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Varliero G, Lebre PH, Adams B, Chown SL, Convey P, Dennis PG, Fan D, Ferrari B, Frey B, Hogg ID, Hopkins DW, Kong W, Makhalanyane T, Matcher G, Newsham KK, Stevens MI, Weigh KV, Cowan DA. Biogeographic survey of soil bacterial communities across Antarctica. Microbiome 2024; 12:9. [PMID: 38212738 PMCID: PMC10785390 DOI: 10.1186/s40168-023-01719-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 07/07/2023] [Accepted: 11/11/2023] [Indexed: 01/13/2024]
Abstract
BACKGROUND Antarctica and its unique biodiversity are increasingly at risk from the effects of global climate change and other human influences. A significant recent element underpinning strategies for Antarctic conservation has been the development of a system of Antarctic Conservation Biogeographic Regions (ACBRs). The datasets supporting this classification are, however, dominated by eukaryotic taxa, with contributions from the bacterial domain restricted to Actinomycetota and Cyanobacteriota. Nevertheless, the ice-free areas of the Antarctic continent and the sub-Antarctic islands are dominated in terms of diversity by bacteria. Our study aims to generate a comprehensive phylogenetic dataset of Antarctic bacteria with wide geographical coverage on the continent and sub-Antarctic islands, to investigate whether bacterial diversity and distribution is reflected in the current ACBRs. RESULTS Soil bacterial diversity and community composition did not fully conform with the ACBR classification. Although 19% of the variability was explained by this classification, the largest differences in bacterial community composition were between the broader continental and maritime Antarctic regions, where a degree of structural overlapping within continental and maritime bacterial communities was apparent, not fully reflecting the division into separate ACBRs. Strong divergence in soil bacterial community composition was also apparent between the Antarctic/sub-Antarctic islands and the Antarctic mainland. Bacterial communities were partially shaped by bioclimatic conditions, with 28% of dominant genera showing habitat preferences connected to at least one of the bioclimatic variables included in our analyses. These genera were also reported as indicator taxa for the ACBRs. CONCLUSIONS Overall, our data indicate that the current ACBR subdivision of the Antarctic continent does not fully reflect bacterial distribution and diversity in Antarctica. We observed considerable overlap in the structure of soil bacterial communities within the maritime Antarctic region and within the continental Antarctic region. Our results also suggest that bacterial communities might be impacted by regional climatic and other environmental changes. The dataset developed in this study provides a comprehensive baseline that will provide a valuable tool for biodiversity conservation efforts on the continent. Further studies are clearly required, and we emphasize the need for more extensive campaigns to systematically sample and characterize Antarctic and sub-Antarctic soil microbial communities. Video Abstract.
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Affiliation(s)
- Gilda Varliero
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, 0002, South Africa
- Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland
| | - Pedro H Lebre
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, 0002, South Africa
| | - Byron Adams
- Department of Biology, Brigham Young University, Provo, UT, 84602, USA
- Monte L. Bean Life Science Museum, Brigham Young University, Provo, UT, 84602, USA
| | - Steven L Chown
- Securing Antarctica's Environmental Future, School of Biological Sciences, Monash University, Clayton, VA, 3800, Australia
| | - Peter Convey
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
- Department of Zoology, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa
- Biodiversity of Antarctic and Sub-Antarctic Ecosystems (BASE), Santiago, Chile
| | - Paul G Dennis
- School of the Environment, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Dandan Fan
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Belinda Ferrari
- School of Biotechnology and Biomolecular Sciences, University of NSW, Sydney, NSW, 2052, Australia
| | - Beat Frey
- Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland
| | - Ian D Hogg
- School of Science, University of Waikato, Hamilton, New Zealand
- Canadian High Arctic Research Station, Polar Knowledge Canada, Cambridge Bay, NU, Canada
| | - David W Hopkins
- SRUC - Scotland's Rural College, West Mains Road, Edinburgh, EH9 3JG, Scotland, UK
| | - Weidong Kong
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Thulani Makhalanyane
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, 0002, South Africa
| | - Gwynneth Matcher
- Department of Biochemistry and Microbiology, Rhodes University, Makhanda, South Africa
| | - Kevin K Newsham
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - Mark I Stevens
- Securing Antarctica's Environmental Future, Earth and Biological Sciences, South Australian Museum, Adelaide, SA, 5000, Australia
- School of Biological Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Katherine V Weigh
- School of the Environment, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Don A Cowan
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, 0002, South Africa.
