1
|
Stanish LF, Kohler TJ, Darling J, McKnight DM. Drifting along: using diatoms to track the contribution of microbial mats to particulate organic matter transport in a glacial meltwater stream in the McMurdo Dry Valleys, Antarctica. Front Microbiol 2024; 15:1352666. [PMID: 38784810 PMCID: PMC11112031 DOI: 10.3389/fmicb.2024.1352666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 04/25/2024] [Indexed: 05/25/2024] Open
Abstract
Flow pulses mobilize particulate organic matter (POM) in streams from the surrounding landscape and streambed. This POM serves as a source of energy and nutrients, as well as a means for organismal dispersal, to downstream communities. In the barren terrestrial landscape of the McMurdo Dry Valleys (MDV) of Antarctica, benthic microbial mats occupying different in-stream habitat types are the dominant POM source in the many glacier-fed streams. Many of these streams experience daily flow peaks that mobilize POM, and diatoms recovered from underlying stream sediments suggest that mat-derived diatoms in the POM are retained there through hyporheic exchange. Yet, 'how much' and 'when' different in-stream habitat types contribute to POM diatom assemblages is unknown. To quantify the contribution of different in-stream habitat types to POM diatom assemblages, we collected time-integrated POM samples over four diel experiments, which spanned a gradient of flow conditions over three summers. Diatoms from POM samples were identified, quantified, and compared with dominant habitat types (i.e., benthic 'orange' mats, marginal 'black' mats, and bare sediments). Like bulk POM, diatom cell concentrations followed a clockwise hysteresis pattern with stream discharge over the daily flow cycles, indicating supply limitation. Diatom community analyses showed that different habitat types harbor distinct diatom communities, and mixing models revealed that a substantial proportion of POM diatoms originated from bare sediments during baseflow conditions. Meanwhile, orange and black mats contribute diatoms to POM primarily during daily flow peaks when both cell concentrations and discharge are highest, making mats the most important contributors to POM diatom assemblages at high flows. These observations may help explain the presence of mat-derived diatoms in hyporheic sediments. Our results thus indicate a varying importance of different in-stream habitats to POM generation and export on daily to seasonal timescales, with implications for biogeochemical cycling and the local diatom metacommunity.
Collapse
Affiliation(s)
- Lee F. Stanish
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, United States
| | - Tyler J. Kohler
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, United States
- Department of Ecology, Faculty of Science, Charles University, Prague, Czechia
| | - Joshua Darling
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, United States
| | - Diane M. McKnight
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, United States
- Department of Civil and Environmental Engineering, University of Colorado, Boulder, CO, United States
| |
Collapse
|
2
|
Ray AE, Tribbia DZ, Cowan DA, Ferrari BC. Clearing the air: unraveling past and guiding future research in atmospheric chemosynthesis. Microbiol Mol Biol Rev 2023; 87:e0004823. [PMID: 37914532 PMCID: PMC10732025 DOI: 10.1128/mmbr.00048-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023] Open
Abstract
SUMMARY Atmospheric chemosynthesis is a recently proposed form of chemoautotrophic microbial primary production. The proposed process relies on the oxidation of trace concentrations of hydrogen (≤530 ppbv), carbon monoxide (≤90 ppbv), and methane (≤1,870 ppbv) gases using high-affinity enzymes. Atmospheric hydrogen and carbon monoxide oxidation have been primarily linked to microbial growth in desert surface soils scarce in liquid water and organic nutrients, and low in photosynthetic communities. It is well established that the oxidation of trace hydrogen and carbon monoxide gases widely supports the persistence of microbial communities in a diminished metabolic state, with the former potentially providing a reliable source of metabolic water. Microbial atmospheric methane oxidation also occurs in oligotrophic desert soils and is widespread throughout copiotrophic environments, with established links to microbial growth. Despite these findings, the direct link between trace gas oxidation and carbon fixation remains disputable. Here, we review the supporting evidence, outlining major gaps in our understanding of this phenomenon, and propose approaches to validate atmospheric chemosynthesis as a primary production process. We also explore the implications of this minimalistic survival strategy in terms of nutrient cycling, climate change, aerobiology, and astrobiology.
