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Ehrenfels B, Baumann KBL, Niederdorfer R, Mbonde AS, Kimirei IA, Kuhn T, Magyar PM, Odermatt D, Schubert CJ, Bürgmann H, Lehmann MF, Wehrli B, Callbeck CM. Hydrodynamic regimes modulate nitrogen fixation and the mode of diazotrophy in Lake Tanganyika. Nat Commun 2023; 14:6591. [PMID: 37852975 PMCID: PMC10584864 DOI: 10.1038/s41467-023-42391-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 10/10/2023] [Indexed: 10/20/2023] Open
Abstract
The factors that govern the geographical distribution of nitrogen fixation are fundamental to providing accurate nitrogen budgets in aquatic environments. Model-based insights have demonstrated that regional hydrodynamics strongly impact nitrogen fixation. However, the mechanisms establishing this physical-biological coupling have yet to be constrained in field surveys. Here, we examine the distribution of nitrogen fixation in Lake Tanganyika - a model system with well-defined hydrodynamic regimes. We report that nitrogen fixation is five times higher under stratified than under upwelling conditions. Under stratified conditions, the limited resupply of inorganic nitrogen to surface waters, combined with greater light penetration, promotes the activity of bloom-forming photoautotrophic diazotrophs. In contrast, upwelling conditions support predominantly heterotrophic diazotrophs, which are uniquely suited to chemotactic foraging in a more dynamic nutrient landscape. We suggest that these hydrodynamic regimes (stratification versus mixing) play an important role in governing both the rates and the mode of nitrogen fixation.
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Affiliation(s)
- Benedikt Ehrenfels
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
- ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zurich, Switzerland
| | - Kathrin B L Baumann
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
- ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zurich, Switzerland
| | - Robert Niederdorfer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
| | | | - Ismael A Kimirei
- TAFIRI, Tanzania Fisheries Research Institute, Kigoma, Tanzania
- TAFIRI, Tanzania Fisheries Research Institute, Dar es Salaam, Tanzania
| | - Thomas Kuhn
- University of Basel, Department of Environmental Sciences, Basel, Switzerland
| | - Paul M Magyar
- University of Basel, Department of Environmental Sciences, Basel, Switzerland
| | - Daniel Odermatt
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
| | - Carsten J Schubert
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
- ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zurich, Switzerland
| | - Helmut Bürgmann
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
| | - Moritz F Lehmann
- University of Basel, Department of Environmental Sciences, Basel, Switzerland
| | - Bernhard Wehrli
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
- ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zurich, Switzerland
| | - Cameron M Callbeck
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland.
- University of Basel, Department of Environmental Sciences, Basel, Switzerland.
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2
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Saini JS, Manni M, Hassler C, Cable RN, Duhaime MB, Zdobnov EM. Genomic insights into the coupling of a Chlorella-like microeukaryote and sulfur bacteria in the chemocline of permanently stratified Lake Cadagno. THE ISME JOURNAL 2023; 17:903-915. [PMID: 37031343 DOI: 10.1038/s41396-023-01396-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 03/14/2023] [Accepted: 03/16/2023] [Indexed: 04/10/2023]
Abstract
Meromictic Lake Cadagno is a permanently stratified system with a persistent microbial bloom within the oxic-anoxic boundary called the chemocline. The association between oxygenic and anoxygenic photosynthesis within the chemocline has been known for at least two decades. Although anoxygenic purple and green sulfur bacteria have been well studied, reports on oxygenic phytoplankton have remained sparse since their discovery in the 1920s. Nearly a century later, this study presents the first near-complete genome of a photosynthetic microbial eukaryote from the chemocline of Lake Cadagno, provisionally named Chlorella-like MAG. The 18.9 Mbp nuclear genome displays a high GC content (71.5%), and the phylogenetic placement suggests that it is a novel species of the genus Chlorella of Chlorophytes. Functional annotation of the Chlorella-like metagenome-assembled genome predicted 10,732 protein-coding genes, with an approximate 0.6% proportion potentially involved in carbon, sulfur, and nitrogen (C, N, and S) metabolism. In addition to C4 photosynthesis, this study detected genes for heat shock proteins (HSPs) in the Chlorella-like algae, consistent with the other Chlorella species. Altogether, the genomic insights in this study suggest the cooperation of photosynthetic algae with phototrophic sulfur bacteria via C, N, and S metabolism, which may aid their collective persistence in the Lake Cadagno chemocline. Furthermore, this work additionally presents the chloroplast genome of Cryptomonas-like species, which was likely to be presumed as cyanobacteria in previous studies because of the presence of phycobilisomes.
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Affiliation(s)
- Jaspreet S Saini
- Department F.-A Forel for Environmental and Aquatic Sciences, Earth and Environmental Sciences, University of Geneva, Geneva, Switzerland.
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.
- Swiss Institute of Bioinformatics, Lausanne, Switzerland.
- Laboratory for Environmental Biotechnology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
| | - Mosè Manni
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Christel Hassler
- Department F.-A Forel for Environmental and Aquatic Sciences, Earth and Environmental Sciences, University of Geneva, Geneva, Switzerland
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | - Rachel N Cable
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Melissa B Duhaime
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Evgeny M Zdobnov
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.
- Swiss Institute of Bioinformatics, Lausanne, Switzerland.
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3
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Wu L, Jin T, Chen H, Shen Z, Zhou Y. Conductive materials as fantastic toolkits to stimulate direct interspecies electron transfer in anaerobic digestion: new insights into methanogenesis contribution, characterization technology, and downstream treatment. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 326:116732. [PMID: 36402020 DOI: 10.1016/j.jenvman.2022.116732] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 10/29/2022] [Accepted: 11/05/2022] [Indexed: 06/16/2023]
Abstract
Direct interspecies electron transfer (DIET) stimulated by conductive materials (CMs) enables intercellular metabolic coupling that can address the unfavorable thermodynamical dilemma inherent in anaerobic digestion (AD). Although the DIET mechanism and stimulation have been extensively summarized, the methanogenesis contribution, characterization techniques, and downstream processes of CMs-led DIET in AD are surprisingly under-reviewed. Therefore, this review aimed to address these gaps. First, the contribution of CMs-led DIET to methanogenesis was re-evaluated by comparing the effect of various factors, including volatile fatty acids, free ammonia, and functional enzymes. It was revealed that AD systems are usually intricate and cannot allow the methanogenesis stimulation to be singularly attributed to the establishment of DIET. Additionally, considerable attention has been attached to the characterization of DIET occurrence, involving species identification, gene expression, electrical properties, cellular features, and syntrophic metabolism, suggesting the significance of accurate characterization methods for identifying the syntrophic metabolism interactions. Moreover, the type of CMs has a significant impact on AD downstream processes involving biogas purity, sludge dewaterability, and biosolids management. Finally, the central bottleneck consists in building a mathematical model of DIET to explain the mechanism of DIET in a deeper level from kinetics and thermodynamics.
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Affiliation(s)
- Linjun Wu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environment Sciences, Beijing 100012, PR China; Research Center of Environmental Pollution Control Engineering Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China; School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Tao Jin
- China Construction Eco-environmental Group CO.,LTD, Beijing 100037, PR China
| | - Hong Chen
- Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha, 410114, China
| | - Zhiqiang Shen
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environment Sciences, Beijing 100012, PR China; Research Center of Environmental Pollution Control Engineering Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
| | - Yuexi Zhou
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environment Sciences, Beijing 100012, PR China; Research Center of Environmental Pollution Control Engineering Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
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Bacterial, Phytoplankton, and Viral Distributions and Their Biogeochemical Contexts in Meromictic Lake Cadagno Offer Insights into the Proterozoic Ocean Microbial Loop. mBio 2022; 13:e0005222. [PMID: 35726916 PMCID: PMC9426590 DOI: 10.1128/mbio.00052-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lake Cadagno, a permanently stratified high-alpine lake with a persistent microbial bloom in its chemocline, has long been considered a model for the low-oxygen, high-sulfide Proterozoic ocean. Although the lake has been studied for over 25 years, the absence of concerted study of the bacteria, phytoplankton, and viruses, together with primary and secondary production, has hindered a comprehensive understanding of its microbial food web. Here, the identities, abundances, and productivity of microbes were evaluated in the context of Lake Cadagno biogeochemistry. Photosynthetic pigments together with 16S rRNA gene phylogenies suggest the prominence of eukaryotic phytoplankton chloroplasts, primarily chlorophytes. Chloroplasts closely related to those of high-alpine-adapted Ankyra judayi persisted with oxygen in the mixolimnion, where photosynthetic efficiency was high, while chloroplasts of Closteriopsis-related chlorophytes peaked in the chemocline and monimolimnion. The anoxygenic phototrophic sulfur bacterium Chromatium dominated the chemocline along with Lentimicrobium, a genus of known fermenters. Secondary production peaked in the chemocline, which suggested that anoxygenic primary producers depended on heterotrophic nutrient remineralization. The virus-to-microbe ratio peaked with phytoplankton abundances in the mixolimnion and were at a minimum where Chromatium abundance was highest, trends that suggest that viruses may play a role in the modulation of primary production. Through the combined analysis of bacterial, eukaryotic, viral, and biogeochemical spatial dynamics, we provide a comprehensive synthesis of the Lake Cadagno microbial loop. This study offers a new ecological perspective on how biological and geochemical connections may have occurred in the chemocline of the Proterozoic ocean, where eukaryotic microbial life is thought to have evolved.
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Li M, Wei D, Zhang Z, Fan D, Du B, Zeng H, Li D, Zhang J. Enhancing 2,6-dichlorophenol degradation and nitrate removal in the nano-zero-valent iron (nZVI) solid-phase denitrification system. CHEMOSPHERE 2022; 287:132249. [PMID: 34555584 DOI: 10.1016/j.chemosphere.2021.132249] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 07/11/2021] [Accepted: 09/12/2021] [Indexed: 06/13/2023]
Abstract
Nano-zero-valent iron (nZVI), as a typical nano-material, has been recently used in wastewater treatment and combination with bioreactors. Using nZVI coupled denitrification system research the effect and influence of nZVI enhanced denitrification sludge on the degradation of toxic compounds and system performance. The nZVI coupled denitrification system showed better resistance to 2,6-DCP impact, and the concentrations of effluent NO2- and NO3- were below 2.0 mg/L. At the same time, the addition of nZVI enabled the denitrification system to quickly adapt to the toxic environment of 2,6-DCP within 15 days, and the degradation efficiency of 2,6-DCP reached 99.9%. The released SMP reduced after nZVI coupled with denitrification sludge in 2,6-DCP environment, which could improve the effluent water quality. Nuclear magnetic resonance spectroscopy showed that the addition of nZVI would change the structure of EPS in denitrification sludge. After 90 days of operation, the dominant bacteria in the denitrifying sludge have undergone great changes. Moreover, Thauera was responsible as the dominant bacteria for degrading 2,6-DCP in the denitrification system. The increased in the proportion of functional bacteria with nitrate_reduction, nitrogen_respiration, nitrate_respiration and nitrite_respiration in the presence of NZVI further reveals the mechanism of enhanced denitrification.
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Affiliation(s)
- Mingrun Li
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China; School of Resources and Environment, University of Jinan, Jinan, 250022, PR China
| | - Dong Wei
- School of Resources and Environment, University of Jinan, Jinan, 250022, PR China; Anhui Guozhen Environmental Protection Technology Joint Stock Co., Ltd, Hefei, 230088, PR China.
| | - Zhaoran Zhang
- Jinan Environmental Research Academy, Jinan, 250102, PR China
| | - Dawei Fan
- School of Resources and Environment, University of Jinan, Jinan, 250022, PR China
| | - Bin Du
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China
| | - Huiping Zeng
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China
| | - Dong Li
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China.
| | - Jie Zhang
- Key Laboratory of Water Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100123, China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, PR China
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Calabrese F, Stryhanyuk H, Moraru C, Schlömann M, Wick LY, Richnow HH, Musat F, Musat N. Metabolic history and metabolic fitness as drivers of anabolic heterogeneity in isogenic microbial populations. Environ Microbiol 2021; 23:6764-6776. [PMID: 34472201 DOI: 10.1111/1462-2920.15756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 08/30/2021] [Accepted: 08/30/2021] [Indexed: 11/26/2022]
Abstract
Microbial populations often display different degrees of heterogeneity in their substrate assimilation, that is, anabolic heterogeneity. It has been shown that nutrient limitations are a relevant trigger for this behaviour. Here we explore the dynamics of anabolic heterogeneity under nutrient replete conditions. We applied time-resolved stable isotope probing and nanoscale secondary ion mass spectrometry to quantify substrate assimilation by individual cells of Pseudomonas putida, P. stutzeri and Thauera aromatica. Acetate and benzoate at different concentrations were used as substrates. Anabolic heterogeneity was quantified by the cumulative differentiation tendency index. We observed two major, opposing trends of anabolic heterogeneity over time. Most often, microbial populations started as highly heterogeneous, with heterogeneity decreasing by various degrees over time. The second, less frequently observed trend, saw microbial populations starting at low or very low heterogeneity, and remaining largely stable over time. We explain these trends as an interplay of metabolic history (e.g. former growth substrate or other nutrient limitations) and metabolic fitness (i.e. the fine-tuning of metabolic pathways to process a defined growth substrate). Our results offer a new viewpoint on the intra-population functional diversification often encountered in the environment, and suggests that some microbial populations may be intrinsically heterogeneous.