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Quiroga MV, Stegen JC, Mataloni G, Cowan D, Lebre PH, Valverde A. Microdiverse bacterial clades prevail across Antarctic wetlands. Mol Ecol 2024; 33:e17189. [PMID: 37909659 DOI: 10.1111/mec.17189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/06/2023] [Accepted: 10/16/2023] [Indexed: 11/03/2023]
Abstract
Antarctica's extreme environmental conditions impose selection pressures on microbial communities. Indeed, a previous study revealed that bacterial assemblages at the Cierva Point Wetland Complex (CPWC) are shaped by strong homogeneous selection. Yet which bacterial phylogenetic clades are shaped by selection processes and their ecological strategies to thrive in such extreme conditions remain unknown. Here, we applied the phyloscore and feature-level βNTI indexes coupled with phylofactorization to successfully detect bacterial monophyletic clades subjected to homogeneous (HoS) and heterogenous (HeS) selection. Remarkably, only the HoS clades showed high relative abundance across all samples and signs of putative microdiversity. The majority of the amplicon sequence variants (ASVs) within each HoS clade clustered into a unique 97% sequence similarity operational taxonomic unit (OTU) and inhabited a specific environment (lotic, lentic or terrestrial). Our findings suggest the existence of microdiversification leading to sub-taxa niche differentiation, with putative distinct ecotypes (consisting of groups of ASVs) adapted to a specific environment. We hypothesize that HoS clades thriving in the CPWC have phylogenetically conserved traits that accelerate their rate of evolution, enabling them to adapt to strong spatio-temporally variable selection pressures. Variable selection appears to operate within clades to cause very rapid microdiversification without losing key traits that lead to high abundance. Variable and homogeneous selection, therefore, operate simultaneously but on different aspects of organismal ecology. The result is an overall signal of homogeneous selection due to rapid within-clade microdiversification caused by variable selection. It is unknown whether other systems experience this dynamic, and we encourage future work evaluating the transferability of our results.
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Affiliation(s)
- María V Quiroga
- Instituto Tecnológico de Chascomús (CONICET-UNSAM), Buenos Aires, Argentina
- Escuela de Bio y Nanotecnologías (UNSAM), Buenos Aires, Argentina
| | - James C Stegen
- Pacific Northwest National Laboratory, Ecosystem Science Team, Richland, Washington, USA
| | - Gabriela Mataloni
- Instituto de Investigación e Ingeniería Ambiental (IIIA, CONICET-UNSAM), Buenos Aires, Argentina
| | - Don Cowan
- Centre for Microbial Ecology and Genomics (CMEG), Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Pedro H Lebre
- Centre for Microbial Ecology and Genomics (CMEG), Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Angel Valverde
- Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA), Consejo Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
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Mashamaite L, Lebre PH, Varliero G, Maphosa S, Ortiz M, Hogg ID, Cowan DA. Microbial diversity in Antarctic Dry Valley soils across an altitudinal gradient. Front Microbiol 2023; 14:1203216. [PMID: 37555066 PMCID: PMC10406297 DOI: 10.3389/fmicb.2023.1203216] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 06/23/2023] [Indexed: 08/10/2023] Open
Abstract
INTRODUCTION The Antarctic McMurdo Dry Valleys are geologically diverse, encompassing a wide variety of soil habitats. These environments are largely dominated by microorganisms, which drive the ecosystem services of the region. While altitude is a well-established driver of eukaryotic biodiversity in these Antarctic ice-free areas (and many non-Antarctic environments), little is known of the relationship between altitude and microbial community structure and functionality in continental Antarctica. METHODS We analysed prokaryotic and lower eukaryotic diversity from soil samples across a 684 m altitudinal transect in the lower Taylor Valley, Antarctica and performed a phylogenic characterization of soil microbial communities using short-read sequencing of the 16S rRNA and ITS marker gene amplicons. RESULTS AND DISCUSSION Phylogenetic analysis showed clear altitudinal trends in soil microbial composition and structure. Cyanobacteria were more prevalent in higher altitude samples, while the highly stress resistant Chloroflexota and Deinococcota were more prevalent in lower altitude samples. We also detected a shift from Basidiomycota to Chytridiomycota with increasing altitude. Several genera associated with trace gas chemotrophy, including Rubrobacter and Ornithinicoccus, were widely distributed across the entire transect, suggesting that trace-gas chemotrophy may be an important trophic strategy for microbial survival in oligotrophic environments. The ratio of trace-gas chemotrophs to photoautotrophs was significantly higher in lower altitude samples. Co-occurrence network analysis of prokaryotic communities showed some significant differences in connectivity within the communities from different altitudinal zones, with cyanobacterial and trace-gas chemotrophy-associated taxa being identified as potential keystone taxa for soil communities at higher altitudes. By contrast, the prokaryotic network at low altitudes was dominated by heterotrophic keystone taxa, thus suggesting a clear trophic distinction between soil prokaryotic communities at different altitudes. Based on these results, we conclude that altitude is an important driver of microbial ecology in Antarctic ice-free soil habitats.
