1
|
Ramkissoon NK, Macey MC, Kucukkilic-Stephens E, Barton T, Steele A, Johnson DN, Stephens BP, Schwenzer SP, Pearson VK, Olsson-Francis K. Experimental Identification of Potential Martian Biosignatures in Open and Closed Systems. ASTROBIOLOGY 2024; 24:538-558. [PMID: 38648554 DOI: 10.1089/ast.2023.0013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
NASA's Perseverance and ESA's Rosalind Franklin rovers have the scientific goal of searching for evidence of ancient life on Mars. Geochemical biosignatures that form because of microbe-mineral interactions could play a key role in achieving this, as they can be preserved for millions of years on Earth, and the same could be true for Mars. Previous laboratory experiments have explored the formation of biosignatures under closed systems, but these do not represent the open systems that are found in natural martian environments, such as channels and lakes. In this study, we have conducted environmental simulation experiments using a global regolith simulant (OUCM-1), a thermochemically modelled groundwater, and an anaerobic microbial community to explore the formation of geochemical biosignatures within plausible open and closed systems on Mars. This initial investigation showed differences in the diversity of the microbial community developed after 28 days. In an open-system simulation (flow-through experiment), the acetogenic Acetobacterium (49% relative abundance) and the sulfate reducer Desulfosporomusa (43% relative abundance) were the dominant genera. Whereas in the batch experiment, the sulfate reducers Desulfovibrio, Desulfomicrobium, and Desulfuromonas (95% relative abundance in total) were dominant. We also found evidence of enhanced mineral dissolution within the flow-through experiment, but there was little evidence of secondary deposits in the presence of biota. In contrast, SiO2 and Fe deposits formed within the batch experiment with biota but not under abiotic conditions. The results from these initial experiments indicate that different geochemical biosignatures can be generated between open and closed systems, and therefore, biosignature formation in open systems warrants further investigation.
Collapse
Affiliation(s)
| | - Michael C Macey
- AstrobiologyOU, STEM Faculty, The Open University, Milton Keynes, UK
| | | | - Timothy Barton
- AstrobiologyOU, STEM Faculty, The Open University, Milton Keynes, UK
| | - Andrew Steele
- Earth and Planetary Laboratory, Carnegie Institution of Washington, Washington, DC, USA
| | - David N Johnson
- AstrobiologyOU, STEM Faculty, The Open University, Milton Keynes, UK
| | - Ben P Stephens
- AstrobiologyOU, STEM Faculty, The Open University, Milton Keynes, UK
| | | | | | | |
Collapse
|
2
|
Tunsakul N, Wongsaroj L, Janchot K, Pongpirul K, Somboonna N. Non-significant influence between aerobic and anaerobic sample transport materials on gut (fecal) microbiota in healthy and fat-metabolic disorder Thai adults. PeerJ 2024; 12:e17270. [PMID: 38650647 PMCID: PMC11034497 DOI: 10.7717/peerj.17270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 03/29/2024] [Indexed: 04/25/2024] Open
Abstract
Background The appropriate sample handling for human fecal microbiota studies is essential to prevent changes in bacterial composition and quantities that could lead to misinterpretation of the data. Methods This study firstly identified the potential effect of aerobic and anaerobic fecal sample collection and transport materials on microbiota and quantitative microbiota in healthy and fat-metabolic disorder Thai adults aged 23-43 years. We employed metagenomics followed by 16S rRNA gene sequencing and 16S rRNA gene qPCR, to analyze taxonomic composition, alpha diversity, beta diversity, bacterial quantification, Pearson's correlation with clinical factors for fat-metabolic disorder, and the microbial community and species potential metabolic functions. Results Our study successfully obtained microbiota results in percent and quantitative compositions. Each sample exhibited quality sequences with a >99% Good's coverage index, and a relatively plateau rarefaction curve. Alpha diversity indices showed no statistical difference in percent and quantitative microbiota OTU richness and evenness, between aerobic and anaerobic sample transport materials. Obligate and facultative anaerobic species were analyzed and no statistical difference was observed. Supportively, the beta diversity analysis by non-metric multidimensional