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Affiliation(s)
- Federica Calabrese
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Hryhoriy Stryhanyuk
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Cristina Moraru
- Institute for Chemistry and Biology of Marine Environment, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Michael Schlömann
- Department of Environmental Microbiology, Institute of Biosciences, TU-Bergakademie Freiberg, Germany
| | - Lukas Y Wick
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Hans H Richnow
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Florin Musat
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Niculina Musat
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
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7
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Philippi M, Kitzinger K, Berg JS, Tschitschko B, Kidane AT, Littmann S, Marchant HK, Storelli N, Winkel LHE, Schubert CJ, Mohr W, Kuypers MMM. Purple sulfur bacteria fix N 2 via molybdenum-nitrogenase in a low molybdenum Proterozoic ocean analogue. Nat Commun 2021; 12:4774. [PMID: 34362886 PMCID: PMC8346585 DOI: 10.1038/s41467-021-25000-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 07/15/2021] [Indexed: 01/04/2023] Open
Abstract
Biological N2 fixation was key to the expansion of life on early Earth. The N2-fixing microorganisms and the nitrogenase type used in the Proterozoic are unknown, although it has been proposed that the canonical molybdenum-nitrogenase was not used due to low molybdenum availability. We investigate N2 fixation in Lake Cadagno, an analogue system to the sulfidic Proterozoic continental margins, using a combination of biogeochemical, molecular and single cell techniques. In Lake Cadagno, purple sulfur bacteria (PSB) are responsible for high N2 fixation rates, to our knowledge providing the first direct evidence for PSB in situ N2 fixation. Surprisingly, no alternative nitrogenases are detectable, and N2 fixation is exclusively catalyzed by molybdenum-nitrogenase. Our results show that molybdenum-nitrogenase is functional at low molybdenum conditions in situ and that in contrast to previous beliefs, PSB may have driven N2 fixation in the Proterozoic ocean.
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Affiliation(s)
- Miriam Philippi
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Katharina Kitzinger
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany.
| | - Jasmine S Berg
- Department of Environmental Systems Science, ETH-Zurich, Zurich, Switzerland
| | - Bernhard Tschitschko
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Abiel T Kidane
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Sten Littmann
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Hannah K Marchant
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Nicola Storelli
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
| | - Lenny H E Winkel
- Department of Environmental Systems Science, ETH-Zurich, Zurich, Switzerland.,Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Carsten J Schubert
- Department of Environmental Systems Science, ETH-Zurich, Zurich, Switzerland.,Eawag, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
| | - Wiebke Mohr
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Marcel M M Kuypers
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
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Lambrecht N, Stevenson Z, Sheik CS, Pronschinske MA, Tong H, Swanner ED. " Candidatus Chlorobium masyuteum," a Novel Photoferrotrophic Green Sulfur Bacterium Enriched From a Ferruginous Meromictic Lake. Front Microbiol 2021; 12:695260. [PMID: 34305861 PMCID: PMC8302410 DOI: 10.3389/fmicb.2021.695260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 06/07/2021] [Indexed: 11/13/2022] Open
Abstract
Anoxygenic phototrophic bacteria can be important primary producers in some meromictic lakes. Green sulfur bacteria (GSB) have been detected in ferruginous lakes, with some evidence that they are photosynthesizing using Fe(II) as an electron donor (i.e., photoferrotrophy). However, some photoferrotrophic GSB can also utilize reduced sulfur compounds, complicating the interpretation of Fe-dependent photosynthetic primary productivity. An enrichment (BLA1) from meromictic ferruginous Brownie Lake, Minnesota, United States, contains an Fe(II)-oxidizing GSB and a metabolically flexible putative Fe(III)-reducing anaerobe. "Candidatus Chlorobium masyuteum" grows photoautotrophically with Fe(II) and possesses the putative Fe(II) oxidase-encoding cyc2 gene also known from oxygen-dependent Fe(II)-oxidizing bacteria. It lacks genes for oxidation of reduced sulfur compounds. Its genome encodes for hydrogenases and a reverse TCA cycle that may allow it to utilize H2 and acetate as electron donors, an inference supported by the abundance of this organism when the enrichment was supplied by these substrates and light. The anaerobe "Candidatus Pseudopelobacter ferreus" is in low abundance (∼1%) in BLA1 and is a putative Fe(III)-reducing bacterium from the Geobacterales ord. nov. While "Ca. C. masyuteum" is closely related to the photoferrotrophs C. ferroooxidans strain KoFox and C. phaeoferrooxidans strain KB01, it is unique at the genomic level. The main light-harvesting molecule was identified as bacteriochlorophyll c with accessory carotenoids of the chlorobactene series. BLA1 optimally oxidizes Fe(II) at a pH of 6.8, and the rate of Fe(II) oxidation was 0.63 ± 0.069 mmol day-1, comparable to other photoferrotrophic GSB cultures or enrichments. Investigation of BLA1 expands the genetic basis for phototrophic Fe(II) oxidation by GSB and highlights the role these organisms may play in Fe(II) oxidation and carbon cycling in ferruginous lakes.
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Affiliation(s)
- Nicholas Lambrecht
- Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, United States
| | - Zackry Stevenson
- Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, United States
| | - Cody S. Sheik
- Department of Biology, University of Minnesota Duluth, Duluth, MN, United States
- Large Lakes Observatory, University of Minnesota Duluth, Duluth, MN, United States
| | - Matthew A. Pronschinske
- Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, United States
| | - Hui Tong
- Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, United States
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Institute of Eco-environmental Science and Technology, Guangdong Academy of Sciences, Guangzhou, China
| | - Elizabeth D. Swanner
- Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, United States
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Tian L, Yan Z, Wang C, Xu S, Jiang H. Habitat heterogeneity induces regional differences in sediment nitrogen fixation in eutrophic freshwater lake. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 772:145594. [PMID: 33770866 DOI: 10.1016/j.scitotenv.2021.145594] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/25/2021] [Accepted: 01/29/2021] [Indexed: 06/12/2023]
Abstract
Biological nitrogen fixation (BNF) in sediments is an important source of bioavailable nitrogen in aquatic systems. However, the effect of habitat change caused by eutrophication on nitrogen fixation within sediments is still unclear. In this study, nitrogen fixation rates and diazotroph diversities in sediments with heterogeneous ecological status in one eutrophic lake were investigated by using an isotope tracer method and sequencing of nitrogen-fixing (nif) genes. The results showed that both nitrogenase activity (NA) and nifH abundance in sediments of blooms area were higher than those in vegetation-dominated habitats. Correlation analysis showed that NA was correlated closely to nifH abundance, dissolved sulfide, and iron. The diazotrophic assemblage contained mainly Proteobacterial sequences belonging to Cluster I and III, and the variations of diazotrophic community could be explained by total nitrogen content, total phosphorus content, organic matters, sulfides, ammonium and iron content. Moreover, the co-occurrence network analysis showed the Alphaproteobacteria shaped the major interactions in diazotrophic community, and sediment properties had stronger effect on diazotrophic community in cyanobacteria-dominated habitat. This study revealed that habitat heterogeneity in eutrophic lakes shaped different succession of BNF in sediments and cyanobacterial blooms significantly improved the nitrogen-fixing activity in sediments, which broadened our understanding of nitrogen cycle and nutrient management in eutrophic freshwater lakes.
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Affiliation(s)
- Linqi Tian
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zaisheng Yan
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Changhui Wang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Shengqi Xu
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Helong Jiang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
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10
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Anoxic chlorophyll maximum enhances local organic matter remineralization and nitrogen loss in Lake Tanganyika. Nat Commun 2021; 12:830. [PMID: 33547297 PMCID: PMC7864930 DOI: 10.1038/s41467-021-21115-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 01/08/2021] [Indexed: 01/12/2023] Open
Abstract
In marine and freshwater oxygen-deficient zones, the remineralization of sinking organic matter from the photic zone is central to driving nitrogen loss. Deep blooms of photosynthetic bacteria, which form the suboxic/anoxic chlorophyll maximum (ACM), widespread in aquatic ecosystems, may also contribute to the local input of organic matter. Yet, the influence of the ACM on nitrogen and carbon cycling remains poorly understood. Using a suite of stable isotope tracer experiments, we examined the transformation of nitrogen and carbon under an ACM (comprising of Chlorobiaceae and Synechococcales) and a non-ACM scenario in the anoxic zone of Lake Tanganyika. We find that the ACM hosts a tight coupling of photo/litho-autotrophic and heterotrophic processes. In particular, the ACM was a hotspot of organic matter remineralization that controlled an important supply of ammonium driving a nitrification-anammox coupling, and thereby played a key role in regulating nitrogen loss in the oxygen-deficient zone. Enigmatic blooms of phytoplankton in aquatic oxygen-deficient zones could exacerbate depletion of nitrogen. Here the authors perform stable isotope experiments on the oxygen-deficient waters of Lake Tanganyika in Africa, finding that blooms drive down fixed nitrogen and could expand as a result of climate change.
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11
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Fernandez L, Peura S, Eiler A, Linz AM, McMahon KD, Bertilsson S. Diazotroph Genomes and Their Seasonal Dynamics in a Stratified Humic Bog Lake. Front Microbiol 2020; 11:1500. [PMID: 32714313 PMCID: PMC7341956 DOI: 10.3389/fmicb.2020.01500] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 06/09/2020] [Indexed: 12/28/2022] Open
Abstract
Aquatic N-fixation is generally associated with the growth and mass development of Cyanobacteria in nitrogen-deprived photic zones. However, sequenced genomes and environmental surveys suggest active aquatic N-fixation also by many non-cyanobacterial groups. Here, we revealed the seasonal variation and genomic diversity of potential N-fixers in a humic bog lake using metagenomic data and nif gene clusters analysis. Groups with diazotrophic operons were functionally divergent and included Cholorobi, Geobacter, Desulfobacterales, Methylococcales, and Acidobacteria. In addition to nifH (a gene that encodes the dinitrogenase reductase component of the molybdenum nitrogenase), we also identified sequences corresponding to vanadium and iron-only nitrogenase genes. Within the Chlorobi population, the nitrogenase (nifH) cluster was included in a well-structured retrotransposon. Furthermore, the presence of light-harvesting photosynthesis genes implies that anoxygenic photosynthesis may fuel nitrogen fixation under the prevailing low-irradiance conditions. The presence of rnf genes (related to the expression of H+/Na+-translocating ferredoxin: NAD+ oxidoreductase) in Methylococcales and Desulfobacterales suggests that other energy-generating processes may drive the costly N-fixation in the absence of photosynthesis. The highly reducing environment of the anoxic bottom layer of Trout Bog Lake may thus also provide a suitable niche for active N-fixers and primary producers. While future studies on the activity of these potential N-fixers are needed to clarify their role in freshwater nitrogen cycling, the metagenomic data presented here enabled an initial characterization of previously overlooked diazotrophs in freshwater biomes.