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Affiliation(s)
- Lefentse Mashamaite
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
| | - Pedro H. Lebre
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
| | - Gilda Varliero
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
- Rhizosphere Processes Group, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
| | - Silindile Maphosa
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
| | - Max Ortiz
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
- Clemson University Genomics & Bioinformatics Facility, Clemson University, Clemson, SC, United States
| | - Ian D. Hogg
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
- School of Science, University of Waikato, Hamilton, New Zealand
- Canadian High Arctic Research Station, Polar Knowledge Canada, Cambridge Bay, NU, Canada
| | - Don A. Cowan
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
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Cowan DA, Cary SC, DiRuggiero J, Eckardt F, Ferrari B, Hopkins DW, Lebre PH, Maggs-Kölling G, Pointing SB, Ramond JB, Tribbia D, Warren-Rhodes K. 'Follow the Water': Microbial Water Acquisition in Desert Soils. Microorganisms 2023; 11:1670. [PMID: 37512843 PMCID: PMC10386458 DOI: 10.3390/microorganisms11071670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/12/2023] [Accepted: 06/16/2023] [Indexed: 07/30/2023] Open
Abstract
Water availability is the dominant driver of microbial community structure and function in desert soils. However, these habitats typically only receive very infrequent large-scale water inputs (e.g., from precipitation and/or run-off). In light of recent studies, the paradigm that desert soil microorganisms are largely dormant under xeric conditions is questionable. Gene expression profiling of microbial communities in desert soils suggests that many microbial taxa retain some metabolic functionality, even under severely xeric conditions. It, therefore, follows that other, less obvious sources of water may sustain the microbial cellular and community functionality in desert soil niches. Such sources include a range of precipitation and condensation processes, including rainfall, snow, dew, fog, and nocturnal distillation, all of which may vary quantitatively depending on the location and geomorphological characteristics of the desert ecosystem. Other more obscure sources of bioavailable water may include groundwater-derived water vapour, hydrated minerals, and metabolic hydro-genesis. Here, we explore the possible sources of bioavailable water in the context of microbial survival and function in xeric desert soils. With global climate change projected to have profound effects on both hot and cold deserts, we also explore the potential impacts of climate-induced changes in water availability on soil microbiomes in these extreme environments.