scale (NMDS) constructed using various beta diversity coefficients showed resembling microbiota community structures between aerobic and anaerobic sample transport groups (P = 0.86). On the other hand, the beta diversity could distinguish microbiota community structures between healthy and fat-metabolic disorder groups (P = 0.02), along with Pearson's correlated clinical parameters (i.e., age, liver stiffness, GGT, BMI, and TC), the significantly associated bacterial species and their microbial metabolic functions. For example, genera such as Ruminococcus and Bifidobacterium in healthy human gut provide functions in metabolisms of cofactors and vitamins, biosynthesis of secondary metabolites against gut pathogens, energy metabolisms, digestive system, and carbohydrate metabolism. These microbial functional characteristics were also predicted as healthy individual biomarkers by LEfSe scores. In conclusion, this study demonstrated that aerobic sample collection and transport (<48 h) did not statistically affect the microbiota and quantitative microbiota analyses in alpha and beta diversity measurements. The study also showed that the short-term aerobic sample collection and transport still allowed fecal microbiota differentiation between healthy and fat-metabolic disorder subjects, similar to anaerobic sample collection and transport. The core microbiota were analyzed, and the findings were consistent. Moreover, the microbiota-related metabolic potentials and bacterial species biomarkers in healthy and fat-metabolic disorder were suggested with statistical bioinformatics (i.e., Bacteroides plebeius).
Collapse
Affiliation(s)
- Naruemon Tunsakul
- Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Lampet Wongsaroj
- Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Kantima Janchot
- Center of Excellence in Preventive and Integrative Medicine (CE-PIM) and Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Krit Pongpirul
- Center of Excellence in Preventive and Integrative Medicine (CE-PIM) and Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Naraporn Somboonna
- Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
- Microbiome Research Unit for Probiotics in Food and Cosmetics, Chulalongkorn University, Bangkok, Thailand
- Omics Sciences and Bioinformatics Center, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
- Multi-Omics for Functional Products in Food, Cosmetics and Animals Research Unit, Chulalongkorn University, Bangkok, Thailand
| |
Collapse
|
3
|
Pinnell LJ, Wolfe CA, Castle J, Crosby WB, Doster E, Morley PS. Effectiveness of stabilization methods for the immediate and short-term preservation of bovine fecal and upper respiratory tract genomic DNA. PLoS One 2024; 19:e0300285. [PMID: 38564604 PMCID: PMC10987004 DOI: 10.1371/journal.pone.0300285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 02/24/2024] [Indexed: 04/04/2024] Open
Abstract
Previous research on stabilization methods for microbiome investigations has largely focused on human fecal samples. There are a few studies using feces from other species, but no published studies investigating preservation of samples collected from cattle. Given that microbial taxa are differentially impacted during storage it is warranted to study impacts of preservation methods on microbial communities found in samples outside of human fecal samples. Here we tested methods of preserving bovine fecal respiratory specimens for up to 2 weeks at four temperatures (room temperature, 4°C, -20°C, and -80°C) by comparing microbial diversity and community composition to samples extracted immediately after collection. Importantly, fecal specimens preserved and analyzed were technical replicates, providing a look at the effects of preservation method in the absence of biological variation. We found that preservation with the OMNIgene®•GUT kit resulted in community structure most like that of fresh samples extracted immediately, even when stored at room temperature (~20°C). Samples that were flash-frozen without added preservation solution were the next most representative of original communities, while samples preserved with ethanol were the least representative. These results contradict previous reports that ethanol is effective in preserving fecal communities and suggest for studies investigating cattle either flash-freezing of samples without preservative or preservation with OMNIgene®•GUT will yield more representative microbial communities.