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Affiliation(s)
- Leyden Fernandez
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Sari Peura
- Department of Forest Mycology and Plant Pathology, Science for Life Laboratory, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Alexander Eiler
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
- Centre for Biogeochemistry in the Anthropocene, Department of Biosciences, Section for Aquatic Biology and Toxicology, University of Oslo, Oslo, Norway
| | - Alexandra M. Linz
- Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin–Madison, Madison, WI, United States
| | - Katherine D. McMahon
- Department of Bacteriology, University of Wisconsin–Madison, Madison, WI, United States
- Department of Civil and Environmental Engineering, University of Wisconsin–Madison, Madison, WI, United States
| | - Stefan Bertilsson
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
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12
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Haas S, Desai DK, LaRoche J, Pawlowicz R, Wallace DWR. Geomicrobiology of the carbon, nitrogen and sulphur cycles in Powell Lake: a permanently stratified water column containing ancient seawater. Environ Microbiol 2019; 21:3927-3952. [PMID: 31314947 DOI: 10.1111/1462-2920.14743] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 07/12/2019] [Accepted: 07/13/2019] [Indexed: 11/30/2022]
Abstract
We present the first geomicrobiological characterization of the meromictic water column of Powell Lake (British Columbia, Canada), a former fjord, which has been stably stratified since the last glacial period. Its deepest layers (300-350 m) retain isolated, relict seawater from that period. Fine-scale vertical profiling of the water chemistry and microbial communities allowed subdivision of the water column into distinct geomicrobiological zones. These zones were further characterized by phylogenetic and functional marker genes from amplicon and shotgun metagenome sequencing. Binning of metagenomic reads allowed the linkage of function to specific taxonomic groups. Statistical analyses (analysis of similarities, Bray-Curtis similarity) confirmed that the microbial community structure followed closely the geochemical zonation. Yet, our characterization of the genetic potential relevant to carbon, nitrogen and sulphur cycling of each zone revealed unexpected features, including potential for facultative anaerobic methylotrophy, nitrogen fixation despite high ammonium concentrations and potential micro-aerobic nitrifiers within the chemocline. At the oxic-suboxic interface, facultative anaerobic potential was found in the widespread freshwater lineage acI (Actinobacteria), suggesting intriguing ecophysiological similarities to the marine SAR11. Evolutionary divergent lineages among diverse phyla were identified in the ancient seawater zone and may indicate novel adaptations to this unusual environment.
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Affiliation(s)
- Sebastian Haas
- Department of Oceanography, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia, Canada
| | - Dhwani K Desai
- Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia, Canada
| | - Julie LaRoche
- Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia, Canada
| | - Rich Pawlowicz
- Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia, Canada
| | - Douglas W R Wallace
- Department of Oceanography, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia, Canada
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13
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Manzella M, Geiss R, Hall EK. Evaluating the stoichiometric trait distributions of cultured bacterial populations and uncultured microbial communities. Environ Microbiol 2019; 21:3613-3626. [PMID: 31090973 DOI: 10.1111/1462-2920.14684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 10/26/2022]
Abstract
We measured the stoichiometric trait distribution of cultured freshwater bacterial populations under different resource conditions and compared them to natural microbial communities sampled from three lakes. Trait distributions showed population differences among growth phases and community differences among lakes that would have been masked by only reporting the mean biomass value. The stoichiometric trait distribution of the environmental isolates changed with P availability, growth phase and genotype, with P availability having the strongest effect. The distribution of biomass ratios within each isolate growth experiment were the most constrained during the stages of rapid growth and commonly had unimodal distributions. In contrast to the population distributions, the distribution of N:P and C:P for a similar number of cells from each of the lake communities had narrower stoichiometric distributions and more commonly exhibited multiple modes. © 2019 Society for Applied Microbiology and John Wiley & Sons Ltd.
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Affiliation(s)
- Michael Manzella
- Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO, 80523, USA.,Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | - Roy Geiss
- Central Instrument Facility, Department of Chemistry, Colorado State University, Fort Collins, CO, 80523, USA
| | - Ed K Hall
- Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO, 80523, USA.,Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80523, USA
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14
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Mauerhofer LM, Pappenreiter P, Paulik C, Seifert AH, Bernacchi S, Rittmann SKMR. Methods for quantification of growth and productivity in anaerobic microbiology and biotechnology. Folia Microbiol (Praha) 2019; 64:321-360. [PMID: 30446943 PMCID: PMC6529396 DOI: 10.1007/s12223-018-0658-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/12/2018] [Indexed: 12/17/2022]
Abstract
Anaerobic microorganisms (anaerobes) possess a fascinating metabolic versatility. This characteristic makes anaerobes interesting candidates for physiological studies and utilizable as microbial cell factories. To investigate the physiological characteristics of an anaerobic microbial population, yield, productivity, specific growth rate, biomass production, substrate uptake, and product formation are regarded as essential variables. The determination of those variables in distinct cultivation systems may be achieved by using different techniques for sampling, measuring of growth, substrate uptake, and product formation kinetics. In this review, a comprehensive overview of methods is presented, and the applicability is discussed in the frame of anaerobic microbiology and biotechnology.
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Affiliation(s)
- Lisa-Maria Mauerhofer
- Archaea Physiology & Biotechnology Group, Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, Althanstraße 14, 1090, Wien, Austria
| | - Patricia Pappenreiter
- Institute for Chemical Technology of Organic Materials, Johannes Kepler University Linz, Linz, Austria
| | - Christian Paulik
- Institute for Chemical Technology of Organic Materials, Johannes Kepler University Linz, Linz, Austria
| | | | | | - Simon K-M R Rittmann
- Archaea Physiology & Biotechnology Group, Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, Althanstraße 14, 1090, Wien, Austria.
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15
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Luedin SM, Storelli N, Danza F, Roman S, Wittwer M, Pothier JF, Tonolla M. Mixotrophic Growth Under Micro-Oxic Conditions in the Purple Sulfur Bacterium " Thiodictyon syntrophicum". Front Microbiol 2019; 10:384. [PMID: 30891015 PMCID: PMC6413534 DOI: 10.3389/fmicb.2019.00384] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/13/2019] [Indexed: 12/23/2022] Open
Abstract
The microbial ecosystem of the meromictic Lake Cadagno (Ticino, Swiss Alps) has been studied intensively in order to understand structure and functioning of the anoxygenic phototrophic sulfur bacteria community living in the chemocline. It has been found that the purple sulfur bacterium "Thiodictyon syntrophicum" strain Cad16T, belonging to the Chromatiaceae, fixes around 26% of all bulk inorganic carbon in the chemocline, both during day and night. With this study, we elucidated for the first time the mode of carbon fixation of str. Cad16T under micro-oxic conditions with a combination of long-term monitoring of key physicochemical parameters with CTD, 14C-incorporation experiments and quantitative proteomics using in-situ dialysis bag incubations of str. Cad16T cultures. Regular vertical CTD profiling during the study period in summer 2017 revealed that the chemocline sank from 12 to 14 m which was accompanied by a bloom of cyanobacteria and the subsequent oxygenation of the deeper water column. Sampling was performed both day and night. CO2 assimilation rates were higher during the light period compared to those in the dark, both in the chemocline population and in the incubated cultures. The relative change in the proteome between day and night (663 quantified proteins) comprised only 1% of all proteins encoded in str. Cad16T. Oxidative respiration pathways were upregulated at light, whereas stress-related mechanisms prevailed during the night. These results indicate that low light availability and the co-occurring oxygenation of the chemocline induced mixotrophic growth in str. Cad16T. Our study thereby helps to further understand the consequences micro-oxic conditions for phototrophic sulfur oxidizing bacteria. The complete proteome data have been deposited to the ProteomeXchange database with identifier PXD010641.
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Affiliation(s)
- Samuel M. Luedin
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
- Spiez Laboratory, Biology Division, Federal Office for Civil Protection, Spiez, Switzerland
| | - Nicola Storelli
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
| | - Francesco Danza
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
| | - Samuele Roman
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
- Alpine Biology Center Foundation, Bellinzona, Switzerland
| | - Matthias Wittwer
- Spiez Laboratory, Biology Division, Federal Office for Civil Protection, Spiez, Switzerland
| | - Joël F. Pothier
- Environmental Genomics and System Biology Research Group, Institute of Natural Resource Sciences, Zurich University of Applied Sciences (ZHAW), Wädenswil, Switzerland
| | - Mauro Tonolla
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
- Alpine Biology Center Foundation, Bellinzona, Switzerland
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16
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Berg JS, Pjevac P, Sommer T, Buckner CRT, Philippi M, Hach PF, Liebeke M, Holtappels M, Danza F, Tonolla M, Sengupta A, Schubert CJ, Milucka J, Kuypers MMM. Dark aerobic sulfide oxidation by anoxygenic phototrophs in anoxic waters. Environ Microbiol 2019; 21:1611-1626. [PMID: 30689286 DOI: 10.1111/1462-2920.14543] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 12/25/2022]
Abstract
Anoxygenic phototrophic sulfide oxidation by green and purple sulfur bacteria (PSB) plays a key role in sulfide removal from anoxic shallow sediments and stratified waters. Although some PSB can also oxidize sulfide with nitrate and oxygen, little is known about the prevalence of this chemolithotrophic lifestyle in the environment. In this study, we investigated the role of these phototrophs in light-independent sulfide removal in the chemocline of Lake Cadagno. Our temporally resolved, high-resolution chemical profiles indicated that dark sulfide oxidation was coupled to high oxygen consumption rates of ~9 μM O2 ·h-1 . Single-cell analyses of lake water incubated with 13 CO2 in the dark revealed that Chromatium okenii was to a large extent responsible for aerobic sulfide oxidation and it accounted for up to 40% of total dark carbon fixation. The genome of Chr. okenii reconstructed from the Lake Cadagno metagenome confirms its capacity for microaerophilic growth and provides further insights into its metabolic capabilities. Moreover, our genomic and single-cell data indicated that other PSB grow microaerobically in these apparently anoxic waters. Altogether, our observations suggest that aerobic respiration may not only play an underappreciated role in anoxic environments but also that organisms typically considered strict anaerobes may be involved.
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Affiliation(s)
- Jasmine S Berg
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany.,Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology Zurich, 8092, Zurich, Switzerland
| | - Petra Pjevac
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, 1090, Vienna, Austria
| | - Tobias Sommer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
| | - Caroline R T Buckner
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany
| | - Miriam Philippi
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany
| | - Philipp F Hach
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany
| | - Manuel Liebeke
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany
| | - Moritz Holtappels
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Alten Hafen 26, 27568, Bremerhaven, Germany
| | - Francesco Danza
- Laboratory of Applied Microbiology (LMA), Department for Environmental Constructions and Design (DACD), University of Applied Sciences and Arts of Southern Switzerland (SUPSI), via Mirasole 22a, 6500, Bellinzona, Switzerland.,Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Mauro Tonolla
- Laboratory of Applied Microbiology (LMA), Department for Environmental Constructions and Design (DACD), University of Applied Sciences and Arts of Southern Switzerland (SUPSI), via Mirasole 22a, 6500, Bellinzona, Switzerland.,Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Anupam Sengupta
- Physics and Materials Science Research Unit, University of Luxembourg, 162 A, Avenue de la Faencerie, L-1511, Luxembourg City, Luxembourg
| | - Carsten J Schubert
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
| | - Jana Milucka
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany
| | - Marcel M M Kuypers
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany
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17
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Luedin SM, Liechti N, Cox RP, Danza F, Frigaard NU, Posth NR, Pothier JF, Roman S, Storelli N, Wittwer M, Tonolla M. Draft Genome Sequence of Chromatium okenii Isolated from the Stratified Alpine Lake Cadagno. Sci Rep 2019; 9:1936. [PMID: 30760771 PMCID: PMC6374484 DOI: 10.1038/s41598-018-38202-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 12/21/2018] [Indexed: 01/07/2023] Open
Abstract
Blooms of purple sulfur bacteria (PSB) are important drivers of the global sulfur cycling oxidizing reduced sulfur in intertidal flats and stagnant water bodies. Since the discovery of PSB Chromatium okenii in 1838, it has been found that this species is characteristic of for stratified, sulfidic environments worldwide and its autotrophic metabolism has been studied in depth since. We describe here the first high-quality draft genome of a large-celled, phototrophic, γ-proteobacteria of the genus Chromatium isolated from the stratified alpine Lake Cadagno, C. okenii strain LaCa. Long read technology was used to assemble the 3.78 Mb genome that encodes 3,016 protein-coding genes and 67 RNA genes. Our findings are discussed from an ecological perspective related to Lake Cadagno. Moreover, findings of previous studies on the phototrophic and the proposed chemoautotrophic metabolism of C. okenii were confirmed on a genomic level. We additionally compared the C. okenii genome with other genomes of sequenced, phototrophic sulfur bacteria from the same environment. We found that biological functions involved in chemotaxis, movement and S-layer-proteins were enriched in strain LaCa. We describe these features as possible adaptions of strain LaCa to rapidly changing environmental conditions within the chemocline and the protection against phage infection during blooms. The high quality draft genome of C. okenii strain LaCa thereby provides a basis for future functional research on bioconvection and phage infection dynamics of blooming PSB.
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Affiliation(s)
- Samuel M Luedin
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland.
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland.
