1
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Li J, Wang J, Liu H, Macdonald CA, Singh BK. Microbial inoculants with higher capacity to colonize soils improved wheat drought tolerance. Microb Biotechnol 2023; 16:2131-2144. [PMID: 37815273 PMCID: PMC10616649 DOI: 10.1111/1751-7915.14350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/16/2023] [Accepted: 09/20/2023] [Indexed: 10/11/2023] Open
Abstract
Microbial inoculants have gained increasing attention worldwide as an eco-friendly solution for improving agriculture productivity. Several studies have demonstrated their potential benefits, such as enhanced resistance to drought, salinity, and pathogens. However, the beneficial impacts of inoculants remain inconsistent. This variability is attributed to limited knowledge of the mechanisms by which microbial inoculants affect crop growth and a lack of ecological characteristics of these inoculants that limit our ability to predict their beneficial effects. The first important step is believed to be the evaluation of the inoculant's ability to colonize new habitats (soils and plant roots), which could provide crops with beneficial functions and improve the consistency and efficiency of the inoculants. In this study, we aimed to investigate the impact of three microbial inoculants (two bacterial: P1 and P2, and one fungal: P3) on the growth and stress responses of three wheat varieties in two different soil types under drought conditions. Furthermore, we investigated the impact of microbial inoculants on soil microbial communities. Plant biomass and traits were measured, and high-throughput sequencing was used to characterize bulk and rhizosphere soil microbiomes after exposure to drought stress. Under drought conditions, plant shoot weight significantly increased (11.37%) under P1 treatments compared to uninoculated controls. In addition, total nitrogen enzyme activity increased significantly under P1 in sandy soil but not in clay soil. Importantly, network analyses revealed that P1, consisting of Bacillus paralicheniformis and Bacillus subtilis, emerged as the keystone taxa in sandy soil. Conversely, P2 and P3 failed to establish as keystone taxa, which may explain their insignificant impact on wheat performance under drought conditions. In conclusion, our study emphasizes the importance of effective colonization by microbial inoculants in promoting crop growth under drought conditions. Our findings support the development of microbial inoculants that robustly colonize plant roots for improved agricultural productivity.
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Affiliation(s)
- Jiayu Li
- Hawkesbury Institute for the Environment, Western Sydney University, New South Wales, Penrith, Australia
| | - Juntao Wang
- Hawkesbury Institute for the Environment, Western Sydney University, New South Wales, Penrith, Australia
- Global Centre for Land-Based Innovation, Western Sydney University, New South Wales, Penrith, Australia
- School of Science, Western Sydney University, Penrith, New South Wales, Australia
| | - Hongwei Liu
- Hawkesbury Institute for the Environment, Western Sydney University, New South Wales, Penrith, Australia
| | - Catriona A Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, New South Wales, Penrith, Australia
| | - Brajesh K Singh
- Hawkesbury Institute for the Environment, Western Sydney University, New South Wales, Penrith, Australia
- Global Centre for Land-Based Innovation, Western Sydney University, New South Wales, Penrith, Australia
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2
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Zhang H, Churchill AC, Anderson IC, Igwenagu C, Power SA, Plett JM, Macdonald CA, Pendall E, Carrillo Y, Powell JR. Ecological stoichiometry and fungal community turnover reveal variation among mycorrhizal partners in their responses to warming and drought. Mol Ecol 2023; 32:229-243. [PMID: 34779067 DOI: 10.1111/mec.16278] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/24/2021] [Accepted: 10/26/2021] [Indexed: 12/29/2022]
Abstract
Symbiotic fungi mediate important energy and nutrient transfers in terrestrial ecosystems. Environmental change can lead to shifts in communities of symbiotic fungi, but the consequences of these shifts for nutrient dynamics among symbiotic partners are poorly understood. Here, we assessed variation in carbon (C), nitrogen (N) and phosphorus (P) in tissues of arbuscular mycorrhizal (AM) fungi and a host plant (Medicago sativa) in response to experimental warming and drought. We linked compositional shifts in AM fungal communities in roots and soil to variation in hyphal chemistry by using high-throughput DNA sequencing and joint species distribution modelling. Compared to plants, AM hyphae was 43% lower in (C) and 24% lower in (N) but more than nine times higher in (P), with significantly lower C:N, C:P and N:P ratios. Warming and drought resulted in increases in (P) and reduced C:P and N:P ratios in all tissues, indicating fungal P accumulation was exacerbated by climate-associated stress. Warming and drought modified the composition of AM fungal communities, and many of the AM fungal genera that were linked to shifts in mycelial chemistry were also negatively impacted by climate variation. Our study offers a unified framework to link climate change, fungal community composition, and community-level functional traits. Thus, our study provides insight into how environmental change can alter ecosystem functions via the promotion or reduction of fungal taxa with different stoichiometric characteristics and responses.
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Affiliation(s)
- Haiyang Zhang
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | - Amber C Churchill
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota, USA
| | - Ian C Anderson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | - Chioma Igwenagu
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | - Sally A Power
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | - Jonathan M Plett
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | - Catriona A Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | - Elise Pendall
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | - Yolima Carrillo
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | - Jeff R Powell
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
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3
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Qiu Z, Verma JP, Liu H, Wang J, Batista BD, Kaur S, de Araujo Pereira AP, Macdonald CA, Trivedi P, Weaver T, Conaty WC, Tissue DT, Singh BK. Response of the plant core microbiome to Fusarium oxysporum infection and identification of the pathobiome. Environ Microbiol 2022; 24:4652-4669. [PMID: 36059126 DOI: 10.1111/1462-2920.16194] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 09/01/2022] [Indexed: 11/29/2022]
Abstract
Plant core microbiomes consist of persistent key members that provide critical host functions, but their assemblages can be interrupted by biotic and abiotic stresses. The pathobiome is comprised of dynamic microbial interactions in response to disease status of the host. Hence, identifying variation in the core microbiome and pathobiome can significantly advance our understanding of microbial-microbial interactions and consequences for disease progression and host functions. In this study, we combined glasshouse and field studies to analyse the soil and plant rhizosphere microbiome of cotton plants (Gossypium hirsutum) in the presence of a cotton-specific fungal pathogen, Fusarium oxysporum f. sp. vasinfectum (FOV). We found that FOV directly and consistently altered the rhizosphere microbiome, but the biocontrol agents enabled microbial assemblages to resist pathogenic stress. Using co-occurrence network analysis of the core microbiome, we identified the pathobiome comprised of the pathogen and key associate phylotypes in the cotton microbiome. Isolation and application of some negatively correlated pathobiome members provided protection against plant infection. Importantly, our field survey from multiple cotton fields validated the pattern and responses of core microbiomes under FOV infection. This study advances key understanding of core microbiome responses and existence of plant pathobiomes, which provides a novel framework to better manage plant diseases in agriculture and natural settings. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Zhiguang Qiu
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Jay Prakash Verma
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia.,Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Hongwei Liu
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Juntao Wang
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia.,Global Centre for Land-Based Innovation, Western Sydney University, Penrith, NSW, Australia
| | - Bruna D Batista
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Simranjit Kaur
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | | | - Catriona A Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Pankaj Trivedi
- Microbiome Network and Department of Agricultural Biology, Colorado State University, Fort Collins, CO, USA
| | - Tim Weaver
- CSIRO Agriculture & Food, Locked Bag 59, Narrabri, NSW, Australia
| | - Warren C Conaty
- CSIRO Agriculture & Food, Locked Bag 59, Narrabri, NSW, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia.,Global Centre for Land-Based Innovation, Western Sydney University, Penrith, NSW, Australia
| | - Brajesh K Singh
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia.,Global Centre for Land-Based Innovation, Western Sydney University, Penrith, NSW, Australia
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4
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Jurburg SD, Eisenhauer N, Buscot F, Chatzinotas A, Chaudhari NM, Heintz-Buschart A, Kallies R, Küsel K, Litchman E, Macdonald CA, Müller S, Reuben RC, da Rocha UN, Panagiotou G, Rillig MC, Singh BK. Potential of microbiome-based solutions for agrifood systems. Nat Food 2022; 3:557-560. [PMID: 37118595 DOI: 10.1038/s43016-022-00576-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Affiliation(s)
- Stephanie D Jurburg
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
- Institute of Biology, Leipzig University, Leipzig, Germany.
