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Méndez-Sánchez D, Schrecengost A, Rotterová J, Koštířová K, Beinart RA, Čepička I. Methanogenic symbionts of anaerobic ciliates are host and habitat specific. THE ISME JOURNAL 2024; 18:wrae164. [PMID: 39163261 PMCID: PMC11378729 DOI: 10.1093/ismejo/wrae164] [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: 02/06/2024] [Revised: 06/29/2024] [Accepted: 08/16/2024] [Indexed: 08/22/2024]
Abstract
The association between anaerobic ciliates and methanogenic archaea has been recognized for over a century. Nevertheless, knowledge of these associations is limited to a few ciliate species, and so the identification of patterns of host-symbiont specificity has been largely speculative. In this study, we integrated microscopy and genetic identification to survey the methanogenic symbionts of 32 free-living anaerobic ciliate species, mainly from the order Metopida. Based on Sanger and Illumina sequencing of the 16S rRNA gene, our results show that a single methanogenic symbiont population, belonging to Methanobacterium, Methanoregula, or Methanocorpusculum, is dominant in each host strain. Moreover, the host's taxonomy (genus and above) and environment (i.e. endobiotic, marine/brackish, or freshwater) are linked with the methanogen identity at the genus level, demonstrating a strong specificity and fidelity in the association. We also established cultures containing artificially co-occurring anaerobic ciliate species harboring different methanogenic symbionts. This revealed that the host-methanogen relationship is stable over short timescales in cultures without evidence of methanogenic symbiont exchanges, although our intraspecific survey indicated that metopids also tend to replace their methanogens over longer evolutionary timescales. Therefore, anaerobic ciliates have adapted a mixed transmission mode to maintain and replace their methanogenic symbionts, allowing them to thrive in oxygen-depleted environments.
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Affiliation(s)
- Daniel Méndez-Sánchez
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czech Republic
| | - Anna Schrecengost
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, United States
| | - Johana Rotterová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czech Republic
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, United States
- Department of Marine Sciences, University of Puerto Rico Mayagüez, Mayagüez, PR 00680, United States
| | - Kateřina Koštířová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czech Republic
| | - Roxanne A Beinart
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, United States
| | - Ivan Čepička
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czech Republic
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Methanogenesis in the Digestive Tracts of the Tropical Millipedes Archispirostreptus gigas (Diplopoda, Spirostreptidae) and Epibolus pulchripes (Diplopoda, Pachybolidae). Appl Environ Microbiol 2021; 87:e0061421. [PMID: 34020937 DOI: 10.1128/aem.00614-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methanogens represent the final decomposition step in anaerobic degradation of organic matter, occurring in the digestive tracts of various invertebrates. However, factors determining their community structure and activity in distinct gut sections are still debated. In this study, we focused on the tropical millipede species Archispirostreptus gigas (Diplopoda, Spirostreptidae) and Epibolus pulchripes (Diplopoda, Pachybolidae), which release considerable amounts of methane. We aimed to characterize relationships between physicochemical parameters, methane production rates, and methanogen community structure in the two major gut sections, midgut and hindgut. Microsensor measurements revealed that both sections were strictly anoxic, with reducing conditions prevailing in both millipedes. Hydrogen concentration peaked in the anterior hindgut of E. pulchripes. In both species, the intestinal pH was significantly higher in the hindgut than in the midgut. An accumulation of acetate and formate in the gut indicated bacterial fermentation activities in the digestive tracts of both species. Phylogenetic analysis of 16S rRNA genes showed a prevalence of Methanobrevibacter spp. (Methanobacteriales), accompanied by a small fraction of so-far-unclassified "Methanomethylophilaceae" (Methanomassiliicoccales), in both species, which suggests that methanogenesis is mostly hydrogenotrophic. We conclude that anoxic conditions, negative redox potential, and bacterial production of hydrogen and formate promote gut colonization by methanogens. The higher activities of methanogens in the hindgut are explained by the higher pH of this compartment and their association with ciliates, which are restricted to this compartment and present an additional source of methanogenic substrates. IMPORTANCE Methane (CH4) is the second most important atmospheric greenhouse gas after CO2 and is believed to account for 17% of global warming. Methanogens are a diverse group of archaea and can be found in various anoxic habitats, including digestive tracts of plant-feeding animals. Termites, cockroaches, the larvae of scarab beetles, and millipedes are the only arthropods known to host methanogens and emit large amounts of methane. Millipedes are ranked as the third most important detritivores after termites and earthworms, and they are considered keystone species in many terrestrial ecosystems. Both methane-producing and non-methane-emitting species of millipedes have been observed, but what limits their methanogenic potential is not known. In the present study, we show that physicochemical gut conditions and the distribution of symbiotic ciliates are important factors determining CH4 emission in millipedes. We also found close similarities to other methane-emitting arthropods, which might be associated with their similar plant-feeding habits.