- Biology Division, Spiez Laboratory, Federal Office for Civil Protection, Spiez, Switzerland.
| | - Nicole Liechti
- Biology Division, Spiez Laboratory, Federal Office for Civil Protection, Spiez, Switzerland
- Interfaculty Bioinformatics Unit, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Raymond P Cox
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Francesco Danza
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
| | | | - Nicole R Posth
- Department of Biology, University of Southern Denmark, Odense, Denmark
- Department of Geosciences and Natural Resource Management (IGN), University of Copenhagen, Copenhagen, Denmark
| | - Joël F Pothier
- Environmental Genomics and System Biology Research Group, Zurich University of Applied Sciences (ZHAW), Wädenswil, Switzerland
| | - Samuele Roman
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
- Alpine Biology Center Foundation, Bellinzona, Switzerland
| | - Nicola Storelli
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
| | - Matthias Wittwer
- Biology Division, Spiez Laboratory, Federal Office for Civil Protection, Spiez, Switzerland
| | - Mauro Tonolla
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland.
- Laboratory of Applied Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland.
- Alpine Biology Center Foundation, Bellinzona, Switzerland.
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18
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Li S, Peng C, Cheng T, Wang C, Guo L, Li D. Nitrogen-cycling microbial community functional potential and enzyme activities in cultured biofilms with response to inorganic nitrogen availability. J Environ Sci (China) 2019; 76:89-99. [PMID: 30528038 DOI: 10.1016/j.jes.2018.03.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 03/21/2018] [Accepted: 03/21/2018] [Indexed: 05/03/2023]
Abstract
Biofilms mediate crucial biochemical processes in aquatic ecosystems. It was hypothesized that eutrophication may promote the growth of biofilms, resulting in larger numbers of functional genes. However, the metabolic activity and the roles of biofilms in N cycling will be affected by ambient inorganic nitrogen availability, not by the abundance of functional genes. Biofilms were cultured either with replete inorganic nitrogen (N-rep) or without exogenous inorganic nitrogen supply (N-def) in a flow incubator, and the N-cycling gene abundances (nifH, N2 fixation; amoA, ammonia oxidation, archaea and bacteria; nirS and nirK, denitrification) and enzyme activities (nitrogenase and nitrate reductase) were analyzed. The results showed that, comparing the N-def and N-rep biofilms, the former contained lower nifH gene abundance, but higher nitrogenase activity (NA), while the latter contained higher nifH gene abundance, but lower NA. Different patterns of NA diel variations corresponded to the dynamic microbial community composition and different stages of biofilm colonization. Ammonia oxidizing bacteria (AOB), detected only in N-def biofilms, were responsible for nitrification in biofilms. N-rep biofilms contained high nirS and nirK gene abundance and high denitrification enzyme activity, but N-def biofilms contained significantly lower denitrification gene abundance and activity. In general, the strong N2 fixation in N-def biofilms and strong denitrification in N-rep biofilms assured the balance of aquatic ecosystems. The results suggested that evaluation of the functional processes of N cycling should not only focus on genetic potential, but also on the physiological activity of biofilms.
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Affiliation(s)
- Shuangshuang Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Hebei Engineering Research Center for Water Pollution Control and Water Ecological Remediation, College of Energy and Environmental Engineering, Hebei University of Engineering, Handan 056038, China
| | - Chengrong Peng
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Taisheng Cheng
- National University of Tainan, Department of Biological Sciences and Technology, Tainan 70005, China
| | - Chun Wang
- Environmental Simulation and Pollution Control State Key Joint Laboratory and State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 10084, China
| | - Liangliang Guo
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Dunhai Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
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19
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Wu YT, Yang CY, Chiang PW, Tseng CH, Chiu HH, Saeed I, Baatar B, Rogozin D, Halgamuge S, Degermendzhi A, Tang SL. Comprehensive Insights Into Composition, Metabolic Potentials, and Interactions Among Archaeal, Bacterial, and Viral Assemblages in Meromictic Lake Shunet in Siberia. Front Microbiol 2018; 9:1763. [PMID: 30177915 PMCID: PMC6109700 DOI: 10.3389/fmicb.2018.01763] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 07/16/2018] [Indexed: 11/20/2022] Open
Abstract
Microorganisms are critical to maintaining stratified biogeochemical characteristics in meromictic lakes; however, their community composition and potential roles in nutrient cycling are not thoroughly described. Both metagenomics and metaviromics were used to determine the composition and capacity of archaea, bacteria, and viruses along the water column in the landlocked meromictic Lake Shunet in Siberia. Deep sequencing of 265 Gb and high-quality assembly revealed a near-complete genome corresponding to Nonlabens sp. sh3vir. in a viral sample and 38 bacterial bins (0.2–5.3 Mb each). The mixolimnion (3.0 m) had the most diverse archaeal, bacterial, and viral communities, followed by the monimolimnion (5.5 m) and chemocline (5.0 m). The bacterial and archaeal communities were dominated by Thiocapsa and Methanococcoides, respectively, whereas the viral community was dominated by Siphoviridae. The archaeal and bacterial assemblages and the associated energy metabolism were significantly related to the various depths, in accordance with the stratification of physicochemical parameters. Reconstructed elemental nutrient cycles of the three layers were interconnected, including co-occurrence of denitrification and nitrogen fixation in each layer and involved unique processes due to specific biogeochemical properties at the respective depths. According to the gene annotation, several pre-dominant yet unknown and uncultured bacteria also play potentially important roles in nutrient cycling. Reciprocal BLAST analysis revealed that the viruses were specific to the host archaea and bacteria in the mixolimnion. This study provides insights into the bacterial, archaeal, and viral assemblages and the corresponding capacity potentials in Lake Shunet, one of the three meromictic lakes in central Asia. Lake Shunet was determined to harbor specific and diverse viral, bacterial, and archaeal communities that intimately interacted, revealing patterns shaped by indigenous physicochemical parameters.
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Affiliation(s)
- Yu-Ting Wu
- Department of Forestry, National Pingtung University of Science and Technology, Neipu, Taiwan.,Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Cheng-Yu Yang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Pei-Wen Chiang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Ching-Hung Tseng
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.,Germark Biotechnology Co., Ltd., Taichung, Taiwan
| | - Hsiu-Hui Chiu
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Isaam Saeed
- Optimisation and Pattern Recognition Group, Melbourne School of Engineering, The University of Melbourne, Melbourne, VIC, Australia
| | - Bayanmunkh Baatar
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.,Molecular and Biological Agricultural Sciences, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan.,Department of Life Sciences, Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan
| | - Denis Rogozin
- Institute of Biophysics, Siberian Division of Russian Academy of Sciences, Krasnoyarsk, Russia.,Siberian Federal University, Krasnoyarsk, Russia
| | - Saman Halgamuge
- Optimisation and Pattern Recognition Group, Melbourne School of Engineering, The University of Melbourne, Melbourne, VIC, Australia
| | - Andrei Degermendzhi
- Institute of Biophysics, Siberian Division of Russian Academy of Sciences, Krasnoyarsk, Russia
| | - Sen-Lin Tang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.,Molecular and Biological Agricultural Sciences, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan.,Department of Life Sciences, Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan
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20
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Zimmermann M, Escrig S, Lavik G, Kuypers MMM, Meibom A, Ackermann M, Schreiber F. Substrate and electron donor limitation induce phenotypic heterogeneity in different metabolic activities in a green sulphur bacterium. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:179-183. [PMID: 29393582 DOI: 10.1111/1758-2229.12616] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 10/13/2017] [Accepted: 01/14/2018] [Indexed: 06/07/2023]
Abstract
Populations of genetically identical cells can display marked variation in phenotypic traits; such variation is termed phenotypic heterogeneity. Here, we investigate the effect of substrate and electron donor limitation on phenotypic heterogeneity in N2 and CO2 fixation in the green sulphur bacterium Chlorobium phaeobacteroides. We grew populations in chemostats and batch cultures and used stable isotope labelling combined with nanometer-scale secondary ion mass spectrometry (NanoSIMS) to quantify phenotypic heterogeneity. Experiments in H2 S (i.e. electron donor) limited chemostats show that varying levels of NH4+ limitation induce heterogeneity in N2 fixation. Comparison of phenotypic heterogeneity between chemostats and batch (unlimited for H2 S) populations indicates that electron donor limitation drives heterogeneity in N2 and CO2 fixation. Our results demonstrate that phenotypic heterogeneity in a certain metabolic activity can be driven by different modes of limitation and that heterogeneity can emerge in different metabolic processes upon the same mode of limitation. In conclusion, our data suggest that limitation is a general driver of phenotypic heterogeneity in microbial populations.
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Affiliation(s)
- M Zimmermann
- Department of Environmental Systems Science, ETH Zurich - Swiss Federal Institute of Technology, Zurich, Switzerland
- Department of Environmental Microbiology, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - S Escrig
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - G Lavik
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - M M M Kuypers
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - A Meibom
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | - M Ackermann
- Department of Environmental Systems Science, ETH Zurich - Swiss Federal Institute of Technology, Zurich, Switzerland
- Department of Environmental Microbiology, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - F Schreiber
- Department of Environmental Systems Science, ETH Zurich - Swiss Federal Institute of Technology, Zurich, Switzerland
- Department of Environmental Microbiology, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Division Biodeterioration and Reference Organisms, Department of Materials and Environment, Federal Institute for Materials Research and Testing (BAM), Berlin, Germany
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21
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Castellano-Hinojosa A, Correa-Galeote D, Carrillo P, Bedmar EJ, Medina-Sánchez JM. Denitrification and Biodiversity of Denitrifiers in a High-Mountain Mediterranean Lake. Front Microbiol 2017; 8:1911. [PMID: 29056928 PMCID: PMC5635049 DOI: 10.3389/fmicb.2017.01911] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 09/19/2017] [Indexed: 11/13/2022] Open
Abstract
Wet deposition of reactive nitrogen (Nr) species is considered a main factor contributing to N inputs, of which nitrate ([Formula: see text]) is usually the major component in high-mountain lakes. The microbial group of denitrifiers are largely responsible for reduction of nitrate to molecular dinitrogen (N2) in terrestrial and aquatic ecosystems, but the role of denitrification in removal of contaminant nitrates in high-mountain lakes is not well understood. We have used the oligotrophic, high-altitude La Caldera lake in the Sierra Nevada range (Spain) as a model to study the role of denitrification in nitrate removal. Dissolved inorganic Nr concentration in the water column of la Caldera, mainly nitrate, decreased over the ice-free season which was not associated with growth of microbial plankton or variations in the ultraviolet radiation. Denitrification activity, estimated as nitrous oxide (N2O) production, was measured in the water column and in sediments of the lake, and had maximal values in the month of August. Relative abundance of denitrifying bacteria in sediments was studied by quantitative polymerase chain reaction of the 16S rRNA and the two phylogenetically distinct clades nosZI and nosZII genes encoding nitrous oxide reductases. Diversity of denitrifiers in sediments was assessed using a culture-dependent approach and after the construction of clone libraries employing the nosZI gene as a molecular marker. In addition to genera Polymorphum, Paracoccus, Azospirillum, Pseudomonas, Hyphomicrobium, Thauera, and Methylophaga, which were present in the clone libraries, Arthrobacter, Burkholderia, and Rhizobium were also detected in culture media that were not found in the clone libraries. Analysis of biological activities involved in the C, N, P, and S cycles from sediments revealed that nitrate was not a limiting nutrient in the lake, allowed N2O production and determined denitrifiers' community structure. All these results indicate that denitrification could be a major biochemical process responsible for the N losses that occur in La Caldera lake.
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Affiliation(s)
- Antonio Castellano-Hinojosa
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain.,Instituto Universitario de Investigación del Agua, Universidad de Granada, Granada, Spain
| | - David Correa-Galeote
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Presentación Carrillo
- Instituto Universitario de Investigación del Agua, Universidad de Granada, Granada, Spain.,Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - Eulogio J Bedmar
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Juan M Medina-Sánchez
- Instituto Universitario de Investigación del Agua, Universidad de Granada, Granada, Spain.,Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
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Abstract
Secondary ion mass spectrometry (SIMS) has become an increasingly utilized tool in biologically relevant studies. Of these, high lateral resolution methodologies using the NanoSIMS 50/50L have been especially powerful within many biological fields over the past decade. Here, the authors provide a review of this technology, sample preparation and analysis considerations, examples of recent biological studies, data analyses, and current outlooks. Specifically, the authors offer an overview of SIMS and development of the NanoSIMS. The authors describe the major experimental factors that should be considered prior to NanoSIMS analysis and then provide information on best practices for data analysis and image generation, which includes an in-depth discussion of appropriate colormaps. Additionally, the authors provide an open-source method for data representation that allows simultaneous visualization of secondary electron and ion information within a single image. Finally, the authors present a perspective on the future of this technology and where they think it will have the greatest impact in near future.