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
| | - Nico Eisenhauer
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Institute of Biology, Leipzig University, Leipzig, Germany
| | - François Buscot
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Department of Soil Ecology, Helmholtz Centre for Environmental Research-UFZ, Halle, Germany
| | - Antonis Chatzinotas
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Institute of Biology, Leipzig University, Leipzig, Germany
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Narendrakumar M Chaudhari
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Aquatic Geomicrobiology, Institute of Biodiversity, Friedrich Schiller University, Jena, Germany
| | - Anna Heintz-Buschart
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Department of Soil Ecology, Helmholtz Centre for Environmental Research-UFZ, Halle, Germany
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Rene Kallies
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Kirsten Küsel
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Aquatic Geomicrobiology, Institute of Biodiversity, Friedrich Schiller University, Jena, Germany
| | - Elena Litchman
- Kellogg Biological Station, Michigan State University, Hickory Corners, MI, USA
- Ecology, Evolution and Behavior Program, Michigan State University, East Lansing, MI, USA
- Department of Global Ecology, Carnegie Institution for Science, Stanford, CA, USA
| | - Catriona A Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
| | - Susann Müller
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Rine C Reuben
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Institute of Biology, Leipzig University, Leipzig, Germany
| | - Ulisses Nunes da Rocha
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Gianni Panagiotou
- Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
- The State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Kowloon, Hong Kong SAR, China
- Department of Medicine, The University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Matthias C Rillig
- Institut für Biologie, Freie Universität Berlin, Berlin, Germany
- Berlin-Brandenburg Institute of Advanced Biodiversity Research, Berlin, Germany
| | - Brajesh K Singh
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia.
- Global Centre for Land-Based Innovation, Western Sydney University, Penrith, New South Wales, Australia.
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5
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Eldridge DJ, Oliver I, Powell JR, Dorrough J, Carrillo Y, Nielsen UN, Macdonald CA, Wilson B, Fyfe C, Amarasinghe A, Kuginis L, Peake T, Robinson T, Howe B, Delgado‐Baquerizo M. Temporal dynamics in biotic and functional recovery following mining. J Appl Ecol 2022. [DOI: 10.1111/1365-2664.14172] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- David J. Eldridge
- Department of Planning, Industry and Environment, c/‐ Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences University of New South Wales Sydney, New South Wales 2052 Australia
| | - Ian Oliver
- Department of Planning, Industry and Environment, Locked Bag 2906 Lisarow NSW 2250 Australia
| | - Jeff R. Powell
- Hawkesbury Institute for the Environment Western Sydney University Penrith, NSW 2751 Australia
| | - Josh Dorrough
- Department of Planning, Industry and Environment, P.O. Box PO Box 656, Merimbula NSW 2548 Australia
| | - Yolima Carrillo
- Hawkesbury Institute for the Environment Western Sydney University Penrith, NSW 2751 Australia
| | - Uffe N. Nielsen
- Hawkesbury Institute for the Environment Western Sydney University Penrith, NSW 2751 Australia
| | - Catriona A. Macdonald
- Hawkesbury Institute for the Environment Western Sydney University Penrith, NSW 2751 Australia
| | - Brian Wilson
- Department of Planning, Industry and Environment, c/‐ School of Environmental and Rural Science University of New England Armidale, NSW 2351 Australia
| | - Christine Fyfe
- chool of Environmental and Rural Science University of New England Armidale, NSW 2351 Australia
| | - Apsara Amarasinghe
- chool of Environmental and Rural Science University of New England Armidale, NSW 2351 Australia
| | - Laura Kuginis
- Department of Planning, Industry and Environment, P.O. Box 1226 Newcastle, NSW, 2300 Australia
| | - Travis Peake
- Umwelt (Australia) Pty Limited, 75 York Street, Teralba NSW 2284 Australia
| | - Trish Robinson
- Umwelt (Australia) Pty Limited, 75 York Street, Teralba NSW 2284 Australia
| | - Belinda Howe
- Umwelt (Australia) Pty Limited, 75 York Street, Teralba NSW 2284 Australia
| | - Manuel Delgado‐Baquerizo
- Laboratorio de Biodiversidad y Funcionamiento Ecosistémico. Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Av. Reina Mercedes 10, E‐41012 Sevilla Spain
- Unidad Asociada CSIC‐UPO (BioFun). Universidad Pablo de Olavide, 41013 Sevilla Spain
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6
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Churchill AC, Zhang H, Fuller KJ, Amiji B, Anderson IC, Barton CVM, Carrillo Y, Catunda KLM, Chandregowda MH, Igwenagu C, Jacob V, Kim GW, Macdonald CA, Medlyn BE, Moore BD, Pendall E, Plett JM, Post AK, Powell JR, Tissue DT, Tjoelker MG, Power SA. Pastures and Climate Extremes: Impacts of Cool Season Warming and Drought on the Productivity of Key Pasture Species in a Field Experiment. Front Plant Sci 2022; 13:836968. [PMID: 35321443 PMCID: PMC8937038 DOI: 10.3389/fpls.2022.836968] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Shifts in the timing, intensity and/or frequency of climate extremes, such as severe drought and heatwaves, can generate sustained shifts in ecosystem function with important ecological and economic impacts for rangelands and managed pastures. The Pastures and Climate Extremes experiment (PACE) in Southeast Australia was designed to investigate the impacts of a severe winter/spring drought (60% rainfall reduction) and, for a subset of species, a factorial combination of drought and elevated temperature (ambient +3°C) on pasture productivity. The experiment included nine common pasture and Australian rangeland species from three plant functional groups (C3 grasses, C4 grasses and legumes) planted in monoculture. Winter/spring drought resulted in productivity declines of 45% on average and up to 74% for the most affected species (Digitaria eriantha) during the 6-month treatment period, with eight of the nine species exhibiting significant yield reductions. Despite considerable variation in species' sensitivity to drought, C4 grasses were more strongly affected by this treatment than C3 grasses or legumes. Warming also had negative effects on cool-season productivity, associated at least partially with exceedance of optimum growth temperatures in spring and indirect effects on soil water content. The combination of winter/spring drought and year-round warming resulted in the greatest yield reductions. We identified responses that were either additive (Festuca), or less-than-additive (Medicago), where warming reduced the magnitude of drought effects. Results from this study highlight the sensitivity of diverse pasture species to increases in winter and spring drought severity similar to those predicted for this region, and that anticipated benefits of cool-season warming are unlikely to be realized. Overall, the substantial negative impacts on productivity suggest that future, warmer, drier climates will result in shortfalls in cool-season forage availability, with profound implications for the livestock industry and natural grazer communities.
