1
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Quantifying potential N turnover rates in hypersaline microbial mats by 15N tracer techniques. Appl Environ Microbiol 2021; 87:AEM.03118-20. [PMID: 33579680 PMCID: PMC8091114 DOI: 10.1128/aem.03118-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microbial mats, due to stratification of the redox zones, have a potential to include a complete N cycle, however an attempt to evaluate a complete N cycle in these ecosystems has not been yet made. In this study, occurrence and rates of major N cycle processes were evaluated in intact microbial mats from Elkhorn Slough, Monterey Bay, CA, USA, and Baja California Sur, Mexico under oxic and anoxic conditions using 15N-labeling techniques. All of the major N transformation pathways, with the exception of anammox, were detected in both microbial mats. Nitrification rates were found to be low at both sites for both seasons investigated. The highest rates of ammonium assimilation were measured in Elkhorn Slough mats in April and corresponded to high in situ ammonium concentration in the overlying water. Baja mats featured higher ammonification than ammonium assimilation rates and this, along with their higher affinity for nitrate compared to ammonium and low dissimilatory nitrate reduction to ammonium rates, characterized their differences from Elkhorn Slough mats. Nitrogen fixation rates in Elkhorn Slough microbial mats were found to be low implying that other processes such as recycling and assimilation from water are main sources of N for these mats at the times sampled. Denitrification in all of the mats was incomplete with nitrous oxide as end product and not dinitrogen. Our findings highlight N cycling features not previously quantified in microbial mats and indicate a need of further investigations in these microbial ecosystems.Importance: Nitrogen is essential for life. The nitrogen cycle on Earth is mediated by microbial activity and has had a profound impact on both the atmosphere and the biosphere throughout geologic time. Microbial mats, present in many modern environments, have been regarded as living records of the organisms, genes, and phylogenies of microbes, as they are one of the most ancient ecosystems on Earth. While rates of major nitrogen metabolic pathways have been evaluated in a number of ecosystems, it remains elusive in microbial mats. In particular it is unclear what factors affect nitrogen cycling in these ecosystems and how morphological differences between mats impact nitrogen transformations. In this study we investigate nitrogen cycling in two microbial mats having morphological differences. Our findings provide insight for further understanding of biogeochemistry and microbial ecology of microbial mats.
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2
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Meng H, Zhou Z, Wu R, Wang Y, Gu JD. Diazotrophic microbial community and abundance in acidic subtropical natural and re-vegetated forest soils revealed by high-throughput sequencing of nifH gene. Appl Microbiol Biotechnol 2018; 103:995-1005. [PMID: 30474727 DOI: 10.1007/s00253-018-9466-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 09/17/2018] [Accepted: 10/09/2018] [Indexed: 01/09/2023]
Abstract
Biological nitrogen fixation (BNF) is an important natural biochemical process converting the inert dinitrogen gas (N2) in the atmosphere to ammonia (NH3) in the N cycle. In this study, the nifH gene was chosen to detect the diazotrophic microorganisms with high-throughput sequencing from five acidic forest soils, including three natural forests and two re-vegetated forests. Soil samples were taken in two seasons (summer and winter) at two depth layers (surface and lower depths). A dataset of 179,600 reads obtained from 20 samples were analyzed to provide the microbial community structure, diversity, abundance, and relationship with physiochemical parameters. Both archaea and bacteria were detected in these samples and diazotrophic bacteria were the dominant members contributing to the biological dinitrogen fixation in the acidic forest soils. Cyanobacteria, Firmicutes, Proteobacteria, Spirocheates, and Verrucomicrobia were observed, especially the Proteobacteria as the most abundant phylum. The core genera were Bradyrhizobium and Methylobacterium from α-Proteobacteia, and Desulfovibrio from δ-Proteobacteia in the phylum of Proteobacteia of these samples. The diversity indices and the gene abundances of all samples were higher in the surface layer than the lower layer. Diversity was apparently higher in re-vegetated forests than the natural forests. Significant positive correlation to the organic matter and nitrogen-related parameters was observed, but there was no significant seasonal variation on the community structure and diversity in these samples between the summer and winter. The application of high-throughput sequencing method provides a better understanding and more comprehensive information of diazotrophs in acidic forest soils than conventional and PCR-based ones.
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Affiliation(s)
- Han Meng
- School of Environment, Nanjing Normal University, Nanjing, 210023, China
- Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, Faculty of Science, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, People's Republic of China
| | - Zhichao Zhou
- Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, Faculty of Science, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, People's Republic of China
| | - Ruonan Wu
- Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, Faculty of Science, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, People's Republic of China
| | - Yongfeng Wang
- Guangdong Provincial Key Laboratory of Silviculture, Protection and Utilization, Guangdong Academy of Forestry, 233 Guangshan 1st Road, Guangzhou, People's Republic of China
| | - Ji-Dong Gu
- Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, Faculty of Science, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, People's Republic of China.