Collapse
Affiliation(s)
- Lee J. Pinnell
- Veterinary Education, Research and Outreach Program, Texas A&M University, Canyon, TX, United States of America
| | - Cory A. Wolfe
- Veterinary Education, Research and Outreach Program, Texas A&M University, Canyon, TX, United States of America
| | - Jake Castle
- Veterinary Education, Research and Outreach Program, Texas A&M University, Canyon, TX, United States of America
| | - William B. Crosby
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Starkville, Mississippi State, United States of America
| | - Enrique Doster
- Veterinary Education, Research and Outreach Program, Texas A&M University, Canyon, TX, United States of America
| | - Paul S. Morley
- Veterinary Education, Research and Outreach Program, Texas A&M University, Canyon, TX, United States of America
| |
Collapse
|
4
|
Rey-Velasco X, Deulofeu-Capo O, Sanz-Sáez I, Cardelús C, Ferrera I, Gasol JM, Sánchez O. Expanding success in the isolation of abundant marine bacteria after reduction in grazing and viral pressure and increase in nutrient availability. Microbiol Spectr 2023; 11:e0089023. [PMID: 37747249 PMCID: PMC10580928 DOI: 10.1128/spectrum.00890-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 08/03/2023] [Indexed: 09/26/2023] Open
Abstract
Isolation of microorganisms is a useful approach to gathering knowledge about their genomic properties, physiology, and ecology, in addition to allowing the characterization of novel taxa. We performed an extensive isolation effort on samples from seawater manipulation experiments that were carried out during the four astronomical seasons in a coastal site of the northwest Mediterranean to evaluate the impact of grazing, viral mortality, resource competition reduction, and light presence/absence on bacterioplankton growth. Isolates were retrieved using two growth media, and their full 16S rRNA gene was sequenced to assess their identity and calculate their culturability across seasons and experimental conditions. A total of 1,643 isolates were obtained, mainly affiliated to the classes Gammaproteobacteria (44%), Alphaproteobacteria (26%), and Bacteroidia (17%). Isolates pertaining to class Gammaproteobacteria were the most abundant in all experiments, while Bacteroidia were preferentially enriched in the treatments with reduced grazing. Sixty-one isolates had a similarity below 97% to cultured taxa and are thus putatively novel. Comparison of isolate sequences with 16S rRNA gene amplicon sequences from the same samples showed that the percentage of reads corresponding to isolates was 21.4% within the whole data set, with dramatic increases in the summer virus-reduced (71%) and diluted (47%) treatments. In fact, we were able to isolate the top 10 abundant taxa in several experiments and from the whole data set. We also show that top-down and bottom-up controls differentially affect taxa in terms of culturability. Our results indicate that culturing marine bacteria using agar plates can be successful in certain ecological situations. IMPORTANCE Bottom-up and top-down controls greatly influence marine microbial community composition and dynamics, which in turn have effects on their culturability. We isolated a high amount of heterotrophic bacterial strains from experiments where seawater environmental conditions had been manipulated and found that decreasing grazing and viral pressure as well as rising nutrient availability are key factors increasing the success in culturing marine bacteria. Our data hint at factors influencing culturability and underpin bacterial cultures as a powerful way to discover new taxa.