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23
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Zadereev ES, Gulati RD, Camacho A. Biological and Ecological Features, Trophic Structure and Energy Flow in Meromictic Lakes. ECOLOGY OF MEROMICTIC LAKES 2017. [DOI: 10.1007/978-3-319-49143-1_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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24
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Berg JS, Michellod D, Pjevac P, Martinez-Perez C, Buckner CRT, Hach PF, Schubert CJ, Milucka J, Kuypers MMM. Intensive cryptic microbial iron cycling in the low iron water column of the meromictic Lake Cadagno. Environ Microbiol 2016; 18:5288-5302. [DOI: 10.1111/1462-2920.13587] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/18/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Jasmine S. Berg
- Max Planck Institute for Marine Microbiology; Bremen 28359 Germany
| | - Dolma Michellod
- Max Planck Institute for Marine Microbiology; Bremen 28359 Germany
| | - Petra Pjevac
- Max Planck Institute for Marine Microbiology; Bremen 28359 Germany
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science; University of Vienna; Vienna Austria
| | | | | | - Philipp F. Hach
- Max Planck Institute for Marine Microbiology; Bremen 28359 Germany
| | - Carsten J. Schubert
- Eawag, Swiss Federal Institute of Aquatic Science and Technology; Kastanienbaum Switzerland
| | - Jana Milucka
- Max Planck Institute for Marine Microbiology; Bremen 28359 Germany
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25
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Ho A, Angel R, Veraart AJ, Daebeler A, Jia Z, Kim SY, Kerckhof FM, Boon N, Bodelier PLE. Biotic Interactions in Microbial Communities as Modulators of Biogeochemical Processes: Methanotrophy as a Model System. Front Microbiol 2016; 7:1285. [PMID: 27602021 PMCID: PMC4993757 DOI: 10.3389/fmicb.2016.01285] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 08/04/2016] [Indexed: 11/13/2022] Open
Abstract
Microbial interaction is an integral component of microbial ecology studies, yet the role, extent, and relevance of microbial interaction in community functioning remains unclear, particularly in the context of global biogeochemical cycles. While many studies have shed light on the physico-chemical cues affecting specific processes, (micro)biotic controls and interactions potentially steering microbial communities leading to altered functioning are less known. Yet, recent accumulating evidence suggests that the concerted actions of a community can be significantly different from the combined effects of individual microorganisms, giving rise to emergent properties. Here, we exemplify the importance of microbial interaction for ecosystem processes by analysis of a reasonably well-understood microbial guild, namely, aerobic methane-oxidizing bacteria (MOB). We reviewed the literature which provided compelling evidence for the relevance of microbial interaction in modulating methane oxidation. Support for microbial associations within methane-fed communities is sought by a re-analysis of literature data derived from stable isotope probing studies of various complex environmental settings. Putative positive interactions between active MOB and other microbes were assessed by a correlation network-based analysis with datasets covering diverse environments where closely interacting members of a consortium can potentially alter the methane oxidation activity. Although, methanotrophy is used as a model system, the fundamentals of our postulations may be applicable to other microbial guilds mediating other biogeochemical processes.
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Affiliation(s)
- Adrian Ho
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands
| | - Roey Angel
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, Research Network Chemistry meets Microbiology, University of Vienna Vienna, Austria
| | - Annelies J Veraart
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands
| | - Anne Daebeler
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, Research Network Chemistry meets Microbiology, University of Vienna Vienna, Austria
| | - Zhongjun Jia
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences Nanjing, China
| | - Sang Yoon Kim
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands
| | - Frederiek-Maarten Kerckhof
- Center for Microbial Ecology and Technology, Faculty of Bioscience Engineering, Ghent University Ghent, Belgium
| | - Nico Boon
- Center for Microbial Ecology and Technology, Faculty of Bioscience Engineering, Ghent University Ghent, Belgium
| | - Paul L E Bodelier
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands
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26
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Phenotypic heterogeneity driven by nutrient limitation promotes growth in fluctuating environments. Nat Microbiol 2016; 1:16055. [PMID: 27572840 DOI: 10.1038/nmicrobiol.2016.55] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/24/2016] [Indexed: 11/09/2022]
Abstract
Most microorganisms live in environments where nutrients are limited and fluctuate over time. Cells respond to nutrient fluctuations by sensing and adapting their physiological state. Recent studies suggest phenotypic heterogeneity(1) in isogenic populations as an alternative strategy in fluctuating environments, where a subpopulation of cells express a function that allows growth under conditions that might arise in the future(2-9). It is unknown how environmental factors such as nutrient limitation shape phenotypic heterogeneity in metabolism and whether this allows cells to respond to nutrient fluctuations. Here, we show that substrate limitation increases phenotypic heterogeneity in metabolism, and this heterogeneity allows cells to cope with substrate fluctuations. We subjected the N2-fixing bacterium Klebsiella oxytoca to different levels of substrate limitation and substrate shifts, and obtained time-resolved single-cell measurements of metabolic activities using nanometre-scale secondary ion mass spectrometry (NanoSIMS). We found that the level of NH4(+) limitation shapes phenotypic heterogeneity in N2 fixation. In turn, the N2 fixation rate of single cells during NH4(+) limitation correlates positively with their growth rate after a shift to NH4(+) depletion, experimentally demonstrating the benefit of heterogeneity. The results indicate that phenotypic heterogeneity is a general solution to two important ecological challenges-nutrient limitation and fluctuations-that many microorganisms face.
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27
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Eichorst SA, Strasser F, Woyke T, Schintlmeister A, Wagner M, Woebken D. Advancements in the application of NanoSIMS and Raman microspectroscopy to investigate the activity of microbial cells in soils. FEMS Microbiol Ecol 2015; 91:fiv106. [PMID: 26324854 PMCID: PMC4629873 DOI: 10.1093/femsec/fiv106] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/04/2015] [Accepted: 08/24/2015] [Indexed: 11/15/2022] Open
Abstract
The combined approach of incubating environmental samples with stable isotope-labeled substrates followed by single-cell analyses through high-resolution secondary ion mass spectrometry (NanoSIMS) or Raman microspectroscopy provides insights into the in situ function of microorganisms. This approach has found limited application in soils presumably due to the dispersal of microbial cells in a large background of particles. We developed a pipeline for the efficient preparation of cell extracts from soils for subsequent single-cell methods by combining cell detachment with separation of cells and soil particles followed by cell concentration. The procedure was evaluated by examining its influence on cell recoveries and microbial community composition across two soils. This approach generated a cell fraction with considerably reduced soil particle load and of sufficient small size to allow single-cell analysis by NanoSIMS, as shown when detecting active N2-fixing and cellulose-responsive microorganisms via (15)N2 and (13)C-UL-cellulose incubations, respectively. The same procedure was also applicable for Raman microspectroscopic analyses of soil microorganisms, assessed via microcosm incubations with a (13)C-labeled carbon source and deuterium oxide (D2O, a general activity marker). The described sample preparation procedure enables single-cell analysis of soil microorganisms using NanoSIMS and Raman microspectroscopy, but should also facilitate single-cell sorting and sequencing.
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Affiliation(s)
- Stephanie A Eichorst
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research network 'Chemistry meets Microbiology', University of Vienna, Vienna 1090 Austria
| | - Florian Strasser
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research network 'Chemistry meets Microbiology', University of Vienna, Vienna 1090 Austria
| | - Tanja Woyke
- DOE Joint Genome Institute, Walnut Creek, CA 94598, USA
| | - Arno Schintlmeister
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research network 'Chemistry meets Microbiology', University of Vienna, Vienna 1090 Austria Large-Instrument Facility for Advanced Isotope Research, University of Vienna, Vienna 1090 Austria
| | - Michael Wagner
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research network 'Chemistry meets Microbiology', University of Vienna, Vienna 1090 Austria Large-Instrument Facility for Advanced Isotope Research, University of Vienna, Vienna 1090 Austria
| | - Dagmar Woebken
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research network 'Chemistry meets Microbiology', University of Vienna, Vienna 1090 Austria
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28
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Genomics and Ecophysiology of Heterotrophic Nitrogen-Fixing Bacteria Isolated from Estuarine Surface Water. mBio 2015; 6:e00929. [PMID: 26152586 PMCID: PMC4495170 DOI: 10.1128/mbio.00929-15] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability to reduce atmospheric nitrogen (N2) to ammonia, known as N2 fixation, is a widely distributed trait among prokaryotes that accounts for an essential input of new N to a multitude of environments. Nitrogenase reductase gene (nifH) composition suggests that putative N2-fixing heterotrophic organisms are widespread in marine bacterioplankton, but their autecology and ecological significance are unknown. Here, we report genomic and ecophysiology data in relation to N2 fixation by three environmentally relevant heterotrophic bacteria isolated from Baltic Sea surface water: Pseudomonas stutzeri strain BAL361 and Raoultella ornithinolytica strain BAL286, which are gammaproteobacteria, and Rhodopseudomonas palustris strain BAL398, an alphaproteobacterium. Genome sequencing revealed that all were metabolically versatile and that the gene clusters encoding the N2 fixation complex varied in length and complexity between isolates. All three isolates could sustain growth by N2 fixation in the absence of reactive N, and this fixation was stimulated by low concentrations of oxygen in all three organisms (≈4 to 40 µmol O2 liter−1). P. stutzeri BAL361 did, however, fix N at up to 165 µmol O2 liter−1, presumably accommodated through aggregate formation. Glucose stimulated N2 fixation in general, and reactive N repressed N2 fixation, except that ammonium (NH4+) stimulated N2 fixation in R. palustris BAL398, indicating the use of nitrogenase as an electron sink. The lack of correlations between nitrogenase reductase gene expression and ethylene (C2H4) production indicated tight posttranscriptional-level control. The N2 fixation rates obtained suggested that, given the right conditions, these heterotrophic diazotrophs could contribute significantly to in situ rates. The biological process of importing atmospheric N2 is of paramount importance in terrestrial and aquatic ecosystems. In the oceans, a diverse array of prokaryotes seemingly carry the genetic capacity to perform this process, but lack of knowledge about their autecology and the factors that constrain their N2 fixation hamper an understanding of their ecological importance in marine waters. The present study documents a high variability of genomic and ecophysiological properties related to N2 fixation in three heterotrophic isolates obtained from estuarine surface waters and shows that these organisms fix N2 under a surprisingly broad range of conditions and at significant rates. The observed intricate regulation of N2 fixation for the isolates indicates that indigenous populations of heterotrophic diazotrophs have discrete strategies to cope with environmental controls of N2 fixation. Hence, community-level generalizations about the regulation of N2 fixation in marine heterotrophic bacterioplankton may be problematic.
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29
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Saarenheimo J, Tiirola MA, Rissanen AJ. Functional gene pyrosequencing reveals core proteobacterial denitrifiers in boreal lakes. Front Microbiol 2015; 6:674. [PMID: 26191058 PMCID: PMC4486872 DOI: 10.3389/fmicb.2015.00674] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 06/19/2015] [Indexed: 11/13/2022] Open
Abstract
Denitrification is an important microbial process in aquatic ecosystems that can reduce the effects of eutrophication. Here, quantification and pyrosequencing of nirS, nirK, and nosZ genes encoding for nitrite and nitrous oxide reductases was performed in sediment samples from four boreal lakes to determine the structure and seasonal stability of denitrifying microbial populations. Sediment quality and nitrate concentrations were linked to the quantity and diversity of denitrification genes, the abundance of denitrifying populations (nirS and nosZ genes) correlated with coupled nitrification-denitrification (Dn), and the denitrification of the overlying water NO3- (Dw) correlated with the nirS/nirK ratio. The number of core nirS, nirK, and nosZ operational taxonomical units (OTUs) was low (6, 7, and 3, respectively), and most of these core OTUs were shared among the lakes. Dominant nirK sequences matched best with those of the order Rhizobiales, which was one of the main bacterial orders present in the sediment microbiomes, whereas the dominant nirS sequences were affiliated with the order Burkholderiales. Over half of the nosZ sequences belonged to a single OTU of the order Burkholderiales, but coupled nitrification–denitrification rate correlated with another dominant nosZ OTU assigned to the order Rhodospirillales. The study indicates that a few core proteobacterial clusters may drive denitrification in boreal lake sediments, as the same Alpha- and Betaproteobacteria denitrifier clusters were present in different lakes and seasons.