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Affiliation(s)
- Amber C. Churchill
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Haiyang Zhang
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Kathryn J. Fuller
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Burhan Amiji
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Ian C. Anderson
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Craig V. M. Barton
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Yolima Carrillo
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Karen L. M. Catunda
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | | | - Chioma Igwenagu
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Vinod Jacob
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Gil Won Kim
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju, South Korea
| | - Catriona A. Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Belinda E. Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Ben D. Moore
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Elise Pendall
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Jonathan M. Plett
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Alison K. Post
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- The Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
| | - Jeff R. Powell
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - David T. Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- Global Centre for Land-Based Innovation, Western Sydney University, Hawkesbury Campus, Richmond, NSW, Australia
| | - Mark G. Tjoelker
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Sally A. Power
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
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7
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Jayaramaiah RH, Egidi E, Macdonald CA, Wang J, Jeffries TC, Megharaj M, Singh BK. Soil initial bacterial diversity and nutrient availability determine the rate of xenobiotic biodegradation. Microb Biotechnol 2022; 15:318-336. [PMID: 34689422 PMCID: PMC8719800 DOI: 10.1111/1751-7915.13946] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 09/28/2021] [Accepted: 09/29/2021] [Indexed: 01/23/2023] Open
Abstract
Understanding the relative importance of soil microbial diversity, plants and nutrient management is crucial to implement an effective bioremediation approach to xenobiotics-contaminated soils. To date, knowledge on the interactive effects of soil microbiome, plant and nutrient supply on influencing biodegradation potential of soils remains limited. In this study, we evaluated the individual and interactive effects of soil initial bacterial diversity, nutrient amendments (organic and inorganic) and plant presence on the biodegradation rate of pyrene, a polycyclic aromatic hydrocarbon. Initial bacterial diversity had a strong positive impact on soil biodegradation potential, with soil harbouring higher bacterial diversity showing ~ 2 times higher degradation rates than soils with lower bacterial diversity. Both organic and inorganic nutrient amendments consistently improved the degradation rate in lower diversity soils and had negative (inorganic) to neutral (organic) effect in higher diversity soils. Interestingly, plant presence/type did not show any significant effect on the degradation rate in most of the treatments. Structural equation modelling demonstrated that initial bacterial diversity had a prominent role in driving pyrene biodegradation rates. We provide novel evidence that suggests that soil initial microbial diversity, and nutrient amendments should be explicitly considered in the design and employment of bioremediation management strategies for restoring natural habitats disturbed by organic pollutants.
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Affiliation(s)
- Ramesha H. Jayaramaiah
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSW2751Australia
| | - Eleonora Egidi
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSW2751Australia
- Global Centre for Land‐based InnovationWestern Sydney UniversityPenrithNSW2751Australia
| | - Catriona A. Macdonald
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSW2751Australia
| | - Jun‐Tao Wang
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSW2751Australia
- Global Centre for Land‐based InnovationWestern Sydney UniversityPenrithNSW2751Australia
| | - Thomas C. Jeffries
- Global Centre for Land‐based InnovationWestern Sydney UniversityPenrithNSW2751Australia
- School of ScienceWestern Sydney UniversityPenrithNSW2751Australia
| | - Mallavarapu Megharaj
- Global Centre for Environmental RemediationThe University of NewcastleCallaghanNSW2308Australia
| | - Brajesh K. Singh
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSW2751Australia
- Global Centre for Land‐based InnovationWestern Sydney UniversityPenrithNSW2751Australia
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8
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Martins CSC, Nazaries L, Delgado‐Baquerizo M, Macdonald CA, Anderson IC, Singh BK. Rainfall frequency and soil water availability regulate soil methane and nitrous oxide fluxes from a native forest exposed to elevated carbon dioxide. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Loïc Nazaries
- Hawkesbury Institute for the EnvironmentWestern Sydney University Penrith NSW Australia
| | - Manuel Delgado‐Baquerizo
- Departamento de Sistemas Físicos Químicos y Naturales Universidad Pablo de Olavide Sevilla Spain
| | - Catriona A. Macdonald
- Hawkesbury Institute for the EnvironmentWestern Sydney University Penrith NSW Australia
| | - Ian C. Anderson
- Hawkesbury Institute for the EnvironmentWestern Sydney University Penrith NSW Australia
| | - Brajesh K. Singh
- Hawkesbury Institute for the EnvironmentWestern Sydney University Penrith NSW Australia
- Global Centre for Land‐Based Innovation Western Sydney University Penrith NSW Australia
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9
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Kostin JE, Cesarz S, Lochner A, Schädler M, Macdonald CA, Eisenhauer N. Land-use drives the temporal stability and magnitude of soil microbial functions and modulates climate effects. Ecol Appl 2021; 31:e02325. [PMID: 33709490 DOI: 10.1002/eap.2325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 11/01/2020] [Accepted: 11/30/2020] [Indexed: 06/12/2023]
Abstract
Soil microbial community functions are essential indicators of ecosystem multifunctionality in managed land-use systems. Going forward, the development of adaptation strategies and predictive models under future climate scenarios will require a better understanding of how both land-use and climate disturbances influence soil microbial functions over time. Between March and November 2018, we assessed the effects of climate change on the magnitude and temporal stability of soil basal respiration, soil microbial biomass and soil functional diversity across a range of land-use types and intensities in a large-scale field experiment. Soils were sampled from five common land-use types including conventional and organic croplands, intensive and extensive meadows, and extensive pastures, under ambient and projected future climate conditions (reduced summer precipitation and increased temperature) at the Global Change Experimental Facility (GCEF) in Bad Lauchstädt, Germany. Land-use and climate treatment interaction effects were significant in September, a month when precipitation levels slightly rebounded following a period of drought in central Germany: compared to ambient climate, in future climate treatments, basal respiration declined in pastures and increased in intensive meadows, functional diversity declined in pastures and croplands, and respiration-to-biomass ratio increased in intensive and extensive meadows. Low rainfall between May and August likely strengthened soil microbial responses toward the future climate treatment in September. Although microbial biomass showed declining levels in extensive meadows and pastures under future climate treatments, overall, microbial function magnitudes were higher in these land-use types compared to croplands, indicating that improved management practices could sustain high microbial ecosystem functioning in future climates. In contrast to our hypothesis that more disturbed land-use systems would have destabilized microbial functions, intensive meadows and organic croplands showed stabilized soil microbial biomass compared to all other land-use types, suggesting that temporal stability, in addition to magnitude-based measurements, may be useful for revealing context-dependent effects on soil ecosystem functioning.
