1
|
Campbell MA, Bauersachs T, Schwark L, Proemse BC, Eberhard RS, Coolen MJL, Grice K. Salinity-driven ecology and diversity changes of heterocytous cyanobacteria in Australian freshwater and coastal-marine microbial mats. Environ Microbiol 2022; 24:6493-6509. [PMID: 36156347 PMCID: PMC10092834 DOI: 10.1111/1462-2920.16225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 09/23/2022] [Indexed: 01/12/2023]
Abstract
N2 -fixing heterocytous cyanobacteria are considered to play a minor role in sustaining coastal microbial mat communities developing under normal marine to hypersaline conditions. Here, we investigated microbial mats growing under different salinities from freshwater mats of Giblin River (Tasmania) to metahaline and hypersaline mats of Shark Bay (Western Australia). Analyses of genetic (rRNA and mRNA) and biological markers (heterocyte glycolipids) revealed an unexpectedly large diversity of heterocytous cyanobacteria in all the studied microbial mat communities. It was observed that the taxonomic distribution as well as abundance of cyanobacteria is strongly affected by salinity. Low salinity favoured the presence of heterocytous cyanobacteria in freshwater mats, while mats thriving in higher salinities mainly supported the growth unicellular and filamentous non-heterocytous genera. However, even though mRNA transcripts derived from heterocytous cyanobacteria were lower in Shark Bay (<6%) microbial mats, functional analyses revealed that these diazotrophs were transcribing a substantial proportion of the genes involved in biofilm formation and nitrogen fixation. Overall, our data reveal an unexpectedly high diversity of heterocytous cyanobacteria (e.g. Calothrix, Scytonema, Nodularia, Gloeotrichia, Stigonema, Fischerella and Chlorogloeopsis) that had yet to be described in metahaline and hypersaline microbial mats from Shark Bay and that they play a vital role in sustaining the ecosystem functioning of coastal-marine microbial mat systems.
Collapse
Affiliation(s)
- Matthew A Campbell
- Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
| | - Thorsten Bauersachs
- Institute of Geosciences, Organic Geochemistry Group, Christian-Albrechts-University, Kiel, Germany
| | - Lorenz Schwark
- Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia.,Institute of Geosciences, Organic Geochemistry Group, Christian-Albrechts-University, Kiel, Germany
| | - Bernadette C Proemse
- Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Tasmania, Australia
| | - Rolan S Eberhard
- Natural and Cultural Heritage Division, Department of Primary Industries Parks, Water and Environment, Hobart, Tasmania, Australia
| | - Marco J L Coolen
- Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
| | - Kliti Grice
- Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
| |
Collapse
|
2
|
Campbell MA, Grice K, Visscher PT, Morris T, Wong HL, White RA, Burns BP, Coolen MJL. Functional Gene Expression in Shark Bay Hypersaline Microbial Mats: Adaptive Responses. Front Microbiol 2020; 11:560336. [PMID: 33312167 PMCID: PMC7702295 DOI: 10.3389/fmicb.2020.560336] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 10/09/2020] [Indexed: 11/25/2022] Open
Abstract
Microbial mat communities possess extensive taxonomic and functional diversity, which drive high metabolic rates and rapid cycling of major elements. Modern microbial mats occurring in hypersaline environments are considered as analogs to extinct geobiological formations dating back to ∼ 3.5 Gyr ago. Despite efforts to understand the diversity and metabolic potential of hypersaline microbial mats in Shark Bay, Western Australia, there has yet to be molecular analyses at the transcriptional level in these microbial communities. In this study, we generated metatranscriptomes for the first time from actively growing mats comparing the type of mat, as well as the influence of diel and seasonal cycles. We observed that the overall gene transcription is strongly influenced by microbial community structure and seasonality. The most transcribed genes were associated with tackling the low nutrient conditions by the uptake of fatty acids, phosphorus, iron, and nickel from the environment as well as with protective mechanisms against elevated salinity conditions and to prevent build-up of ammonium produced by nitrate reducing microorganisms. A range of pathways involved in carbon, nitrogen, and sulfur cycles were identified in mat metatranscriptomes, with anoxygenic photosynthesis and chemoautotrophy using the Arnon–Buchanan cycle inferred as major pathways involved in the carbon cycle. Furthermore, enrichment of active anaerobic pathways (e.g., sulfate reduction, methanogenesis, Wood–Ljungdahl) in smooth mats corroborates previous metagenomic studies and further advocates the potential of these communities as modern analogs of ancient microbialites.
