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Complete Genome Sequence of " Candidatus Hydrogeosomobacter endosymbioticus," an Intracellular Bacterial Symbiont of the Anaerobic Ciliate Scuticociliate GW7. Microbiol Resour Announc 2022; 11:e0115021. [PMID: 35175121 PMCID: PMC8852324 DOI: 10.1128/mra.01150-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacterium "Candidatus Hydrogenosomobacter endosymbioticus" is an intracellular symbiont of anaerobic scuticociliate GW7, which is associated with hydrogenosome together with methanogenic archaea. Here, we report a complete genome sequence of the symbiont consisting of 827 kbp. Knowing this sequence would contribute to the understanding of the metabolic interactions and evolution of the tripartite symbiosis.
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Hirakata Y, Hatamoto M, Oshiki M, Watari T, Araki N, Yamaguchi T. Food selectivity of anaerobic protists and direct evidence for methane production using carbon from prey bacteria by endosymbiotic methanogen. ISME JOURNAL 2020; 14:1873-1885. [PMID: 32341474 DOI: 10.1038/s41396-020-0660-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/05/2020] [Accepted: 04/07/2020] [Indexed: 01/28/2023]
Abstract
Anaerobic protists are major predators of prokaryotes in anaerobic ecosystems. However, little is known about the predation behavior of anaerobic protists because almost none have been cultured. In particular, these characteristics of anaerobic protists in the phyla Metamonada and Cercozoa have not been reported previously. In this study, we isolated three anaerobic protists, Cyclidium sp., Trichomitus sp., and Paracercomonas sp., from anaerobic granular sludge in an up-flow anaerobic sludge blanket reactor used to treat domestic sewage. Ingestion and digestion of food bacteria by anaerobic protists with or without endosymbiotic methanogens were demonstrated using tracer experiments with green fluorescent protein and a stable carbon isotope. These tracer experiments also demonstrated that Cyclidium sp. supplied CO2 and hydrogen to endosymbiotic methanogens. While Cyclidium sp. and Trichomitus sp. ingested both Gram-negative and -positive bacteria, Paracercomonas sp. could only take up Gram-negative bacteria. Archaeal cells such as Methanobacterium beijingense and Methanospirillum hungatei did not support the growth of these protists. Metabolite patterns of all three protists differed and were influenced by food bacterial species. These reported growth rates, ingestion rates, food selectivity, and metabolite patterns provide important insights into the ecological roles of these protists in anaerobic ecosystems.
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Affiliation(s)
- Yuga Hirakata
- Department of Science of Technology Innovation, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Masashi Hatamoto
- Department of Civil and Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan.
| | - Mamoru Oshiki
- Department of Civil Engineering, Nagaoka College, National Institute of Technology, Nagaoka, Niigata, Japan
| | - Takahiro Watari
- Department of Civil and Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Nobuo Araki
- Department of Civil Engineering, Nagaoka College, National Institute of Technology, Nagaoka, Niigata, Japan
| | - Takashi Yamaguchi
- Department of Science of Technology Innovation, Nagaoka University of Technology, Nagaoka, Niigata, Japan.,Department of Civil and Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
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Tripartite Symbiosis of an Anaerobic Scuticociliate with Two Hydrogenosome-Associated Endosymbionts, a Holospora-Related Alphaproteobacterium and a Methanogenic Archaeon. Appl Environ Microbiol 2019; 85:AEM.00854-19. [PMID: 31585988 DOI: 10.1128/aem.00854-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 09/17/2019] [Indexed: 11/20/2022] Open
Abstract
A number of anaerobic ciliates, unicellular eukaryotes, intracellularly possess methanogenic archaea and bacteria as symbiotic partners. Although this tripartite relationship is of interest in terms of the fact that each participant is from a different domain, the difficulty in culture and maintenance of those host species with symbiotic partners has disturbed both ecological and functional studies so far. In this study, we obtained a stable culture of a small anaerobic scuticociliate, strain GW7. By transmission electron microscopic observation and fluorescent in situ hybridization with domain-specific probes, we demonstrate that GW7 possesses both archaeal and bacterial endosymbionts in its cytoplasm. These endosymbionts are in dependently associated with hydrogenosomes, which are organelle producing hydrogen and ATP under anaerobic conditions. Clone library analyses targeting prokaryotic 16S rRNA genes, fluorescent in situ hybridization with endosymbiont-specific probes, and molecular phylogenetic analyses revealed the phylogenetic affiliations and intracellular localizations of these endosymbionts. The endosymbiotic archaeon is a methanogen belonging to the genus Methanoregula (order Methanomicrobiales); a member of this genus has previously been described as the endosymbiont of an anaerobic ciliate from the genus Metopus (class Armophorea), which is only distantly related to strain GW7 (class Oligohymenophorea). The endosymbiotic bacterium belongs to the family Holosporaceae of the class Alphaproteobacteria, which also comprises several endosymbionts of various aerobic ciliates. For this endosymbiotic bacterium, we propose a novel candidate genus and species, "Candidatus Hydrogenosomobacter endosymbioticus."IMPORTANCE Tripartite symbioses between anaerobic ciliated protists and their intracellular archaeal and bacterial symbionts are not uncommon, but most reports have been based mainly on microscopic observations. Deeper insights into the function, ecology, and evolution of these fascinating symbioses involving partners from all three domains of life have been hampered by the difficulties of culturing anaerobic ciliates in the laboratory and the frequent loss of their prokaryotic partners during long-term cultivation. In the present study, we report the isolation of an anaerobic scuticociliate, strain GW7, which has been stably maintained in our laboratory for more than 3 years without losing either of its endosymbionts. Unexpectedly, molecular characterization of the endosymbionts revealed that the bacterial partner of GW7 is phylogenetically related to intranuclear endosymbionts of aerobic ciliates. This strain will enable future genomic, transcriptomic, and proteomic analyses of the interactions in this tripartite symbiosis and a comparison with endosymbioses in aerobic ciliates.