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Affiliation(s)
- Julia E Kostin
- German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, 04103, Germany
- Faculty of Management Science and Economics, Leipzig University, Grimmaische Straße 12, Leipzig, 04109, Germany
| | - Simone Cesarz
- German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, 04103, Germany
- Institute of Biology, Leipzig University, Deutscher Platz 5e, Leipzig, 04103, Germany
| | - Alfred Lochner
- German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, 04103, Germany
| | - Martin Schädler
- German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, 04103, Germany
- Department of Community Ecology, Helmholtz-Centre for Environmental Research - UFZ, Theodor-Lieser-Street 4, Halle, 06120, Germany
| | - Catriona A Macdonald
- Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
| | - Nico Eisenhauer
- German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, 04103, Germany
- Institute of Biology, Leipzig University, Deutscher Platz 5e, Leipzig, 04103, Germany
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10
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Bond‐Lamberty B, Christianson DS, Malhotra A, Pennington SC, Sihi D, AghaKouchak A, Anjileli H, Altaf Arain M, Armesto JJ, Ashraf S, Ataka M, Baldocchi D, Andrew Black T, Buchmann N, Carbone MS, Chang S, Crill P, Curtis PS, Davidson EA, Desai AR, Drake JE, El‐Madany TS, Gavazzi M, Görres C, Gough CM, Goulden M, Gregg J, Gutiérrez del Arroyo O, He J, Hirano T, Hopple A, Hughes H, Järveoja J, Jassal R, Jian J, Kan H, Kaye J, Kominami Y, Liang N, Lipson D, Macdonald CA, Maseyk K, Mathes K, Mauritz M, Mayes MA, McNulty S, Miao G, Migliavacca M, Miller S, Miniat CF, Nietz JG, Nilsson MB, Noormets A, Norouzi H, O’Connell CS, Osborne B, Oyonarte C, Pang Z, Peichl M, Pendall E, Perez‐Quezada JF, Phillips CL, Phillips RP, Raich JW, Renchon AA, Ruehr NK, Sánchez‐Cañete EP, Saunders M, Savage KE, Schrumpf M, Scott RL, Seibt U, Silver WL, Sun W, Szutu D, Takagi K, Takagi M, Teramoto M, Tjoelker MG, Trumbore S, Ueyama M, Vargas R, Varner RK, Verfaillie J, Vogel C, Wang J, Winston G, Wood TE, Wu J, Wutzler T, Zeng J, Zha T, Zhang Q, Zou J. COSORE: A community database for continuous soil respiration and other soil-atmosphere greenhouse gas flux data. Glob Chang Biol 2020; 26:7268-7283. [PMID: 33026137 PMCID: PMC7756728 DOI: 10.1111/gcb.15353] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/04/2020] [Accepted: 09/04/2020] [Indexed: 05/07/2023]
Abstract
Globally, soils store two to three times as much carbon as currently resides in the atmosphere, and it is critical to understand how soil greenhouse gas (GHG) emissions and uptake will respond to ongoing climate change. In particular, the soil-to-atmosphere CO2 flux, commonly though imprecisely termed soil respiration (RS ), is one of the largest carbon fluxes in the Earth system. An increasing number of high-frequency RS measurements (typically, from an automated system with hourly sampling) have been made over the last two decades; an increasing number of methane measurements are being made with such systems as well. Such high frequency data are an invaluable resource for understanding GHG fluxes, but lack a central database or repository. Here we describe the lightweight, open-source COSORE (COntinuous SOil REspiration) database and software, that focuses on automated, continuous and long-term GHG flux datasets, and is intended to serve as a community resource for earth sciences, climate change syntheses and model evaluation. Contributed datasets are mapped to a single, consistent standard, with metadata on contributors, geographic location, measurement conditions and ancillary data. The design emphasizes the importance of reproducibility, scientific transparency and open access to data. While being oriented towards continuously measured RS , the database design accommodates other soil-atmosphere measurements (e.g. ecosystem respiration, chamber-measured net ecosystem exchange, methane fluxes) as well as experimental treatments (heterotrophic only, etc.). We give brief examples of the types of analyses possible using this new community resource and describe its accompanying R software package.
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Affiliation(s)
- Ben Bond‐Lamberty
- Pacific Northwest National LaboratoryJoint Global Change Research Institute at the University of Maryland–College ParkCollege ParkMDUSA
| | | | - Avni Malhotra
- Department of Earth System ScienceStanford UniversityStanfordCAUSA
| | - Stephanie C. Pennington
- Pacific Northwest National LaboratoryJoint Global Change Research Institute at the University of Maryland–College ParkCollege ParkMDUSA
| | - Debjani Sihi
- Climate Change Science Institute and Environmental Sciences DivisionOak Ridge National LaboratoryOak RidgeTNUSA
- Present address:
Department of Environmental SciencesEmory UniversityAtlantaGAUSA
| | - Amir AghaKouchak
- Department of Civil and Environmental EngineeringUniversity of California IrvineIrvineCAUSA
| | - Hassan Anjileli
- Department of Civil and Environmental EngineeringUniversity of California IrvineIrvineCAUSA
| | - M. Altaf Arain
- School of Geography and Earth SciencesMcMaster UniversityHamiltonOntarioCanada
| | - Juan J. Armesto
- Departamento de EcologíaPontificia Universidad Católica de ChileSantiagoChile
- Instituto de Ecología y BiodiversidadSantiagoChile
| | - Samaneh Ashraf
- Department of Building, Civil and Environmental EngineeringConcordia UniversityMontrealQCCanada
| | - Mioko Ataka
- Research Institute for Sustainable HumanosphereKyoto UniversityUji CityKyotoJapan
| | - Dennis Baldocchi
- Department of Environmental Science, Policy, and ManagementUniversity of CaliforniaBerkeleyCAUSA
| | - Thomas Andrew Black
- Faculty of Land and Food SystemsUniversity of British ColumbiaVancouverBCCanada
| | - Nina Buchmann
- Department of Environmental Systems ScienceInstitute of Agricultural SciencesETH ZurichZurichSwitzerland
| | - Mariah S. Carbone
- Center for Ecosystem Science and SocietyNorthern Arizona UniversityFlagstaffAZUSA
| | - Shih‐Chieh Chang
- Department of Natural Resources and Environmental StudiesCenter for Interdisciplinary Research on Ecology and SustainabilityNational Dong Hwa UniversityHualienTaiwan
| | - Patrick Crill
- Department of Geological Sciences and Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
| | - Peter S. Curtis
- Department of Evolution, Ecology and Organismal BiologyOhio State UniversityColumbusOHUSA
| | - Eric A. Davidson
- Appalachian LaboratoryUniversity of Maryland Center for Environmental ScienceFrostburgMDUSA
| | - Ankur R. Desai
- Department of Atmospheric and Oceanic SciencesUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - John E. Drake
- Sustainable Resources ManagementSUNY‐ESFSyracuseNYUSA
| | | | - Michael Gavazzi
- Eastern Forest Environmental Threat Assessment CenterUSDA Forest ServiceResearch Triangle ParkNCUSA
| | | | | | | | - Jillian Gregg
- Sustainability Double Degree ProgramOregon State UniversityCorvallisORUSA
| | | | - Jin‐Sheng He
- Institute of EcologyCollege of Urban and Environmental SciencesPeking UniversityBeijingChina
| | - Takashi Hirano
- Research Faculty of AgricultureHokkaido UniversitySapporoJapan
| | - Anya Hopple
- Pacific Northwest National LaboratoryRichlandWAUSA
- Smithsonian Environmental Research CenterEdgewaterMDUSA
| | - Holly Hughes
- School of Forest ResourcesUniversity of MaineOronoMEUSA
| | - Järvi Järveoja
- Department of Forest Ecology and ManagementSwedish University of Agricultural SciencesUmeåSweden
| | - Rachhpal Jassal
- Faculty of Land and Food SystemsUniversity of British ColumbiaVancouverBCCanada
| | - Jinshi Jian
- Pacific Northwest National LaboratoryJoint Global Change Research Institute at the University of Maryland–College ParkCollege ParkMDUSA
| | - Haiming Kan
- Beijing Research & Development Centre for Grass and EnvironmentBeijing Academy of Agriculture and Forestry SciencesBeijingChina