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3
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Moisander PH, Benavides M, Bonnet S, Berman-Frank I, White AE, Riemann L. Chasing after Non-cyanobacterial Nitrogen Fixation in Marine Pelagic Environments. Front Microbiol 2017; 8:1736. [PMID: 28943875 PMCID: PMC5596534 DOI: 10.3389/fmicb.2017.01736] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Accepted: 08/25/2017] [Indexed: 11/22/2022] Open
Abstract
Traditionally, cyanobacterial activity in oceanic photic layers was considered responsible for the marine pelagic dinitrogen (N2) fixation. Other potentially N2-fixing bacteria and archaea have also been detected in the pelagic water column, however, the activity and importance of these non-cyanobacterial diazotrophs (NCDs) remain poorly constrained. In this perspective we summarize the N2 fixation rates from recently published studies on photic and aphotic layers that have been attributed to NCD activity via parallel molecular measurements, and discuss the status, challenges, and data gaps in estimating non-cyanobacterial N2 fixation NCNF in the ocean. Rates attributed to NCNF have generally been near the detection limit thus far (<1 nmol N L−1 d−1). Yet, if considering the large volume of the dark ocean, even low rates of NCNF could make a significant contribution to the new nitrogen input to the ocean. The synthesis here shows that nifH transcription data for NCDs have been reported in only a few studies where N2 fixation rates were detected in the absence of diazotrophic cyanobacteria. In addition, high apparent diversity and regional variability in the NCDs complicate investigations of these communities. Future studies should focus on further investigating impacts of environmental drivers including oxygen, dissolved organic matter, and dissolved inorganic nitrogen on NCNF. Describing the ecology of NCDs and accurately measuring NCNF rates, are critical for a future evaluation of the contribution of NCNF to the marine nitrogen budget.
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Affiliation(s)
- Pia H Moisander
- Department of Biology, University of Massachusetts DartmouthNorth Dartmouth, MA, United States
| | - Mar Benavides
- Marine Biology Section, Department of Biology, University of CopenhagenHelsingør, Denmark
| | - Sophie Bonnet
- Centre National de la Recherche Scientifique, IRD, Aix-Marseille Université, Université de ToulonMarseille, France
| | - Ilana Berman-Frank
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan UniversityRamat Gan, Israel
| | - Angelicque E White
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State UniversityCorvallis, OR, United States
| | - Lasse Riemann
- Marine Biology Section, Department of Biology, University of CopenhagenHelsingør, Denmark
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4
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Li S, Peng C, Wang C, Zheng J, Hu Y, Li D. Microbial Succession and Nitrogen Cycling in Cultured Biofilms as Affected by the Inorganic Nitrogen Availability. MICROBIAL ECOLOGY 2017; 73:1-15. [PMID: 27538871 DOI: 10.1007/s00248-016-0827-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 07/27/2016] [Indexed: 06/06/2023]
Abstract
Biofilms play important roles in nutrients and energy cycling in aquatic ecosystems. We hypothesized that as eutrophication could change phytoplankton community and decrease phytoplankton diversity, ambient inorganic nitrogen level will affect the microbial community and diversity of biofilms and the roles of biofilms in nutrient cycling. Biofilms were cultured using a flow incubator either with replete inorganic nitrogen (N-rep) or without exogenous inorganic nitrogen supply (N-def). The results showed that the biomass and nitrogen and phosphorous accumulation of biofilms were limited by N deficiency; however, as expected, the N-def biofilms had significantly higher microbial diversity than that of N-rep biofilms. The microbial community of biofilms shifted in composition and abundance in response to ambient inorganic nitrogen level. For example, as compared between the N-def and the N-rep biofilms, the former consisted of more diazotrophs, while the latter consisted of more denitrifying bacteria. As a result of the shift of the functional microbial community, the N concentration of N-rep medium kept decreasing, while that of N-def medium showed an increasing trend in the late stage. This indicates that biofilms can serve as the source or the sink of nitrogen in aquatic ecosystems, and it depends on the inorganic nitrogen availability.
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Affiliation(s)
- Shuangshuang Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chengrong Peng
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Chun Wang
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Jiaoli Zheng
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yao Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Dunhai Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
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5
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Tu Q, Deng Y, Yan Q, Shen L, Lin L, He Z, Wu L, Van Nostrand JD, Buzzard V, Michaletz ST, Enquist BJ, Weiser MD, Kaspari M, Waide RB, Brown JH, Zhou J. Biogeographic patterns of soil diazotrophic communities across six forests in North America. Mol Ecol 2016; 25:2937-48. [PMID: 27085668 DOI: 10.1111/mec.13651] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/23/2016] [Accepted: 04/12/2016] [Indexed: 11/29/2022]
Abstract
Soil diazotrophs play important roles in ecosystem functioning by converting atmospheric N2 into biologically available ammonium. However, the diversity and distribution of soil diazotrophic communities in different forests and whether they follow biogeographic patterns similar to macroorganisms still remain unclear. By sequencing nifH gene amplicons, we surveyed the diversity, structure and biogeographic patterns of soil diazotrophic communities across six North American forests (126 nested samples). Our results showed that each forest harboured markedly different soil diazotrophic communities and that these communities followed traditional biogeographic patterns similar to plant and animal communities, including the taxa-area relationship (TAR) and latitudinal diversity gradient. Significantly higher community diversity and lower microbial spatial turnover rates (i.e. z-values) were found for rainforests (~0.06) than temperate forests (~0.1). The gradient pattern of TARs and community diversity was strongly correlated (r(2) > 0.5) with latitude, annual mean temperature, plant species richness and precipitation, and weakly correlated (r(2) < 0.25) with pH and soil moisture. This study suggests that even microbial subcommunities (e.g. soil diazotrophs) follow general biogeographic patterns (e.g. TAR, latitudinal diversity gradient), and indicates that the metabolic theory of ecology and habitat heterogeneity may be the major underlying ecological mechanisms shaping the biogeographic patterns of soil diazotrophic communities.