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Affiliation(s)
- Jatta Saarenheimo
- Department of Biological and Environmental Science, University of Jyväskylä Jyväskylä, Finland
| | - Marja Annika Tiirola
- Department of Biological and Environmental Science, University of Jyväskylä Jyväskylä, Finland
| | - Antti J Rissanen
- Department of Biological and Environmental Science, University of Jyväskylä Jyväskylä, Finland
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30
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Zimmermann M, Escrig S, Hübschmann T, Kirf MK, Brand A, Inglis RF, Musat N, Müller S, Meibom A, Ackermann M, Schreiber F. Phenotypic heterogeneity in metabolic traits among single cells of a rare bacterial species in its natural environment quantified with a combination of flow cell sorting and NanoSIMS. Front Microbiol 2015; 6:243. [PMID: 25932020 PMCID: PMC4399338 DOI: 10.3389/fmicb.2015.00243] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 03/12/2015] [Indexed: 11/24/2022] Open
Abstract
Populations of genetically identical microorganisms residing in the same environment can display marked variability in their phenotypic traits; this phenomenon is termed phenotypic heterogeneity. The relevance of such heterogeneity in natural habitats is unknown, because phenotypic characterization of a sufficient number of single cells of the same species in complex microbial communities is technically difficult. We report a procedure that allows to measure phenotypic heterogeneity in bacterial populations from natural environments, and use it to analyze N2 and CO2 fixation of single cells of the green sulfur bacterium Chlorobium phaeobacteroides from the meromictic lake Lago di Cadagno. We incubated lake water with 15N2 and 13CO2 under in situ conditions with and without NH4+. Subsequently, we used flow cell sorting with auto-fluorescence gating based on a pure culture isolate to concentrate C. phaeobacteroides from its natural abundance of 0.2% to now 26.5% of total bacteria. C. phaeobacteroides cells were identified using catalyzed-reporter deposition fluorescence in situ hybridization (CARD-FISH) targeting the 16S rRNA in the sorted population with a species-specific probe. In a last step, we used nanometer-scale secondary ion mass spectrometry to measure the incorporation 15N and 13C stable isotopes in more than 252 cells. We found that C. phaeobacteroides fixes N2 in the absence of NH4+, but not in the presence of NH4+ as has previously been suggested. N2 and CO2 fixation were heterogeneous among cells and positively correlated indicating that N2 and CO2 fixation activity interact and positively facilitate each other in individual cells. However, because CARD-FISH identification cannot detect genetic variability among cells of the same species, we cannot exclude genetic variability as a source for phenotypic heterogeneity in this natural population. Our study demonstrates the technical feasibility of measuring phenotypic heterogeneity in a rare bacterial species in its natural habitat, thus opening the door to study the occurrence and relevance of phenotypic heterogeneity in nature.
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Affiliation(s)
- Matthias Zimmermann
- Department of Environmental Systems Sciences, ETH Zurich - Swiss Federal Institute of Technology Zurich, Switzerland ; Molecular Microbial Ecology Group, Department of Environmental Microbiology, Eawag - Swiss Federal Institute of Aquatic Science and Technology Zurich, Switzerland
| | - Stéphane Escrig
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research, Leipzig Germany
| | - Thomas Hübschmann
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research, Leipzig Germany
| | - Mathias K Kirf
- Department of Environmental Systems Sciences, ETH Zurich - Swiss Federal Institute of Technology Zurich, Switzerland ; Department of Surface Waters, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum Switzerland
| | - Andreas Brand
- Department of Environmental Systems Sciences, ETH Zurich - Swiss Federal Institute of Technology Zurich, Switzerland ; Department of Surface Waters, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum Switzerland
| | - R Fredrik Inglis
- Department of Environmental Systems Sciences, ETH Zurich - Swiss Federal Institute of Technology Zurich, Switzerland ; Molecular Microbial Ecology Group, Department of Environmental Microbiology, Eawag - Swiss Federal Institute of Aquatic Science and Technology Zurich, Switzerland
| | - Niculina Musat
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research, Leipzig Germany
| | - Susann Müller
- Department of Environmental Systems Sciences, ETH Zurich - Swiss Federal Institute of Technology Zurich, Switzerland
| | - Anders Meibom
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne Lausanne, Switzerland ; Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, Lausanne Switzerland
| | - Martin Ackermann
- Department of Environmental Systems Sciences, ETH Zurich - Swiss Federal Institute of Technology Zurich, Switzerland ; Molecular Microbial Ecology Group, Department of Environmental Microbiology, Eawag - Swiss Federal Institute of Aquatic Science and Technology Zurich, Switzerland
| | - Frank Schreiber
- Department of Environmental Systems Sciences, ETH Zurich - Swiss Federal Institute of Technology Zurich, Switzerland ; Molecular Microbial Ecology Group, Department of Environmental Microbiology, Eawag - Swiss Federal Institute of Aquatic Science and Technology Zurich, Switzerland
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31
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McCarthy A, Chiang E, Schmidt ML, Denef VJ. RNA preservation agents and nucleic acid extraction method bias perceived bacterial community composition. PLoS One 2015; 10:e0121659. [PMID: 25798612 PMCID: PMC4370824 DOI: 10.1371/journal.pone.0121659] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 02/11/2015] [Indexed: 01/08/2023] Open
Abstract
Bias is a pervasive problem when characterizing microbial communities. An important source is the difference in lysis efficiencies of different populations, which vary depending on the extraction protocol used. To avoid such biases impacting comparisons between gene and transcript abundances in the environment, the use of one protocol that simultaneously extracts both types of nucleic acids from microbial community samples has gained popularity. However, knowledge regarding tradeoffs to combined nucleic acid extraction protocols is limited, particularly regarding yield and biases in the observed community composition. Here, we evaluated a commercially available protocol for simultaneous extraction of DNA and RNA, which we adapted for freshwater microbial community samples that were collected on filters. DNA and RNA yields were comparable to other commonly used, but independent DNA and RNA extraction protocols. RNA protection agents benefited RNA quality, but decreased DNA yields significantly. Choice of extraction protocol influenced the perceived bacterial community composition, with strong method-dependent biases observed for specific phyla such as the Verrucomicrobia. The combined DNA/RNA extraction protocol detected significantly higher levels of Verrucomicrobia than the other protocols, and those higher numbers were confirmed by microscopic analysis. Use of RNA protection agents as well as independent sequencing runs caused a significant shift in community composition as well, albeit smaller than the shift caused by using different extraction protocols. Despite methodological biases, sample origin was the strongest determinant of community composition. However, when the abundance of specific phylogenetic groups is of interest, researchers need to be aware of the biases their methods introduce. This is particularly relevant if different methods are used for DNA and RNA extraction, in addition to using RNA protection agents only for RNA samples.
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Affiliation(s)
- Ann McCarthy
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
| | - Edna Chiang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
| | - Marian L. Schmidt
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
| | - Vincent J. Denef
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
- * E-mail:
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32
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Milucka J, Kirf M, Lu L, Krupke A, Lam P, Littmann S, Kuypers MMM, Schubert CJ. Methane oxidation coupled to oxygenic photosynthesis in anoxic waters. ISME JOURNAL 2015; 9:1991-2002. [PMID: 25679533 DOI: 10.1038/ismej.2015.12] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 12/14/2014] [Accepted: 12/19/2014] [Indexed: 11/09/2022]
Abstract
Freshwater lakes represent large methane sources that, in contrast to the Ocean, significantly contribute to non-anthropogenic methane emissions to the atmosphere. Particularly mixed lakes are major methane emitters, while permanently and seasonally stratified lakes with anoxic bottom waters are often characterized by strongly reduced methane emissions. The causes for this reduced methane flux from anoxic lake waters are not fully understood. Here we identified the microorganisms and processes responsible for the near complete consumption of methane in the anoxic waters of a permanently stratified lake, Lago di Cadagno. Interestingly, known anaerobic methanotrophs could not be detected in these waters. Instead, we found abundant gamma-proteobacterial aerobic methane-oxidizing bacteria active in the anoxic waters. In vitro incubations revealed that, among all the tested potential electron acceptors, only the addition of oxygen enhanced the rates of methane oxidation. An equally pronounced stimulation was also observed when the anoxic water samples were incubated in the light. Our combined results from molecular, biogeochemical and single-cell analyses indicate that methane removal at the anoxic chemocline of Lago di Cadagno is due to true aerobic oxidation of methane fuelled by in situ oxygen production by photosynthetic algae. A similar mechanism could be active in seasonally stratified lakes and marine basins such as the Black Sea, where light penetrates to the anoxic chemocline. Given the widespread occurrence of seasonally stratified anoxic lakes, aerobic methane oxidation coupled to oxygenic photosynthesis might have an important but so far neglected role in methane emissions from lakes.
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Affiliation(s)
- Jana Milucka
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Mathias Kirf
- Department of Surface Waters-Research and Management, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Kastanienbaum, Switzerland
| | - Lu Lu
- 1] Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany [2] State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province, China [3] University of Chinese Academy of Sciences, Beijing, China
| | - Andreas Krupke
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Phyllis Lam
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Sten Littmann
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Marcel M M Kuypers
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Carsten J Schubert
- Department of Surface Waters-Research and Management, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Kastanienbaum, Switzerland
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Woebken D, Burow LC, Behnam F, Mayali X, Schintlmeister A, Fleming ED, Prufert-Bebout L, Singer SW, Cortés AL, Hoehler TM, Pett-Ridge J, Spormann AM, Wagner M, Weber PK, Bebout BM. Revisiting N₂ fixation in Guerrero Negro intertidal microbial mats with a functional single-cell approach. THE ISME JOURNAL 2015; 9:485-96. [PMID: 25303712 PMCID: PMC4303640 DOI: 10.1038/ismej.2014.144] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 06/15/2014] [Accepted: 06/29/2014] [Indexed: 11/09/2022]
Abstract
Photosynthetic microbial mats are complex, stratified ecosystems in which high rates of primary production create a demand for nitrogen, met partially by N₂ fixation. Dinitrogenase reductase (nifH) genes and transcripts from Cyanobacteria and heterotrophic bacteria (for example, Deltaproteobacteria) were detected in these mats, yet their contribution to N2 fixation is poorly understood. We used a combined approach of manipulation experiments with inhibitors, nifH sequencing and single-cell isotope analysis to investigate the active diazotrophic community in intertidal microbial mats at Laguna Ojo de Liebre near Guerrero Negro, Mexico. Acetylene reduction assays with specific metabolic inhibitors suggested that both sulfate reducers and members of the Cyanobacteria contributed to N₂ fixation, whereas (15)N₂ tracer experiments at the bulk level only supported a contribution of Cyanobacteria. Cyanobacterial and nifH Cluster III (including deltaproteobacterial sulfate reducers) sequences dominated the nifH gene pool, whereas the nifH transcript pool was dominated by sequences related to Lyngbya spp. Single-cell isotope analysis of (15)N₂-incubated mat samples via high-resolution secondary ion mass spectrometry (NanoSIMS) revealed that Cyanobacteria were enriched in (15)N, with the highest enrichment being detected in Lyngbya spp. filaments (on average 4.4 at% (15)N), whereas the Deltaproteobacteria (identified by CARD-FISH) were not significantly enriched. We investigated the potential dilution effect from CARD-FISH on the isotopic composition and concluded that the dilution bias was not substantial enough to influence our conclusions. Our combined data provide evidence that members of the Cyanobacteria, especially Lyngbya spp., actively contributed to N₂ fixation in the intertidal mats, whereas support for significant N₂ fixation activity of the targeted deltaproteobacterial sulfate reducers could not be found.