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Nitla V, Serra V, Fokin SI, Modeo L, Verni F, Sandeep BV, Kalavati C, Petroni G. Critical revision of the family Plagiopylidae (Ciliophora: Plagiopylea), including the description of two novel species, Plagiopyla ramani and Plagiopyla narasimhamurtii, and redescription of Plagiopyla nasuta Stein, 1860 from India. Zool J Linn Soc 2018. [DOI: 10.1093/zoolinnean/zly041] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | | | - Sergei I Fokin
- Department of Biology, University of Pisa, Pisa, Italy
- Department of Invertebrate Zoology, St. Petersburg State University, St. Petersburg, Russia
| | - Letizia Modeo
- Department of Biology, University of Pisa, Pisa, Italy
| | - Franco Verni
- Department of Biology, University of Pisa, Pisa, Italy
| | - Bhagavatula Venkata Sandeep
- Department of Zoology, Andhra University, Visakhapatnam, India
- Department of Biotechnology, Andhra University, Visakhapatnam, India
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Beinart R, Rotterová J, Čepička I, Gast R, Edgcomb V. The genome of an endosymbiotic methanogen is very similar to those of its free‐living relatives. Environ Microbiol 2018; 20:2538-2551. [DOI: 10.1111/1462-2920.14279] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- R.A. Beinart
- Department of Geology and Geophysics Woods Hole Oceanographic Institution Woods Hole MA USA
- Department of Biology Woods Hole Oceanographic Institution Woods Hole MA USA
| | - J. Rotterová
- Department of Zoology Charles University Prague Czech Republic
| | - I. Čepička
- Department of Zoology Charles University Prague Czech Republic
| | - R.J. Gast
- Department of Biology Woods Hole Oceanographic Institution Woods Hole MA USA
| | - V.P. Edgcomb
- Department of Geology and Geophysics Woods Hole Oceanographic Institution Woods Hole MA USA
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Tashyreva D, Prokopchuk G, Votýpka J, Yabuki A, Horák A, Lukeš J. Life Cycle, Ultrastructure, and Phylogeny of New Diplonemids and Their Endosymbiotic Bacteria. mBio 2018; 9:e02447-17. [PMID: 29511084 PMCID: PMC5845003 DOI: 10.1128/mbio.02447-17] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 01/31/2018] [Indexed: 11/20/2022] Open
Abstract
Diplonemids represent a hyperdiverse and abundant yet poorly studied group of marine protists. Here we describe two new members of the genus Diplonema (Diplonemea, Euglenozoa), Diplonema japonicum sp. nov. and Diplonema aggregatum sp. nov., based on life cycle, morphology, and 18S rRNA gene sequences. Along with euglenozoan apomorphies, they contain several unique features. Their life cycle is complex, consisting of a trophic stage that is, following the depletion of nutrients, transformed into a sessile stage and subsequently into a swimming stage. The latter two stages are characterized by the presence of tubular extrusomes and the emergence of a paraflagellar rod, the supportive structure of the flagellum, which is prominently lacking in the trophic stage. These two stages also differ dramatically in motility and flagellar size. Both diplonemid species host endosymbiotic bacteria that are closely related to each other and constitute a novel branch within Holosporales, for which a new genus, "Candidatus Cytomitobacter" gen. nov., has been established. Remarkably, the number of endosymbionts in the cytoplasm varies significantly, as does their localization within the cell, where they seem to penetrate the mitochondrion, a rare occurrence.IMPORTANCE We describe the morphology, behavior, and life cycle of two new Diplonema species that established a relationship with two Holospora-like bacteria in the first report of an endosymbiosis in diplonemids. Both endosymbionts reside in the cytoplasm and the mitochondrion, which establishes an extremely rare case. Within their life cycle, the diplonemids undergo transformation from a trophic to a sessile and eventually a highly motile swimming stage. These stages differ in several features, such as the presence or absence of tubular extrusomes and a paraflagellar rod, along with the length of the flagella. These morphological and behavioral interstage differences possibly reflect distinct functions in dispersion and invasion of the host and/or prey and may provide novel insight into the virtually unknown function of diplonemids in the oceanic ecosystem.
