [PMID: 24487544 DOI: 10.1128/aem.04105-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biopolymers are important substrates for heterotrophic bacteria in (ultra)oligotrophic freshwater environments, but information about their utilization at microgram-per-liter levels by attached freshwater bacteria is lacking. This study aimed at characterizing biopolymer utilization in drinking-water-related biofilms by exposing such biofilms to added carbohydrates or proteins at 10 μg C liter(-1) in flowing tap water for up to 3 months. Individually added amylopectin was not utilized by the biofilms, whereas laminarin, gelatin, and caseinate were. Amylopectin was utilized during steady-state biofilm growth with simultaneously added maltose but not with simultaneously added acetate. Biofilm formation rates (BFR) at 10 μg C liter(-1) per substrate were ranked as follows, from lowest to highest: blank or amylopectin (≤6 pg ATP cm(-2) day(-1)), gelatin or caseinate, laminarin, maltose, acetate alone or acetate plus amylopectin, and maltose plus amylopectin (980 pg ATP cm(-2) day(-1)). Terminal restriction fragment length polymorphism (T-RFLP) and 16S rRNA gene sequence analyses revealed that the predominant maltose-utilizing bacteria also dominated subsequent amylopectin utilization, indicating catabolic repression and (extracellular) enzyme induction. The accelerated BFR with amylopectin in the presence of maltose probably resulted from efficient amylopectin binding to and hydrolysis by inductive enzymes attached to the bacterial cells. Cytophagia, Flavobacteriia, Gammaproteobacteria, and Sphingobacteriia grew during polysaccharide addition, and Alpha-, Beta-, and Gammaproteobacteria, Cytophagia, Flavobacteriia, and Sphingobacteriia grew during protein addition. The succession of bacterial populations in the biofilms coincided with the decrease in the specific growth rate during biofilm formation. Biopolymers can clearly promote biofilm formation at microgram-per-liter levels in drinking water distribution systems and, depending on their concentrations, might impair the biological stability of distributed drinking water.
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Arnosti C, Steen AD. Patterns of extracellular enzyme activities and microbial metabolism in an Arctic fjord of Svalbard and in the northern Gulf of Mexico: contrasts in carbon processing by pelagic microbial communities. Front Microbiol 2013; 4:318. [PMID: 24198812 PMCID: PMC3813923 DOI: 10.3389/fmicb.2013.00318] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 10/10/2013] [Indexed: 11/22/2022] Open
Abstract
The microbial community composition of polar and temperate ocean waters differs substantially, but the potential functional consequences of these differences are largely unexplored. We measured bacterial production, glucose metabolism, and the abilities of microbial communities to hydrolyze a range of polysaccharides in an Arctic fjord of Svalbard (Smeerenburg Fjord), and thus to initiate remineralization of high-molecular weight organic matter. We compared these data with similar measurements previously carried out in the northern Gulf of Mexico in order to investigate whether differences in the spectrum of enzyme activities measurable in Arctic and temperate environments are reflected in “downstream” aspects of microbial metabolism (metabolism of monomers and biomass production). Only four of six polysaccharide substrates were hydrolyzed in Smeerenburg Fjord; all were hydrolyzed in the upper water column of the Gulf. These patterns are consistent on an interannual basis. Bacterial protein production was comparable at both locations, but the pathways of glucose utilization differed. Glucose incorporation rate constants were comparatively higher in Svalbard, but glucose respiration rate constants were higher in surface waters of the Gulf. As a result, at the time of sampling ca. 75% of the glucose was incorporated into biomass in Svalbard, but in the northern Gulf of Mexico most of the glucose was respired to CO2. A limited range of enzyme activities is therefore not a sign of a dormant community or one unable to further process substrates resulting from extracellular enzymatic hydrolysis. The ultimate fate of carbohydrates in marine waters, however, is strongly dependent upon the specific capabilities of heterotrophic microbial communities in these disparate environments.