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Affiliation(s)
- Dagmar Woebken
- Departments of Chemical Engineering, and of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, USA
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Luke C Burow
- Departments of Chemical Engineering, and of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, USA
| | - Faris Behnam
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Xavier Mayali
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Arno Schintlmeister
- Large-Instrument Facility for Advanced Isotope Research, University of Vienna, Vienna, Austria
| | - Erich D Fleming
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, USA
| | | | - Steven W Singer
- Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Alejandro López Cortés
- Laboratory of Geomicrobiology and Biotechnology, Northwestern Center for Biological Research (CIBNOR), La Paz, Mexico
| | - Tori M Hoehler
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, USA
| | - Jennifer Pett-Ridge
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Alfred M Spormann
- Departments of Chemical Engineering, and of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
| | - Michael Wagner
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
- Large-Instrument Facility for Advanced Isotope Research, University of Vienna, Vienna, Austria
| | - Peter K Weber
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Brad M Bebout
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, USA
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Vila-Costa M, Bartrons M, Catalan J, Casamayor EO. Nitrogen-cycling genes in epilithic biofilms of oligotrophic high-altitude lakes (central Pyrenees, Spain). MICROBIAL ECOLOGY 2014; 68:60-69. [PMID: 24743884 DOI: 10.1007/s00248-014-0417-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 04/02/2014] [Indexed: 06/03/2023]
Abstract
Microbial biofilms in oligotrophic environments are the most reactive component of the ecosystem. In high-altitude lakes, exposed bedrock, boulders, gravel, and sand in contact with highly oxygenated water and where a very thin epilithic biofilm develops usually dominate the littoral zone. Traditionally, these surfaces have been considered unsuitable for denitrification, but recent investigations have shown higher biological diversity than expected, including diverse anaerobic microorganisms. In this study, we explored the presence of microbial N-cycling nirS and nirK (denitrification through the conversion of NO2(-) to NO), nifH (N2 fixation), anammox (anaerobic ammonium oxidation), and amoA (aerobic ammonia oxidation, both bacterial and archaeal) genes in epilithic biofilms of a set of high-altitude oligotrophic lakes in the Pyrenees. The concentrations of denitrifying genes determined by quantitative PCR were two orders of magnitude higher than those of ammonia-oxidizing genes. Both types of genes were significantly correlated, suggesting a potential tight coupling nitrification-denitrification in these biofilms that deserves further confirmation. The nifH gene was detected after nested PCR, and no signal was detected for the anammox-specific genes used. The taxonomic composition of denitrifying and nitrogen-fixing genes was further explored by cloning and sequencing. Interestingly, both microbial functional groups were richer and more genetically diverse than expected. The nirK gene, mostly related to Alphaproteobacteria (Bradyrhizobiaceae), dominated the denitrifying gene pool as expected for oxygen-exposed habitats, whereas Deltaproteobacteria (Geobacter like) and Cyanobacteria were the most abundant among nitrogen fixers. Overall, these results suggest an epilithic community more metabolically diverse than previously thought and with the potential to carry out an active role in the biogeochemical nitrogen cycling of high-altitude ecosystems. Measurements of activity rates should be however carried out to substantiate and further explore these findings.
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Affiliation(s)
- Maria Vila-Costa
- Biogeodynamics&Biodiversity Group (B&B), Centre for Advanced Studies of Blanes, CEAB-CSIC, Blanes, Spain,
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Musat N, Stryhanyuk H, Bombach P, Adrian L, Audinot JN, Richnow HH. The effect of FISH and CARD-FISH on the isotopic composition of 13C- and 15N-labeled Pseudomonas putida cells measured by nanoSIMS. Syst Appl Microbiol 2014; 37:267-76. [DOI: 10.1016/j.syapm.2014.02.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 02/17/2014] [Accepted: 02/18/2014] [Indexed: 11/26/2022]
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Facets of diazotrophy in the oxygen minimum zone waters off Peru. ISME JOURNAL 2014; 8:2180-92. [PMID: 24813564 DOI: 10.1038/ismej.2014.71] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 03/20/2014] [Accepted: 03/30/2014] [Indexed: 11/09/2022]
Abstract
Nitrogen fixation, the biological reduction of dinitrogen gas (N2) to ammonium (NH4(+)), is quantitatively the most important external source of new nitrogen (N) to the open ocean. Classically, the ecological niche of oceanic N2 fixers (diazotrophs) is ascribed to tropical oligotrophic surface waters, often depleted in fixed N, with a diazotrophic community dominated by cyanobacteria. Although this applies for large areas of the ocean, biogeochemical models and phylogenetic studies suggest that the oceanic diazotrophic niche may be much broader than previously considered, resulting in major implications for the global N-budget. Here, we report on the composition, distribution and abundance of nifH, the functional gene marker for N2 fixation. Our results show the presence of eight clades of diazotrophs in the oxygen minimum zone (OMZ) off Peru. Although proteobacterial clades dominated overall, two clusters affiliated to spirochaeta and archaea were identified. N2 fixation was detected within OMZ waters and was stimulated by the addition of organic carbon sources supporting the view that non-phototrophic diazotrophs were actively fixing dinitrogen. The observed co-occurrence of key functional genes for N2 fixation, nitrification, anammox and denitrification suggests that a close spatial coupling of N-input and N-loss processes exists in the OMZ off Peru. The wide distribution of diazotrophs throughout the water column adds to the emerging view that the habitat of marine diazotrophs can be extended to low oxygen/high nitrate areas. Furthermore, our statistical analysis suggests that NO2(-) and PO4(3-) are the major factors affecting diazotrophic distribution throughout the OMZ. In view of the predicted increase in ocean deoxygenation resulting from global warming, our findings indicate that the importance of OMZs as niches for N2 fixation may increase in the future.
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Diverse sulfate-reducing bacteria of the Desulfosarcina/Desulfococcus clade are the key alkane degraders at marine seeps. ISME JOURNAL 2014; 8:2029-44. [PMID: 24722631 DOI: 10.1038/ismej.2014.51] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/26/2014] [Accepted: 03/04/2014] [Indexed: 11/08/2022]
Abstract
Biogeochemical and microbiological data indicate that the anaerobic oxidation of non-methane hydrocarbons by sulfate-reducing bacteria (SRB) has an important role in carbon and sulfur cycling at marine seeps. Yet, little is known about the bacterial hydrocarbon degraders active in situ. Here, we provide the link between previous biogeochemical measurements and the cultivation of degraders by direct identification of SRB responsible for butane and dodecane degradation in complex on-site microbiota. Two contrasting seep sediments from Mediterranean Amon mud volcano and Guaymas Basin (Gulf of California) were incubated with (13)C-labeled butane or dodecane under sulfate-reducing conditions and analyzed via complementary stable isotope probing (SIP) techniques. Using DNA- and rRNA-SIP, we identified four specialized clades of alkane oxidizers within Desulfobacteraceae to be distinctively active in oxidation of short- and long-chain alkanes. All clades belong to the Desulfosarcina/Desulfococcus (DSS) clade, substantiating the crucial role of these bacteria in anaerobic hydrocarbon degradation at marine seeps. The identification of key enzymes of anaerobic alkane degradation, subsequent β-oxidation and the reverse Wood-Ljungdahl pathway for complete substrate oxidation by protein-SIP further corroborated the importance of the DSS clade and indicated that biochemical pathways, analog to those discovered in the laboratory, are of great relevance for natural settings. The high diversity within identified subclades together with their capability to initiate alkane degradation and growth within days to weeks after substrate amendment suggest an overlooked potential of marine benthic microbiota to react to natural changes in seepage, as well as to massive hydrocarbon input, for example, as encountered during anthropogenic oil spills.
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Kubota K, Morono Y, Ito M, Terada T, Itezono S, Harada H, Inagaki F. Gold-ISH: a nano-size gold particle-based phylogenetic identification compatible with NanoSIMS. Syst Appl Microbiol 2014; 37:261-6. [PMID: 24702906 DOI: 10.1016/j.syapm.2014.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 02/20/2014] [Accepted: 02/20/2014] [Indexed: 11/25/2022]
Abstract
The linkage of microbial phylogenetic and metabolic analyses by combining ion imaging analysis with nano-scale secondary ion mass spectrometry (NanoSIMS) has become a powerful means of exploring the metabolic functions of environmental microorganisms. Phylogenetic identification using NanoSIMS typically involves probing by horseradish peroxidase-mediated deposition of halogenated fluorescent tyramides, which permits highly sensitive detection of specific microbial cells. However, the methods require permeabilization of target microbial cells and inactivation of endogenous peroxidase activity, and the use of halogens as the target atom is limited because of heavy background signals due to the presence of halogenated minerals in soil and sediment samples. Here, we present "Gold-ISH," a non-halogen phylogenetic probing method in which oligonucleotide probes are directly labeled with Undecagold, an ultra-small gold nanoparticle. Undecagold-labeled probes were generated using a thiol-maleimide chemical coupling reaction and they were purified by polyacrylamide gel electrophoresis. The method was optimized with a mixture of axenic (13)C-labeled Escherichia coli and Methanococcus maripaludis cells and applied to investigate sulfate-reducing bacteria in an anaerobic sludge sample. Clear gold-derived target signals were detected in microbial cells using NanoSIMS ion imaging. It was concluded that Gold-ISH can be a useful approach for metabolic studies of naturally occurring microbial ecosystems using NanoSIMS.
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Affiliation(s)
- Kengo Kubota
- Department of Civil and Environmental Engineering, Tohoku University, 6-6-06 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
| | - Yuki Morono
- Geomicrobiology Group, Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Monobe B200, Nankoku, Kochi 783-8502, Japan; Geobio-Engineering and Technology Group, Submarine Resources Research Project, JAMSTEC, Natsushima-cho 2-15, Yokosuka 237-0061, Japan.
| | - Motoo Ito
- Geochemical Research Group, Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Monobe B200, Nankoku, Kochi 783-8502, Japan; Geobio-Engineering and Technology Group, Submarine Resources Research Project, JAMSTEC, Natsushima-cho 2-15, Yokosuka 237-0061, Japan
| | - Takeshi Terada
- Department of Ocean Drilling Science Technical Support, Marine Works Japan LTD, Yokohama 236-0042, Japan
| | - Shogo Itezono
- Department of Civil and Environmental Engineering, Tohoku University, 6-6-06 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan
| | - Hideki Harada
- Department of Civil and Environmental Engineering, Tohoku University, 6-6-06 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan
| | - Fumio Inagaki
- Geomicrobiology Group, Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Monobe B200, Nankoku, Kochi 783-8502, Japan; Geobio-Engineering and Technology Group, Submarine Resources Research Project, JAMSTEC, Natsushima-cho 2-15, Yokosuka 237-0061, Japan
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Bentzon-Tilia M, Farnelid H, Jürgens K, Riemann L. Cultivation and isolation of N2-fixing bacteria from suboxic waters in the Baltic Sea. FEMS Microbiol Ecol 2014; 88:358-71. [PMID: 24579891 DOI: 10.1111/1574-6941.12304] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 01/20/2014] [Accepted: 02/10/2014] [Indexed: 11/30/2022] Open
Abstract
Nitrogenase genes (nifH) from heterotrophic dinitrogen (N2)-fixing bacteria appear ubiquitous in marine bacterioplankton, but the significance of these bacteria for N cycling is unknown. Quantitative data on the N2-fixation potential of marine and estuarine heterotrophs are scarce, and the shortage of cultivated specimens currently precludes ecophysiological characterization of these bacteria. Through the cultivation of diazotrophs from suboxic (1.79 μmol O2 L(-1)) Baltic Sea water in an artificial seawater medium devoid of combined N, we report the cultivability of a considerable fraction of the diazotrophic community in the Gotland Deep. Two nifH clades were present both in situ and in enrichment cultures showing gene abundances of up to 4.6 × 10(5) and 5.8 × 10(5) nifH gene copies L(-1) within two vertical profiles in the Baltic Sea. The distributions of the two clades suggested a relationship with the O2 concentrations in the water column as abundances increased in the suboxic and anoxic waters. It was possible to cultivate and isolate representatives from one of these prevalent clades, and preliminary analysis of their ecophysiology demonstrated growth optima at 0.5-15 μmol O2 L(-1) and 186-194 μmol O2 L(-1) in the absence of combined N.
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Affiliation(s)
- Mikkel Bentzon-Tilia
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
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40
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Abstract
With its low detection limits and the ability to analyze most of the elements in the periodic table, secondary ion mass spectrometry (SIMS) represents one of the most versatile in situ analytical techniques available, and recent developments have resulted in significant advantages for the use of imaging mass spectrometry in biological and biomedical research. Increases in spatial resolution and sensitivity allow detailed interrogation of samples at relevant scales and chemical concentrations. Advances in dynamic SIMS, specifically with the advent of NanoSIMS, now allow the tracking of stable isotopes within biological systems at subcellular length scales, while static SIMS combines subcellular imaging with molecular identification. In this chapter, we present an introduction to the SIMS technique, with particular reference to NanoSIMS, and discuss its application in biological and biomedical research.
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Affiliation(s)
- Matt R Kilburn
- Centre for Microscopy, Characterization and Analysis, The University of Western Australia, Crawley, WA, Australia
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Chapleur O, Wu TD, Guerquin-Kern JL, Mazéas L, Bouchez T. SIMSISH technique does not alter the apparent isotopic composition of bacterial cells. PLoS One 2013; 8:e77522. [PMID: 24204855 PMCID: PMC3812282 DOI: 10.1371/journal.pone.0077522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 09/04/2013] [Indexed: 12/03/2022] Open
Abstract
In order to identify the function of uncultured microorganisms in their environment, the SIMSISH method, combining in situ hybridization (ISH) and nanoscale secondary ion mass spectrometry (nanoSIMS) imaging, has been proposed to determine the quantitative uptake of specific labelled substrates by uncultured microbes at the single cell level. This technique requires the hybridization of rRNA targeted halogenated DNA probes on fixed and permeabilized microorganisms. Exogenous atoms are introduced into cells and endogenous atoms removed during the experimental procedures. Consequently differences between the original and the apparent isotopic composition of cells may occur. In the present study, the influence of the experimental procedures of SIMSISH on the isotopic composition of carbon in E. coli cells was evaluated with nanoSIMS and compared to elemental analyser-isotopic ratio mass spectrometer (EA-IRMS) measurements. Our results show that fixation and hybridization have a very limited, reproducible and homogeneous influence on the isotopic composition of cells. Thereby, the SIMSISH procedure minimizes the contamination of the sample by exogenous atoms, thus providing a means to detect the phylogenetic identity and to measure precisely the carbon isotopic composition at the single cell level. This technique was successfully applied to a complex sample with double bromine – iodine labelling targeting a large group of bacteria and a specific archaea to evaluate their specific 13C uptake during labelled methanol anaerobic degradation.
