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Deng F, Xie H, Zheng T, Yang Y, Bao X, He H, Zhang X, Liang C. Dynamic responses of soil microbial communities to seasonal freeze-thaw cycles in a temperate agroecosystem. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 950:175228. [PMID: 39102954 DOI: 10.1016/j.scitotenv.2024.175228] [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: 03/05/2024] [Revised: 06/22/2024] [Accepted: 07/31/2024] [Indexed: 08/07/2024]
Abstract
Soil freeze-thaw cycles (FTCs) are common in temperate agricultural ecosystems during the non-growing season and are progressively influenced by climate change. The impact of these cycles on soil microbial communities, crucial for ecosystem functioning, varies under different agricultural management practices. Here, we investigated the dynamic changes in soil microbial communities in a Mollisol during seasonal FTCs and examined the effects of stover mulching and nitrogen fertilization. We revealed distinct responses between bacterial and fungal communities. The dominant bacterial phyla reacted differently to FTCs: for example, Proteobacteria responded opportunistically, Actinobacteria, Acidobacteria, Choroflexi and Gemmatimonadetes responded sensitively, and Saccharibacteria exhibited a tolerance response. In contrast, the fungal community composition remained relatively stable during FTCs, except for a decline in Glomeromycota. Certain bacterial OTUs acted as sensitive indicators of FTCs, forming keystone modules in the network that are closely linked to soil carbon, nitrogen content and potential functions. Additionally, neither stover mulching nor nitrogen fertilization significantly influenced microbial richness, diversity and potential functions. However, over time, more indicator species specific to these agricultural practices began to emerge within the networks and gradually occupied the central positions. Furthermore, our findings suggest that farming practices, by introducing keystone microbes and changing interspecies interactions (even without changing microbial richness and diversity), can enhance microbial community stability against FTC disturbances. Specifically, higher nitrogen input with stover removal promotes fungal stability during soil freezing, while lower nitrogen levels increase bacterial stability during soil thawing. Considering the fungal tolerance to FTCs, we recommend reducing nitrogen input for manipulating bacterial interactions, thereby enhancing overall microbial resilience to seasonal FTCs. In summary, our research reveals that microbial responses to seasonal FTCs are reshaped through land management to support ecosystem functions under environmental stress amid climate change.
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Affiliation(s)
- Fangbo Deng
- Key Lab of Conservation Tillage & Ecological Agriculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongtu Xie
- Key Lab of Conservation Tillage & Ecological Agriculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Tiantian Zheng
- Key Lab of Conservation Tillage & Ecological Agriculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Yali Yang
- Key Lab of Conservation Tillage & Ecological Agriculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Xuelian Bao
- Key Lab of Conservation Tillage & Ecological Agriculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Hongbo He
- Key Lab of Conservation Tillage & Ecological Agriculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Xudong Zhang
- Key Lab of Conservation Tillage & Ecological Agriculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Chao Liang
- Key Lab of Conservation Tillage & Ecological Agriculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
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Gao D, Luster J, Zürcher A, Arend M, Bai E, Gessler A, Rigling A, Schaub M, Hartmann M, Werner RA, Joseph J, Poll C, Hagedorn F. Drought resistance and resilience of rhizosphere communities in forest soils from the cellular to ecosystem scale - insights from 13C pulse labeling. THE NEW PHYTOLOGIST 2024; 242:960-974. [PMID: 38402527 DOI: 10.1111/nph.19612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 02/06/2024] [Indexed: 02/26/2024]
Abstract
The link between above- and belowground communities is a key uncertainty in drought and rewetting effects on forest carbon (C) cycle. In young beech model ecosystems and mature naturally dry pine forest exposed to 15-yr-long irrigation, we performed 13C pulse labeling experiments, one during drought and one 2 wk after rewetting, tracing tree assimilates into rhizosphere communities. The 13C pulses applied in tree crowns reached soil microbial communities of the young and mature forests one and 4 d later, respectively. Drought decreased the transfer of labeled assimilates relative to the irrigation treatment. The 13C label in phospholipid fatty acids (PLFAs) indicated greater drought reduction of assimilate incorporation by fungi (-85%) than by gram-positive (-43%) and gram-negative bacteria (-58%). 13C label incorporation was more strongly reduced for PLFAs (cell membrane) than for microbial cytoplasm extracted by chloroform. This suggests that fresh rhizodeposits are predominantly used for osmoregulation or storage under drought, at the expense of new cell formation. Two weeks after rewetting, 13C enrichment in PLFAs was greater in previously dry than in continuously moist soils. Drought and rewetting effects were greater in beech systems than in pine forest. Belowground C allocation and rhizosphere communities are highly resilient to drought.