| | - Jason Kaye
- The Pennsylvania State UniversityUniversity ParkPAUSA
| | - Yuji Kominami
- Forestry and Forest Products Research InstituteTsukuba‐cityJapan
| | - Naishen Liang
- Center for Global Environmental ResearchNational Institute for Environmental StudiesTsukubaJapan
| | - David Lipson
- Biology DepartmentSan Diego State UniversitySan DiegoCAUSA
| | - Catriona A. Macdonald
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSWAustralia
| | - Kadmiel Maseyk
- School of Environment, Earth and Ecosystem SciencesThe Open UniversityMilton KeynesUK
| | - Kayla Mathes
- Integrated Life SciencesVirginia Commonwealth UniversityRichmondVAUSA
| | | | - Melanie A. Mayes
- Climate Change Science Institute and Environmental Sciences DivisionOak Ridge National LaboratoryOak RidgeTNUSA
| | - Steve McNulty
- Eastern Forest Environmental Threat Assessment CenterUSDA Forest ServiceResearch Triangle ParkNCUSA
| | - Guofang Miao
- School of Geographical SciencesFujian Normal UniversityFuzhouP.R. China
| | | | - Scott Miller
- University at AlbanyState University of New YorkNew YorkNYUSA
| | - Chelcy F. Miniat
- USDA Forest ServiceSouthern Research StationCoweeta Hydrologic LabOttoNCUSA
| | - Jennifer G. Nietz
- Department of Evolution, Ecology and Organismal BiologyOhio State UniversityColumbusOHUSA
| | - Mats B. Nilsson
- Department of Forest Ecology and ManagementSwedish University of Agricultural SciencesUmeåSweden
| | - Asko Noormets
- Department of Ecology and Conservation BiologyTexas A&M UniversityCollege StationTXUSA
| | - Hamidreza Norouzi
- New York City College of Technology and the Graduate CenterThe City University of New YorkNew YorkNYUSA
| | - Christine S. O’Connell
- Department of Environmental Science, Policy, and ManagementUniversity of CaliforniaBerkeleyCAUSA
- Department of Environmental StudiesMacalester CollegeSt PaulMNUSA
| | - Bruce Osborne
- UCD School of Biology and Environmental Science and UCD Earth InstituteUniversity College DublinDublinIreland
| | | | - Zhuo Pang
- Beijing Research & Development Centre for Grass and EnvironmentBeijing Academy of Agriculture and Forestry SciencesBeijingChina
| | - Matthias Peichl
- Department of Forest Ecology and ManagementSwedish University of Agricultural SciencesUmeåSweden
| | - Elise Pendall
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSWAustralia
| | - Jorge F. Perez‐Quezada
- Department of Environmental Science and Renewable Natural ResourcesUniversity of ChileSantiagoChile
- Institute of Ecology and BiodiversitySantiagoChile
| | - Claire L. Phillips
- USDA Agricultural Research ServiceForage Seed and Cereal Research UnitCorvallisORUSA
| | | | - James W. Raich
- Department of Ecology, Evolution & Organismal BiologyIowa State UniversityAmesIAUSA
| | - Alexandre A. Renchon
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSWAustralia
| | - Nadine K. Ruehr
- Institute of Meteorology and Climate Research–Atmospheric Environmental ResearchKIT‐Campus AlpinKarlsruhe Institute of TechnologyGarmisch‐PartenkirchenGermany
| | | | - Matthew Saunders
- School of Natural SciencesBotany DepartmentTrinity College DublinDublinIreland
| | | | | | | | - Ulli Seibt
- Department of Atmospheric and Oceanic SciencesUniversity of California Los AngelesLos AngelesCAUSA
| | - Whendee L. Silver
- Department of Environmental Science, Policy, and ManagementUniversity of CaliforniaBerkeleyCAUSA
| | - Wu Sun
- Department of Global EcologyCarnegie Institution for ScienceStanfordCAUSA
| | - Daphne Szutu
- Department of Environmental Science, Policy, and ManagementUniversity of CaliforniaBerkeleyCAUSA
| | - Kentaro Takagi
- Field Science Center for Northern BiosphereHokkaido UniversityHoronobeJapan
| | | | - Munemasa Teramoto
- Center for Global Environmental ResearchNational Institute for Environmental StudiesTsukubaJapan
- Present address:
Arid Land Research CenterTottori UniversityTottori680–0001Japan
| | - Mark G. Tjoelker
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSWAustralia
| | | | - Masahito Ueyama
- Graduate School of Life and Environmental SciencesOsaka Prefecture UniversitySakaiJapan
| | - Rodrigo Vargas
- Department of Plant and Soil SciencesUniversity of DelawareNewarkDEUSA
| | - Ruth K. Varner
- Department of Earth Sciences and Institute for the Study of Earth, Oceans and SpaceUniversity of New HampshireDurhamNHUSA
| | - Joseph Verfaillie
- Department of Environmental Science, Policy, and ManagementUniversity of CaliforniaBerkeleyCAUSA
| | | | - Jinsong Wang
- Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijingChina
| | - Greg Winston
- Department of Science, Engineering and MathematicsCypress CollegeCypressCAUSA
| | - Tana E. Wood
- USDA Forest Service International Institute of Tropical ForestryRío PiedrasPuerto Rico
| | - Juying Wu
- Beijing Research & Development Centre for Grass and EnvironmentBeijing Academy of Agriculture and Forestry SciencesBeijingChina
| | | | - Jiye Zeng
- Center for Global Environmental ResearchNational Institute for Environmental StudiesTsukubaJapan
| | - Tianshan Zha
- School of Soil and Water ConservationBeijing Forestry UniversityBeijingP.R. China
| | - Quan Zhang
- State Key Laboratory of Water Resources and Hydropower Engineering ScienceWuhan UniversityWuhanP.R. China
| | - Junliang Zou
- Beijing Research & Development Centre for Grass and EnvironmentBeijing Academy of Agriculture and Forestry SciencesBeijingChina
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Liu H, Macdonald CA, Cook J, Anderson IC, Singh BK. An Ecological Loop: Host Microbiomes across Multitrophic Interactions. Trends Ecol Evol 2019; 34:1118-1130. [DOI: 10.1016/j.tree.2019.07.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 07/12/2019] [Accepted: 07/22/2019] [Indexed: 10/26/2022]
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Singh BK, Trivedi P, Singh S, Macdonald CA, Verma JP. Emerging microbiome technologies for sustainable increase in farm productivity and environmental security. Microbiol Aust 2018. [DOI: 10.1071/ma18006] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Farming systems are under pressure to sustainably increase productivity to meet demand for food and fibre for a growing global population under shrinking arable lands and changing climatic conditions. Furthermore, conventional farming has led to declines in soil fertility and, in some cases, inappropriate and excessive use of chemical fertilisers and pesticides has caused soil degradation, negatively impacting human and environmental health. The soil and plant microbiomes are significant determinants of plant fitness and productivity. Microbes are also the main drivers of global biogeochemical cycles and thus key to sustainable agriculture. There is increasing evidence that with development of appropriate technologies, the plant microbiome can be harnessed to potentially decrease the frequency of plant diseases, increase resource use efficiencies and ultimately enhance agricultural productivity, while simultaneously decreasing the input of chemical fertilisers and pesticides, resulting in reduced greenhouse gas emissions and promoting environmental sustainability. However, to successfully translate potential to practical outcomes, both fundamental and applied research are needed to overcome current constraints. Research efforts need to be embedded in industrial requirements and policy and social frameworks to expedite the process of innovation, commercialisation and adoption. We propose that learning from the advancement in the human microbiome can significantly expedite the discovery and innovation of effective microbial products for sustainable and productive farming. This article summarises the emergence of microbiome technologies for the agriculture industry and how to facilitate the development and adoption of environmentally friendly microbiome technologies for sustainable increase in farm productivity.
