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Marguš M, Ahel M, Čanković M, Ljubešić Z, Terzić S, Hodak Kobasić V, Ciglenečki I. Phytoplankton pigment dynamics in marine lake fluctuating between stratified and holomictic euxinic conditions. MARINE POLLUTION BULLETIN 2023; 191:114931. [PMID: 37075558 DOI: 10.1016/j.marpolbul.2023.114931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 04/05/2023] [Accepted: 04/07/2023] [Indexed: 05/03/2023]
Abstract
Biomass dynamics in the marine lake are strongly dependent on seasonal variability in vertical stratification, indicating rapid adaptation of phytoplankton to short-term changes in the water column. A small marine lake (Rogoznica Lake, Croatia), which fluctuates between stably stratified and holomictic euxinic conditions, was used as a model to study the phytoplankton responses to environmental perturbations, in particular the anoxic stress, caused by periodic holomixia. The epilimnion showed significant temporal and vertical variability with a chlorophyll a subsurface maximum with the highest biomass near the chemocline. Fucoxanthin-containing biomass (diatoms) dominated in the epilimnion in colder seasons and was first to recover after holomictic euxinic events. The shift towards the smaller groups prevailed during highly stratified water column conditions in warmer seasons. Results for the hypolimnion were more enigmatic, with high concentrations of alloxanthin, zeaxanthin, and violaxanthin indicating the presence of a viable small-size mixotrophic community under extreme conditions.
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Affiliation(s)
- Marija Marguš
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
| | - Marijan Ahel
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
| | - Milan Čanković
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Zrinka Ljubešić
- Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000 Zagreb, Croatia
| | - Senka Terzić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Vedranka Hodak Kobasić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Irena Ciglenečki
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
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Cai M, Liu Y, Yin X, Zhou Z, Friedrich MW, Richter-Heitmann T, Nimzyk R, Kulkarni A, Wang X, Li W, Pan J, Yang Y, Gu JD, Li M. Diverse Asgard archaea including the novel phylum Gerdarchaeota participate in organic matter degradation. SCIENCE CHINA-LIFE SCIENCES 2020; 63:886-897. [PMID: 32201928 DOI: 10.1007/s11427-020-1679-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 03/12/2020] [Indexed: 01/14/2023]
Abstract
Asgard is an archaeal superphylum that might hold the key to understand the origin of eukaryotes, but its diversity and ecological roles remain poorly understood. Here, we reconstructed 15 metagenomic-assembled genomes from coastal sediments covering most known Asgard archaea and a novel group, which is proposed as a new Asgard phylum named as the "Gerdarchaeota". Genomic analyses predict that Gerdarchaeota are facultative anaerobes in utilizing both organic and inorganic carbon. Unlike their closest relatives Heimdallarchaeota, Gerdarchaeota have genes encoding for cellulase and enzymes involved in the tetrahydromethanopterin-based Wood-Ljungdahl pathway. Transcriptomics showed that most of our identified Asgard archaea are capable of degrading organic matter, including peptides, amino acids and fatty acids, occupying ecological niches in different depths of layers of the sediments. Overall, this study broadens the diversity of the mysterious Asgard archaea and provides evidence for their ecological roles in coastal sediments.
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Affiliation(s)
- Mingwei Cai
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Yang Liu
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
| | - Xiuran Yin
- Microbial Ecophysiology Group, Faculty of Biology/Chemistry, University of Bremen, Bremen, D-28359, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, D-28359, Germany
| | - Zhichao Zhou
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
- Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Hong Kong, 999077, China
| | - Michael W Friedrich
- Microbial Ecophysiology Group, Faculty of Biology/Chemistry, University of Bremen, Bremen, D-28359, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, D-28359, Germany
| | - Tim Richter-Heitmann
- Microbial Ecophysiology Group, Faculty of Biology/Chemistry, University of Bremen, Bremen, D-28359, Germany
| | - Rolf Nimzyk
- Department of Microbe-Plant Interactions, Faculty of Biology/Chemistry, University of Bremen, Bremen, D-28359, Germany
| | - Ajinkya Kulkarni
- Microbial Ecophysiology Group, Faculty of Biology/Chemistry, University of Bremen, Bremen, D-28359, Germany
| | - Xiaowen Wang
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Wenjin Li
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
| | - Jie Pan
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
| | - Yuchun Yang
- Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Hong Kong, 999077, China
| | - Ji-Dong Gu
- Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Hong Kong, 999077, China
| | - Meng Li
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China.