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Affiliation(s)
- Decai Gao
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 100101, Beijing, China
- College of Resources and Environment, University of Chinese Academy of Sciences, 100190, Beijing, China
| | - Jörg Luster
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
| | - Alois Zürcher
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
| | - Matthias Arend
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
- Physiological Plant Ecology, University of Basel, 4056, Basel, Switzerland
| | - Edith Bai
- Key Laboratory of Geographical Processes and Ecological Security of Changbai Mountains, Ministry of Education, Northeast Normal University, 130024, Changchun, China
| | - Arthur Gessler
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
- Terrestrial Ecosystems, ETH Zürich, 8092, Zürich, Switzerland
| | - Andreas Rigling
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
- Terrestrial Ecosystems, ETH Zürich, 8092, Zürich, Switzerland
| | - Marcus Schaub
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
| | - Martin Hartmann
- Sustainable Agroecosystems Group, Department of Environmental Systems Science, Institute of Agricultural Sciences, ETH Zürich, 8092, Zürich, Switzerland
| | - Roland A Werner
- Agricultural Sciences, ETH Zürich, 8092, Zürich, Switzerland
| | - Jobin Joseph
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
| | - Christian Poll
- Soil Biology, University of Hohenheim, 70599, Stuttgart, Germany
| | - Frank Hagedorn
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
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Noirungsee N, Changkhong S, Phinyo K, Suwannajak C, Tanakul N, Inwongwan S. Genome-scale metabolic modelling of extremophiles and its applications in astrobiological environments. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13231. [PMID: 38192220 PMCID: PMC10866088 DOI: 10.1111/1758-2229.13231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 12/19/2023] [Indexed: 01/10/2024]
Abstract
Metabolic modelling approaches have become the powerful tools in modern biology. These mathematical models are widely used to predict metabolic phenotypes of the organisms or communities of interest, and to identify metabolic targets in metabolic engineering. Apart from a broad range of industrial applications, the possibility of using metabolic modelling in the contexts of astrobiology are poorly explored. In this mini-review, we consolidated the concepts and related applications of applying metabolic modelling in studying organisms in space-related environments, specifically the extremophilic microbes. We recapitulated the current state of the art in metabolic modelling approaches and their advantages in the astrobiological context. Our review encompassed the applications of metabolic modelling in the theoretical investigation of the origin of life within prebiotic environments, as well as the compilation of existing uses of genome-scale metabolic models of extremophiles. Furthermore, we emphasize the current challenges associated with applying this technique in extreme environments, and conclude this review by discussing the potential implementation of metabolic models to explore theoretically optimal metabolic networks under various space conditions. Through this mini-review, our aim is to highlight the potential of metabolic modelling in advancing the study of astrobiology.
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Affiliation(s)
- Nuttapol Noirungsee
- Department of Biology, Faculty of ScienceChiang Mai UniversityChiang MaiThailand
- Research Center of Microbial Diversity and Sustainable Utilizations, Faculty of ScienceChiang Mai UniversityChiang MaiThailand
| | - Sakunthip Changkhong
- Department of Biology, Faculty of ScienceChiang Mai UniversityChiang MaiThailand
- Department of Thoracic SurgeryUniversity Hospital ZurichZurichSwitzerland
| | - Kittiya Phinyo
- Department of Biology, Faculty of ScienceChiang Mai UniversityChiang MaiThailand
- Research group on Earth—Space Ecology (ESE), Faculty of ScienceChiang Mai UniversityChiang MaiThailand
- Office of Research AdministrationChiang Mai UniversityChiang MaiThailand
| | | | - Nahathai Tanakul
- National Astronomical Research Institute of ThailandChiang MaiThailand
| | - Sahutchai Inwongwan
- Department of Biology, Faculty of ScienceChiang Mai UniversityChiang MaiThailand
- Research Center of Microbial Diversity and Sustainable Utilizations, Faculty of ScienceChiang Mai UniversityChiang MaiThailand
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Quiroga MV, Valverde A, Mataloni G, Casa V, Stegen JC, Cowan D. The ecological assembly of bacterial communities in Antarctic wetlands varies across levels of phylogenetic resolution. Environ Microbiol 2022; 24:3486-3499. [PMID: 35049116 PMCID: PMC9541017 DOI: 10.1111/1462-2920.15912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 01/10/2022] [Accepted: 01/13/2022] [Indexed: 11/28/2022]
Abstract
As functional traits are conserved at different phylogenetic depths, the ability to detect community assembly processes can be conditional on the phylogenetic resolution; yet most previous work quantifying their influence has focused on a single level of phylogenetic resolution. Here, we have studied the ecological assembly of bacterial communities from an Antarctic wetland complex, applying null models across different levels of phylogenetic resolution (i.e. clustering ASVs into OTUs with decreasing sequence identity thresholds). We found that the relative influence of the community assembly processes varies with phylogenetic resolution. More specifically, selection processes seem to impose stronger influence at finer (100% sequence similarity ASV) than at coarser (99%–97% sequence similarity OTUs) resolution. We identified environmental features related with the ecological processes and propose a conceptual model for the bacterial community assembly in this Antarctic ecosystem. Briefly, eco‐evolutionary processes appear to be leading to different but very closely related ASVs in lotic, lentic and terrestrial environments. In all, this study shows that assessing community assembly processes at different phylogenetic resolutions is key to improve our understanding of microbial ecology. More importantly, a failure to detect selection processes at coarser phylogenetic resolution does not imply the absence of such processes at finer resolutions.