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Martins CSC, Nazaries L, Delgado‐Baquerizo M, Macdonald CA, Anderson IC, Hobbie SE, Venterea RT, Reich PB, Singh BK. Identifying environmental drivers of greenhouse gas emissions under warming and reduced rainfall in boreal–temperate forests. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12928] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Catarina S. C. Martins
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Loïc Nazaries
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Manuel Delgado‐Baquerizo
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
- Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder CO USA
| | - Catriona A. Macdonald
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Ian C. Anderson
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Sarah E. Hobbie
- Department of Ecology, Evolution & Behaviour University of Minnesota Saint Paul MN USA
| | - Rodney T. Venterea
- Department of Soil, Water and Climate University of Minnesota Saint Paul MN USA
- USDA‐ARS Soil & Water Management Research Unit Saint Paul MN USA
| | - Peter B. Reich
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
- Department of Forest Resources University of Minnesota Saint Paul MN USA
| | - Brajesh K. Singh
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
- Global Centre for Land‐based Innovation Western Sydney University Penrith NSW Australia
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15
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Medlyn BE, De Kauwe MG, Zaehle S, Walker AP, Duursma RA, Luus K, Mishurov M, Pak B, Smith B, Wang YP, Yang X, Crous KY, Drake JE, Gimeno TE, Macdonald CA, Norby RJ, Power SA, Tjoelker MG, Ellsworth DS. Using models to guide field experiments: a priori predictions for the CO2 response of a nutrient- and water-limited native Eucalypt woodland. Glob Chang Biol 2016; 22:2834-51. [PMID: 26946185 DOI: 10.1111/gcb.13268] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 02/01/2016] [Accepted: 02/09/2016] [Indexed: 05/27/2023]
Abstract
The response of terrestrial ecosystems to rising atmospheric CO2 concentration (Ca ), particularly under nutrient-limited conditions, is a major uncertainty in Earth System models. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment, recently established in a nutrient- and water-limited woodland presents a unique opportunity to address this uncertainty, but can best do so if key model uncertainties have been identified in advance. We applied seven vegetation models, which have previously been comprehensively assessed against earlier forest FACE experiments, to simulate a priori possible outcomes from EucFACE. Our goals were to provide quantitative projections against which to evaluate data as they are collected, and to identify key measurements that should be made in the experiment to allow discrimination among alternative model assumptions in a postexperiment model intercomparison. Simulated responses of annual net primary productivity (NPP) to elevated Ca ranged from 0.5 to 25% across models. The simulated reduction of NPP during a low-rainfall year also varied widely, from 24 to 70%. Key processes where assumptions caused disagreement among models included nutrient limitations to growth; feedbacks to nutrient uptake; autotrophic respiration; and the impact of low soil moisture availability on plant processes. Knowledge of the causes of variation among models is now guiding data collection in the experiment, with the expectation that the experimental data can optimally inform future model improvements.
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Affiliation(s)
- Belinda E Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Martin G De Kauwe
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Sönke Zaehle
- Biogeochemical Integration Department, Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, D-07745, Jena, Germany
| | - Anthony P Walker
- Oak Ridge National Laboratory, Environmental Sciences Division and Climate Change Science Institute, 1 Bethel Valley Road, Oak Ridge, TN, USA
| | - Remko A Duursma
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Kristina Luus
- Biogeochemical Integration Department, Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, D-07745, Jena, Germany
| | - Mikhail Mishurov
- Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, 22362, Lund, Sweden
| | - Bernard Pak
- CSIRO Oceans and Atmosphere Flagship, Private Bag 1, Aspendale, Vic., 3195, Australia
| | - Benjamin Smith
- Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, 22362, Lund, Sweden
| | - Ying-Ping Wang
- CSIRO Oceans and Atmosphere Flagship, Private Bag 1, Aspendale, Vic., 3195, Australia
| | - Xiaojuan Yang
- Oak Ridge National Laboratory, Environmental Sciences Division and Climate Change Science Institute, 1 Bethel Valley Road, Oak Ridge, TN, USA
| | - Kristine Y Crous
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - John E Drake
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Teresa E Gimeno
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- ISPA, Bordeaux Science Agro, INRA, 33140, Villenave d'Ornon, France
| | - Catriona A Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Richard J Norby
- Oak Ridge National Laboratory, Environmental Sciences Division and Climate Change Science Institute, 1 Bethel Valley Road, Oak Ridge, TN, USA
| | - Sally A Power
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Mark G Tjoelker
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - David S Ellsworth
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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Hasegawa S, Macdonald CA, Power SA. Elevated carbon dioxide increases soil nitrogen and phosphorus availability in a phosphorus-limited Eucalyptus woodland. Glob Chang Biol 2016; 22:1628-43. [PMID: 26546164 DOI: 10.1111/gcb.13147] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 10/16/2015] [Accepted: 10/27/2015] [Indexed: 05/26/2023]
Abstract
Free-air CO2 enrichment (FACE) experiments have demonstrated increased plant productivity in response to elevated (e)CO2, with the magnitude of responses related to soil nutrient status. Whilst understanding nutrient constraints on productivity responses to eCO2 is crucial for predicting carbon uptake and storage, very little is known about how eCO2 affects nutrient cycling in phosphorus (P)-limited ecosystems. Our study investigates eCO2 effects on soil N and P dynamics at the EucFACE experiment in Western Sydney over an 18-month period. Three ambient and three eCO2 (+150 ppm) FACE rings were installed in a P-limited, mature Cumberland Plain Eucalyptus woodland. Levels of plant accessible nutrients, evaluated using ion exchange resins, were increased under eCO2, compared to ambient, for nitrate (+93%), ammonium (+12%) and phosphate (+54%). There was a strong seasonality to responses, particularly for phosphate, resulting in a relatively greater stimulation in available P, compared to N, under eCO2 in spring and summer. eCO2 was also associated with faster nutrient turnover rates in the first six months of the experiment, with higher N (+175%) and P (+211%) mineralization rates compared to ambient rings, although this difference did not persist. Seasonally dependant effects of eCO2 were seen for concentrations of dissolved organic carbon in soil solution (+31%), and there was also a reduction in bulk soil pH (-0.18 units) observed under eCO2. These results demonstrate that CO2 fertilization increases nutrient availability - particularly for phosphate - in P-limited soils, likely via increased plant belowground investment in labile carbon and associated enhancement of microbial turnover of organic matter and mobilization of chemically bound P. Early evidence suggests that there is the potential for the observed increases in P availability to support increased ecosystem C-accumulation under future predicted CO2 concentrations.