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Affiliation(s)
- Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
| | - S Craig Cary
- School of Biological Sciences, University of Waikato, Hamilton 3216, New Zealand
| | - Jocelyne DiRuggiero
- Departments of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
- Departments of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Frank Eckardt
- Department of Environmental and Geographical Science, University of Cape Town, Cape Town 7701, South Africa
| | - Belinda Ferrari
- School of Biotechnology and Biological Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - David W Hopkins
- Scotland's Rural College, West Mains Road, Edinburgh EH9 3JG, UK
| | - Pedro H Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
| | | | - Stephen B Pointing
- Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore
| | - Jean-Baptiste Ramond
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
- Departamento Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Dana Tribbia
- School of Biotechnology and Biological Sciences, University of New South Wales, Sydney, NSW 2052, Australia
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Varliero G, Lebre PH, Stevens MI, Czechowski P, Makhalanyane T, Cowan DA. The use of different 16S rRNA gene variable regions in biogeographical studies. Environ Microbiol Rep 2023; 15:216-228. [PMID: 36810880 PMCID: PMC10464692 DOI: 10.1111/1758-2229.13145] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 01/23/2023] [Indexed: 05/06/2023]
Abstract
16S rRNA gene amplicon sequencing is routinely used in environmental surveys to identify microbial diversity and composition of the samples of interest. The dominant sequencing technology of the past decade (Illumina) is based on the sequencing of 16S rRNA hypervariable regions. Online sequence data repositories, which represent an invaluable resource for investigating microbial distributional patterns across spatial, environmental or temporal scales, contain amplicon datasets from diverse 16S rRNA gene variable regions. However, the utility of these sequence datasets is potentially reduced by the use of different 16S rRNA gene amplified regions. By comparing 10 Antarctic soil samples sequenced for five different 16S rRNA amplicons, we explore whether sequence data derived from diverse 16S rRNA variable regions can be validly used as a resource for biogeographical studies. Patterns of shared and unique taxa differed among samples as a result of variable taxonomic resolutions of the assessed 16S rRNA variable regions. However, our analyses also suggest that the use of multi-primer datasets for biogeographical studies of the domain Bacteria is a valid approach to explore bacterial biogeographical patterns due to the preservation of bacterial taxonomic and diversity patterns across different variable region datasets. We deem composite datasets useful for biogeographical studies.
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Affiliation(s)
- Gilda Varliero
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and GenomicsUniversity of PretoriaPretoriaSouth Africa
| | - Pedro H. Lebre
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and GenomicsUniversity of PretoriaPretoriaSouth Africa
| | - Mark I. Stevens
- Securing Antarctica's Environmental FutureEarth & Biological Sciences, South Australian MuseumAdelaideAustralia
- School of Biological SciencesUniversity of AdelaideAdelaideAustralia
| | - Paul Czechowski
- Helmholtz Institute for Metabolic, Obesity and Vascular Research Leipzig (HI‐MAG)LeipzigGermany
| | - Thulani Makhalanyane
- Department of Biochemistry, Genetics and MicrobiologyUniversity of PretoriaPretoriaSouth Africa
| | - Don A. Cowan
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and GenomicsUniversity of PretoriaPretoriaSouth Africa
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Varliero G, Lebre PH, Frey B, Fountain AG, Anesio AM, Cowan DA. Glacial Water: A Dynamic Microbial Medium. Microorganisms 2023; 11:1153. [PMID: 37317127 DOI: 10.3390/microorganisms11051153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/15/2023] [Accepted: 04/19/2023] [Indexed: 06/16/2023] Open
Abstract
Microbial communities and nutrient dynamics in glaciers and ice sheets continuously change as the hydrological conditions within and on the ice change. Glaciers and ice sheets can be considered bioreactors as microbiomes transform nutrients that enter these icy systems and alter the meltwater chemistry. Global warming is increasing meltwater discharge, affecting nutrient and cell export, and altering proglacial systems. In this review, we integrate the current understanding of glacial hydrology, microbial activity, and nutrient and carbon dynamics to highlight their interdependence and variability on daily and seasonal time scales, as well as their impact on proglacial environments.