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Affiliation(s)
- Daria Tashyreva
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
| | - Galina Prokopchuk
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
| | - Jan Votýpka
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Akinori Yabuki
- Department of Marine Diversity, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
| | - Aleš Horák
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Julius Lukeš
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
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Beinart RA, Beaudoin DJ, Bernhard JM, Edgcomb VP. Insights into the metabolic functioning of a multipartner ciliate symbiosis from oxygen-depleted sediments. Mol Ecol 2018; 27:1794-1807. [PMID: 29271011 DOI: 10.1111/mec.14465] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/21/2017] [Accepted: 11/24/2017] [Indexed: 12/13/2022]
Abstract
Symbioses between anaerobic or microaerophilic protists and prokaryotes are common in anoxic and oxygen-depleted habitats ranging from marine sediments to gastrointestinal tracts. Nevertheless, little is known about the mechanisms of metabolic interaction between partners. In these putatively syntrophic associations, consumption of fermentative end products (e.g., hydrogen) by the prokaryotic symbionts is thought to facilitate protistan anaerobic metabolism. Here, we employed metagenomic and metatranscriptomic sequencing of a microaerophilic or anaerobic karyorelictid ciliate and its prokaryotic symbionts from oxygen-depleted Santa Barbara Basin (CA, USA) sediments to assess metabolic coupling within this consortium. This sequencing confirmed the predominance of deltaproteobacterial symbionts from the Families Desulfobacteraceae and Desulfobulbaceae and suggested active symbiont reduction of host-provided sulphate, transfer of small organic molecules from host to symbionts and hydrogen cycling among the symbionts. In addition, patterns of gene expression indicated active cell division by the symbionts, their growth via autotrophic processes and nitrogen exchange with the ciliate host. Altogether, this research underscores the importance of symbiont metabolism to host fermentative metabolism and, thus, likely its success in anoxic and low-oxygen habitats, but also suggests ciliate-associated prokaryotes play a role in important biogeochemical processes.
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Affiliation(s)
- R A Beinart
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - D J Beaudoin
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - J M Bernhard
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - V P Edgcomb
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
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Rumen microbial community composition varies with diet and host, but a core microbiome is found across a wide geographical range. Sci Rep 2015; 5:14567. [PMID: 26449758 PMCID: PMC4598811 DOI: 10.1038/srep14567] [Citation(s) in RCA: 863] [Impact Index Per Article: 95.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 09/01/2015] [Indexed: 12/01/2022] Open
Abstract
Ruminant livestock are important sources of human food and global greenhouse gas emissions. Feed degradation and methane formation by ruminants rely on metabolic interactions between rumen microbes and affect ruminant productivity. Rumen and camelid foregut microbial community composition was determined in 742 samples from 32 animal species and 35 countries, to estimate if this was influenced by diet, host species, or geography. Similar bacteria and archaea dominated in nearly all samples, while protozoal communities were more variable. The dominant bacteria are poorly characterised, but the methanogenic archaea are better known and highly conserved across the world. This universality and limited diversity could make it possible to mitigate methane emissions by developing strategies that target the few dominant methanogens. Differences in microbial community compositions were predominantly attributable to diet, with the host being less influential. There were few strong co-occurrence patterns between microbes, suggesting that major metabolic interactions are non-selective rather than specific.