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Affiliation(s)
- Qichao Tu
- Department of Marine Sciences, Ocean College, Zhejiang University, Zhejiang, 310058, China.,Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA
| | - Ye Deng
- Research Center for Eco-Environmental Science, Chinese Academy of Sciences, Beijing, 100085, China
| | - Qingyun Yan
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA
| | - Lina Shen
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA
| | - Lu Lin
- Department of Marine Sciences, Ocean College, Zhejiang University, Zhejiang, 310058, China
| | - Zhili He
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA
| | - Liyou Wu
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA
| | - Joy D Van Nostrand
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA
| | - Vanessa Buzzard
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Sean T Michaletz
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA.,Earth and Environmental Sciences Division, Los Alamos National Laboratory, MS J495, Los Alamos, NM 87545, USA
| | - Brian J Enquist
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA.,The Santa Fe Institute, 1399 Hyde Park Rd, Santa Fe, NM, 87501, USA
| | - Michael D Weiser
- Department of Biology, EEB Graduate Program, University of Oklahoma, Norman, OK, 73019, USA
| | - Michael Kaspari
- Department of Biology, EEB Graduate Program, University of Oklahoma, Norman, OK, 73019, USA.,Smithsonian Tropical Research Institute, Balboa, 0843-03092, Republic of Panama
| | - Robert B Waide
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - James H Brown
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Jizhong Zhou
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA.,State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.,Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94270, USA
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6
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Tu Q, Zhou X, He Z, Xue K, Wu L, Reich P, Hobbie S, Zhou J. The Diversity and Co-occurrence Patterns of N₂-Fixing Communities in a CO₂-Enriched Grassland Ecosystem. MICROBIAL ECOLOGY 2016; 71:604-615. [PMID: 26280746 DOI: 10.1007/s00248-015-0659-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 08/03/2015] [Indexed: 06/04/2023]
Abstract
Diazotrophs are the major organismal group responsible for atmospheric nitrogen (N2) fixation in natural ecosystems. The extensive diversity and structure of N2-fixing communities in grassland ecosystems and their responses to increasing atmospheric CO2 remain to be further explored. Through pyrosequencing of nifH gene amplicons and extraction of nifH genes from shotgun metagenomes, coupled with co-occurrence ecological network analysis approaches, we comprehensively analyzed the diazotrophic community in a grassland ecosystem exposed to elevated CO2 (eCO2) for 12 years. Long-term eCO2 increased the abundance of nifH genes but did not change the overall nifH diversity and diazotrophic community structure. Taxonomic and phylogenetic analysis of amplified nifH sequences suggested a high diversity of nifH genes in the soil ecosystem, the majority belonging to nifH clusters I and II. Co-occurrence ecological network analysis identified different co-occurrence patterns for different groups of diazotrophs, such as Azospirillum/Actinobacteria, Mesorhizobium/Conexibacter, and Bradyrhizobium/Acidobacteria. This indicated a potential attraction of non-N2-fixers by diazotrophs in the soil ecosystem. Interestingly, more complex co-occurrence patterns were found for free-living diazotrophs than commonly known symbiotic diazotrophs, which is consistent with the physical isolation nature of symbiotic diazotrophs from the environment by root nodules. The study provides novel insights into our understanding of the microbial ecology of soil diazotrophs in natural ecosystems.
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Affiliation(s)
- Qichao Tu
- Department of Marine Sciences, Ocean College, Zhejiang University, Hangzhou, Zhejiang, 310058, China
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK, 73019, USA
| | - Xishu Zhou
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK, 73019, USA
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, 410083, China
| | - Zhili He
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, 410083, China
| | - Kai Xue
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, 410083, China
| | - Liyou Wu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, 410083, China
| | - Peter Reich
- Department of Forest Resources, University of Minnesota, St. Paul, MN, 55455, USA
- Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, 2753, NSW, Australia
| | - Sarah Hobbie
- Department of Forest Resources, University of Minnesota, St. Paul, MN, 55455, USA
| | - Jizhong Zhou
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK, 73019, USA.
- Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
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7
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Severin I, Bentzon-Tilia M, Moisander PH, Riemann L. Nitrogenase expression in estuarine bacterioplankton influenced by organic carbon and availability of oxygen. FEMS Microbiol Lett 2015; 362:fnv105. [PMID: 26152701 DOI: 10.1093/femsle/fnv105] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2015] [Indexed: 11/14/2022] Open
Abstract
The genetic capacity to fix gaseous nitrogen (N) is distributed among diverse diazotrophs belonging to the Bacteria and Archaea. However, only a subset of the putative diazotrophs present actively fix N at any given time in the environment. We experimentally tested whether the availability of carbon and inhibition by oxygen constrain N fixation by diazotrophs in coastal seawater. The goal was to test whether by alleviating these constraints an increased overlap between nitrogenase (nifH)-gene-carrying and -expressing organisms could be achieved. We incubated water from a eutrophic but N-limited fjord in Denmark under high-carbon/low-oxygen conditions and determined bacterial growth and production, diazotrophic community composition (Illumina nifH amplicon sequencing), and nifH gene abundance and expression [quantitative PCR (qPCR) and quantitative reverse transcriptase PCR (qRT-PCR)]. Bacterial abundances and production increased under high-carbon/low-oxygen conditions as did the similarity between present and active diazotrophic communities. This was caused by the loss of specific abundant yet non-active gammaproteobacterial phylotypes and increased expression by others. The prominent active gamma- and epsilonproteobacterial diazotrophs did not, however, respond to these conditions in a uniform way, highlighting the difficulty to assess how a change in environmental conditions may affect a diverse indigenous diazotrophic community.