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Affiliation(s)
- Gilda Varliero
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
- Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland
| | - Pedro H Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
| | - Beat Frey
- Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland
| | - Andrew G Fountain
- Departments of Geology and Geography, Portland State University, Portland, OR 97212, USA
| | - Alexandre M Anesio
- Department of Environmental Science, iClimate, Aarhus University, DK-4000 Roskilde, Denmark
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
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Cowan DA, Lebre PH, Amon C, Becker RW, Boga HI, Boulangé A, Chiyaka TL, Coetzee T, de Jager PC, Dikinya O, Eckardt F, Greve M, Harris MA, Hopkins DW, Houngnandan HB, Houngnandan P, Jordaan K, Kaimoyo E, Kambura AK, Kamgan-Nkuekam G, Makhalanyane TP, Maggs-Kölling G, Marais E, Mondlane H, Nghalipo E, Olivier BW, Ortiz M, Pertierra LR, Ramond JB, Seely M, Sithole-Niang I, Valverde A, Varliero G, Vikram S, Wall DH, Zeze A. Biogeographical survey of soil microbiomes across sub-Saharan Africa: structure, drivers, and predicted climate-driven changes. Microbiome 2022; 10:131. [PMID: 35996183 PMCID: PMC9396824 DOI: 10.1186/s40168-022-01297-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [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: 03/09/2022] [Accepted: 05/15/2022] [Indexed: 05/20/2023]
Abstract
BACKGROUND Top-soil microbiomes make a vital contribution to the Earth's ecology and harbor an extraordinarily high biodiversity. They are also key players in many ecosystem services, particularly in arid regions of the globe such as the African continent. While several recent studies have documented patterns in global soil microbial ecology, these are largely biased towards widely studied regions and rely on models to interpolate the microbial diversity of other regions where there is low data coverage. This is the case for sub-Saharan Africa, where the number of regional microbial studies is very low in comparison to other continents. RESULTS The aim of this study was to conduct an extensive biogeographical survey of sub-Saharan Africa's top-soil microbiomes, with a specific focus on investigating the environmental drivers of microbial ecology across the region. In this study, we sampled 810 sample sites across 9 sub-Saharan African countries and used taxonomic barcoding to profile the microbial ecology of these regions. Our results showed that the sub-Saharan nations included in the study harbor qualitatively distinguishable soil microbiomes. In addition, using soil chemistry and climatic data extracted from the same sites, we demonstrated that the top-soil microbiome is shaped by a broad range of environmental factors, most notably pH, precipitation, and temperature. Through the use of structural equation modeling, we also developed a model to predict how soil microbial biodiversity in sub-Saharan Africa might be affected by future climate change scenarios. This model predicted that the soil microbial biodiversity of countries such as Kenya will be negatively affected by increased temperatures and decreased precipitation, while the fungal biodiversity of Benin will benefit from the increase in annual precipitation. CONCLUSION This study represents the most extensive biogeographical survey of sub-Saharan top-soil microbiomes to date. Importantly, this study has allowed us to identify countries in sub-Saharan Africa that might be particularly vulnerable to losses in soil microbial ecology and productivity due to climate change. Considering the reliance of many economies in the region on rain-fed agriculture, this study provides crucial information to support conservation efforts in the countries that will be most heavily impacted by climate change. Video Abstract.
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Affiliation(s)
- D A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa.
| | - P H Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa.
| | - Cer Amon
- Institut National Polytechnique Houphouet-Boigny, Cote d'Ivoire, Yamoussoukro, South Africa
| | - R W Becker
- Biodiversity Research Centre, Department of Agriculture and Natural Resources Sciences, Namibia University of Science and Technology, Windhoek, Namibia
| | - H I Boga
- Taita Taveta University, Voi, Kenya
| | - A Boulangé
- Centro de Biotecnologia, Universidade Eduardo Mondlane, Maputo, Mozambique
- UMR InterTryp, CIRAD-IRD, 34398, Montpellier, France
| | - T L Chiyaka
- Department of Biotechnology and Biochemistry, University of Zimbabwe, Harare, Zimbabwe
| | - T Coetzee
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - P C de Jager
- Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa
| | - O Dikinya
- Department of Environmental Science, University of Botswana, Gaborone, Botswana
| | - F Eckardt
- Department of Geography, University of Cape Town, Cape Town, South Africa
| | - M Greve
- Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa
| | - M A Harris
- Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa
| | - D W Hopkins
- Scotland's Rural College, Edinburgh, EH9 3JG, UK
| | - H B Houngnandan
- Université Nationale d'Agriculture, Porto-Novo, Benin (Laboratoire de Microbiologie Des Sols Et d'Ecologie Microbienne), Porto-Novo, Benin
| | - P Houngnandan
- Université Nationale d'Agriculture, Porto-Novo, Benin (Laboratoire de Microbiologie Des Sols Et d'Ecologie Microbienne), Porto-Novo, Benin
| | - K Jordaan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Departamento de Genética Molecular Y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - E Kaimoyo
- University of Zambia, Lusaka, Zambia
| | | | - G Kamgan-Nkuekam
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - T P Makhalanyane
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | | | - E Marais
- Gobabeb-Namib Research Institute, Walvis Bay, Namibia
| | - H Mondlane
- Centro de Biotecnologia, Universidade Eduardo Mondlane, Maputo, Mozambique
| | - E Nghalipo
- Biodiversity Research Centre, Department of Agriculture and Natural Resources Sciences, Namibia University of Science and Technology, Windhoek, Namibia
| | - B W Olivier
- Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa
| | - M Ortiz
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Department of Biological Sciences, Clemson University, Clemson, SC, USA
| | - L R Pertierra
- Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa
| | - J-B Ramond
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Departamento de Genética Molecular Y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - M Seely
- Gobabeb-Namib Research Institute, Walvis Bay, Namibia
| | - I Sithole-Niang
- Department of Biotechnology and Biochemistry, University of Zimbabwe, Harare, Zimbabwe
| | - A Valverde
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - G Varliero
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - S Vikram
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - D H Wall
- Department of Biology, Colorado State University, Fort Collins, USA
| | - A Zeze
- Institut National Polytechnique Houphouet-Boigny, Cote d'Ivoire, Yamoussoukro, South Africa
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Bosch J, Marais E, Maggs-Kölling G, Ramond JB, Lebre PH, Eckardt F, Cowan DA. Water inputs across the Namib Desert: implications for dryland edaphic microbiology. Frontiers of Biogeography 2022. [DOI: 10.21425/f5fbg55302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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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Salawu-Rotimi A, Lebre PH, Vos HC, Fister W, Kuhn N, Eckardt FD, Cowan DA. Gone with the Wind: Microbial Communities Associated with Dust from Emissive Farmlands. Microb Ecol 2021; 82:859-869. [PMID: 33656686 DOI: 10.1007/s00248-021-01717-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 10/29/2020] [Accepted: 02/07/2021] [Indexed: 06/12/2023]
Abstract
Dust is a major vehicle for the dispersal of microorganisms across the globe. While much attention has been focused on microbial dispersal in dust plumes from major natural dust sources, very little is known about the fractionation processes that select for the "dust microbiome." The recent identification of highly emissive, agricultural land dust sources in South Africa has provided the opportunity to study the displacement of microbial communities through dust generation and transport. In this study, we aimed to document the microbial communities that are carried in the dust from one of South Africa's most emissive locations, and to investigate the selective factors that control the partitioning of microbial communities from soil to dust. For this purpose, dust samples were generated at different emission sources using a Portable In-Situ Wind Erosion Lab (PI-SWERL), and the taxonomic composition of the resulting microbiomes was compared with the source soils. Dust emission processes resulted in the clear fractionation of the soil bacterial community, where dust samples were significantly enriched in spore-forming taxa. Conversely, little fractionation was observed in the soil fungal communities, such that the dust fungal fingerprint could be used to identify the source soil. Dust microbiomes were also found to vary according to the emission source, suggesting that land use significantly affected the structure and fractionation of microbial communities transported in dust plumes. In addition, several potential biological allergens of fungal origin were detected in the dust microbiomes, highlighting the potential detrimental effects of dust plumes emitted in South Africa. This study represents the first description of the fractionation of microbial taxa occurring at the source of dust plumes and provides a direct link between land use and its impact on the dust microbiome.
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Affiliation(s)
- Adeola Salawu-Rotimi
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, 0002, South Africa
| | - Pedro H Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, 0002, South Africa.