Collapse
Affiliation(s)
| | - Ona Deulofeu-Capo
- Institut de Ciències del Mar (ICM-CSIC), Barcelona, Catalonia, Spain
| | - Isabel Sanz-Sáez
- Institut de Ciències del Mar (ICM-CSIC), Barcelona, Catalonia, Spain
- Instituto de Diagnóstico Ambiental y Estudios del Agua (IDAEA-CSIC), Barcelona, Catalonia, Spain
| | - Clara Cardelús
- Institut de Ciències del Mar (ICM-CSIC), Barcelona, Catalonia, Spain
| | - Isabel Ferrera
- Institut de Ciències del Mar (ICM-CSIC), Barcelona, Catalonia, Spain
- Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, (IEO-CSIC), Fuengirola, Málaga, Spain
| | - Josep M. Gasol
- Institut de Ciències del Mar (ICM-CSIC), Barcelona, Catalonia, Spain
| | - Olga Sánchez
- Departament de Genètica i Microbiologia, Facultat de Biociències, Universitat Autònoma de Barcelona, Bellaterra, Spain
| |
Collapse
|
5
|
Kivistik C, Käiro K, Tammert H, Sokolova IM, Kisand V, Herlemann DPR. Distinct stages of the intestinal bacterial community of Ampullaceana balthica after salinization. Front Microbiol 2022; 13:767334. [PMID: 36110301 PMCID: PMC9468257 DOI: 10.3389/fmicb.2022.767334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 07/19/2022] [Indexed: 12/15/2022] Open
Abstract
Environmental disturbances influence bacterial community structure and functioning. To investigate the effect of environmental disturbance caused by changes in salinity on host-protected bacterial communities, we analyzed the microbiome within the gastrointestinal tract of Ampullaceana balthica in different salinities. A. balthica is a benthic gastropod found in fresh- and mesohaline waters. Whereas the total energy reserves of A. balthica were unaffected by an increase of salinity to 3, a high mortality rate was detected after a shift from freshwater to salinity 6 suggesting a major disruption of energy homeostasis. The shift to salinity 6 also caused a change in the gastrointestinal bacterial community composition. At salinity 3, the bacterial community composition of different host individuals was related either to the freshwater or salinity 6 gastrointestinal bacterial community, indicating an ambivalent nature of salinity 3. Since salinity 3 represents the range where aquatic gastropods are able to regulate their osmolarity, this may be an important tipping point during salinization. The change in the intestinal microbiome was uncoupled from the change in the water bacterial community and unrelated to the food source microbiome. Our study shows that environmental disturbance caused by salinity acts also on the host-protected microbiome. In light of the sea-level rise, our findings indicate that salinization of the near-shore freshwater bodies will cause changes in organisms' intestinal microbiomes if a critical salinity threshold (presumably ∼3) is exceeded.
Collapse
Affiliation(s)
- Carmen Kivistik
- Estonian University of Life Sciences, Center for Limnology, Tartu, Estonia
| | - Kairi Käiro
- Estonian University of Life Sciences, Center for Limnology, Tartu, Estonia
| | - Helen Tammert
- Estonian University of Life Sciences, Center for Limnology, Tartu, Estonia
| | - Inna M. Sokolova
- Department of Marine Biology, Institute for Biological Sciences, University of Rostock, Rostock, Germany
- Department of Maritime Systems, Interdisciplinary Faculty, University of Rostock, Rostock, Germany
| | - Veljo Kisand
- Estonian University of Life Sciences, Center for Limnology, Tartu, Estonia
- Institute of Technology, University of Tartu, Tartu, Estonia
| | | |
Collapse
|
6
|
Pellerin A, Lotem N, Walter Anthony K, Eliani Russak E, Hasson N, Røy H, Chanton JP, Sivan O. Methane production controls in a young thermokarst lake formed by abrupt permafrost thaw. GLOBAL CHANGE BIOLOGY 2022; 28:3206-3221. [PMID: 35243729 PMCID: PMC9310722 DOI: 10.1111/gcb.16151] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 12/21/2021] [Accepted: 02/11/2022] [Indexed: 06/01/2023]
Abstract
Methane (CH4 ) release to the atmosphere from thawing permafrost contributes significantly to global CH4 emissions. However, constraining the effects of thaw that control the production and emission of CH4 is needed to anticipate future Arctic emissions. Here are presented robust rate measurements of CH4 production and cycling in a region of rapidly degrading permafrost. Big Trail Lake, located in central Alaska, is a young, actively expanding thermokarst lake. The lake was investigated by taking two 1 m cores of sediment from different regions. Two independent methods of measuring microbial CH4 production, long term (CH4 accumulation) and short term (14 C tracer), produced similar average rates of 11 ± 3.5 and 9 ± 3.6 nmol cm-3 d-1 , respectively. The rates had small variations between the different lithological units, indicating homogeneous CH4 production despite heterogeneous lithology in the surface ~1 m of sediment. To estimate the total CH4 production, the CH4 production rates were multiplied through the 10-15 m deep talik (thaw bulb). This estimate suggests that CH4 production is higher than emission by a maximum factor of ~2, which is less than previous estimates. Stable and radioactive carbon isotope measurements showed that 50% of dissolved CH4 in the first meter was produced further below. Interestingly, labeled 14 C incubations with 2-14 C acetate and 14 C CO2 indicate that variations in the pathway used by microbes to produce CH4 depends on the age and type of organic matter in the sediment, but did not appear to influence the rates at which CH4 was produced. This study demonstrates that at least half of the CH4 produced by microbial breakdown of organic matter in actively expanding thermokarst is emitted to the atmosphere, and that the majority of this CH4 is produced in the deep sediment.