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Affiliation(s)
- Yoichi Kamagata
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
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Complete Genome Sequence of the Intracellular Bacterial Symbiont TC1 in the Anaerobic Ciliate Trimyema compressum. GENOME ANNOUNCEMENTS 2016; 4:4/5/e01032-16. [PMID: 27660797 PMCID: PMC5034148 DOI: 10.1128/genomea.01032-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A free-living ciliate, Trimyema compressum, found in anoxic freshwater environments harbors methanogenic archaea and a bacterial symbiont named TC1 in its cytoplasm. Here, we report the complete genome sequence of the TC1 symbiont, consisting of a 1.59-Mb chromosome and a 35.8-kb plasmid, which was determined using the PacBio RSII sequencer.
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Shinzato N, Watanabe I, Meng XY, Sekiguchi Y, Tamaki H, Matsui T, Kamagata Y. Phylogenetic analysis and fluorescence in situ hybridization detection of archaeal and bacterial endosymbionts in the anaerobic ciliate trimyema compressum. MICROBIAL ECOLOGY 2007; 54:627-36. [PMID: 17468963 DOI: 10.1007/s00248-007-9218-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2006] [Revised: 12/09/2006] [Accepted: 01/13/2007] [Indexed: 05/15/2023]
Abstract
The anaerobic free-living ciliate, Trimyema compressum, is known to harbor both methanogenic archaeal and bacterial symbionts in the cytoplasm. To clarify their phylogenetic belongings, a full-cycle rRNA approach was applied to this symbiosis. Phylogenetic analysis showed that the methanogenic symbiont was related to Methanobrevibacter arboriphilicus, which was distantly related to symbionts found in other Trimyema species. This result suggested that Trimyema species do not require very specific methanogenic symbionts, and symbiont replacement could have occurred in the history of Trimyema species. On the other hand, the bacterial symbiont was located near the lineage of the family Syntrophomonadaceae in the phylum Firmicutes. The sequence similarity between the bacterial symbiont and the nearest species was 85%, indicating that bacterial symbionts may be specific to the Trimyema species. The elimination of bacterial symbionts from the ciliate cell by antibiotic treatment resulted in considerably decreased host growth. However, it was not restored by stigmasterol addition (<2 microg ml(-1)), which was different from the previous report that showed that the symbiont-free strain required exogenous sterols for growth. In addition, the decline of host growth was not accompanied by host metabolism shift toward the formation of more reduced products, which suggested that the contribution of bacterial symbionts to the host ciliate was not a dispose of excessive reducing equivalent arising from the host's fermentative metabolism as methanogenic symbionts do. This study showed that bacterial symbionts make a significant contribution to the host ciliate by an unknown function and suggested that interactions between bacterial symbionts and T. compressum are more complicated than hitherto proposed.
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Affiliation(s)
- Naoya Shinzato
- Center of Molecular Biosciences, University of the Ryukyus, Nishihara-cho, Nakagami-gun, Okinawa, 903-0213, Japan.