| | - Heleen Cornelia Vos
- Department of Environmental Sciences, University of Basel, 4056, Basel, Switzerland
| | - Wolfgang Fister
- Department of Environmental Sciences, University of Basel, 4056, Basel, Switzerland
| | - Nikolaus Kuhn
- Department of Environmental Sciences, University of Basel, 4056, Basel, Switzerland
| | - Frank D Eckardt
- Department of Environmental and Geographical Sciences, University of Cape Town, Cape Town, 7701, South Africa
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, 0002, South Africa
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Lebre PH, Bottos E, Makhalanyane TP, Hogg I, Cowan DA. Islands in the sand: are all hypolithic microbial communities the same? FEMS Microbiol Ecol 2021; 97:5928546. [PMID: 33068395 DOI: 10.1093/femsec/fiaa216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 05/29/2020] [Accepted: 10/16/2020] [Indexed: 01/04/2023] Open
Abstract
Hypolithic microbial communities (hypolithons) are complex assemblages of phototrophic and heterotrophic organisms associated with the ventral surfaces of translucent minerals embedded in soil surfaces. Past studies on the assembly, structure and function of hypolithic communities have tended to use composite samples (i.e. bulked hypolithic biomass) with the underlying assumption that samples collected from within a 'homogeneous' locality are phylogenetically homogeneous. In this study, we question this assumption by analysing the prokaryote phylogenetic diversity of multiple individual hypolithons: i.e. asking the seemingly simple question of 'Are all hypolithons the same'? Using 16S rRNA gene-based phylogenetic analysis of hypolithons recovered for a localized moraine region in the Taylor Valley, McMurdo Dry Valleys, Antarctica, we demonstrate that these communities are heterogeneous at very small spatial scales (<5 m). Using null models of phylogenetic turnover, we showed that this heterogeneity between hypolithons is probably due to stochastic effects such as dispersal limitations, which is entirely consistent with the physically isolated nature of the hypolithic communities ('islands in the sand') and the almost complete absence of a liquid continuum as a mode of microbial transport between communities.
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Affiliation(s)
- Pedro H Lebre
- Centre for Microbial Ecology and Genomic, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Lynwood Road, Hatfield, Pretoria, 0028, South Africa
| | - Eric Bottos
- Department of Biological Sciences, Thompson Rivers University, 805 TRU Way, Kamloops, British Colombia, BC V2C 0C8, Canada
| | - Thulani P Makhalanyane
- Centre for Microbial Ecology and Genomic, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Lynwood Road, Hatfield, Pretoria, 0028, South Africa
| | - Ian Hogg
- Canadian High Arctic Research Station, rue Uvajuq place, Cambridge Bay, Nunavut, CP 2150, Canada
| | - Don A Cowan
- Centre for Microbial Ecology and Genomic, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Lynwood Road, Hatfield, Pretoria, 0028, South Africa
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Gwizdala M, Lebre PH, Maggs-Kölling G, Marais E, Cowan DA, Krüger TPJ. Sub-lithic photosynthesis in hot desert habitats. Environ Microbiol 2021; 23:3867-3880. [PMID: 33817951 DOI: 10.1111/1462-2920.15505] [Citation(s) in RCA: 6] [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: 11/19/2020] [Accepted: 04/03/2021] [Indexed: 11/26/2022]
Abstract
In hyper-arid soil environments, photosynthetic microorganisms are largely restricted to hypolithic (sub-lithic) habitats: i.e., on the ventral surfaces of translucent pebbles in desert pavements. Here, we combined fluorometric, spectroscopic, biochemical and metagenomic approaches to investigate in situ the light transmission properties of quartz stones in the Namib Desert, and assess the photosynthetic activity of the underlying hypolithic cyanobacterial biofilms. Quartz pebbles greatly reduced the total photon flux to the ventral surface biofilms and filtered out primarily the short wavelength portion of the solar spectrum. Chlorophylls d and f were not detected in biofilm pigment extracts; however, hypolithic cyanobacterial communities showed some evidence of adaptation to sub-lithic conditions, including the prevalence of genes encoding Helical Carotenoid Proteins, which are associated with desiccation stress. Under water-saturated conditions, hypolithic communities showed no evidence of light stress, even when the quartz stones were exposed to full midday sunlight. This initial study creates a foundation for future in-situ and laboratory exploration of various adaptation mechanisms employed by photosynthetic organisms forming hypolithic microbial communities.
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Affiliation(s)
- Michal Gwizdala
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa.,Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | - Pedro H Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | | | - Eugene Marais
- Gobabeb-Namib Research Institute, Walvis Bay, Namibia
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | - Tjaart P J Krüger
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa.,Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
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van Hougenhouck-Tulleken WG, Lebre PH, Said M, Cowan DA. Bacterial pathogens in peritoneal dialysis peritonitis: Insights from next-generation sequencing. Perit Dial Int 2020; 40:581-586. [PMID: 32162597 DOI: 10.1177/0896860820908473] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Peritoneal dialysis (PD) peritonitis is a feared complication of PD, with significant sequelae for the patient. The cause of PD peritonitis is largely due to a single organism (≥75% of cases) and rarely due to multiple organisms. METHODS In this pilot study, we investigated 25 cases of PD peritonitis with 16S ribosomal RNA (rRNA) next-generation sequencing (NGS) techniques. RESULTS Total concordance between culture and NGS was noted. In addition, the NGS technique was highly sensitive, identifying 33 different bacteria (including a nonculturable bacterium), compared to 13 bacterial species using culture-based techniques. This was counterbalanced by a lack of specificity with NGS, largely due to the small size of the 16S rRNA gene segment sequenced. CONCLUSIONS For the clinician, our results suggest that PD peritonitis may often be a polymicrobial disease and that treating a dominant organism may not totally eradicate all bacterial contamination within the peritoneum. For the clinical scientist, additional use of a larger 16S rRNA segment (V5 or V6) is likely to outperform the use of the V4 segment only.