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Affiliation(s)
- Ina Severin
- Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark
| | - Mikkel Bentzon-Tilia
- Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark
| | - Pia H Moisander
- Department of Biology, University of Massachusetts Dartmouth, North Dartmouth, MA 02747, USA
| | - Lasse Riemann
- Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark
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8
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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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9
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A microarray for assessing transcription from pelagic marine microbial taxa. ISME JOURNAL 2014; 8:1476-91. [PMID: 24477198 DOI: 10.1038/ismej.2014.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 12/16/2013] [Accepted: 12/31/2013] [Indexed: 02/08/2023]
Abstract
Metagenomic approaches have revealed unprecedented genetic diversity within microbial communities across vast expanses of the world's oceans. Linking this genetic diversity with key metabolic and cellular activities of microbial assemblages is a fundamental challenge. Here we report on a collaborative effort to design MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories), a high-density oligonucleotide microarray that targets functional genes of diverse taxa in pelagic and coastal marine microbial communities. MicroTOOLs integrates nucleotide sequence information from disparate data types: genomes, PCR-amplicons, metagenomes, and metatranscriptomes. It targets 19 400 unique sequences over 145 different genes that are relevant to stress responses and microbial metabolism across the three domains of life and viruses. MicroTOOLs was used in a proof-of-concept experiment that compared the functional responses of microbial communities following Fe and P enrichments of surface water samples from the North Pacific Subtropical Gyre. We detected transcription of 68% of the gene targets across major taxonomic groups, and the pattern of transcription indicated relief from Fe limitation and transition to N limitation in some taxa. Prochlorococcus (eHLI), Synechococcus (sub-cluster 5.3) and Alphaproteobacteria SAR11 clade (HIMB59) showed the strongest responses to the Fe enrichment. In addition, members of uncharacterized lineages also responded. The MicroTOOLs microarray provides a robust tool for comprehensive characterization of major functional groups of microbes in the open ocean, and the design can be easily amended for specific environments and research questions.
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10
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Farías ME, Rascovan N, Toneatti DM, Albarracín VH, Flores MR, Poiré DG, Collavino MM, Aguilar OM, Vazquez MP, Polerecky L. The discovery of stromatolites developing at 3570 m above sea level in a high-altitude volcanic lake Socompa, Argentinean Andes. PLoS One 2013; 8:e53497. [PMID: 23308236 PMCID: PMC3538587 DOI: 10.1371/journal.pone.0053497] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 11/29/2012] [Indexed: 11/24/2022] Open
Abstract
We describe stromatolites forming at an altitude of 3570 m at the shore of a volcanic lake Socompa, Argentinean Andes. The water at the site of stromatolites formation is alkaline, hypersaline, rich in inorganic nutrients, very rich in arsenic, and warm (20-24°C) due to a hydrothermal input. The stromatolites do not lithify, but form broad, rounded and low-domed bioherms dominated by diatom frustules and aragonite micro-crystals agglutinated by extracellular substances. In comparison to other modern stromatolites, they harbour an atypical microbial community characterized by highly abundant representatives of Deinococcus-Thermus, Rhodobacteraceae, Desulfobacterales and Spirochaetes. Additionally, a high proportion of the sequences that could not be classified at phylum level showed less than 80% identity to the best hit in the NCBI database, suggesting the presence of novel distant lineages. The primary production in the stromatolites is generally high and likely dominated by Microcoleus sp. Through negative phototaxis, the location of these cyanobacteria in the stromatolites is controlled by UV light, which greatly influences their photosynthetic activity. Diatoms, dominated by Amphora sp., are abundant in the anoxic, sulfidic and essentially dark parts of the stromatolites. Although their origin in the stromatolites is unclear, they are possibly an important source of anaerobically degraded organic matter that induces in situ aragonite precipitation. To the best of our knowledge, this is so far the highest altitude with documented actively forming stromatolites. Their generally rich, diverse and to a large extent novel microbial community likely harbours valuable genetic and proteomic reserves, and thus deserves active protection. Furthermore, since the stromatolites flourish in an environment characterized by a multitude of extremes, including high exposure to UV radiation, they can be an excellent model system for studying microbial adaptations under conditions that, at least in part, resemble those during the early phase of life evolution on Earth.