Collapse
Affiliation(s)
- Angelique E. Ray
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, Australia
- Australian Centre for Astrobiology, UNSW Sydney, Sydney, Australia
| | - Dana Z. Tribbia
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, Australia
- Australian Centre for Astrobiology, UNSW Sydney, Sydney, Australia
| | - Don A. Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Belinda C. Ferrari
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, Australia
- Australian Centre for Astrobiology, UNSW Sydney, Sydney, Australia
| |
Collapse
|
3
|
Tytgat B, Verleyen E, Sweetlove M, Van den Berge K, Pinseel E, Hodgson DA, Chown SL, Sabbe K, Wilmotte A, Willems A, Vyverman W. Polar lake microbiomes have distinct evolutionary histories. SCIENCE ADVANCES 2023; 9:eade7130. [PMID: 37976353 PMCID: PMC10656066 DOI: 10.1126/sciadv.ade7130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 10/19/2023] [Indexed: 11/19/2023]
Abstract
Toward the poles, life on land is increasingly dominated by microorganisms, yet the evolutionary origin of polar microbiomes remains poorly understood. Here, we use metabarcoding of Arctic, sub-Antarctic, and Antarctic lacustrine benthic microbial communities to test the hypothesis that high-latitude microbiomes are recruited from a globally dispersing species pool through environmental selection. We demonstrate that taxonomic overlap between the regions is limited within most phyla, even at higher-order taxonomic levels, with unique deep-branching phylogenetic clades being present in each region. We show that local and regional taxon richness and net diversification rate of regionally restricted taxa differ substantially between polar regions in both microeukaryotic and bacterial biota. This suggests that long-term evolutionary divergence resulting from low interhemispheric dispersal and diversification in isolation has been a prominent process shaping present-day polar lake microbiomes. Our findings illuminate the distinctive biogeography of polar lake ecosystems and underscore that conservation efforts should include their unique microbiota.
Collapse
Affiliation(s)
- Bjorn Tytgat
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Gent, Belgium
| | - Elie Verleyen
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Gent, Belgium
| | - Maxime Sweetlove
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Gent, Belgium
| | - Koen Van den Berge
- Department of Applied Mathematics, Computer Science and Statistics, Ghent University, Gent, Belgium
| | - Eveline Pinseel
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Gent, Belgium
- Meise Botanic Garden, Meise, Belgium
| | - Dominic A. Hodgson
- British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
- Department of Geography, Durham University, Durham, UK
| | - Steven L. Chown
- Securing Antarctica’s Environmental Future, School of Biological Sciences, Monash University, Melbourne, VIC, Australia
| | - Koen Sabbe
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Gent, Belgium
| | - Annick Wilmotte
- InBio-Centre for Protein Engineering, University of Liège, Liège, Belgium
| | - Anne Willems
- Laboratory of Microbiology, Ghent University, Gent, Belgium
| | | | - Wim Vyverman
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Gent, Belgium
| |
Collapse
|
4
|
Kollár J, Kopalová K, Kavan J, Vrbická K, Nývlt D, Nedbalová L, Stibal M, Kohler TJ. Recently formed Antarctic lakes host less diverse benthic bacterial and diatom communities than their older counterparts. FEMS Microbiol Ecol 2023; 99:fiad087. [PMID: 37516444 PMCID: PMC10446143 DOI: 10.1093/femsec/fiad087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 07/24/2023] [Accepted: 07/28/2023] [Indexed: 07/31/2023] Open
Abstract
Glacier recession is creating new water bodies in proglacial forelands worldwide, including Antarctica. Yet, it is unknown how microbial communities of recently formed "young" waterbodies (originating decades to a few centuries ago) compare with established "old" counterparts (millennia ago). Here, we compared benthic microbial communities of different lake types on James Ross Island, Antarctic Peninsula, using 16S rDNA metabarcoding and light microscopy to explore bacterial and diatom communities, respectively. We found that the older lakes host significantly more diverse bacterial and diatom communities compared to the young ones. To identify potential mechanisms for these differences, linear models and dbRDA analyses suggested combinations of water temperature, pH, and conductivity to be the most important factors for diversity and community structuring, while differences in geomorphological and hydrological stability, though more difficult to quantify, are likely also influential. These results, along with an indicator species analysis, suggest that physical and chemical constraints associated with individual lakes histories are likely more influential to the assembly of the benthic microbial communities than lake age alone. Collectively, these results improve our understanding of microbial community drivers in Antarctic freshwaters, and help predict how the microbial landscape may shift with future habitat creation within a changing environment.