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Affiliation(s)
- María V Quiroga
- Instituto Tecnológico de Chascomús (INTECH, UNSAM - CONICET), Chascomús, Argentina
| | - Angel Valverde
- Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Consejo Superior de Investigaciones Científicas, Salamanca, Spain
| | - Gabriela Mataloni
- Instituto de Investigación e Ingeniería Ambiental (IIIA, UNSAM-CONICET), San Martín, Buenos Aires, Argentina
| | - Valeria Casa
- Instituto de Investigación e Ingeniería Ambiental (IIIA, UNSAM-CONICET), San Martín, Buenos Aires, Argentina
| | - James C Stegen
- Pacific Northwest National Laboratory, Ecosystem Science Team, Richland, WA, USA
| | - Don Cowan
- Centre for Microbial Ecology and Genomics (CMEG), Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
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Predominance of Anaerobic, Spore-Forming Bacteria in Metabolically Active Microbial Communities from Ancient Siberian Permafrost. Appl Environ Microbiol 2019; 85:AEM.00560-19. [PMID: 31152014 DOI: 10.1128/aem.00560-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 05/22/2019] [Indexed: 11/20/2022] Open
Abstract
The prevalence of microbial life in permafrost up to several million years (Ma) old has been well documented. However, the long-term survivability, evolution, and metabolic activity of the entombed microbes over this time span remain underexplored. We integrated aspartic acid (Asp) racemization assays with metagenomic sequencing to characterize the microbial activity, phylogenetic diversity, and metabolic functions of indigenous microbial communities across a ∼0.01- to 1.1-Ma chronosequence of continuously frozen permafrost from northeastern Siberia. Although Asp in the older bulk sediments (0.8 to 1.1 Ma) underwent severe racemization relative to that in the youngest sediment (∼0.01 Ma), the much lower d-Asp/l-Asp ratio (0.05 to 0.14) in the separated cells from all samples suggested that indigenous microbial communities were viable and metabolically active in ancient permafrost up to 1.1 Ma. The microbial community in the youngest sediment was the most diverse and was dominated by the phyla Actinobacteria and Proteobacteria In contrast, microbial diversity decreased dramatically in the older sediments, and anaerobic, spore-forming bacteria within Firmicutes became overwhelmingly dominant. In addition to the enrichment of sporulation-related genes, functional genes involved in anaerobic metabolic pathways such as fermentation, sulfate reduction, and methanogenesis were more abundant in the older sediments. Taken together, the predominance of spore-forming bacteria and associated anaerobic metabolism in the older sediments suggest that a subset of the original indigenous microbial community entrapped in the permafrost survived burial over geological time.IMPORTANCE Understanding the long-term survivability and associated metabolic traits of microorganisms in ancient permafrost frozen millions of years ago provides a unique window into the burial and preservation processes experienced in general by subsurface microorganisms in sedimentary deposits because of permafrost's hydrological isolation and exceptional DNA preservation. We employed aspartic acid racemization modeling and metagenomics to determine which microbial communities were metabolically active in the 1.1-Ma permafrost from northeastern Siberia. The simultaneous sequencing of extracellular and intracellular genomic DNA provided insight into the metabolic potential distinguishing extinct from extant microorganisms under frozen conditions over this time interval. This in-depth metagenomic sequencing advances our understanding of the microbial diversity and metabolic functions of extant microbiomes from early Pleistocene permafrost. Therefore, these findings extend our knowledge of the survivability of microbes in permafrost from 33,000 years to 1.1 Ma.