Collapse
Affiliation(s)
- André Pellerin
- Department of Earth and Environmental SciencesBen Gurion University of the NegevBeershevaIsrael
| | - Noam Lotem
- Department of Earth and Environmental SciencesBen Gurion University of the NegevBeershevaIsrael
| | - Katey Walter Anthony
- Water and Environmental Research CenterUniversity of Alaska FairbanksFairbanksAlaskaUSA
- International Arctic Research CenterFairbanksAlaskaUSA
| | - Efrat Eliani Russak
- Department of Earth and Environmental SciencesBen Gurion University of the NegevBeershevaIsrael
| | - Nicholas Hasson
- Water and Environmental Research CenterUniversity of Alaska FairbanksFairbanksAlaskaUSA
| | - Hans Røy
- Department of BiologyAarhus UniversityAarhusDenmark
| | - Jeffrey P. Chanton
- Department of Earth Ocean and Atmospheric ScienceFlorida State UniversityTallahasseeFloridaUSA
| | - Orit Sivan
- Department of Earth and Environmental SciencesBen Gurion University of the NegevBeershevaIsrael
| |
Collapse
|
7
|
Hua Z, Ouellette M, Makkay AM, Papke RT, Zhaxybayeva O. Nutrient supplementation experiments with saltern microbial communities implicate utilization of DNA as a source of phosphorus. THE ISME JOURNAL 2021; 15:2853-2864. [PMID: 33846564 PMCID: PMC8443641 DOI: 10.1038/s41396-021-00960-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 02/25/2021] [Accepted: 03/08/2021] [Indexed: 02/01/2023]
Abstract
All environments including hypersaline ones harbor measurable concentrations of dissolved extracellular DNA (eDNA) that can be utilized by microbes as a nutrient. However, it remains poorly understood which eDNA components are used, and who in a community utilizes it. For this study, we incubated a saltern microbial community with combinations of carbon, nitrogen, phosphorus, and DNA, and tracked the community response in each microcosm treatment via 16S rRNA and rpoB gene sequencing. We show that microbial communities used DNA only as a phosphorus source, and provision of other sources of carbon and nitrogen was needed to exhibit a substantial growth. The taxonomic composition of eDNA in the water column changed with the availability of inorganic phosphorus or supplied DNA, hinting at preferential uptake of eDNA from specific organismal sources. Especially favored for growth was eDNA from the most abundant taxa, suggesting some haloarchaea prefer eDNA from closely related taxa. The preferential eDNA consumption and differential growth under various nutrient availability regimes were associated with substantial shifts in the taxonomic composition and diversity of microcosm communities. Therefore, we conjecture that in salterns the microbial community assembly is driven by the available resources, including eDNA.