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Nakamura K, Terada T, Sekiguchi Y, Shinzato N, Meng XY, Enoki M, Kamagata Y. Application of pseudomurein endoisopeptidase to fluorescence in situ hybridization of methanogens within the family Methanobacteriaceae. Appl Environ Microbiol 2006; 72:6907-13. [PMID: 16950902 PMCID: PMC1636154 DOI: 10.1128/aem.01499-06] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In situ detection of methanogens within the family Methanobacteriaceae is sometimes known to be unsuccessful due to the difficulty in permeability of oligonucleotide probes. Pseudomurein endoisopeptidase (Pei), a lytic enzyme that specifically acts on their cell walls, was applied prior to 16S rRNA-targeting fluorescence in situ hybridization (FISH). For this purpose, pure cultured methanogens within this family, Methanobacterium bryantii, Methanobrevibacter ruminantium, Methanosphaera stadtmanae, and Methanothermobacter thermautotrophicus together with a Methanothermobacter thermautotrophicus-containing syntrophic acetate-oxidizing coculture, endosymbiotic Methanobrevibacter methanogens within an anaerobic ciliate, and an upflow anaerobic sludge blanket (UASB) granule were examined. Even without the Pei treatment, Methanobacterium bryantii and Methanothermobacter thermautotrophicus cells are relatively well hybridized with oligonucleotide probes. However, almost none of the cells of Methanobrevibacter ruminantium, Methanosphaera stadtmanae, cocultured Methanothermobacter thermautotrophicus, and the endosymbiotic methanogens and the cells within UASB granule were hybridized. Pei treatment was able to increase the probe hybridization ratio in every specimen, particularly in the specimen that had shown little hybridization. Interestingly, the hybridizing signal intensity of Methanothermobacter thermautotrophicus cells in coculture with an acetate-oxidizing H(2)-producing syntroph was significantly improved by Pei pretreatment, whereas the probe was well hybridized with the cells of pure culture of the same strain. We found that the difference is attributed to the differences in cell wall thicknesses between the two culture conditions. These results indicate that Pei treatment is effective for FISH analysis of methanogens that show impermeability to the probe.
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Affiliation(s)
- Kohei Nakamura
- Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba 305-8566, Japan
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Yamada K, Kamagata Y, Nakamura K. The effect of endosymbiotic methanogens on the growth and metabolic profile of the anaerobic free-living ciliate Trimyema compressum. FEMS Microbiol Lett 2006. [DOI: 10.1111/j.1574-6968.1997.tb10319.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Baumgartner M, Stetter KO, Foissner W. Morphological, small subunit rRNA, and physiological characterization of Trimyema minutum (Kahl, 1931), an anaerobic ciliate from submarine hydrothermal vents growing from 28 degrees C to 52 degrees C. J Eukaryot Microbiol 2002; 49:227-38. [PMID: 12120988 DOI: 10.1111/j.1550-7408.2002.tb00527.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A thermophilic strain of Trimyema minutum was isolated from the hydrothermally heated sea floor at Vulcano Island (Italy) and cultivated monoxenically on Marinobacter sp. and Methanococcus thermolithotrophicus. It can be propagated strictly anaerobically and is sensitive to oxygen: if exposed to air at 48 degrees C all cells die within 60 min. It grows from 0.45-7.2% (w/v) salt and at pH 6.0-8.0. The isolate is the most extreme thermophilic ciliate which ever has been cultivated, exhibiting an optimal growth temperature of 48 degrees C (doubling time 6 h). Growth occurs between 28 degrees C and 52 degrees C. Trimyema minutum is redescribed using live observation and silver impregnation. Its morphology and the small subunit ribosomal RNA sequence is distinctly different from that of T. compressum, but morphology is highly similar to that of T. shoalsia Nerad et al. 1995, which is thus probably a junior synonym of T. minutum. To stabilize the bewildering species taxonomy in Trimyema, we suggest to recognize our population as a neotype of T. minutum.
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Biagini GA, McIntyre PS, Finlay BJ, Lloyd D. Carbohydrate and Amino Acid Fermentation in the Free-Living Primitive Protozoon Hexamita sp. Appl Environ Microbiol 1998; 64:203-7. [PMID: 16349480 PMCID: PMC124694 DOI: 10.1128/aem.64.1.203-207.1998] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/1997] [Accepted: 10/27/1997] [Indexed: 11/20/2022] Open
Abstract
Hexamita sp. is an amitochondriate free-living diplomonad which inhabits O(2)-limited environments, such as the deep waters and sediments of lakes and marine basins. C nuclear magnetic resonance spectroscopy reveals ethanol, lactate, acetate, and alanine as products of glucose fermentation under microaerobic conditions (23 to 34 muM O(2)). Propionic acid and butyric acid were also detected and are believed to be the result of fermentation of alternative substrates. Production of organic acids was greatest under microaerobic conditions (15 muM O(2)) and decreased under anaerobic (<0.25 muM O(2)) and aerobic (200 to 250 muM O(2)) conditions. Microaerobic incubation resulted in the production of high levels of oxidized end products (70% acetate) compared to that produced under anoxic conditions (20% acetate). In addition, data suggest that Hexamita cells contain the arginine dihydrolase pathway, generating energy from the catabolism of arginine to citrulline, ornithine, NH(4), and CO(2). The rate of arginine catabolism was higher under anoxic conditions than under microaerobic conditions. Hexamita cells were able to grow in the absence of a carbohydrate source, albeit with a lower growth rate and yield.
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Affiliation(s)
- G A Biagini
- Microbiology Group, School of Pure and Applied Biology, University of Wales College of Cardiff, Cardiff CF1 3TL, and School of Applied Sciences, University of Glamorgan, Pontypridd, Mid Glamorgan CF37 1DL, Wales, and Institute of Freshwater Ecology, Windermere Laboratory, The Ferry House, Ambleside, Cumbria LA22 OLP, United Kingdom
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