Collapse
Affiliation(s)
- Matthew A Campbell
- WA-Organic Isotope Geochemistry Centre, The Institute for Geoscience Research, School of Earth and Planetary Sciences, Curtin University, Perth, WA, Australia
| | - Kliti Grice
- WA-Organic Isotope Geochemistry Centre, The Institute for Geoscience Research, School of Earth and Planetary Sciences, Curtin University, Perth, WA, Australia
| | - Pieter T Visscher
- Departments of Marine Sciences and Geoscience, University of Connecticut, Storrs, CT, United States.,Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW, Australia
| | - Therese Morris
- Applied Geology, Curtin University, Perth, WA, Australia
| | - Hon Lun Wong
- Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW, Australia.,School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Richard Allen White
- Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW, Australia.,Plant Pathology, Washington State University, Pullman, WA, United States.,RAW Molecular Systems (RMS) LLC, Spokane, WA, United States
| | - Brendan P Burns
- Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW, Australia.,School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Marco J L Coolen
- WA-Organic Isotope Geochemistry Centre, The Institute for Geoscience Research, School of Earth and Planetary Sciences, Curtin University, Perth, WA, Australia
| |
Collapse
|
3
|
Tang T, Mohr W, Sattin SR, Rogers DR, Girguis PR, Pearson A. Geochemically distinct carbon isotope distributions in Allochromatium vinosum DSM 180 T grown photoautotrophically and photoheterotrophically. GEOBIOLOGY 2017; 15:324-339. [PMID: 28042698 DOI: 10.1111/gbi.12221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 11/07/2016] [Indexed: 06/06/2023]
Abstract
Anoxygenic, photosynthetic bacteria are common at redox boundaries. They are of interest in microbial ecology and geosciences through their role in linking the carbon, sulfur, and iron cycles, yet much remains unknown about how their flexible carbon metabolism-permitting either autotrophic or heterotrophic growth-is recorded in the bulk sedimentary and lipid biomarker records. Here, we investigated patterns of carbon isotope fractionation in a model photosynthetic sulfur-oxidizing bacterium, Allochromatium vinosum DSM180T . In one treatment, A. vinosum was grown with CO2 as the sole carbon source, while in a second treatment, it was grown on acetate. Different intracellular isotope patterns were observed for fatty acids, phytol, individual amino acids, intact proteins, and total RNA between the two experiments. Photoautotrophic CO2 fixation yielded typical isotopic ordering for the lipid biomarkers: δ13 C values of phytol > n-alkyl lipids. In contrast, growth on acetate greatly suppressed intracellular isotopic heterogeneity across all molecular classes, except for a marked 13 C-depletion in phytol. This caused isotopic "inversion" in the lipids (δ13 C values of phytol < n-alkyl lipids). The finding suggests that inverse δ13 C patterns of n-alkanes and pristane/phytane in the geologic record may be at least in part a signal for photoheterotrophy. In both experimental scenarios, the relative isotope distributions could be predicted from an isotope flux-balance model, demonstrating that microbial carbon metabolisms can be interrogated by combining compound-specific stable isotope analysis with metabolic modeling. Isotopic differences among molecular classes may be a means of fingerprinting microbial carbon metabolism, both in the modern environment and the geologic record.
Collapse
Affiliation(s)
- T Tang
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - W Mohr
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - S R Sattin
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
| | - D R Rogers
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
- Department of Chemistry, Stonehill College, Easton, MA, USA
| | - P R Girguis
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - A Pearson
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
| |
Collapse
|
4
|
Pagès A, Grice K, Welsh DT, Teasdale PT, Van Kranendonk MJ, Greenwood P. Lipid Biomarker and Isotopic Study of Community Distribution and Biomarker Preservation in a Laminated Microbial Mat from Shark Bay, Western Australia. MICROBIAL ECOLOGY 2015; 70:459-472. [PMID: 25812998 DOI: 10.1007/s00248-015-0598-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 03/09/2015] [Indexed: 06/04/2023]
Abstract
Modern microbial mats from Shark Bay present some structural similarities with ancient stromatolites; thus, the functionality of microbial communities and processes of diagenetic preservation of modern mats may provide an insight into ancient microbial assemblages and preservation. In this study, the vertical distribution of microbial communities was investigated in a well-laminated smooth mat from Shark Bay. Biolipid and compound-specific isotopic analyses were performed to investigate the distribution of microbial communities in four distinct layers of the mat. Biomarkers indicative of cyanobacteria were more abundant in the uppermost oxic layer. Diatom markers (e.g. C25 HBI alkene, C20:4ω6 and C20:5ω3 polar lipid fatty acids (PLFAs)) were also detected in high abundance in the uppermost layer, but also in the deepest layer under conditions of permanent darkness and anoxia, where they probably used NO3 (-) for respiration. CycC19:0, an abundant PLFA of purple sulfur bacteria (PSB), was detected in all layers and presented the most (13)C-depleted values of all PLFAs, consistent with photoautotrophic PSB. Sulfur-bound aliphatic and aromatic biomarkers were detected in all layers, highlighting the occurrence of early sulfurisation which may be an important mechanism in the sedimentary preservation of functional biolipids in living and, thus, also ancient mats.
Collapse
Affiliation(s)
- Anais Pagès
- WA Organic and Isotope Geochemistry Centre, Department of Chemistry, The Institute for Geoscience Research, Curtin University, GPO Box U1987, Perth, Western Australia, 6845, Australia,
| | | | | | | | | | | |
Collapse
|
5
|
Davis JP, Pitt KA, Connolly RM, Fry B. Community structure and dietary pathways for invertebrates on intertidal coral reef flats. FOOD WEBS 2015. [DOI: 10.1016/j.fooweb.2015.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|