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Bute TF, Wyness A, Wasserman RJ, Dondofema F, Keates C, Dalu T. Microbial community and extracellular polymeric substance dynamics in arid-zone temporary pan ecosystems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 932:173059. [PMID: 38723976 DOI: 10.1016/j.scitotenv.2024.173059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 05/04/2024] [Accepted: 05/06/2024] [Indexed: 05/12/2024]
Abstract
Microbial extracellular polymeric substances (EPS) are an important component in sediment ecology. However, most research is highly skewed towards the northern hemisphere and in more permanent systems. This paper investigates EPS (i.e., carbohydrates and proteins) dynamics in arid Austral zone temporary pans sediments. Colorimetric methods and sequence-based metagenomics techniques were employed in a series of small temporary pan ecosystems characterised by alternating wet and dry hydroperiods. Microbial community patterns of distribution were evaluated between seasons (hot-wet and cool-dry) and across depths (and inferred inundation period) based on estimated elevation. Carbohydrates generally occurred in relatively higher proportions than proteins; the carbohydrate:protein ratio was 2.8:1 and 1.6:1 for the dry and wet season respectively, suggesting that EPS found in these systems was largely diatom produced. The wet- hydroperiods (Carbohydrate mean 102 μg g-1; Protein mean 65 μg g-1) supported more EPS production as compared to the dry- hydroperiods (Carbohydrate mean 73 μg g-1; Protein mean 26 μg g-1). A total of 15,042 Unique Amplicon Sequence Variants (ASVs) were allocated to 51 bacterial phyla and 1127 genera. The most abundant genera had commonality in high temperature tolerance, with Firmicutes, Actinobacteria and Proteobacteria in high abundances. Microbial communities were more distinct between seasons compared to within seasons which further suggested that the observed metagenome functions could be seasonally driven. This study's findings implied that there were high levels of denitrification by mostly nitric oxide reductase and nitrite reductase enzymes. EPS production was high in the hot-wet season as compared to relatively lower rates of nitrification in the cool-dry season by ammonia monooxygenases. Both EPS quantities and metagenome functions were highly associated with availability of water, with high rates being mainly associated with wet- hydroperiods compared to dry- hydroperiods. These data suggest that extended dry periods threaten microbially mediated processes in temporary wetlands, with implications to loss of biodiversity by desiccation.
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Affiliation(s)
- Tafara F Bute
- Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa.
| | - Adam Wyness
- Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa; Scottish Association for Marine Science, Oban PA37 1QA, United Kingdom
| | - Ryan J Wasserman
- Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa; South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa
| | - Farai Dondofema
- Department of Geography and Environmental Sciences, University of Venda, Thohoyandou 0950, South Africa
| | - Chad Keates
- Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa; South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa
| | - Tatenda Dalu
- South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa; School of Biology and Environmental Sciences, University of Mpumalanga, Nelspruit 1200, South Africa
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Le Geay M, Mayers K, Küttim M, Lauga B, Jassey VEJ. Development of a digital droplet PCR approach for the quantification of soil micro-organisms involved in atmospheric CO 2 fixation. Environ Microbiol 2024; 26:e16666. [PMID: 38889760 DOI: 10.1111/1462-2920.16666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 05/23/2024] [Indexed: 06/20/2024]
Abstract
Carbon-fixing micro-organisms (CFMs) play a pivotal role in soil carbon cycling, contributing to carbon uptake and sequestration through various metabolic pathways. Despite their importance, accurately quantifying the absolute abundance of these micro-organisms in soils has been challenging. This study used a digital droplet polymerase chain reaction (ddPCR) approach to measure the abundance of key and emerging CFMs pathways in fen and bog soils at different depths, ranging from 0 to 15 cm. We targeted total prokaryotes, oxygenic phototrophs, aerobic anoxygenic phototrophic bacteria and chemoautotrophs, optimizing the conditions to achieve absolute quantification of these genes. Our results revealed that oxygenic phototrophs were the most abundant CFMs, making up 15% of the total prokaryotic abundance. They were followed by chemoautotrophs at 10% and aerobic anoxygenic phototrophic bacteria at 9%. We observed higher gene concentrations in fen than in bog. There were also variations in depth, which differed between fen and bog for all genes. Our findings underscore the abundance of oxygenic phototrophs and chemoautotrophs in peatlands, challenging previous estimates that relied solely on oxygenic phototrophs for microbial carbon dioxide fixation assessments. Incorporating absolute gene quantification is essential for a comprehensive understanding of microbial contributions to soil processes. This approach sheds light on the complex mechanisms of soil functioning in peatlands.