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Affiliation(s)
- Shun Hasegawa
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, SL5 7PY, UK
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Catriona A Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Sally A Power
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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Drake JE, Macdonald CA, Tjoelker MG, Crous KY, Gimeno TE, Singh BK, Reich PB, Anderson IC, Ellsworth DS. Short-term carbon cycling responses of a mature eucalypt woodland to gradual stepwise enrichment of atmospheric CO2 concentration. Glob Chang Biol 2016; 22:380-90. [PMID: 26426394 DOI: 10.1111/gcb.13109] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 08/25/2015] [Accepted: 08/28/2015] [Indexed: 05/26/2023]
Abstract
Projections of future climate are highly sensitive to uncertainties regarding carbon (C) uptake and storage by terrestrial ecosystems. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment was established to study the effects of elevated atmospheric CO2 concentrations (eCO2 ) on a native mature eucalypt woodland with low fertility soils in southeast Australia. In contrast to other FACE experiments, the concentration of CO2 at EucFACE was increased gradually in steps above ambient (+0, 30, 60, 90, 120, and 150 ppm CO2 above ambient of ~400 ppm), with each step lasting approximately 5 weeks. This provided a unique opportunity to study the short-term (weeks to months) response of C cycle flux components to eCO2 across a range of CO2 concentrations in an intact ecosystem. Soil CO2 efflux (i.e., soil respiration or Rsoil ) increased in response to initial enrichment (e.g., +30 and +60 ppm CO2 ) but did not continue to increase as the CO2 enrichment was stepped up to higher concentrations. Light-saturated photosynthesis of canopy leaves (Asat ) also showed similar stimulation by elevated CO2 at +60 ppm as at +150 ppm CO2 . The lack of significant effects of eCO2 on soil moisture, microbial biomass, or activity suggests that the increase in Rsoil likely reflected increased root and rhizosphere respiration rather than increased microbial decomposition of soil organic matter. This rapid increase in Rsoil suggests that under eCO2, additional photosynthate was produced, transported belowground, and respired. The consequences of this increased belowground activity and whether it is sustained through time in mature ecosystems under eCO2 are a priority for future research.
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Affiliation(s)
- John E Drake
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Catriona A Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Mark G Tjoelker
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Kristine Y Crous
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Teresa E Gimeno
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- INRA UMR 1391, ISPA, CS 20032, F-33140, Villenave d'Ornon, France
| | - Brajesh K Singh
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Peter B Reich
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Department of Forest Resources, University of Minnesota, 1530 Cleveland Avenue North, St. Paul, MN 55108, USA
| | - Ian C Anderson
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - David S Ellsworth
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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Macdonald CA, Crawley MJ, Wright DJ, Kuczynski J, Robinson L, Knight R, Al-Soud WA, Sørensen SJ, Deng Y, Zhou J, Singh BK. Identifying qualitative effects of different grazing types on below-ground communities and function in a long-term field experiment. Environ Microbiol 2014; 17:841-54. [PMID: 24935069 DOI: 10.1111/1462-2920.12539] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 06/09/2014] [Indexed: 11/30/2022]
Abstract
Herbivory is an important modulator of plant biodiversity and productivity in grasslands, but our understanding of herbivore-induced changes on below-ground processes and communities is limited. Using a long-term (17 years) experimental site, we evaluated impacts of rabbit and invertebrate grazers on some soil functions involved in carbon cycling, microbial diversity, structure and functional composition. Both rabbit and invertebrate grazing impacted soil functions and microbial community structure. All functional community measures (functions, biogeochemical cycling genes, network association between different taxa) were more strongly affected by invertebrate grazers than rabbits. Furthermore, our results suggest that exclusion of invertebrate grazers decreases both microbial biomass and abundance of genes associated with key biogeochemical cycles, and could thus have long-term consequences for ecosystem functions. The mechanism behind these impacts are likely to be driven by both direct effects of grazing altering the pattern of nutrient inputs and by indirect effects through changes in plant species composition. However, we could not entirely discount that the pesticide used to exclude invertebrates may have affected some microbial community measures. Nevertheless, our work illustrates that human activity that affects grazing intensity may affect ecosystem functioning and sustainability, as regulated by multi-trophic interactions between above- and below-ground communities.
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Affiliation(s)
- Catriona A Macdonald
- Hawkesbury Institute for the Environment, University of Western Sydney, Penrith, NSW, Australia
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Hu HW, Macdonald CA, Trivedi P, Holmes B, Bodrossy L, He JZ, Singh BK. Water addition regulates the metabolic activity of ammonia oxidizers responding to environmental perturbations in dry subhumid ecosystems. Environ Microbiol 2014; 17:444-61. [DOI: 10.1111/1462-2920.12481] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 04/04/2014] [Indexed: 01/26/2023]
Affiliation(s)
- Hang-Wei Hu
- Hawkesbury Institute for the Environment; University of Western Sydney; Penrith South DC NSW 2751 Australia
- State Key Laboratory of Urban and Regional Ecology; Research Center for Eco-Environmental Sciences; Chinese Academy of Sciences; Beijing 100085 China
| | - Catriona A. Macdonald
- Hawkesbury Institute for the Environment; University of Western Sydney; Penrith South DC NSW 2751 Australia
| | - Pankaj Trivedi
- Hawkesbury Institute for the Environment; University of Western Sydney; Penrith South DC NSW 2751 Australia
| | - Bronwyn Holmes
- Marine and Atmospheric Research and Wealth from Oceans National Research Flagship; CSIRO; Hobart Tas. Australia
| | - Levente Bodrossy
- Marine and Atmospheric Research and Wealth from Oceans National Research Flagship; CSIRO; Hobart Tas. Australia
| | - Ji-Zheng He
- State Key Laboratory of Urban and Regional Ecology; Research Center for Eco-Environmental Sciences; Chinese Academy of Sciences; Beijing 100085 China
| | - Brajesh K. Singh
- Hawkesbury Institute for the Environment; University of Western Sydney; Penrith South DC NSW 2751 Australia
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Singh BK, Quince C, Macdonald CA, Khachane A, Thomas N, Al-Soud WA, Sørensen SJ, He Z, White D, Sinclair A, Crooks B, Zhou J, Campbell CD. Loss of microbial diversity in soils is coincident with reductions in some specialized functions. Environ Microbiol 2014; 16:2408-20. [DOI: 10.1111/1462-2920.12353] [Citation(s) in RCA: 184] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 11/30/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Brajesh K. Singh
- Hawkesbury Institute for the Environment; University of Western Sydney; Penrith NSW Australia
| | | | - Catriona A. Macdonald
- Hawkesbury Institute for the Environment; University of Western Sydney; Penrith NSW Australia
| | - Amit Khachane
- Hawkesbury Institute for the Environment; University of Western Sydney; Penrith NSW Australia
| | | | - Waleed Abu Al-Soud
- Department of Biology; Faculty of Science; University of Copenhagen; Copenhagen Denmark
| | - Søren J. Sørensen
- Department of Biology; Faculty of Science; University of Copenhagen; Copenhagen Denmark
| | - Zhili He
- Department of Botany and Microbiology; Institute for Environmental Genomics; Stephenson Research and Technology Centre; University of Oklahoma; Norman OK USA
| | | | | | - Bill Crooks
- SRUC Auchincruive; Ayr Auchincruive Estate UK
| | - Jizhong Zhou
- Department of Botany and Microbiology; Institute for Environmental Genomics; Stephenson Research and Technology Centre; University of Oklahoma; Norman OK USA
| | - Colin D. Campbell
- The James Hutton Institute; Aberdeen UK
- Department of Soil and Environment; Swedish Agricultural Sciences University; Uppsala Sweden
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Sun T, Macdonald CA. Full-field transmission x-ray imaging with confocal polycapillary x-ray optics. J Appl Phys 2013; 113:53104. [PMID: 23460760 PMCID: PMC3579863 DOI: 10.1063/1.4789799] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 01/11/2013] [Indexed: 06/01/2023]
Abstract
A transmission x-ray imaging setup based on a confocal combination of a polycapillary focusing x-ray optic followed by a polycapillary collimating x-ray optic was designed and demonstrated to have good resolution, better than the unmagnified pixel size and unlimited by the x-ray tube spot size. This imaging setup has potential application in x-ray imaging for small samples, for example, for histology specimens.