Collapse
Affiliation(s)
- Zhengshuang Hua
- grid.254880.30000 0001 2179 2404Department of Biological Sciences, Dartmouth College, Hanover, NH USA ,grid.59053.3a0000000121679639Present Address: Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, PR China
| | - Matthew Ouellette
- grid.63054.340000 0001 0860 4915Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT USA ,grid.38142.3c000000041936754XPresent Address: The Forsyth Institute, Cambridge, MA USA ,grid.38142.3c000000041936754XPresent Address: Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA USA
| | - Andrea M. Makkay
- grid.63054.340000 0001 0860 4915Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT USA
| | - R. Thane Papke
- grid.63054.340000 0001 0860 4915Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT USA
| | - Olga Zhaxybayeva
- grid.254880.30000 0001 2179 2404Department of Biological Sciences, Dartmouth College, Hanover, NH USA ,grid.254880.30000 0001 2179 2404Department of Computer Science, Dartmouth College, Hanover, NH USA
| |
Collapse
|
8
|
Individual Physiological Adaptations Enable Selected Bacterial Taxa To Prevail during Long-Term Incubations. Appl Environ Microbiol 2019; 85:AEM.00825-19. [PMID: 31152013 DOI: 10.1128/aem.00825-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 05/24/2019] [Indexed: 01/22/2023] Open
Abstract
Enclosure experiments are frequently used to investigate the impact of changing environmental conditions on microbial assemblages. Yet, how the incubation itself challenges complex bacterial communities is thus far unknown. In this study, metaproteomic profiling, 16S rRNA gene analyses, and cell counts were combined to evaluate bacterial communities derived from marine, mesohaline, and oligohaline conditions after long-term batch incubations. Early in the experiment, the three bacterial communities were highly diverse and differed significantly in their compositions. Manipulation of the enclosures with terrigenous dissolved organic carbon resulted in notable differences compared to the control enclosures at this early phase of the experiment. However, after 55 days, bacterial communities in the manipulated and the control enclosures under marine and mesohaline conditions were all dominated by gammaproteobacterium Spongiibacter In the oligohaline enclosures, actinobacterial cluster I of the hgc group (hgc-I) remained abundant in the late phase of the incubation. Metaproteome analyses suggested that the ability to use outer membrane-based internal energy stores, in addition to the previously described grazing resistance, may enable the gammaproteobacterium Spongiibacter to prevail in long-time incubations. Under oligohaline conditions, the utilization of external recalcitrant carbon appeared to be more important (hgc-I). Enclosure experiments with complex natural microbial communities are important tools to investigate the effects of manipulations. However, species-specific properties, such as individual carbon storage strategies, can cause manipulation-independent effects and need to be considered when interpreting results from enclosures.IMPORTANCE In microbial ecology, enclosure studies are often used to investigate the effect of single environmental factors on complex bacterial communities. However, in addition to the manipulation, unintended effects ("bottle effect") may occur due to the enclosure itself. In this study, we analyzed the bacterial communities that originated from three different salinities of the Baltic Sea, comparing their compositions and physiological activities both at the early stage and after 55 days of incubation. Our results suggested that internal carbon storage strategies impact the success of certain bacterial species, independent of the experimental manipulation. Thus, while enclosure experiments remain valid tools in environmental research, microbial community composition shifts must be critically followed. This investigation of the metaproteome during long-term batch enclosures expanded our current understanding of the so-called "bottle effect," which is well known to occur during enclosure experiments.