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Saitta ET, Liang R, Lau MCY, Brown CM, Longrich NR, Kaye TG, Novak BJ, Salzberg SL, Norell MA, Abbott GD, Dickinson MR, Vinther J, Bull ID, Brooker RA, Martin P, Donohoe P, Knowles TDJ, Penkman KEH, Onstott T. Cretaceous dinosaur bone contains recent organic material and provides an environment conducive to microbial communities. eLife 2019; 8:e46205. [PMID: 31210129 PMCID: PMC6581507 DOI: 10.7554/elife.46205] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 05/12/2019] [Indexed: 12/12/2022] Open
Abstract
Fossils were thought to lack original organic molecules, but chemical analyses show that some can survive. Dinosaur bone has been proposed to preserve collagen, osteocytes, and blood vessels. However, proteins and labile lipids are diagenetically unstable, and bone is a porous open system, allowing microbial/molecular flux. These 'soft tissues' have been reinterpreted as biofilms. Organic preservation versus contamination of dinosaur bone was examined by freshly excavating, with aseptic protocols, fossils and sedimentary matrix, and chemically/biologically analyzing them. Fossil 'soft tissues' differed from collagen chemically and structurally; while degradation would be expected, the patterns observed did not support this. 16S rRNA amplicon sequencing revealed that dinosaur bone hosted an abundant microbial community different from lesser abundant communities of surrounding sediment. Subsurface dinosaur bone is a relatively fertile habitat, attracting microbes that likely utilize inorganic nutrients and complicate identification of original organic material. There exists potential post-burial taphonomic roles for subsurface microorganisms.
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Affiliation(s)
- Evan T Saitta
- Integrative Research Center, Section of Earth SciencesField Museum of Natural HistoryChicagoUnited States
| | - Renxing Liang
- Department of GeosciencesPrinceton UniversityPrincetonUnited States
| | - Maggie CY Lau
- Department of GeosciencesPrinceton UniversityPrincetonUnited States
- Institute of Deep-Sea Science and EngineeringChinese Academy of SciencesSanyaChina
| | - Caleb M Brown
- Royal Tyrrell Museum of PalaeontologyDrumhellerCanada
| | - Nicholas R Longrich
- Department of Biology and BiochemistryUniversity of BathBathUnited Kingdom
- Milner Centre for EvolutionUniversity of BathBathUnited Kingdom
| | - Thomas G Kaye
- Foundation for Scientific AdvancementSierra VistaUnited States
| | - Ben J Novak
- Revive and RestoreSan FranciscoUnited States
| | - Steven L Salzberg
- Department of Biomedical Engineering, Center for Computational Biology, McKusick-Nathans Institute of Genetic MedicineJohns Hopkins UniversityBaltimoreUnited States
- Department of Computer Science, Center for Computational Biology, McKusick-Nathans Institute of Genetic MedicineJohns Hopkins UniversityBaltimoreUnited States
- Department of Biostatistics, Center for Computational Biology, McKusick-Nathans Institute of Genetic MedicineJohns Hopkins UniversityBaltimoreUnited States
| | - Mark A Norell
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkUnited States
| | - Geoffrey D Abbott
- School of Natural and Environmental SciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | | | - Jakob Vinther
- School of Earth SciencesUniversity of BristolBristolUnited Kingdom
- School of Biological SciencesUniversity of BristolBristolUnited Kingdom
| | - Ian D Bull
- School of ChemistryUniversity of BristolBristolUnited Kingdom
| | | | - Peter Martin
- School of PhysicsUniversity of BristolBristolUnited Kingdom
| | - Paul Donohoe
- School of Natural and Environmental SciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Timothy DJ Knowles
- School of ChemistryUniversity of BristolBristolUnited Kingdom
- School of ArtsUniversity of BristolBristolUnited Kingdom
| | | | - Tullis Onstott
- Department of GeosciencesPrinceton UniversityPrincetonUnited States
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Casillo A, Parrilli E, Tutino ML, Corsaro MM. The outer membrane glycolipids of bacteria from cold environments: isolation, characterization, and biological activity. FEMS Microbiol Ecol 2019; 95:5519854. [DOI: 10.1093/femsec/fiz094] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 06/14/2019] [Indexed: 01/18/2023] Open
Abstract
ABSTRACTLipopolysaccharides (LPSs) are the main components of the external leaflet of the outer membrane of Gram-negative bacteria. Microorganisms that colonize permanently or transiently cold habitats have evolved an array of structural adaptations, some of which involve components of bacterial membranes. These adaptations assure the perfect functionality of the membrane even at freezing or sub-freezing growth temperatures. This review summarizes the state-of-the-art information concerning the structural features of the LPSs produced by cold-adapted bacteria. The LPS structure has recently been elucidated from species mainly belonging to Gammaproteobacteria and Flavobacteriaceae. Although the reported structural heterogeneity may arise from the phylogenetic diversity of the analyzed source strains, some generalized trends can be deduced. For instance, it is clear that only a small portion of LPSs displays the O-chain. In addition, the biological activity of the lipid A portion from several cold-adapted strains is reported.