Collapse
Affiliation(s)
- Jan Kollár
- Faculty of Science, Department of Ecology, Charles University, Viničná 7, Prague 2, CZ-12844, Czech Republic
| | - Kateřina Kopalová
- Faculty of Science, Department of Ecology, Charles University, Viničná 7, Prague 2, CZ-12844, Czech Republic
| | - Jan Kavan
- Polar-Geo-Lab, Faculty of Science, Department of Geography, Masaryk University, Kotlářská 2, Brno, CZ-61137, Czech Republic
- Alfred Jahn Cold Regions Research Centre, University of Wroclaw, pl. Uniwersytecki 1, Wroclaw 50-137, Poland
| | - Kristýna Vrbická
- Faculty of Science, Department of Ecology, Charles University, Viničná 7, Prague 2, CZ-12844, Czech Republic
| | - Daniel Nývlt
- Polar-Geo-Lab, Faculty of Science, Department of Geography, Masaryk University, Kotlářská 2, Brno, CZ-61137, Czech Republic
| | - Linda Nedbalová
- Faculty of Science, Department of Ecology, Charles University, Viničná 7, Prague 2, CZ-12844, Czech Republic
| | - Marek Stibal
- Faculty of Science, Department of Ecology, Charles University, Viničná 7, Prague 2, CZ-12844, Czech Republic
| | - Tyler J Kohler
- Faculty of Science, Department of Ecology, Charles University, Viničná 7, Prague 2, CZ-12844, Czech Republic
| |
Collapse
|
5
|
Active Microbial Airborne Dispersal and Biomorphs as Confounding Factors for Life Detection in the Cell-Degrading Brines of the Polyextreme Dallol Geothermal Field. mBio 2022; 13:e0030722. [PMID: 35384698 PMCID: PMC9040726 DOI: 10.1128/mbio.00307-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Determining the precise limits of life in polyextreme environments is challenging. Studies along gradients of polyextreme conditions in the Dallol proto-volcano area (Danakil salt desert, Ethiopia) showed the occurrence of archaea-dominated communities (up to 99%) in several hypersaline systems but strongly suggested that life did not thrive in the hyperacidic (pH ∼0), hypersaline (∼35% [wt/vol],) and sometimes hot (up to 108°C) ponds of the Dallol dome. However, it was recently claimed that archaea flourish in these brines based on the detection of one Nanohaloarchaeotas 16S rRNA gene and fluorescent in situ hybridization (FISH) experiments with archaea-specific probes. Here, we characterized the diversity of microorganisms in aerosols over Dallol, and we show that, in addition to typical bacteria from soil/dust, they transport halophilic archaea likely originating from neighboring hypersaline ecosystems. We also show that cells and DNA from cultures and natural local halophilic communities are rapidly destroyed upon contact with Dallol brine. Furthermore, we confirm the widespread occurrence of mineral particles, including silica-based biomorphs, in Dallol brines. FISH experiments using appropriate controls show that DNA fluorescent probes and dyes unspecifically bind to mineral precipitates in Dallol brines; cellular morphologies were unambiguously observed only in nearby hypersaline ecosystems. Our results show that airborne cell dispersal and unspecific binding of fluorescent probes are confounding factors likely affecting previous inferences of archaea thriving in Dallol. They highlight the need for controls and the consideration of alternative abiotic explanations before safely drawing conclusions about the presence of life in polyextreme terrestrial or extraterrestrial systems.
Collapse
|