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Affiliation(s)
- Wesley G van Hougenhouck-Tulleken
- Department of Nephrology, Steve Biko Academic Hospital, Pretoria, South Africa.,Department of Internal Medicine, 56410University of Pretoria, South Africa
| | - Pedro H Lebre
- Centre for Microbial Ecology and Genomics, 56410University of Pretoria, South Africa
| | - Mohamed Said
- Department of Medical Microbiology, 56410University of Pretoria, South Africa.,National Health Laboratory Services, Tshwane Academic Division, 56410University of Pretoria, South Africa
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, 56410University of Pretoria, South Africa
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Abstract
Alkalinicity presents a challenge for life due to a "reversed" proton gradient that is unfavourable to many bioenergetic processes across the membranes of microorganisms. Despite this, many bacteria, archaea, and eukaryotes, collectively termed alkaliphiles, are adapted to life in alkaline ecosystems and are of great scientific and biotechnological interest due to their niche specialization and ability to produce highly stable enzymes. Advances in next-generation sequencing technologies have propelled not only the genomic characterization of many alkaliphilic microorganisms that have been isolated from nature alkaline sources but also our understanding of the functional relationships between different taxa in microbial communities living in these ecosystems. In this review, we discuss the genetics and molecular biology of alkaliphiles from an "omics" point of view, focusing on how metagenomics and transcriptomics have contributed to our understanding of these extremophiles. Graphical Abstract.
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Affiliation(s)
- Pedro H Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa.
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Lebre PH, Aliyu H, De Maayer P, Cowan DA. In silico characterization of the global Geobacillus and Parageobacillus secretome. Microb Cell Fact 2018; 17:156. [PMID: 30285747 PMCID: PMC6171300 DOI: 10.1186/s12934-018-1005-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 09/26/2018] [Indexed: 11/17/2022] Open
Abstract
Background Geobacillus and Parageobacillus are two ecologically diverse thermophilic genera within the phylum Firmicutes. These taxa have long been of biotechnological interest due to their ability to secrete thermostable enzymes and other biomolecules that have direct applications in various industrial and clinical fields. Despite the commercial and industrial interest in these microorganisms, the full scope of the secreted protein, i.e. the secretome, of Geobacillus and Parageobacillus species remains largely unexplored, with most studies focusing on single enzymes. A genome-wide exploration of the global secretome can provide a platform for understanding the extracellular functional “protein cloud” and the roles that secreted proteins play in the survival and adaptation of these biotechnologically relevant organisms. Results In the present study, the global secretion profile of 64 Geobacillus and Parageobacillus strains, comprising 772 distinct proteins, was predicted using comparative genomic approaches. Thirty-one of these proteins are shared across all strains used in this study and function in cell-wall/membrane biogenesis as well as transport and metabolism of carbohydrates, amino acids and inorganic ions. An analysis of the clustering patterns of the secretomes of the 64 strains according to shared functional orthology revealed a correlation between the secreted profiles of different strains and their phylogeny, with Geobacillus and Parageobacillus species forming two distinct functional clades. Conclusions The in silico characterization of the global secretome revealed a metabolically diverse set of secreted proteins, which include proteases, glycoside hydrolases, nutrient binding proteins and toxins. Electronic supplementary material The online version of this article (10.1186/s12934-018-1005-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Pedro H Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Habibu Aliyu
- Technical Biology, Institute of Process Engineering in Life Science, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Pieter De Maayer
- School of Molecular and Cell Biology, University of Witwatersrand, Johannesburg, South Africa
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa.
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