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Affiliation(s)
- Angela Casillo
- Department of Chemical Sciences, Università degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, via Cintia, 80126 Naples, Italy
| | - Ermenegilda Parrilli
- Department of Chemical Sciences, Università degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, via Cintia, 80126 Naples, Italy
| | - Maria Luisa Tutino
- Department of Chemical Sciences, Università degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, via Cintia, 80126 Naples, Italy
| | - Maria Michela Corsaro
- Department of Chemical Sciences, Università degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, via Cintia, 80126 Naples, Italy
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Managadze GG, Safronova AA, Luchnikov KA, Vorobyova EA, Duxbury NS, Wurz P, Managadze NG, Chumikov AE, Khamizov RK. A New Method and Mass-Spectrometric Instrument for Extraterrestrial Microbial Life Detection Using the Elemental Composition Analyses of Martian Regolith and Permafrost/Ice. ASTROBIOLOGY 2017; 17:448-458. [PMID: 28520473 DOI: 10.1089/ast.2016.1511] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We propose a new technique for the detection of microorganisms by elemental composition analyses of a sample extracted from regolith, permafrost, and ice of extraterrestrial bodies. We also describe the design of the ABIMAS instrument, which consists of the onboard time-of-flight laser mass-reflectron (TOF LMR) and the sample preparation unit (SPU) for biomass extraction. This instrument was initially approved to fly on board the ExoMars 2020 lander mission. The instrument can be used to analyze the elemental composition of possible extraterrestrial microbial communities and compare it to that of terrestrial microorganisms. We have conducted numerous laboratory studies to confirm the possibility of biomass identification via the following biomarkers: P/S and Ca/K ratios, and C and N abundances. We underline that only the combination of these factors will allow one to discriminate microbial samples from geological ones. Our technique has been tested experimentally in numerous laboratory trials on cultures of microorganisms and polar permafrost samples as terrestrial analogues for martian polar soils. We discuss various methods of extracting microorganisms and sample preparation. The developed technique can be used to search for and identify microorganisms in different martian samples and in the subsurface of other planets, satellites, comets, and asteroids-in particular, Europa, Ganymede, and Enceladus. Key Words: Mass spectrometry-Life-detection instruments-Biomarkers-Earth Mars-Biomass spectra. Astrobiology 17, 448-458.
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Affiliation(s)
- G G Managadze
- 1 Space Research Institute , Russian Academy of Sciences, Moscow, Russian Federation
| | - A A Safronova
- 1 Space Research Institute , Russian Academy of Sciences, Moscow, Russian Federation
| | - K A Luchnikov
- 1 Space Research Institute , Russian Academy of Sciences, Moscow, Russian Federation
| | - E A Vorobyova
- 1 Space Research Institute , Russian Academy of Sciences, Moscow, Russian Federation
- 2 Soil Science Faculty, Lomonosov Moscow State University , Moscow, Russian Federation
| | - N S Duxbury
- 3 Department of Physics, Astronomy and Computational Sciences, George Mason University , Fairfax, Virginia, USA
- 4 Geology Faculty, Lomonosov Moscow State University , Moscow, Russian Federation
| | - P Wurz
- 5 Physics Institute, University of Bern , Bern, Switzerland
| | - N G Managadze
- 1 Space Research Institute , Russian Academy of Sciences, Moscow, Russian Federation
| | - A E Chumikov
- 1 Space Research Institute , Russian Academy of Sciences, Moscow, Russian Federation
| | - R Kh Khamizov
- 6 Institute of Geological Chemistry , Russian Academy of Sciences, Moscow, Russian Federation
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Potential microbial contamination during sampling of permafrost soil assessed by tracers. Sci Rep 2017; 7:43338. [PMID: 28230151 PMCID: PMC5322388 DOI: 10.1038/srep43338] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 01/25/2017] [Indexed: 11/08/2022] Open
Abstract
Drilling and handling of permanently frozen soil cores without microbial contamination is of concern because contamination e.g. from the active layer above may lead to incorrect interpretation of results in experiments investigating potential and actual microbial activity in these low microbial biomass environments. Here, we present an example of how microbial contamination from active layer soil affected analysis of the potentially active microbial community in permafrost soil. We also present the development and use of two tracers: (1) fluorescent plastic microspheres and (2) Pseudomonas putida genetically tagged with Green Fluorescent Protein production to mimic potential microbial contamination of two permafrost cores. A protocol with special emphasis on avoiding microbial contamination was developed and employed to examine how far microbial contamination can penetrate into permafrost cores. The quantity of tracer elements decreased with depth into the permafrost cores, but the tracers were detected as far as 17 mm from the surface of the cores. The results emphasize that caution should be taken to avoid microbial contamination of permafrost cores and that the application of tracers represents a useful tool to assess penetration of potential microbial contamination into permafrost cores.