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Affiliation(s)
- Carol Arnosti
- Department of Marine Sciences, University of North Carolina-Chapel Hill, Chapel Hill NC, USA
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Sinkko H, Lukkari K, Sihvonen LM, Sivonen K, Leivuori M, Rantanen M, Paulin L, Lyra C. Bacteria contribute to sediment nutrient release and reflect progressed eutrophication-driven hypoxia in an organic-rich continental sea. PLoS One 2013; 8:e67061. [PMID: 23825619 PMCID: PMC3692436 DOI: 10.1371/journal.pone.0067061] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 05/14/2013] [Indexed: 11/18/2022] Open
Abstract
In the sedimental organic matter of eutrophic continental seas, such as the largest dead zone in the world, the Baltic Sea, bacteria may directly participate in nutrient release by mineralizing organic matter or indirectly by altering the sediment's ability to retain nutrients. Here, we present a case study of a hypoxic sea, which receives riverine nutrient loading and in which microbe-mediated vicious cycles of nutrients prevail. We showed that bacterial communities changed along the horizontal loading and vertical mineralization gradients in the Gulf of Finland of the Baltic Sea, using multivariate statistics of terminal restriction fragments and sediment chemical, spatial and other properties of the sampling sites. The change was mainly explained by concentrations of organic carbon, nitrogen and phosphorus, which showed strong positive correlation with Flavobacteria, Sphingobacteria, Alphaproteobacteria and Gammaproteobacteria. These bacteria predominated in the most organic-rich coastal surface sediments overlain by oxic bottom water, whereas sulphate-reducing bacteria, particularly the genus Desulfobacula, prevailed in the reduced organic-rich surface sediments in the open sea. They correlated positively with organic nitrogen and phosphorus, as well as manganese oxides. These relationships suggest that the bacterial groups participated in the aerobic and anaerobic degradation of organic matter and contributed to nutrient cycling. The high abundance of sulphate reducers in the surficial sediment layers reflects the persistence of eutrophication-induced hypoxia causing ecosystem-level changes in the Baltic Sea. The sulphate reducers began to decrease below depths of 20 cm, where members of the family Anaerolineaceae (phylum Chloroflexi) increased, possibly taking part in terminal mineralization processes. Our study provides valuable information on how organic loading affects sediment bacterial community compositions, which consequently may maintain active nutrient recycling. This information is needed to improve our understanding on nutrient cycling in shallow seas where the dead zones are continuously spreading worldwide.
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Affiliation(s)
- Hanna Sinkko
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Kaarina Lukkari
- Marine Research Centre, Finnish Environment Institute, Helsinki, Finland
| | - Leila M. Sihvonen
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
- National Institute for Health and Welfare, Helsinki, Finland
| | - Kaarina Sivonen
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Mirja Leivuori
- Reference Laboratory, Finnish Environment Institute, Helsinki, Finland
| | - Matias Rantanen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Lars Paulin
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Christina Lyra
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
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Arnosti C, Fuchs BM, Amann R, Passow U. Contrasting extracellular enzyme activities of particle-associated bacteria from distinct provinces of the North Atlantic Ocean. Front Microbiol 2012; 3:425. [PMID: 23248623 PMCID: PMC3521168 DOI: 10.3389/fmicb.2012.00425] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 11/27/2012] [Indexed: 12/31/2022] Open
Abstract
Microbial communities play a key role in the marine carbon cycle, processing much of phytoplankton-derived organic matter. The composition of these communities varies by depth, season, and location in the ocean; the functional consequences of these compositional variations for the carbon cycle are only beginning to be explored. We measured the abilities of microbial communities in the large-particle fraction (retained by a 10-μm pore-size cartridge filter) to enzymatically hydrolyze high molecular weight substrates, and therefore initiate carbon remineralization in four distinct oceanic provinces: the boreal polar (BPLR), the Arctic oceanic (ARCT), the North Atlantic drift (NADR), and the North Atlantic subtropical (NAST) provinces. Since we expected the large-particle fraction to include phytoplankton cells, we measured the hydrolysis of polysaccharide substrates (laminarin, fucoidan, xylan, and chondroitin sulfate) expected to be associated with phytoplankton. Hydrolysis rates and patterns clustered into two groups, the BPLR/ARCT and the NADR/NAST. All four substrates were hydrolyzed by the BPLR/ARCT communities; hydrolysis rates of individual substrate varied by factors of ca. 1–4. In contrast, chondroitin was not hydrolyzed in the NADR/NAST, and hydrolytic activity was dominated by laminarinase. Fluorescence in situ hybridization of the large-particle fraction post-incubation showed a substantial contribution (15–26%) of CF319a-positive cells (Bacteroidetes) to total DAPI-stainable cells. Concurrent studies of microbial community composition and of fosmids from these same stations also demonstrated similarities between BPLR and ARCT stations, which were distinct from the NADR/NAST stations. Together, these data support a picture of compositionally as well as functionally distinct communities across these oceanic provinces.