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Affiliation(s)
- Marie Le Geay
- Centre de Recherche sur la Biodiversité et l'Environnement (CRBE), Université de Toulouse, CNRE, IRD, Toulouse INP, Université Toulouse 3-Paul Sabatier (UT3), Toulouse, France
| | - Kyle Mayers
- NORCE Norwegian Research Centre AS, Bergen, Norway
| | - Martin Küttim
- Institute of Ecology, School of Natural Sciences and Health, Tallinn University, Tallinn, Estonia
| | - Béatrice Lauga
- Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Vincent E J Jassey
- Centre de Recherche sur la Biodiversité et l'Environnement (CRBE), Université de Toulouse, CNRE, IRD, Toulouse INP, Université Toulouse 3-Paul Sabatier (UT3), Toulouse, France
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Von Eggers JM, Wisnoski NI, Calder JW, Capo E, Groff DV, Krist AC, Shuman B. Environmental filtering governs consistent vertical zonation in sedimentary microbial communities across disconnected mountain lakes. Environ Microbiol 2024; 26:e16607. [PMID: 38477387 DOI: 10.1111/1462-2920.16607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 02/28/2024] [Indexed: 03/14/2024]
Abstract
Subsurface microorganisms make up the majority of Earth's microbial biomass, but ecological processes governing surface communities may not explain community patterns at depth because of burial. Depth constrains dispersal and energy availability, and when combined with geographic isolation across landscapes, may influence community assembly. We sequenced the 16S rRNA gene of bacteria and archaea from 48 sediment cores across 36 lakes in four disconnected mountain ranges in Wyoming, USA and used null models to infer assembly processes across depth, spatial isolation, and varying environments. Although we expected strong dispersal limitations across these isolated settings, community composition was primarily shaped by environmental selection. Communities consistently shifted from domination by organisms that degrade organic matter at the surface to methanogenic, low-energy adapted taxa in deeper zones. Stochastic processes-like dispersal limitation-contributed to differences among lakes, but because these effects weakened with depth, selection processes ultimately governed subsurface microbial biogeography.
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Affiliation(s)
- Jordan M Von Eggers
- Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming, USA
- Program in Ecology and Evolution, University of Wyoming, Laramie, Wyoming, USA
| | - Nathan I Wisnoski
- Wyoming Geographic Information Science Center, University of Wyoming, Laramie, Wyoming, USA
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - John W Calder
- Department of Botany, University of Wyoming, Laramie, Wyoming, USA
| | - Eric Capo
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
| | - Dulcinea V Groff
- Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming, USA
| | - Amy C Krist
- Program in Ecology and Evolution, University of Wyoming, Laramie, Wyoming, USA
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, USA
| | - Bryan Shuman
- Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming, USA
- Program in Ecology and Evolution, University of Wyoming, Laramie, Wyoming, USA
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Xu D, Zhang W, Li H, Li N, Lin JM. Advances in droplet digital polymerase chain reaction on microfluidic chips. LAB ON A CHIP 2023; 23:1258-1278. [PMID: 36752545 DOI: 10.1039/d2lc00814a] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The PCR technique has been known to the general public since the pandemic outbreak of COVID-19. This technique has progressed through three stages: from simple PCR to real-time fluorescence PCR to digital PCR. Among them, the microfluidic-based droplet digital PCR technique has attracted much attention and has been widely applied due to its advantages of high throughput, high sensitivity, low reagent consumption, low cross-contamination, and absolute quantification ability. In this review, we introduce various designs of microfluidic-based ddPCR developed within the last decade. The microfluidic-based droplet generation methods, thermal cycle strategies, and signal counting approaches are described, and the applications in the fields of single-cell analysis, disease diagnosis, and pathogen detection are introduced. Further, the challenges and prospects of microfluidic-based ddPCR are discussed. We hope that this review can contribute to the further development of the microfluidic-based ddPCR technique.
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Affiliation(s)
- Danfeng Xu
- Key Laboratory of Chemical Metrology and Applications on Nutrition and Health for State Market Regulation, Division of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, China.
| | - Weifei Zhang
- Key Laboratory of Chemical Metrology and Applications on Nutrition and Health for State Market Regulation, Division of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, China.
| | - Hongmei Li
- Key Laboratory of Chemical Metrology and Applications on Nutrition and Health for State Market Regulation, Division of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, China.
| | - Nan Li
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), China.
| | - Jin-Ming Lin
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), China.