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Nikrad MP, Kerkhof LJ, Häggblom MM. The subzero microbiome: microbial activity in frozen and thawing soils. FEMS Microbiol Ecol 2016; 92:fiw081. [PMID: 27106051 DOI: 10.1093/femsec/fiw081] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2016] [Indexed: 01/15/2023] Open
Abstract
Most of the Earth's biosphere is characterized by low temperatures (<5°C) and cold-adapted microorganisms are widespread. These psychrophiles have evolved a complex range of adaptations of all cellular constituents to counteract the potentially deleterious effects of low kinetic energy environments and the freezing of water. Microbial life continues into the subzero temperature range, and this activity contributes to carbon and nitrogen flux in and out of ecosystems, ultimately affecting global processes. Microbial responses to climate warming and, in particular, thawing of frozen soils are not yet well understood, although the threat of microbial contribution to positive feedback of carbon flux is substantial. To date, several studies have examined microbial community dynamics in frozen soils and permafrost due to changing environmental conditions, and some have undertaken the complicated task of characterizing microbial functional groups and how their activity changes with changing conditions, either in situ or by isolating and characterizing macromolecules. With increasing temperature and wetter conditions microbial activity of key microbes and subsequent efflux of greenhouse gases also increase. In this review, we aim to provide an overview of microbial activity in seasonally frozen soils and permafrost. With a more detailed understanding of the microbiological activities in these vulnerable soil ecosystems, we can begin to predict and model future expectations for carbon release and climate change.
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Affiliation(s)
| | - Lee J Kerkhof
- Department of Marine and Coastal Sciences, Rutgers, the State University of New Jersey, New Brunswick, NJ 08901, USA
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Nunn BL, Slattery KV, Cameron KA, Timmins-Schiffman E, Junge K. Proteomics of Colwellia psychrerythraea at subzero temperatures - a life with limited movement, flexible membranes and vital DNA repair. Environ Microbiol 2015; 17:2319-35. [PMID: 25471130 DOI: 10.1111/1462-2920.12691] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 10/23/2014] [Accepted: 10/23/2014] [Indexed: 11/27/2022]
Abstract
The mechanisms that allow psychrophilic bacteria to remain metabolically active at subzero temperatures result from form and function of their proteins. We present first proteomic evidence of physiological changes of the marine psychrophile Colwellia psychrerythraea 34H (Cp34H) after exposure to subzero temperatures (-1, and -10°C in ice) through 8 weeks. Protein abundance was compared between different treatments to understand the effects of temperature and time, independently and jointly, within cells transitioning to, and being maintained in ice. Parallel [3H]-leucine and [3H]-thymidine incubations indicated active protein and DNA synthesis to -10°C. Mass spectrometry-based proteomics identified 1763 proteins across four experimental treatments. Proteins involved in osmolyte regulation and polymer secretion were found constitutively present across all treatments, suggesting that they are required for metabolic success below 0°C. Differentially abundant protein groups indicated a reallocation of resources from DNA binding to DNA repair and from motility to chemo-taxis and sensing. Changes to iron and nitrogen metabolism, cellular membrane structures, and protein synthesis and folding were also revealed. By elucidating vital strategies during life in ice, this study provides novel insight into the extensive molecular adaptations that occur in cold-adapted marine organisms to sustain cellular function in their habitat.
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Affiliation(s)
- Brook L Nunn
- Department of Genome Sciences, University of Washington, Box 355065, Seattle, WA, 98195, USA
| | - Krystal V Slattery
- Applied Physics Laboratory, Polar Science Center, University of Washington, Box 355640, Seattle, WA, 98195, USA
| | - Karen A Cameron
- Applied Physics Laboratory, Polar Science Center, University of Washington, Box 355640, Seattle, WA, 98195, USA
| | - Emma Timmins-Schiffman
- Department of Genome Sciences, University of Washington, Box 355065, Seattle, WA, 98195, USA
| | - Karen Junge
- Applied Physics Laboratory, Polar Science Center, University of Washington, Box 355640, Seattle, WA, 98195, USA
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Abstract
Permafrost constitutes a major portion of the terrestrial cryosphere of the Earth and is a unique ecological niche for cold-adapted microorganisms. There is a relatively high microbial diversity in permafrost, although there is some variation in community composition across different permafrost features and between sites. Some microorganisms are even active at subzero temperatures in permafrost. An emerging concern is the impact of climate change and the possibility of subsequent permafrost thaw promoting microbial activity in permafrost, resulting in increased potential for greenhouse-gas emissions. This Review describes new data on the microbial ecology of permafrost and provides a platform for understanding microbial life strategies in frozen soil as well as the impact of climate change on permafrost microorganisms and their functional roles.