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3
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Parro V, Puente-Sánchez F, Cabrol NA, Gallardo-Carreño I, Moreno-Paz M, Blanco Y, García-Villadangos M, Tambley C, Tilot VC, Thompson C, Smith E, Sobrón P, Demergasso CS, Echeverría-Vega A, Fernández-Martínez MÁ, Whyte LG, Fairén AG. Microbiology and Nitrogen Cycle in the Benthic Sediments of a Glacial Oligotrophic Deep Andean Lake as Analog of Ancient Martian Lake-Beds. Front Microbiol 2019; 10:929. [PMID: 31130930 PMCID: PMC6509559 DOI: 10.3389/fmicb.2019.00929] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 04/12/2019] [Indexed: 02/06/2023] Open
Abstract
Potential benthic habitats of early Mars lakes, probably oligotrophic, could range from hydrothermal to cold sediments. Dynamic processes in the water column (such as turbidity or UV penetration) as well as in the benthic bed (temperature gradients, turbation, or sedimentation rate) contribute to supply nutrients to a potential microbial ecosystem. High altitude, oligotrophic, and deep Andean lakes with active deglaciation processes and recent or past volcanic activity are natural models to assess the feasibility of life in other planetary lake/ocean environments and to develop technology for their exploration. We sampled the benthic sediments (down to 269 m depth) of the oligotrophic lake Laguna Negra (Central Andes, Chile) to investigate its ecosystem through geochemical, biomarker profiling, and molecular ecology studies. The chemistry of the benthic water was similar to the rest of the water column, except for variable amounts of ammonium (up to 2.8 ppm) and nitrate (up to 0.13 ppm). A life detector chip with a 300-antibody microarray revealed the presence of biomass in the form of exopolysaccharides and other microbial markers associated to several phylogenetic groups and potential microaerobic and anaerobic metabolisms such as nitrate reduction. DNA analyses showed that 27% of the Archaea sequences corresponded to a group of ammonia-oxidizing archaea (AOA) similar (97%) to Nitrosopumilus spp. and Nitrosoarchaeum spp. (Thaumarchaeota), and 4% of Bacteria sequences to nitrite-oxidizing bacteria from the Nitrospira genus, suggesting a coupling between ammonia and nitrite oxidation. Mesocosm experiments with the specific AOA inhibitor 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) demonstrated an AOA-associated ammonia oxidation activity with the simultaneous accumulation of nitrate and sulfate. The results showed a rich benthic microbial community dominated by microaerobic and anaerobic metabolisms thriving under aphotic, low temperature (4°C), and relatively high pressure, that might be a suitable terrestrial analog of other planetary settings.
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Affiliation(s)
- Victor Parro
- Centro de Astrobiología (CSIC-INTA), Madrid, Spain
| | | | - Nathalie A. Cabrol
- SETI Institute, Carl Sagan Center, Mountain View, CA, United States
- NASA Ames Research Center, Mountain View, CA, United States
| | | | | | | | | | | | - Virginie C. Tilot
- Instituto Español de Oceanografía (IEO), Málaga, Spain
- Muséum National d’Histoire Naturelle, Paris, France
| | - Cody Thompson
- School of Environmental Sciences, University of Guelph, Guelph, ON, Canada
| | - Eric Smith
- SETI Institute, Carl Sagan Center, Mountain View, CA, United States
| | - Pablo Sobrón
- SETI Institute, Carl Sagan Center, Mountain View, CA, United States
| | | | - Alex Echeverría-Vega
- Centro de Biotecnología, Universidad Católica del Norte, Antofagasta, Chile
- Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile
| | | | - Lyle G. Whyte
- Department of Natural Resource Sciences, McGill University, Montreal, QC, Canada
| | - Alberto G. Fairén
- Centro de Astrobiología (CSIC-INTA), Madrid, Spain
- Department of Astronomy, Cornell University, Ithaca, NY, United States
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Stal LJ, Bolhuis H, Cretoiu MS. Phototrophic marine benthic microbiomes: the ecophysiology of these biological entities. Environ Microbiol 2018; 21:1529-1551. [PMID: 30507057 DOI: 10.1111/1462-2920.14494] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 01/02/2023]
Abstract
Phototrophic biofilms are multispecies, self-sustaining and largely closed microbial ecosystems. They form macroscopic structures such as microbial mats and stromatolites. These sunlight-driven consortia consist of a number of functional groups of microorganisms that recycle the elements internally. Particularly, the sulfur cycle is discussed in more detail as this is fundamental to marine benthic microbial communities and because recently exciting new insights have been obtained. The cycling of elements demands a tight tuning of the various metabolic processes and require cooperation between the different groups of microorganisms. This is likely achieved through cell-to-cell communication and a biological clock. Biofilms may be considered as a macroscopic biological entity with its own physiology. We review the various components of some marine phototrophic biofilms and discuss their roles in the system. The importance of extracellular polymeric substances (EPS) as the matrix for biofilm metabolism and as substrate for biofilm microorganisms is discussed. We particularly assess the importance of extracellular DNA, horizontal gene transfer and viruses for the generation of genetic diversity and innovation, and for rendering resilience to external forcing to these biological entities.