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Affiliation(s)
- María E. Farías
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CCT, CONICET, San Miguel de Tucumán, Tucumán, Argentina
| | - Nicolás Rascovan
- Instituto de Agrobiotecnologia Rosario (INDEAR), Rosario, Santa Fe, Argentina
| | - Diego M. Toneatti
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CCT, CONICET, San Miguel de Tucumán, Tucumán, Argentina
| | - Virginia H. Albarracín
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CCT, CONICET, San Miguel de Tucumán, Tucumán, Argentina
- Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
- Max-Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr, Germany
| | - María R. Flores
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CCT, CONICET, San Miguel de Tucumán, Tucumán, Argentina
| | - Daniel G. Poiré
- Centro de Investigaciones Geológicas, Universidad Nacional de La Plata-CONICET, La Plata, Argentina
| | - Mónica M. Collavino
- Instituto de Biotecnología y Biología Molecular (IBBM), Universidad Nacional de La Plata-CONICET, La Plata, Argentina
| | - O. Mario Aguilar
- Instituto de Biotecnología y Biología Molecular (IBBM), Universidad Nacional de La Plata-CONICET, La Plata, Argentina
| | - Martin P. Vazquez
- Instituto de Agrobiotecnologia Rosario (INDEAR), Rosario, Santa Fe, Argentina
| | - Lubos Polerecky
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
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11
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Woebken D, Burow LC, Prufert-Bebout L, Bebout BM, Hoehler TM, Pett-Ridge J, Spormann AM, Weber PK, Singer SW. Identification of a novel cyanobacterial group as active diazotrophs in a coastal microbial mat using NanoSIMS analysis. ISME JOURNAL 2012; 6:1427-39. [PMID: 22237543 DOI: 10.1038/ismej.2011.200] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
N(2) fixation is a key process in photosynthetic microbial mats to support the nitrogen demands associated with primary production. Despite its importance, groups that actively fix N(2) and contribute to the input of organic N in these ecosystems still remain largely unclear. To investigate the active diazotrophic community in microbial mats from the Elkhorn Slough estuary, Monterey Bay, CA, USA, we conducted an extensive combined approach, including biogeochemical, molecular and high-resolution secondary ion mass spectrometry (NanoSIMS) analyses. Detailed analysis of dinitrogenase reductase (nifH) transcript clone libraries from mat samples that fixed N(2) at night indicated that cyanobacterial nifH transcripts were abundant and formed a novel monophyletic lineage. Independent NanoSIMS analysis of (15)N(2)-incubated samples revealed significant incorporation of (15)N into small, non-heterocystous cyanobacterial filaments. Mat-derived enrichment cultures yielded a unicyanobacterial culture with similar filaments (named Elkhorn Slough Filamentous Cyanobacterium-1 (ESFC-1)) that contained nifH gene sequences grouping with the novel cyanobacterial lineage identified in the transcript clone libraries, displaying up to 100% amino-acid sequence identity. The 16S rRNA gene sequence recovered from this enrichment allowed for the identification of related sequences from Elkhorn Slough mats and revealed great sequence diversity in this cluster. Furthermore, by combining (15)N(2) tracer experiments, fluorescence in situ hybridization and NanoSIMS, in situ N(2) fixation activity by the novel ESFC-1 group was demonstrated, suggesting that this group may be the most active cyanobacterial diazotroph in the Elkhorn Slough mat. Pyrotag sequences affiliated with ESFC-1 were recovered from mat samples throughout 2009, demonstrating the prevalence of this group. This work illustrates that combining standard and single-cell analyses can link phylogeny and function to identify previously unknown key functional groups in complex ecosystems.
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Affiliation(s)
- Dagmar Woebken
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
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12
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He Z, Van Nostrand JD, Zhou J. Applications of functional gene microarrays for profiling microbial communities. Curr Opin Biotechnol 2012; 23:460-6. [PMID: 22226464 DOI: 10.1016/j.copbio.2011.12.021] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 11/23/2011] [Accepted: 12/19/2011] [Indexed: 10/14/2022]
Abstract
Functional gene arrays (FGAs) have been considered as a specific, sensitive, quantitative, and high throughput metagenomic tool to detect, monitor and characterize microbial communities. Especially GeoChips, the most comprehensive FGAs have been applied to analyze the functional diversity, composition, structure, and metabolic potential or activity of a variety of microbial communities from different habitats, such as aquatic ecosystems, soils, contaminated sites, extreme environments, and bioreactors. FGAs are able to address fundamental questions related to global change, bioremediation, land use, human health, and ecological theories, and link the microbial community structure to environmental properties and ecosystem functioning. This review focuses on applications of FGA technology for profiling microbial communities, including target preparation, hybridization and data processing, and data analysis. We also discuss challenges and future directions of FGA applications.
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Affiliation(s)
- Zhili He
- Institute for Environmental Genomics, Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA
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13
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Zehr JP, Kudela RM. Nitrogen cycle of the open ocean: from genes to ecosystems. ANNUAL REVIEW OF MARINE SCIENCE 2011; 3:197-225. [PMID: 21329204 DOI: 10.1146/annurev-marine-120709-142819] [Citation(s) in RCA: 167] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The marine nitrogen (N) cycle controls the productivity of the oceans. This cycle is driven by complex biogeochemical transformations, including nitrogen fixation, denitrification, and assimilation and anaerobic ammonia oxidation, mediated by microorganisms. New processes and organisms continue to be discovered, complicating the already complex picture of oceanic N cycling. Genomics research has uncovered the diversity of nitrogen metabolism strategies in phytoplankton and bacterioplankton. The elemental ratios of nutrients in biological material are more flexible than previously believed, with implications for vertical export of carbon and associated nutrients to the deep ocean. Estimates of nitrogen fixation and denitrification continue to be modified, and anaerobic ammonia oxidation has been identified as a new process involved in denitrification in oxygen minimum zones. The nitrogen cycle in the oceans is an integral feature of the function of ocean ecosystems and will be a central player in how oceans respond during global environmental change.