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Affiliation(s)
- Janet K Jansson
- 1] Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, MS 70A-3317 Berkeley, California 94720, USA. [2] Joint Genome Institute (JGI), 2800 Mitchell Drive, Walnut Creek, California 94598, USA. [3] Joint BioEnergy Institute (JBEI), 5885 Hollis Street, Emeryville, California 94608, USA. [4] Danish Center for Permafrost (CENPERM), University of Copenhagen, Oester Voldgade 10, DK-1350 Copenhagen, Denmark. [5] Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, California 94720-3102, USA
| | - Neslihan Taş
- Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, MS 70A-3317 Berkeley, California 94720, USA
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13
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Abstract
The survival of microorganisms in ancient glacial ice and permafrost has been ascribed to their ability to persist in a dormant, metabolically inert state. An alternative possibility, supported by experimental data, is that microorganisms in frozen matrices are able to sustain a level of metabolic function that is sufficient for cellular repair and maintenance. To examine this experimentally, frozen populations of Psychrobacter arcticus 273-4 were exposed to ionizing radiation (IR) to simulate the damage incurred from natural background IR sources in the permafrost environment from over ∼225 kiloyears (ky). High-molecular-weight DNA was fragmented by exposure to 450 Gy of IR, which introduced an average of 16 double-strand breaks (DSBs) per chromosome. During incubation at -15°C for 505 days, P. arcticus repaired DNA DSBs in the absence of net growth. Based on the time frame for the assembly of genomic fragments by P. arcticus, the rate of DNA DSB repair was estimated at 7 to 10 DSBs year(-1) under the conditions tested. Our results provide direct evidence for the repair of DNA lesions, extending the range of complex biochemical reactions known to occur in bacteria at frozen temperatures. Provided that sufficient energy and nutrient sources are available, a functional DNA repair mechanism would allow cells to maintain genome integrity and augment microbial survival in icy terrestrial or extraterrestrial environments.
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14
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Doyle SM, Montross SN, Skidmore ML, Christner BC. Characterizing microbial diversity and the potential for metabolic function at -15 °c in the Basal ice of taylor glacier, antarctica. BIOLOGY 2013; 2:1034-53. [PMID: 24833055 PMCID: PMC3960875 DOI: 10.3390/biology2031034] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 07/12/2013] [Accepted: 07/16/2013] [Indexed: 11/16/2022]
Abstract
Measurement of gases entrapped in clean ice from basal portions of the Taylor Glacier, Antarctica, revealed that CO2 ranged from 229 to 328 ppmv and O2 was near 20% of the gas volume. In contrast, vertically adjacent sections of the sediment laden basal ice contained much higher concentrations of CO2 (60,000 to 325,000 ppmv), whereas O2 represented 4 to 18% of the total gas volume. The deviation in gas composition from atmospheric values occurred concurrently with increased microbial cell concentrations in the basal ice profile, suggesting that in situ microbial processes (i.e., aerobic respiration) may have altered the entrapped gas composition. Molecular characterization of 16S rRNA genes amplified from samples of the basal ice indicated a low diversity of bacteria, and most of the sequences characterized (87%) were affiliated with the phylum, Firmicutes. The most abundant phylotypes in libraries from ice horizons with elevated CO2 and depleted O2 concentrations were related to the genus Paenisporosarcina, and 28 isolates from this genus were obtained by enrichment culturing. Metabolic experiments with Paenisporosarcina sp. TG14 revealed its capacity to conduct macromolecular synthesis when frozen in water derived from melted basal ice samples and incubated at −15 °C. The results support the hypothesis that the basal ice of glaciers and ice sheets are cryospheric habitats harboring bacteria with the physiological capacity to remain metabolically active and biogeochemically cycle elements within the subglacial environment.
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Affiliation(s)
- Shawn M Doyle
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - Scott N Montross
- Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA.
| | - Mark L Skidmore
- Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA.
| | - Brent C Christner
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
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15
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Zhang DC, Brouchkov A, Griva G, Schinner F, Margesin R. Isolation and characterization of bacteria from ancient siberian permafrost sediment. BIOLOGY 2013; 2:85-106. [PMID: 24832653 PMCID: PMC4009857 DOI: 10.3390/biology2010085] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/12/2012] [Accepted: 12/25/2012] [Indexed: 11/29/2022]
Abstract
In this study, we isolated and characterized bacterial strains from ancient (Neogene) permafrost sediment that was permanently frozen for 3.5 million years. The sampling site was located at Mammoth Mountain in the Aldan river valley in Central Yakutia in Eastern Siberia. Analysis of phospolipid fatty acids (PLFA) demonstrated the dominance of bacteria over fungi; the analysis of fatty acids specific for Gram-positive and Gram-negative bacteria revealed an approximately twofold higher amount of Gram-negative bacteria compared to Gram-positive bacteria. Direct microbial counts after natural permafrost enrichment showed the presence of (4.7 ± 1.5) × 108 cells g-1 sediment dry mass. Viable heterotrophic bacteria were found at 0 °C, 10 °C and 25 °C, but not at 37 °C. Spore-forming bacteria were not detected. Numbers of viable fungi were low and were only detected at 0 °C and 10 °C. Selected culturable bacterial isolates were identified as representatives of Arthrobacter phenanthrenivorans, Subtercola frigoramans and Glaciimonas immobilis. Representatives of each of these species were characterized with regard to their growth temperature range, their ability to grow on different media, to produce enzymes, to grow in the presence of NaCl, antibiotics, and heavy metals, and to degrade hydrocarbons. All strains could grow at -5 °C; the upper temperature limit for growth in liquid culture was 25 °C or 30 °C. Sensitivity to rich media, antibiotics, heavy metals, and salt increased when temperature decreased (20 °C > 10 °C > 1 °C). In spite of the ligninolytic activity of some strains, no biodegradation activity was detected.