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Affiliation(s)
- Lucas J Stal
- IBED Department of Freshwater and Marine Ecology, University of Amsterdam, Amsterdam, The Netherlands.,Department of Marine Microbiology and Biogeochemistry, and Utrecht University, Netherlands Institute for Sea Research, Den Burg, Texel, The Netherlands
| | - Henk Bolhuis
- Department of Marine Microbiology and Biogeochemistry, and Utrecht University, Netherlands Institute for Sea Research, Den Burg, Texel, The Netherlands
| | - Mariana S Cretoiu
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, 04544, USA
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5
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Chen X, Huang Y, Chen G, Li P, Shen Y, Davis TW. The secretion of organics by living Microcystis under the dark/anoxic condition and its enhancing effect on nitrate removal. CHEMOSPHERE 2018; 196:280-287. [PMID: 29306780 DOI: 10.1016/j.chemosphere.2017.12.197] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 12/27/2017] [Accepted: 12/31/2017] [Indexed: 06/07/2023]
Abstract
Recent studies indicated that the algal decomposition produces particulate and dissolved organic carbon (DOC), and can enhance denitrification in eutrophic lakes. However, the effects of the living cyanobacteria on nitrogen cycling in eutrophic lakes were still an unknown question. This study explores a new underlying mechanism of nitrate removal which is driven by living Microcystis. The results suggested that living Microcystis significantly enhanced the nitrate removal at sediment-water interface, with a nitrate removal rate of 0.54 d-1, which was 2.57 times higher than the nitrate removal rate in the treatment without the addition of Microcystis. Measurements of Chl a and Fv/Fm confirmed that Microcystis was tolerant to the dark/anoxic condition, and the recovery experiments suggested that Microcystis could survive under such stress conditions for at least seven days. Meanwhile, DOC secreted by living Microcystis reached to 4.55 mg C mg-1 Chl a. These secretions were biodegradable hydrophilic and contained carbohydrates and proteins. Our study indicated that during blooms, sinking Microcystis cells could directly provide DOC as carbon source, then consequently enhanced the denitrification at sediment-water interface, and the interactive relationship between living cyanobacteria and permanent nitrate removal should be taken into account while studying nitrogen cycling in aquatic ecosystem.
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Affiliation(s)
- Xuechu Chen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China; Shanghai Engineering Research Center of Landscaping on Challenging Urban Sites, Shanghai, 200232, PR China.
| | - Yingying Huang
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China; Institute of Eco-Chongming, 3663 N. Zhongshan Road, Shanghai, 200062, PR China.
| | - Guiqin Chen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China
| | - Panpan Li
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China
| | - Yingshi Shen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China
| | - Timothy Walter Davis
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, 43403, USA
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6
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Depth Distribution and Assembly of Sulfate-Reducing Microbial Communities in Marine Sediments of Aarhus Bay. Appl Environ Microbiol 2017; 83:AEM.01547-17. [PMID: 28939599 DOI: 10.1128/aem.01547-17] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 09/14/2017] [Indexed: 11/20/2022] Open
Abstract
Most sulfate-reducing microorganisms (SRMs) present in subsurface marine sediments belong to uncultured groups only distantly related to known SRMs, and it remains unclear how changing geochemical zones and sediment depth influence their community structure. We mapped the community composition and abundance of SRMs by amplicon sequencing and quantifying the dsrB gene, which encodes dissimilatory sulfite reductase subunit beta, in sediment samples covering different vertical geochemical zones ranging from the surface sediment to the deep sulfate-depleted subsurface at four locations in Aarhus Bay, Denmark. SRMs were present in all geochemical zones, including sulfate-depleted methanogenic sediment. The biggest shift in SRM community composition and abundance occurred across the transition from bioturbated surface sediments to nonbioturbated sediments below, where redox fluctuations and the input of fresh organic matter due to macrofaunal activity are absent. SRM abundance correlated with sulfate reduction rates determined for the same sediments. Sulfate availability showed a weaker correlation with SRM abundances and no significant correlation with the composition of the SRM community. The overall SRM species diversity decreased with depth, yet we identified a subset of highly abundant community members that persists across all vertical geochemical zones of all stations. We conclude that subsurface SRM communities assemble by the persistence of members of the surface community and that the transition from the bioturbated surface sediment to the unmixed sediment below is a main site of assembly of the subsurface SRM community.IMPORTANCE Sulfate-reducing microorganisms (SRMs) are key players in the marine carbon and sulfur cycles, especially in coastal sediments, yet little is understood about the environmental factors controlling their depth distribution. Our results suggest that macrofaunal activity is a key driver of SRM abundance and community structure in marine sediments and that a small subset of SRM species of high relative abundance in the subsurface SRM community persists from the sulfate-rich surface sediment to sulfate-depleted methanogenic subsurface sediment. More generally, we conclude that SRM communities inhabiting the subsurface seabed assemble by the selective survival of members of the surface community.