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Affiliation(s)
- Jonathan P Zehr
- Ocean Sciences Department, University of California, Santa Cruz, California 95064, USA.
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14
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Rinta-Kanto JM, Bürgmann H, Gifford SM, Sun S, Sharma S, del Valle DA, Kiene RP, Moran MA. Analysis of sulfur-related transcription by Roseobacter communities using a taxon-specific functional gene microarray. Environ Microbiol 2010; 13:453-67. [DOI: 10.1111/j.1462-2920.2010.02350.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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Sipari H, Rantala-Ylinen A, Jokela J, Oksanen I, Sivonen K. Development of a chip assay and quantitative PCR for detecting microcystin synthetase E gene expression. Appl Environ Microbiol 2010; 76:3797-805. [PMID: 20400558 PMCID: PMC2893508 DOI: 10.1128/aem.00452-10] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Accepted: 04/10/2010] [Indexed: 11/20/2022] Open
Abstract
The chip and quantitative real-time PCR (qPCR) assays were optimized to study the expression of microcystin biosynthesis genes (mcy) with RNA samples extracted from cyanobacterial strains and environmental water samples. Both microcystin-producing Anabaena and Microcystis were identified in Lake Tuusulanjärvi samples. Microcystis transcribed the mcyE genes throughout the summer of 2006, while expression by Anabaena became evident later in August and September. Active mcyE gene expression was also detectable when microcystin concentrations were very low. Detection of Anabaena mcyE transcripts by qPCR, as well as certain cyanobacterial 16S rRNAs with the chip assay, showed slightly reduced sensitivity compared with the DNA analyses. In contrast, even groups undetectable or present in low quantities as determined by microscopy could be identified with the chip assay from DNA samples. The methods introduced add to the previously scarce repertoire of applications for mcy expression profiling in environmental samples and enable in situ studies of regulation of microcystin synthesis in response to environmental factors.
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Affiliation(s)
- Hanna Sipari
- Department of Food and Environmental Sciences, Division of Microbiology, University of Helsinki, Viikki Biocenter 1, P.O. Box 56, FI-00014 Helsinki, Finland
| | - Anne Rantala-Ylinen
- Department of Food and Environmental Sciences, Division of Microbiology, University of Helsinki, Viikki Biocenter 1, P.O. Box 56, FI-00014 Helsinki, Finland
| | - Jouni Jokela
- Department of Food and Environmental Sciences, Division of Microbiology, University of Helsinki, Viikki Biocenter 1, P.O. Box 56, FI-00014 Helsinki, Finland
| | - Ilona Oksanen
- Department of Food and Environmental Sciences, Division of Microbiology, University of Helsinki, Viikki Biocenter 1, P.O. Box 56, FI-00014 Helsinki, Finland
| | - Kaarina Sivonen
- Department of Food and Environmental Sciences, Division of Microbiology, University of Helsinki, Viikki Biocenter 1, P.O. Box 56, FI-00014 Helsinki, Finland
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16
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Mayali X, Palenik B, Burton RS. Dynamics of marine bacterial and phytoplankton populations using multiplex liquid bead array technology. Environ Microbiol 2010; 12:975-89. [DOI: 10.1111/j.1462-2920.2004.02142.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Iwai S, Kurisu F, Urakawa H, Yagi O, Furumai H. Characterization of monooxygenase gene diversity in benzene-amended soils. Lett Appl Microbiol 2009; 50:138-45. [PMID: 19912525 DOI: 10.1111/j.1472-765x.2009.02764.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM To understand soil benzene monooxygenase gene diversity by clone library construction and microarray profiling. METHODS AND RESULTS A primer set was designed, and benzene monooxygenase gene diversity was characterized in two benzene-amended soils. The dominant sequence types in the clone libraries were distinct between the two soils, and both sequences were assigned to novel clusters. Monooxygenase gene richness and diversity increased after benzene degradation. Oligonucleotide probes for microarray analysis were designed to detect a number of sequenced clones and reported monooxygenase genes. The microarray detected several genes that were not detected in the clone libraries of the same samples. Six probes were detected in more than one soil. CONCLUSIONS The primer set designed in this study successfully detected diverse benzene monooxygenase genes. The level of diversity may have increased because the degradation of benzene differed from soil to soil. Microarrays have great potential in the comprehensive detection of gene richness as well as the elucidation of key genes for degradation. SIGNIFICANCE AND IMPACT OF THE STUDY This study introduces a new primer set that may be used to identify diverse benzene monooxygenase genes in the environment; moreover, it demonstrates the potential of microarray technology in the profiling of environmental samples.