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Affiliation(s)
- De-Chao Zhang
- Institute of Microbiology, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
| | - Anatoli Brouchkov
- Faculty of Geology, Lomonosov Moscow State University, GSP-1,1 Leninskiye Gory, Moscow 119991, Russia.
| | - Gennady Griva
- Tyumen Scientific Center Siberian Branch of Russian Academy of Science, 86 Malygina, Tyumen 625000, Russia.
| | - Franz Schinner
- Institute of Microbiology, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
| | - Rosa Margesin
- Institute of Microbiology, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
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16
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Youle M, Rohwer F, Stacy A, Whiteley M, Steel BC, Delalez NJ, Nord AL, Berry RM, Armitage JP, Kamoun S, Hogenhout S, Diggle SP, Gurney J, Pollitt EJG, Boetius A, Cary SC. The Microbial Olympics. Nat Rev Microbiol 2012; 10:583-8. [PMID: 22796885 DOI: 10.1038/nrmicro2837] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Every four years, the Olympic Games plays host to competitors who have built on their natural talent by training for many years to become the best in their chosen discipline. Similar spirit and endeavour can be found throughout the microbial world, in which every day is a competition to survive and thrive. Microorganisms are trained through evolution to become the fittest and the best adapted to a particular environmental niche or lifestyle, and to innovate when the 'rules of the game' are changed by alterations to their natural habitats. In this Essay, we honour the best competitors in the microbial world by inviting them to take part in the inaugural Microbial Olympics.
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Affiliation(s)
- Merry Youle
- Rainbow Rock, Ocean View, Hawaii 96737, USA.
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Achberger AM, Brox TI, Skidmore ML, Christner BC. Expression and Partial Characterization of an Ice-Binding Protein from a Bacterium Isolated at a Depth of 3,519 m in the Vostok Ice Core, Antarctica. Front Microbiol 2011; 2:255. [PMID: 22207866 PMCID: PMC3245957 DOI: 10.3389/fmicb.2011.00255] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 12/01/2011] [Indexed: 11/21/2022] Open
Abstract
Cryopreservation of microorganisms in ancient glacial ice is possible if lethal levels of macromolecular damage are not incurred and cellular integrity is not compromised via intracellular ice formation or recrystallization. Previously, a bacterium (isolate 3519-10) recovered from a depth of 3,519 m below the surface in the Vostok ice core was shown to secrete an ice-binding protein (IBP) that inhibits the recrystallization of ice. To explore the advantage that IBPs confer to ice-entrapped cells, experiments were designed to examine the expression of 3519-10’s IBP gene and protein at different temperatures, assess the effect of the IBP on bacterial viability in ice, and determine how the IBP influences the physical structure of the ice. Total RNA isolated from cultures grown between 4 and 25°C and analyzed by reverse transcription-PCR indicated constitutive expression of the IBP gene. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of 3519-10’s extracellular proteins revealed a polypeptide of the predicted size of the 54-kDa IBP at all temperatures tested. In the presence of 100 μg mL−1 of extracellular protein from 3519-10, the survival of Escherichia coli was increased by greater than 100-fold after 5 freeze-thaw cycles. Microscopic analysis of ice formed in the presence of the IBP indicated that per square millimeter field of view, there were ~5 times as many crystals as in ice formed in the presence of washed 3519-10 cells and non-IBP producing bacteria, and ~10 times as many crystals as in filtered deionized water. Presumably, the effect that the IBP has on bacterial viability and ice crystal structure is due to its activity as an inhibitor of ice recrystallization. A myriad of molecular adaptations are likely to play a role in bacterial persistence under frozen conditions, but the ability of 3519-10’s IBP to control ice crystal structure, and thus the liquid vein network within the ice, may provide one explanation for its successful survival deep within the Antarctic ice sheet for thousands of years.
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