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7
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Yang T, Speare K, McKay L, MacGregor BJ, Joye SB, Teske A. Distinct Bacterial Communities in Surficial Seafloor Sediments Following the 2010 Deepwater Horizon Blowout. Front Microbiol 2016; 7:1384. [PMID: 27679609 PMCID: PMC5020131 DOI: 10.3389/fmicb.2016.01384] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 08/22/2016] [Indexed: 11/26/2022] Open
Abstract
A major fraction of the petroleum hydrocarbons discharged during the 2010 Macondo oil spill became associated with and sank to the seafloor as marine snow flocs. This sedimentation pulse induced the development of distinct bacterial communities. Between May 2010 and July 2011, full-length 16S rRNA gene clone libraries demonstrated bacterial community succession in oil-polluted sediment samples near the wellhead area. Libraries from early May 2010, before the sedimentation event, served as the baseline control. Freshly deposited oil-derived marine snow was collected on the surface of sediment cores in September 2010, and was characterized by abundantly detected members of the marine Roseobacter cluster within the Alphaproteobacteria. Samples collected in mid-October 2010 closest to the wellhead contained members of the sulfate-reducing, anaerobic bacterial families Desulfobacteraceae and Desulfobulbaceae within the Deltaproteobacteria, suggesting that the oil-derived sedimentation pulse triggered bacterial oxygen consumption and created patchy anaerobic microniches that favored sulfate-reducing bacteria. Phylotypes of the polycyclic aromatic hydrocarbon-degrading genus Cycloclasticus, previously found both in surface oil slicks and the deep hydrocarbon plume, were also found in oil-derived marine snow flocs sedimenting on the seafloor in September 2010, and in surficial sediments collected in October and November 2010, but not in any of the control samples. Due to the relative recalcitrance and stability of polycyclic aromatic compounds, Cycloclasticus represents the most persistent microbial marker of seafloor hydrocarbon deposition that we could identify in this dataset. The bacterial imprint of the DWH oil spill had diminished in late November 2010, when the bacterial communities in oil-impacted sediment samples collected near the Macondo wellhead began to resemble their pre-spill counterparts and spatial controls. Samples collected in summer of 2011 did not show a consistent bacterial community signature, suggesting that the bacterial community was no longer shaped by the DWH fallout of oil-derived marine snow, but instead by location-specific and seasonal factors.