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Affiliation(s)
- S Iwai
- Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
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18
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Duc L, Neuenschwander S, Rehrauer H, Wagner U, Sobek J, Schlapbach R, Zeyer J. Development and experimental validation of anifHoligonucleotide microarray to study diazotrophic communities in a glacier forefield. Environ Microbiol 2009; 11:2179-89. [DOI: 10.1111/j.1462-2920.2009.01945.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Bulow SE, Francis CA, Jackson GA, Ward BB. Sediment denitrifier community composition andnirSgene expression investigated with functional gene microarrays. Environ Microbiol 2008; 10:3057-69. [DOI: 10.1111/j.1462-2920.2008.01765.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Ogilvie LA, Hirsch PR, Johnston AWB. Bacterial diversity of the broadbalk 'classical' winter wheat experiment in relation to long-term fertilizer inputs. MICROBIAL ECOLOGY 2008; 56:525-537. [PMID: 18347845 DOI: 10.1007/s00248-008-9372-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 01/09/2008] [Accepted: 02/05/2008] [Indexed: 05/26/2023]
Abstract
With more than 160 years of contrasting fertilizer regimes, the Broadbalk winter wheat experiment represents a unique experimental resource for studying the effects of long-term fertilizer application on microbial population diversity. Using DGGE and clone library analysis, we report here on eubacterial species diversity (16S rRNA gene) and diversity within two sets of gene products associated with microbial N acquisition: NifH (nitrogen fixation) and AmtB (ammonium transport). Comparisons were made within and between soils treated with mineral N fertilizer, farmyard manure or receiving no fertilizer. Analysis of 16S rRNA gene DGGE profiles showed no clear patterns to qualitatively distinguish bacterial community structure between the three different treatments (P > 0.05), with all samples containing a range of eubacterial taxa similar to those that are characteristic of soil bacteria reported elsewhere. Intra-plot heterogeneity was high and of a similar magnitude to that between treatments. This lack of qualitative between plot differences was echoed in the representative sequences of 16S rRNA, nifH, and amtB genes in the various samples. Taken together, both phylogenetic and functional gene analyses showed bacterial communities in the Broadbalk-trial soil were very stable and relatively non-responsive to long-term management of balanced fertilizer inputs.
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Affiliation(s)
- Lesley A Ogilvie
- Centre for Soils and Ecosystem Function, Department of Plant Pathology and Microbiology, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK.
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21
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Molecular eco-systems biology: towards an understanding of community function. Nat Rev Microbiol 2008; 6:693-9. [DOI: 10.1038/nrmicro1935] [Citation(s) in RCA: 293] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Iwai S, Kurisu F, Urakawa H, Yagi O, Kasuga I, Furumai H. Development of an oligonucleotide microarray to detect di- and monooxygenase genes for benzene degradation in soil. FEMS Microbiol Lett 2008; 285:111-21. [PMID: 18547327 DOI: 10.1111/j.1574-6968.2008.01223.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Diverse environmental genes have been identified recently. To characterize their functions, it is necessary to understand which genes and what combinations of those genes are responsible for the biodegradation of soil contaminants. In this article, a 60-mer oligonucleotide microarray was constructed to simultaneously detect di- and monooxygenase genes for benzene and related compounds. In total, 148 probes were designed and validated by pure-culture hybridizations using the following criteria to discriminate between highly homologous genes: < or =53-bp identities and < or =25-bp continuous stretch to nontarget sequences. Microarray hybridizations were performed using PCR products amplified from five benzene-amended soils and two oil-contaminated soils. Six of the probes gave a positive signal for more than six soils; thus, they may represent key sequences for benzene degradation in the environment. The microarray developed in this study will be a powerful tool for the screening of key genes involved in benzene degradation and for the rapid profiling of benzene oxygenase gene diversity in contaminated soils.
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Affiliation(s)
- Shoko Iwai
- Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan.
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23
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Moisander PH, Beinart RA, Voss M, Zehr JP. Diversity and abundance of diazotrophic microorganisms in the South China Sea during intermonsoon. ISME JOURNAL 2008; 2:954-67. [PMID: 18528417 DOI: 10.1038/ismej.2008.51] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The spatial heterogeneity of diversity and abundance of diazotrophs were investigated off the Vietnamese coast in the South China Sea (SCS). The study area extended from the Mekong River plume to the shelf region and beyond to stations extending to 1700 m depth. The SCS diazotroph community, based on nifH gene diversity, had components closely related to sequences from open ocean, estuarine, saltmarsh and microbial mat communities. Rarefaction analysis suggested that by using a 97% similarity operational taxonomic unit definition, the majority of nifH sequence diversity in the samples was covered by the 384 nifH clones obtained. The majority of the nifH sequences recovered fell into two clusters: one comprised of Trichodesmium sequences and the other an alpha-proteobacterial group. Unicellular cyanobacterial groups A and B, and symbiotic filamentous cyanobacterial diazotrophs were detected sporadically. Trichodesmium was by far the most abundant diazotroph, with up to 6 x 10(5) nifH gene copies per liter. Quantitative PCR probe-primer sets were designed and used to quantify two proteobacterial groups, revealing abundances up to 10(3)-10(4) nifH gene copies per liter, with the highest abundances in the photic zone. Major components of the clone library were also revealed by a nifH microarray and multidimensional scaling (MDS) analysis. MDS showed that samples from the >10 microm size fraction from 0- to 5-m depths clustered separately from the rest of the samples, primarily due to the abundance of Trichodesmium sequences. The SCS diazotroph community has a relatively low diversity and is a mixture of both estuarine and oceanic fingerprints.