Collapse
|
9
|
Bižić-Ionescu M, Ionescu D, Grossart HP. Organic Particles: Heterogeneous Hubs for Microbial Interactions in Aquatic Ecosystems. Front Microbiol 2018; 9:2569. [PMID: 30416497 PMCID: PMC6212488 DOI: 10.3389/fmicb.2018.02569] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 10/08/2018] [Indexed: 12/15/2022] Open
Abstract
The dynamics and activities of microbes colonizing organic particles (hereafter particles) greatly determine the efficiency of the aquatic carbon pump. Current understanding is that particle composition, structure and surface properties, determined mostly by the forming organisms and organic matter, dictate initial microbial colonization and the subsequent rapid succession events taking place as organic matter lability and nutrient content change with microbial degradation. We applied a transcriptomic approach to assess the role of stochastic events on initial microbial colonization of particles. Furthermore, we asked whether gene expression corroborates rapid changes in carbon-quality. Commonly used size fractionated filtration averages thousands of particles of different sizes, sources, and ages. To overcome this drawback, we used replicate samples consisting each of 3–4 particles of identical source and age and further evaluated the consequences of averaging 10–1000s of particles. Using flow-through rolling tanks we conducted long-term experiments at near in situ conditions minimizing the biasing effects of closed incubation approaches often referred to as “the bottle-effect.” In our open flow-through rolling tank system, however, active microbial communities were highly heterogeneous despite an identical particle source, suggesting random initial colonization. Contrasting previous reports using closed incubation systems, expression of carbon utilization genes didn’t change after 1 week of incubation. Consequently, we suggest that in nature, changes in particle-associated community related to carbon availability are much slower (days to weeks) due to constant supply of labile, easily degradable organic matter. Initial, random particle colonization seems to be subsequently altered by multiple organismic interactions shaping microbial community interactions and functional dynamics. Comparative analysis of thousands particles pooled togethers as well as pooled samples suggests that mechanistic studies of microbial dynamics should be done on single particles. The observed microbial heterogeneity and inter-organismic interactions may have important implications for evolution and biogeochemistry in aquatic systems.
Collapse
Affiliation(s)
- Mina Bižić-Ionescu
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany
| | - Danny Ionescu
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany
| | - Hans-Peter Grossart
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany.,Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| |
Collapse
|
10
|
Herlemann DPR, Manecki M, Dittmar T, Jürgens K. Differential responses of marine, mesohaline and oligohaline bacterial communities to the addition of terrigenous carbon. Environ Microbiol 2017; 19:3098-3117. [PMID: 28474480 DOI: 10.1111/1462-2920.13784] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 04/13/2017] [Accepted: 04/26/2017] [Indexed: 12/21/2022]
Abstract
In response to global warming, increasing quantities of tDOM are transported through estuaries from land to the sea. In this study, we investigated microbial responses to increased tDOM concentrations in three salinity regimes (salinity: 32, 7 and 3) characteristic of the Baltic Sea. Mesocosm experiments performed in May and November revealed low (0-6%) dissolved organic carbon (DOC) utilisation. Molecular DOM analyses using ultrahigh-resolution mass spectrometry identified the terrigenous signal in the tDOM manipulation, but the molecular changes in DOM levels over the course of the experiment were subtle. However, tDOM had significant stimulatory effects on bacterial production in the oligohaline mesocosms. The shift in the bacterial community composition was especially prominent in the tDOM-amended marine and mesohaline mesocosms, but not in the oligohaline mesocosms after 7 and 11 days of incubation. These results suggested the inherent ability of oligohaline bacterial communities to adapt to high tDOM concentrations and therefore to use tDOM. The higher rates of bacterial activity and DOC removal in mesocosms containing UV-pretreated tDOM supported the increased bioavailability of photoinduced, modified tDOM. The overall low rates of microbial tDOM utilisation highlights the importance of abiotic factors in determining the distribution and dynamics of tDOM in estuaries.
Collapse
Affiliation(s)
- D P R Herlemann
- Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Biological Oceanography, Seestrasse 15, Rostock, D-18119, Germany
| | - M Manecki
- Research Group for Marine Geochemistry, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Carl-von-Ossietzky-Str, Oldenburg, 9-11 D-26129, Germany.,Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Marine Chemistry, Seestrasse 15, Rostock, D-18119, Germany
| | - T Dittmar
- Research Group for Marine Geochemistry, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Carl-von-Ossietzky-Str, Oldenburg, 9-11 D-26129, Germany
| | - K Jürgens
- Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Biological Oceanography, Seestrasse 15, Rostock, D-18119, Germany
| |
Collapse
|