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Affiliation(s)
- Tingting Yang
- Department of Marine Sciences, University of North Carolina, Chapel Hill NC, USA
| | - Kelly Speare
- Department of Marine Sciences, University of North Carolina, Chapel Hill NC, USA
| | - Luke McKay
- Department of Marine Sciences, University of North Carolina, Chapel Hill NC, USA
| | - Barbara J MacGregor
- Department of Marine Sciences, University of North Carolina, Chapel Hill NC, USA
| | - Samantha B Joye
- Department of Marine Sciences, University of Georgia, Athens GA, USA
| | - Andreas Teske
- Department of Marine Sciences, University of North Carolina, Chapel Hill NC, USA
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8
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Winkel M, Pjevac P, Kleiner M, Littmann S, Meyerdierks A, Amann R, Mußmann M. Identification and activity of acetate-assimilating bacteria in diffuse fluids venting from two deep-sea hydrothermal systems. FEMS Microbiol Ecol 2014; 90:731-46. [DOI: 10.1111/1574-6941.12429] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 09/10/2014] [Accepted: 09/16/2014] [Indexed: 12/01/2022] Open
Affiliation(s)
- Matthias Winkel
- Department of Molecular Ecology; Max Planck Institute for Marine Microbiology; Bremen Germany
| | - Petra Pjevac
- Department of Molecular Ecology; Max Planck Institute for Marine Microbiology; Bremen Germany
| | - Manuel Kleiner
- Department of Symbiosis; Max Planck Institute for Marine Microbiology; Bremen Germany
| | - Sten Littmann
- Department of Biogeochemistry; Max Planck Institute for Marine Microbiology; Bremen Germany
| | - Anke Meyerdierks
- Department of Molecular Ecology; Max Planck Institute for Marine Microbiology; Bremen Germany
| | - Rudolf Amann
- Department of Molecular Ecology; Max Planck Institute for Marine Microbiology; Bremen Germany
| | - Marc Mußmann
- Department of Molecular Ecology; Max Planck Institute for Marine Microbiology; Bremen Germany
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Natural occurrence of microbial sulphur oxidation by long-range electron transport in the seafloor. ISME JOURNAL 2014; 8:1843-54. [PMID: 24671086 PMCID: PMC4139731 DOI: 10.1038/ismej.2014.41] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 02/04/2014] [Accepted: 02/16/2014] [Indexed: 11/26/2022]
Abstract
Recently, a novel mode of sulphur oxidation was described in marine sediments, in which sulphide oxidation in deeper anoxic layers was electrically coupled to oxygen reduction at the sediment surface. Subsequent experimental evidence identified that long filamentous bacteria belonging to the family Desulfobulbaceae likely mediated the electron transport across the centimetre-scale distances. Such long-range electron transfer challenges some long-held views in microbial ecology and could have profound implications for sulphur cycling in marine sediments. But, so far, this process of electrogenic sulphur oxidation has been documented only in laboratory experiments and so its imprint on the seafloor remains unknown. Here we show that the geochemical signature of electrogenic sulphur oxidation occurs in a variety of coastal sediment environments, including a salt marsh, a seasonally hypoxic basin, and a subtidal coastal mud plain. In all cases, electrogenic sulphur oxidation was detected together with an abundance of Desulfobulbaceae filaments. Complementary laboratory experiments in intertidal sands demonstrated that mechanical disturbance by bioturbating fauna destroys the electrogenic sulphur oxidation signal. A survey of published geochemical data and 16S rRNA gene sequences identified that electrogenic sulphide oxidation is likely present in a variety of marine sediments with high sulphide generation and restricted bioturbation, such as mangrove swamps, aquaculture areas, seasonally hypoxic basins, cold sulphide seeps and possibly hydrothermal vent environments. This study shows for the first time that electrogenic sulphur oxidation occurs in a wide range of marine sediments and that bioturbation may exert a dominant control on its natural distribution.
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10
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Morris BEL, Henneberger R, Huber H, Moissl-Eichinger C. Microbial syntrophy: interaction for the common good. FEMS Microbiol Rev 2013; 37:384-406. [PMID: 23480449 DOI: 10.1111/1574-6976.12019] [Citation(s) in RCA: 446] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2012] [Revised: 02/25/2013] [Accepted: 02/27/2013] [Indexed: 11/30/2022] Open
Abstract
Classical definitions of syntrophy focus on a process, performed through metabolic interaction between dependent microbial partners, such as the degradation of complex organic compounds under anoxic conditions. However, examples from past and current scientific discoveries suggest that a new, simple but wider definition is necessary to cover all aspects of microbial syntrophy. We suggest the term 'obligately mutualistic metabolism', which still focuses on microbial metabolic cooperation but also includes an ecological aspect: the benefit for both partners. By the combined metabolic activity of microorganisms, endergonic reactions can become exergonic through the efficient removal of products and therefore enable a microbial community to survive with minimal energy resources. Here, we explain the principles of classical and non-classical syntrophy and illustrate the concepts with various examples. We present biochemical fundamentals that allow microorganism to survive under a range of environmental conditions and to drive important biogeochemical processes. Novel technologies have contributed to the understanding of syntrophic relationships in cultured and uncultured systems. Recent research highlights that obligately mutualistic metabolism is not limited to certain metabolic pathways nor to certain environments or microorganisms. This beneficial microbial interaction is not restricted to the transfer of reducing agents such as hydrogen or formate, but can also involve the exchange of organic, sulfurous- and nitrogenous compounds or the removal of toxic compounds.
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Affiliation(s)
- Brandon E L Morris
- Microbiology, Institute for Biology II, University of Freiburg, Freiburg, Germany
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