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Affiliation(s)
- Pia H Moisander
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
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Moisander PH, Morrison AE, Ward BB, Jenkins BD, Zehr JP. Spatial-temporal variability in diazotroph assemblages in Chesapeake Bay using an oligonucleotide nifH microarray. Environ Microbiol 2008; 9:1823-35. [PMID: 17564615 DOI: 10.1111/j.1462-2920.2007.01304.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The distribution of nitrogen-fixing microorganisms in the Chesapeake Bay was investigated using fingerprints from a nifH microarray comprised of 706 60-mer oligonucleotide nifH probes representing cultivated organisms and environmental clones from different nifH clusters. Diverse nifH targets, amplified from samples using degenerate nifH primers, were detected in water column and sediment samples collected in April and October, 2001-2002. Total nifH richness and diversity (Simpson's and Shannon indices) were highest at the most riverine, oligohaline North Bay station. In most samples, the highest diversity was in nifH Cluster 3, which includes many anaerobes, while Cluster 1 (alpha-, beta- gamma- Proteobacteria, Cyanobacteria) targets had the greatest microarray signal intensities. In a multidimensional scaling analysis, deep water communities from April and October were similar within each of the sampling sites, while the surface communities had more variability. Diazotroph communities in the water column in the North Bay were distinct from the Mid- and South Bay communities, and there was a gradual change in sediment diazotroph assemblages from the North to the South Bay. Diazotrophic assemblages from the majority of the water column samples from the Mid- and South Bay clustered with the sediment assemblage in Mid-Bay. Dissolved inorganic nitrogen, salinity, dissolved organic carbon and dissolved organic phosphorus had a significant relationship with the diazotrophic bacterioplankton community. Higher diversity in the freshwater end of the system may reflect variability in disturbance rates and environmental conditions such as forms and concentrations of organic matter, nutrients and oxygen.
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Affiliation(s)
- Pia H Moisander
- Ocean Sciences Department, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
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25
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Hewson I, Moisander PH, Morrison AE, Zehr JP. Diazotrophic bacterioplankton in a coral reef lagoon: phylogeny, diel nitrogenase expression and response to phosphate enrichment. ISME JOURNAL 2008; 1:78-91. [PMID: 18043616 DOI: 10.1038/ismej.2007.5] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We investigated diazotrophic bacterioplankton assemblage composition in the Heron Reef lagoon (Great Barrier Reef, Australia) using culture-independent techniques targeting the nifH fragment of the nitrogenase gene. Seawater was collected at 3 h intervals over a period of 72 h (i.e. over diel as well as tidal cycles). An incubation experiment was also conducted to assess the impact of phosphate (PO(4)3*) availability on nifH expression patterns. DNA-based nifH libraries contained primarily sequences that were most similar to nifH from sediment, microbial mat and surface-associated microorganisms, with a few sequences that clustered with typical open ocean phylotypes. In contrast to genomic DNA sequences, libraries prepared from gene transcripts (mRNA amplified by reverse transcription-polymerase chain reaction) were entirely cyanobacterial and contained phylotypes similar to those observed in open ocean plankton. The abundance of Trichodesmium and two uncultured cyanobacterial phylotypes from previous studies (group A and group B) were studied by quantitative-polymerase chain reaction in the lagoon samples. These were detected as transcripts, but were not detected in genomic DNA. The gene transcript abundance of these phylotypes demonstrated variability over several diel cycles. The PO(4)3* enrichment experiment had a clearer pattern of gene expression over diel cycles than the lagoon sampling, however PO(4)3* additions did not result in enhanced transcript abundance relative to control incubations. The results suggest that a number of diazotrophs in bacterioplankton of the reef lagoon may originate from sediment, coral or beachrock surfaces, sloughing into plankton with the flooding tide. The presence of typical open ocean phylotype transcripts in lagoon bacterioplankton may indicate that they are an important component of the N cycle of the coral reef.
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Affiliation(s)
- Ian Hewson
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
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26
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Novel microarray design strategy to study complex bacterial communities. Appl Environ Microbiol 2008; 74:1876-85. [PMID: 18203854 DOI: 10.1128/aem.01722-07] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Assessing bacterial flora composition appears to be of increasing importance to fields as diverse as physiology, development, medicine, epidemiology, the environment, and the food industry. We report here the development and validation of an original microarray strategy that allows analysis of the phylogenic composition of complex bacterial mixtures. The microarray contains approximately 9,500 feature elements targeting 16S rRNA gene-specific regions. Probe design was performed by selecting oligonucleotide sequences specific to each node of the seven levels of the bacterial phylogenetic tree (domain, phylum, class, order, family, genus, and species). This approach, based on sequence information, allows analysis of the bacterial contents of complex bacterial mixtures to detect both known and unknown microorganisms. The presence of unknown organisms can be suspected and mapped on the phylogenetic tree, indicating where to refine analysis. Initial proof-of-concept experiments were performed on oral bacterial communities. Our results show that this hierarchical approach can reveal minor changes (<or=1%) in gingival flora content when samples collected in individuals from similar geographical origins are compared.
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