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Affiliation(s)
- Carol Arnosti
- Department of Marine Sciences, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
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Latitudinal gradients in degradation of marine dissolved organic carbon. PLoS One 2011; 6:e28900. [PMID: 22216139 PMCID: PMC3247214 DOI: 10.1371/journal.pone.0028900] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 11/16/2011] [Indexed: 11/25/2022] Open
Abstract
Heterotrophic microbial communities cycle nearly half of net primary productivity in the ocean, and play a particularly important role in transformations of dissolved organic carbon (DOC). The specific means by which these communities mediate the transformations of organic carbon are largely unknown, since the vast majority of marine bacteria have not been isolated in culture, and most measurements of DOC degradation rates have focused on uptake and metabolism of either bulk DOC or of simple model compounds (e.g. specific amino acids or sugars). Genomic investigations provide information about the potential capabilities of organisms and communities but not the extent to which such potential is expressed. We tested directly the capabilities of heterotrophic microbial communities in surface ocean waters at 32 stations spanning latitudes from 76°S to 79°N to hydrolyze a range of high molecular weight organic substrates and thereby initiate organic matter degradation. These data demonstrate the existence of a latitudinal gradient in the range of complex substrates available to heterotrophic microbial communities, paralleling the global gradient in bacterial species richness. As changing climate increasingly affects the marine environment, changes in the spectrum of substrates accessible by microbial communities may lead to shifts in the location and rate at which marine DOC is respired. Since the inventory of DOC in the ocean is comparable in magnitude to the atmospheric CO2 reservoir, such a change could profoundly affect the global carbon cycle.
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Microbial community composition and function in permanently cold seawater and sediments from an arctic fjord of svalbard. Appl Environ Microbiol 2011; 77:2008-18. [PMID: 21257812 DOI: 10.1128/aem.01507-10] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heterotrophic microbial communities in seawater and sediments metabolize much of the organic carbon produced in the ocean. Although carbon cycling and preservation depend critically on the capabilities of these microbial communities, their compositions and capabilities have seldom been examined simultaneously at the same site. To compare the abilities of seawater and sedimentary microbial communities to initiate organic matter degradation, we measured the extracellular enzymatic hydrolysis rates of 10 substrates (polysaccharides and algal extracts) in surface seawater and bottom water as well as in surface and anoxic sediments of an Arctic fjord. Patterns of enzyme activities differed between seawater and sediments, not just quantitatively, in accordance with higher cell numbers in sediments, but also in their more diversified enzyme spectrum. Sedimentary microbial communities hydrolyzed all of the fluorescently labeled polysaccharide and algal extracts, in most cases at higher rates in subsurface than surface sediments. In seawater, in contrast, only 5 of the 7 polysaccharides and 2 of the 3 algal extracts were hydrolyzed, and hydrolysis rates in surface and deepwater were virtually identical. To compare bacterial communities, 16S rRNA gene clone libraries were constructed from the same seawater and sediment samples; they diverged strongly in composition. Thus, the broader enzymatic capabilities of the sedimentary microbial communities may result from the compositional differences between seawater and sedimentary microbial communities, rather than from gene expression differences among compositionally similar communities. The greater number of phylum- and subphylum-level lineages and operational taxonomic units in sediments than in seawater samples may reflect the necessity of a wider range of enzymatic capabilities and strategies to access organic matter that has already been degraded during passage through the water column. When transformations of marine organic matter are considered, differences in community composition and their different abilities to access organic matter should be taken into account.
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Abstract
Extracellular enzymes initiate microbial remineralization of organic matter by hydrolyzing substrates to sizes sufficiently small to be transported across cell membranes. As much of marine primary productivity is processed by heterotrophic microbes, the substrate specificities of extracellular enzymes, the rates at which they function in seawater and sediments, and factors controlling their production, distribution, and active lifetimes, are central to carbon cycling in marine systems. In this review, these topics are considered from biochemical, microbial/molecular biological, and geochemical perspectives. Our understanding of the capabilities and limitations of heterotrophic microbial communities has been greatly advanced in recent years, in part through genetic and genomic approaches. New methods to measure enzyme activities in the field are needed to keep pace with these advances and to pursue intriguing evidence that patterns of enzyme activities in different environments are linked to differences in microbial community composition that may profoundly affect the marine carbon cycle.
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Affiliation(s)
- Carol Arnosti
- Department of Marine Sciences, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina 27599-3300, USA.
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