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Yap M, O’Sullivan O, O’Toole PW, Cotter PD. Development of sequencing-based methodologies to distinguish viable from non-viable cells in a bovine milk matrix: A pilot study. Front Microbiol 2022; 13:1036643. [PMID: 36466696 PMCID: PMC9713316 DOI: 10.3389/fmicb.2022.1036643] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 10/28/2022] [Indexed: 04/22/2024] Open
Abstract
Although high-throughput DNA sequencing-based methods have been of great value for determining the composition of microbial communities in various environments, there is the potential for inaccuracies arising from the sequencing of DNA from dead microorganisms. In this pilot study, we compared different sequencing-based methods to assess their relative accuracy with respect to distinguishing between viable and non-viable cells, using a live and heat-inactivated model community spiked into bovine milk. The methods used were shotgun metagenomics with and without propidium monoazide (PMA) treatment, RNA-based 16S rRNA sequencing and metatranscriptomics. The results showed that methods were generally accurate, though significant differences were found depending on the library types and sequencing technologies. Different molecular targets were the basis for variations in the results generated using different library types, while differences in the derived composition data from Oxford Nanopore Technologies-and Illumina-based sequencing likely reflect a combination of different sequencing depths, error rates and bioinformatics pipelines. Although PMA was successfully applied in this study, further optimisation is required before it can be applied in a more universal context for complex microbiomes. Overall, these methods show promise and represent another important step towards the ultimate establishment of approaches that can be applied to accurately identify live microorganisms in milk and other food niches.
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Affiliation(s)
- Min Yap
- Teagasc Food Research Centre, Moorepark, Fermoy, Ireland
- School of Microbiology, University College Cork, Cork, Ireland
| | - Orla O’Sullivan
- Teagasc Food Research Centre, Moorepark, Fermoy, Ireland
- APC Microbiome Ireland, Cork, Ireland
| | - Paul W. O’Toole
- School of Microbiology, University College Cork, Cork, Ireland
- APC Microbiome Ireland, Cork, Ireland
| | - Paul D. Cotter
- Teagasc Food Research Centre, Moorepark, Fermoy, Ireland
- APC Microbiome Ireland, Cork, Ireland
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Brasell KA, Pochon X, Howarth J, Pearman JK, Zaiko A, Thompson L, Vandergoes MJ, Simon KS, Wood SA. Shifts in DNA yield and biological community composition in stored sediment: implications for paleogenomic studies. METABARCODING AND METAGENOMICS 2022. [DOI: 10.3897/mbmg.6.78128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Lake sediments hold a wealth of information from past environments that is highly valuable for paleolimnological reconstructions. These studies increasingly apply modern molecular tools targeting sedimentary DNA (sedDNA). However, sediment core sampling can be logistically difficult, making immediate subsampling for sedDNA challenging. Sediment cores are often refrigerated (4 °C) for weeks or months before subsampling. We investigated the impact of storage time on changes in DNA (purified or as cell lysate) concentrations and shifts in biological communities following storage of lake surface sediment at 4 °C for up to 24 weeks. Sediment samples (~ 0.22 g, in triplicate per time point) were spiked with purified DNA (100 or 200 ng) or lysate from a brackish water cyanobacterium that produces the cyanotoxin nodularin or non-spiked. Samples were analysed every 1–4 weeks over a 24-week period. Droplet digital PCR showed no significant decrease in the target gene (nodularin synthetase – subunit F; ndaF) over the 24-week period for samples spiked with purified DNA, while copy number decreased by more than half in cell lysate-spiked samples. There was significant change over time in bacteria and eukaryotic community composition assessed using metabarcoding. Amongst bacteria, the cyanobacterial signal became negligible after 5 weeks while Proteobacteria increased. In the eukaryotic community, Cercozoa became dominant after 6 weeks. These data demonstrate that DNA yields and community composition data shift significantly when sediments are stored chilled for more than 5 weeks. This highlights the need for rapid subsampling and appropriate storage of sediment core samples for paleogenomic studies.
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Picard M, Wood SA, Pochon X, Vandergoes MJ, Reyes L, Howarth JD, Hawes I, Puddick J. Molecular and Pigment Analyses Provide Comparative Results When Reconstructing Historic Cyanobacterial Abundances from Lake Sediment Cores. Microorganisms 2022; 10:microorganisms10020279. [PMID: 35208733 PMCID: PMC8876145 DOI: 10.3390/microorganisms10020279] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/12/2022] [Accepted: 01/17/2022] [Indexed: 12/04/2022] Open
Abstract
Understanding the historical onset of cyanobacterial blooms in freshwater bodies can help identify their potential drivers. Lake sediments are historical archives, containing information on what has occurred in and around lakes over time. Paleolimnology explores these records using a variety of techniques, but choosing the most appropriate method can be challenging. We compared results obtained from a droplet digital PCR assay targeting a cyanobacterial-specific region of the 16S rRNA gene in sedimentary DNA and cyanobacterial pigments (canthaxanthin, echinenone, myxoxanthophyll and zeaxanthin) analysed using high-performance liquid chromatography in four sediment cores. There were strong positive relationships between the 16S rRNA gene copy concentrations and individual pigment concentrations, but relationships differed among lakes and sediment core depths within lakes. The relationships were more consistent when all pigments were summed, which we attribute to different cyanobacteria species, in different lakes, at different times producing different suites of pigments. Each method had benefits and limitations, which should be taken into consideration during method selection and when interpreting paleolimnological data. We recommend this biphasic approach when making inferences about changes in the entire cyanobacterial community because they yielded complementary information. Our results support the view that molecular methods can yield results similar to traditional paleolimnological proxies when caveats are adequately addressed.