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Macdonald CA, Ang R, Cordiner SJ, Horswell J. Discrimination of Soils at Regional and Local Levels Using Bacterial and Fungal T-RFLP Profiling*. J Forensic Sci 2010; 56:61-9. [DOI: 10.1111/j.1556-4029.2010.01542.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Singh BK, Macdonald CA. Drug discovery from uncultivable microorganisms. Drug Discov Today 2010; 15:792-9. [DOI: 10.1016/j.drudis.2010.07.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 06/09/2010] [Accepted: 07/19/2010] [Indexed: 10/19/2022]
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Macdonald CA, Campbell CD, Bacon JR, Singh BK. Multiple profiling of soil microbial communities identifies potential genetic markers of metal-enriched sewage sludge. FEMS Microbiol Ecol 2008; 65:555-64. [DOI: 10.1111/j.1574-6941.2008.00538.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Singh BK, Tate KR, Kolipaka G, Hedley CB, Macdonald CA, Millard P, Murrell JC. Effect of afforestation and reforestation of pastures on the activity and population dynamics of methanotrophic bacteria. Appl Environ Microbiol 2007; 73:5153-61. [PMID: 17574997 PMCID: PMC1950977 DOI: 10.1128/aem.00620-07] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated the effect of afforestation and reforestation of pastures on methane oxidation and the methanotrophic communities in soils from three different New Zealand sites. Methane oxidation was measured in soils from two pine (Pinus radiata) forests and one shrubland (mainly Kunzea ericoides var. ericoides) and three adjacent permanent pastures. The methane oxidation rate was consistently higher in the pine forest or shrubland soils than in the adjacent pasture soils. A combination of phospholipid fatty acid (PLFA) and stable isotope probing (SIP) analyses of these soils revealed that different methanotrophic communities were active in soils under the different vegetations. The C18 PLFAs (signature of type II methanotrophs) predominated under pine and shrublands, and C16 PLFAs (type I methanotrophs) predominated under pastures. Analysis of the methanotrophs by molecular methods revealed further differences in methanotrophic community structure under the different vegetation types. Cloning and sequencing and terminal-restriction fragment length polymorphism analysis of the particulate methane oxygenase gene (pmoA) from different samples confirmed the PLFA-SIP results that methanotrophic bacteria related to type II methanotrophs were dominant in pine forest and shrubland, and type I methanotrophs (related to Methylococcus capsulatus) were dominant in all pasture soils. We report that afforestation and reforestation of pastures caused changes in methane oxidation by altering the community structure of methanotrophic bacteria in these soils.
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Affiliation(s)
- Brajesh K Singh
- Macaulay Institute, Environmental Sciences, Aberdeen AB15 8QH, United Kingdom.
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Abstract
The recent invention of Kumakhov polycapillary x-ray and neutron optics has expanded the ways x-ray beams can be controlled. X rays incident on the interior of glass tubes at small angles can be guided down the tubes by total external reflection. Now, arrays of curved tapered capillaries can be used to focus, collimate, and filter x-ray radiation. Extensive research is being conducted on the performance and potential applications of these optics. Potential medical applications include mammography, digital energy subtraction angiography, and focused beam therapy. Other applications are x-ray lithography, x-ray astronomy, crystal diffraction, x-ray fluorescence, and neutron prompt gamma analysis.
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Affiliation(s)
- C A Macdonald
- Center for X-Ray Optics, University at Albany, Albany, New York I2222
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Chauhan BC, Macdonald CA. Influence of time separation on variability estimates of topographic measurements with confocal scanning laser tomography. J Glaucoma 1995; 4:189-193. [PMID: 19920667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
PURPOSE Confocal scanning laser tomography is a new technique with significant potential in the treatment of glaucoma. Before new techniques are widely implemented in clinical practice, factors that affect the variability of measurements should be identified. The purpose of this study was to determine the influence of various time separations between images on test-retest variability of topographic measurements. SUBJECTS AND METHODS Our sample contained 10 healthy subjects whose mean age was 46.30 years (range 25-60 years). For each subject we obtained six sets of three images each with the Heidelberg Retina Tomograph. The images in set 1 were obtained in one sitting, in set 2 separated by 1 h each, in set 3 by 1 day each, in set 4 by 1 week each, in set 5 by 2 weeks each, and in set 6 by 4 weeks each. RESULTS The mean (+/-1 standard deviation) test-retest variability, estimated in terms of the 90% confidence interval, ranged from 55.63 (+/-24.37) mum in set 1 to 64.37 (+/-28.00) mum in set 4. The differences between the variability estimates were not statistically significantly different among the six sets of images. CONCLUSIONS Our results show that the short-term and long-term variability of topographic measurements with scanning laser tomography are not different. Since variability was not influenced by images obtained at different sittings, our study suggests that the alignment algorithms used by the Heidelberg Retina Tomograph are robust.
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Affiliation(s)
- B C Chauhan
- Departments of *Ophthalmology and dagger;Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
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Abstract
An investigation of perceptual priming and semantic learning in the severely amnesic subject K.C. is reported. He was taught 64 three-word sentences and tested for his ability to produce the final word of each sentence. Despite a total lack of episodic memory, he exhibited (a) strong perceptual priming effects in word-fragment completion, which were retained essentially in full strength for 12 months, and (b) independent of perceptual priming, learning of new semantic facts, many of which were also retained for 12 months. K.C.'s semantic learning may be at least partly attributable to repeated study trials and minimal interference during learning. The findings suggest that perceptual priming and semantic learning are subserved by two memory systems different from episodic memory and that both systems (perceptual representation and semantic memory) are at least partially preserved in some amnesic subjects.
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Affiliation(s)
- E Tulving
- Department of Psychology, University of Toronto, Ontario, Canada
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