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Holmes DE, Giloteaux L, Orellana R, Williams KH, Robbins MJ, Lovley DR. Methane production from protozoan endosymbionts following stimulation of microbial metabolism within subsurface sediments. Front Microbiol 2014; 5:366. [PMID: 25147543 PMCID: PMC4123621 DOI: 10.3389/fmicb.2014.00366] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 07/01/2014] [Indexed: 11/13/2022] Open
Abstract
Previous studies have suggested that protozoa prey on Fe(III)- and sulfate-reducing bacteria that are enriched when acetate is added to uranium contaminated subsurface sediments to stimulate U(VI) reduction. In order to determine whether protozoa continue to impact subsurface biogeochemistry after these acetate amendments have stopped, 18S rRNA and ß-tubulin sequences from this phase of an in situ uranium bioremediation field experiment were analyzed. Sequences most similar to Metopus species predominated, with the majority of sequences most closely related to M. palaeformis, a cilitated protozoan known to harbor methanogenic symbionts. Quantification of mcrA mRNA transcripts in the groundwater suggested that methanogens closely related to Metopus endosymbionts were metabolically active at this time. There was a strong correlation between the number of mcrA transcripts from the putative endosymbiotic methanogen and Metopus ß-tubulin mRNA transcripts during the course of the field experiment, suggesting that the activity of the methanogens was dependent upon the activity of the Metopus species. Addition of the eukaryotic inhibitors cyclohexamide and colchicine to laboratory incubations of acetate-amended subsurface sediments significantly inhibited methane production and there was a direct correlation between methane concentration and Metopus ß-tubulin and putative symbiont mcrA gene copies. These results suggest that, following the stimulation of subsurface microbial growth with acetate, protozoa harboring methanogenic endosymbionts become important members of the microbial community, feeding on moribund biomass and producing methane.
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Affiliation(s)
- Dawn E Holmes
- Department of Microbiology, University of Massachusetts Amherst, MA, USA ; Physical and Biological Sciences, Western New England University Springfield, MA, USA
| | - Ludovic Giloteaux
- Department of Microbiology, University of Massachusetts Amherst, MA, USA
| | - Roberto Orellana
- Department of Microbiology, University of Massachusetts Amherst, MA, USA
| | | | | | - Derek R Lovley
- Department of Microbiology, University of Massachusetts Amherst, MA, USA
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Šustr V, Chroňáková A, Semanová S, Tajovský K, Šimek M. Methane production and methanogenic Archaea in the digestive tracts of millipedes (Diplopoda). PLoS One 2014; 9:e102659. [PMID: 25028969 PMCID: PMC4100924 DOI: 10.1371/journal.pone.0102659] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 06/23/2014] [Indexed: 11/19/2022] Open
Abstract
Methane production by intestinal methanogenic Archaea and their community structure were compared among phylogenetic lineages of millipedes. Tropical and temperate millipedes of 35 species and 17 families were investigated. Species that emitted methane were mostly in the juliform orders Julida, Spirobolida, and Spirostreptida. The irregular phylogenetic distribution of methane production correlated with the presence of the methanogen-specific mcrA gene. The study brings the first detailed survey of methanogens’ diversity in the digestive tract of millipedes. Sequences related to Methanosarcinales, Methanobacteriales, Methanomicrobiales and some unclassified Archaea were detected using molecular profiling (DGGE). The differences in substrate preferences of the main lineages of methanogenic Archaea found in different millipede orders indicate that the composition of methanogen communities may reflect the differences in available substrates for methanogenesis or the presence of symbiotic protozoa in the digestive tract. We conclude that differences in methane production in the millipede gut reflect differences in the activity and proliferation of intestinal methanogens rather than an absolute inability of some millipede taxa to host methanogens. This inference was supported by the general presence of methanogenic activity in millipede faecal pellets and the presence of the 16S rRNA gene of methanogens in all tested taxa in the two main groups of millipedes, the Helminthophora and the Pentazonia.
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Affiliation(s)
- Vladimír Šustr
- Institute of Soil Biology, Biology Centre AS CR, v.v.i., České Budějovice, Czech Republic
- * E-mail:
| | - Alica Chroňáková
- Institute of Soil Biology, Biology Centre AS CR, v.v.i., České Budějovice, Czech Republic
| | - Stanislava Semanová
- Institute of Soil Biology, Biology Centre AS CR, v.v.i., České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Karel Tajovský
- Institute of Soil Biology, Biology Centre AS CR, v.v.i., České Budějovice, Czech Republic
| | - Miloslav Šimek
- Institute of Soil Biology, Biology Centre AS CR, v.v.i., České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
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