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Affiliation(s)
- Maïlys Picard
- Cawthron Institute, Private Bag 2, Nelson 7042, New Zealand; (S.A.W.); (X.P.); (J.P.)
- Department of Biological Sciences, School of Biological Sciences, University of Waikato, Hamilton 3216, New Zealand;
- Correspondence:
| | - Susanna A. Wood
- Cawthron Institute, Private Bag 2, Nelson 7042, New Zealand; (S.A.W.); (X.P.); (J.P.)
| | - Xavier Pochon
- Cawthron Institute, Private Bag 2, Nelson 7042, New Zealand; (S.A.W.); (X.P.); (J.P.)
- Institute of Marine Science, University of Auckland, Private Bag 349, Auckland 0941, New Zealand
| | - Marcus J. Vandergoes
- GNS Science, 1 Fairway Drive, Avalon, Lower Hutt 5011, New Zealand; (M.J.V.); (L.R.)
| | - Lizette Reyes
- GNS Science, 1 Fairway Drive, Avalon, Lower Hutt 5011, New Zealand; (M.J.V.); (L.R.)
| | - Jamie D. Howarth
- School of Geography, Environment and Earth Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6012, New Zealand;
| | - Ian Hawes
- Department of Biological Sciences, School of Biological Sciences, University of Waikato, Hamilton 3216, New Zealand;
| | - Jonathan Puddick
- Cawthron Institute, Private Bag 2, Nelson 7042, New Zealand; (S.A.W.); (X.P.); (J.P.)
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Capo E, Monchamp ME, Coolen MJL, Domaizon I, Armbrecht L, Bertilsson S. Environmental paleomicrobiology: using DNA preserved in aquatic sediments to its full potential. Environ Microbiol 2022; 24:2201-2209. [PMID: 35049133 PMCID: PMC9304175 DOI: 10.1111/1462-2920.15913] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 11/30/2022]
Abstract
In‐depth knowledge about spatial and temporal variation in microbial diversity and function is needed for a better understanding of ecological and evolutionary responses to global change. In particular, the study of microbial ancient DNA preserved in sediment archives from lakes and oceans can help us to evaluate the responses of aquatic microbes in the past and make predictions about future biodiversity change in those ecosystems. Recent advances in molecular genetic methods applied to the analysis of historically deposited DNA in sediments have not only allowed the taxonomic identification of past aquatic microbial communities but also enabled tracing their evolution and adaptation to episodic disturbances and gradual environmental change. Nevertheless, some challenges remain for scientists to take full advantage of the rapidly developing field of paleo‐genetics, including the limited ability to detect rare taxa and reconstruct complete genomes for evolutionary studies. Here, we provide a brief review of some of the recent advances in the field of environmental paleomicrobiology and discuss remaining challenges related to the application of molecular genetic methods to study microbial diversity, ecology, and evolution in sediment archives. We anticipate that, in the near future, environmental paleomicrobiology will shed new light on the processes of microbial genome evolution and microbial ecosystem responses to quaternary environmental changes at an unprecedented level of detail. This information can, for example, aid geological reconstructions of biogeochemical cycles and predict ecosystem responses to environmental perturbations, including in the context of human‐induced global changes.
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Affiliation(s)
- Eric Capo
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden
| | - Marie-Eve Monchamp
- Department of Biology, McGill University, Montréal, QC, H3A 1B1, Canada.,Groupe de recherche interuniversitaire en limnologie (GRIL)
| | - Marco J L Coolen
- Western Australia Organic and Isotope Geochemistry Centre (WA-OIGC), Curtin University, Bentley, 6102, Australia
| | - Isabelle Domaizon
- INRAE, Université Savoie Mont Blanc, CARRTEL, 74200 Thonon les Bains, France.,UMR CARRTEL, Pôle R&D ECLA, 74200 Thonon les Bains, France
| | - Linda Armbrecht
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, 7004, Australia.,Australian Centre for Ancient DNA, School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden
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