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Affiliation(s)
| | - Ting-Di Wu
- U.759, INSERM, Orsay, France
- Laboratoire de Microscopie Ionique, Institut Curie, Orsay, France
| | - Jean-Luc Guerquin-Kern
- U.759, INSERM, Orsay, France
- Laboratoire de Microscopie Ionique, Institut Curie, Orsay, France
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42
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Steinhauser ML, Lechene CP. Quantitative imaging of subcellular metabolism with stable isotopes and multi-isotope imaging mass spectrometry. Semin Cell Dev Biol 2013; 24:661-7. [PMID: 23660233 DOI: 10.1016/j.semcdb.2013.05.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Multi-isotope imaging mass spectrometry (MIMS) is the quantitative imaging of stable isotope labels in cells with a new type of secondary ion mass spectrometer (NanoSIMS). The power of the methodology is attributable to (i) the immense advantage of using non-toxic stable isotope labels, (ii) high resolution imaging that approaches the resolution of usual transmission electron microscopy and (iii) the precise quantification of label down to 1 part-per-million and spanning several orders of magnitude. Here we review the basic elements of MIMS and describe new applications of MIMS to the quantitative study of metabolic processes including protein and nucleic acid synthesis in model organisms ranging from microbes to humans.
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Affiliation(s)
- Matthew L Steinhauser
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA 02115, United States; Division of Genetics, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, United States; Division of Cardiovascular Medicine, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, United States
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43
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Active nitrogen-fixing heterotrophic bacteria at and below the chemocline of the central Baltic Sea. ISME JOURNAL 2013; 7:1413-23. [PMID: 23446833 DOI: 10.1038/ismej.2013.26] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Baltic Sea receives large nitrogen inputs by diazotrophic (N2-fixing) heterocystous cyanobacteria but the significance of heterotrophic N2 fixation has not been studied. Here, the diversity, abundance and transcription of the nifH fragment of the nitrogenase enzyme in two basins of the Baltic Sea proper was examined. N2 fixation was measured at the surface (5 m) and in anoxic water (200 m). Vertical sampling profiles of >10 and <10 μm size fractions were collected in 2007, 2008 and 2011 at the Gotland Deep and in 2011 in the Bornholm Basin. Both of these stations are characterized by permanently anoxic bottom water. The 454-pyrosequencing nifH analysis revealed a diverse assemblage of nifH genes related to alpha-, beta- and gammaproteobacteria (nifH cluster I) and anaerobic bacteria (nifH cluster III) at and below the chemocline. Abundances of genes and transcripts of seven diazotrophic phylotypes were investigated using quantitative polymerase chain reaction revealing abundances of heterotrophic nifH phylotypes of up to 2.1 × 10(7) nifH copies l(-1). Abundant nifH transcripts (up to 3.2 × 10(4) transcripts l(-1)) within nifH cluster III and co-occurring N2 fixation (0.44±0.26 nmol l(-1) day(-1)) in deep water suggests that heterotrophic diazotrophs are fixing N2 in anoxic ammonium-rich waters. Our results reveal that N2 fixation in the Baltic Sea is not limited to illuminated N-deplete surface waters and suggest that N2 fixation could also be of importance in other suboxic regions of the world's oceans.
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44
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Affiliation(s)
- M Ackermann
- Department of Environmental Systems Science, ETH Zurich, Zürich, Switzerland.
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45
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Edberg F, Andersson AF, Holmström SJM. Bacterial community composition in the water column of a lake formed by a former uranium open pit mine. MICROBIAL ECOLOGY 2012; 64:870-880. [PMID: 22622763 DOI: 10.1007/s00248-012-0069-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 04/27/2012] [Indexed: 06/01/2023]
Abstract
Mining of pyrite minerals is a major environmental issue involving both biological and geochemical processes. Here we present a study of an artificial lake of a former uranium open pit mine with the aim to connect the chemistry and bacterial community composition (454-pyrosequencing of 16S rRNA genes) in the stratified water column. A shift in the water chemistry from oxic conditions in the epilimnion to anoxic, alkaline, and metal and sulfide-rich conditions in the hypolimnion was corresponded by a strong shift in the bacterial community, with few shared operational taxonomic units (OTU) between the water layers. The epilimnetic bacterial community of the lake (~20 years old) showed similarities to other temperate freshwater lakes, while the hypolimnetic bacterial community showed similarity to extreme chemical environments. The epilimnetic bacterial community had dominance of Actinobacteria and Betaproteobacteria. The hypolimnion displayed a higher bacterial diversity and was dominated by the phototrophic green sulphur bacterium of the genus Chlorobium (ca. 40 % of the total community). Deltaproteobacteria were only represented in the hypolimnion and the most abundant OTUs were affiliated with ferric iron and sulfate reducers of the genus Geobacter and Desulfobulbus, respectively. The chemistry is clearly controlling, especially the hypolimnetic, bacterial community but the community composition also indicates that the bacteria are involved in metal cycling in the lake.
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Affiliation(s)
- Frida Edberg
- Department of Applied Environmental Science, Stockholm University, 106 91 Stockholm, Sweden
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46
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Effects of iron and nitrogen limitation on sulfur isotope fractionation during microbial sulfate reduction. Appl Environ Microbiol 2012; 78:8368-76. [PMID: 23001667 DOI: 10.1128/aem.01842-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sulfate-reducing microbes utilize sulfate as an electron acceptor and produce sulfide that is depleted in heavy isotopes of sulfur relative to sulfate. Thus, the distribution of sulfur isotopes in sediments can trace microbial sulfate reduction (MSR), and it also has the potential to reflect the physiology of sulfate-reducing microbes. This study investigates the relationship between the availability of iron and reduced nitrogen and the magnitude of S-isotope fractionation during MSR by a marine sulfate-reducing bacterium, DMSS-1, a Desulfovibrio species, isolated from salt marsh in Cape Cod, MA. Submicromolar levels of iron increase sulfur isotope fractionation by about 50% relative to iron-replete cultures of DMSS-1. Iron-limited cultures also exhibit decreased cytochrome c-to-total protein ratios and cell-specific sulfate reduction rates (csSRR), implying changes in the electron transport chain that couples carbon and sulfur metabolisms. When DMSS-1 fixes nitrogen in ammonium-deficient medium, it also produces larger fractionation, but it occurs at faster csSRRs than in the ammonium-replete control cultures. The energy and reducing power required for nitrogen fixation may be responsible for the reverse trend between S-isotope fractionation and csSRR in this case. Iron deficiency and nitrogen fixation by sulfate-reducing microbes may lead to the large observed S-isotope effects in some euxinic basins and various anoxic sediments.
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Vertical distribution of microbial communities in a perennially stratified Arctic lake with saline, anoxic bottom waters. Sci Rep 2012; 2:604. [PMID: 22930670 PMCID: PMC3428602 DOI: 10.1038/srep00604] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 08/09/2012] [Indexed: 11/25/2022] Open
Abstract
Meromictic lakes are useful biogeochemical models because of their stratified chemical gradients and separation of redox reactions down the water column. Perennially ice-covered meromictic lakes are particularly stable, with long term constancy in their density profiles. Here we sampled Lake A, a deep meromictic lake at latitude 83°N in High Arctic Canada. Sampling was before (May) and after (August) an unusual ice-out event during the warm 2008 summer. We determined the bacterial and archaeal community composition by high-throughput 16S rRNA gene tag-pyrosequencing. Both prokaryote communities were stratified by depth and the Bacteria differed between dates, indicating locally driven selection processes. We matched taxa to known taxon-specific biogeochemical functions and found a close correspondence between the depth of functional specialists and chemical gradients. These results indicate a rich microbial diversity despite the extreme location, with pronounced vertical structure in taxonomic and potential functional composition, and with community shifts during ice-out.
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Halm H, Lam P, Ferdelman TG, Lavik G, Dittmar T, LaRoche J, D'Hondt S, Kuypers MMM. Heterotrophic organisms dominate nitrogen fixation in the South Pacific Gyre. THE ISME JOURNAL 2012; 6:1238-49. [PMID: 22170429 PMCID: PMC3358028 DOI: 10.1038/ismej.2011.182] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2011] [Revised: 11/03/2011] [Accepted: 11/03/2011] [Indexed: 11/09/2022]
Abstract
Oceanic subtropical gyres are considered biological deserts because of the extremely low availability of nutrients and thus minimum productivities. The major source of nutrient nitrogen in these ecosystems is N(2)-fixation. The South Pacific Gyre (SPG) is the largest ocean gyre in the world, but measurements of N(2)-fixation therein, or identification of microorganisms involved, are scarce. In the 2006/2007 austral summer, we investigated nitrogen and carbon assimilation at 11 stations throughout the SPG. In the ultra-oligotrophic waters of the SPG, the chlorophyll maxima reached as deep as 200 m. Surface primary production seemed limited by nitrogen, as dissolved inorganic carbon uptake was stimulated upon additions of (15)N-labeled ammonium and leucine in our incubation experiments. N(2)-fixation was detectable throughout the upper 200 m at most stations, with rates ranging from 0.001 to 0.19 nM N h(-1). N(2)-fixation in the SPG may account for the production of 8-20% of global oceanic new nitrogen. Interestingly, comparable (15)N(2)-fixation rates were measured under light and dark conditions. Meanwhile, phylogenetic analyses for the functional gene biomarker nifH and its transcripts could not detect any common photoautotrophic diazotrophs, such as, Trichodesmium, but a prevalence of γ-proteobacteria and the unicellular photoheterotrophic Group A cyanobacteria. The dominance of these likely heterotrophic diazotrophs was further verified by quantitative PCR. Hence, our combined results show that the ultra-oligotrophic SPG harbors a hitherto unknown heterotrophic diazotrophic community, clearly distinct from other oceanic gyres previously visited.
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Affiliation(s)
- Hannah Halm
- Max Planck Institute for Marine Microbiology, Bremen, Germany.
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Ravasi DF, Peduzzi S, Guidi V, Peduzzi R, Wirth SB, Gilli A, Tonolla M. Development of a real-time PCR method for the detection of fossil 16S rDNA fragments of phototrophic sulfur bacteria in the sediments of Lake Cadagno. GEOBIOLOGY 2012; 10:196-204. [PMID: 22433067 DOI: 10.1111/j.1472-4669.2012.00326.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Lake Cadagno is a crenogenic meromictic lake situated in the southern range of the Swiss Alps characterized by a compact chemocline that has been the object of many ecological studies. The population dynamics of phototrophic sulfur bacteria in the chemocline has been monitored since 1994 with molecular methods such as 16S rRNA gene clone library analysis. To reconstruct paleo-microbial community dynamics, we developed a quantitative real-time PCR methodology for specific detection of 16S rRNA gene sequences of purple and green sulfur bacteria populations from sediment samples. We detected fossil 16S rDNA of nine populations of phototrophic sulfur bacteria down to 9-m sediment depth, corresponding to about 9500 years of the lake's biogeological history. These results provide the first evidence for the presence of 16S rDNA of anoxygenic phototrophic bacteria in Holocene sediments of an alpine meromictic lake and indicate that the water column stratification and the bacterial plume were already present in Lake Cadagno thousands of years ago. The finding of Chlorobium clathratiforme remains in all the samples analyzed shows that this population, identified in the water column only in 2001, was already a part of the lake's biota in the past.
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Affiliation(s)
- D F Ravasi
- Piora Alpine Biology Centre Foundation, c/o Cantonal Institute of Microbiology, Bellinzona, Switzerland.
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Behrens S, Kappler A, Obst M. Linking environmental processes to thein situfunctioning of microorganisms by high-resolution secondary ion mass spectrometry (NanoSIMS) and scanning transmission X-ray microscopy (STXM). Environ Microbiol 2012; 14:2851-69. [DOI: 10.1111/j.1462-2920.2012.02724.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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