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Lin YT, Ip JCH, He X, Gao ZM, Perez M, Xu T, Sun J, Qian PY, Qiu JW. Scallop-bacteria symbiosis from the deep sea reveals strong genomic coupling in the absence of cellular integration. THE ISME JOURNAL 2024; 18:wrae048. [PMID: 38531780 PMCID: PMC10999363 DOI: 10.1093/ismejo/wrae048] [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: 02/13/2024] [Revised: 03/06/2024] [Accepted: 03/22/2024] [Indexed: 03/28/2024]
Abstract
Previous studies have revealed tight metabolic complementarity between bivalves and their endosymbiotic chemosynthetic bacteria, but little is known about their interactions with ectosymbionts. Our analysis of the ectosymbiosis between a deep-sea scallop (Catillopecten margaritatus) and a gammaproteobacterium showed that bivalves could be highly interdependent with their ectosymbionts as well. Our microscopic observation revealed abundant sulfur-oxidizing bacteria (SOB) on the surfaces of the gill epithelial cells. Microbial 16S rRNA gene amplicon sequencing of the gill tissues showed the dominance of the SOB. An analysis of the SOB genome showed that it is substantially smaller than its free-living relatives and has lost cellular components required for free-living. Genomic and transcriptomic analyses showed that this ectosymbiont relies on rhodanese-like proteins and SOX multienzyme complex for energy generation, mainly on the Calvin-Benson-Bassham (CBB) cycle and peripherally on a phosphoenolpyruvate carboxylase for carbon assimilation. Besides, the symbiont encodes an incomplete tricarboxylic acid (TCA) cycle. Observation of the scallop's digestive gland and its nitrogen metabolism pathways indicates it does not fully rely on the ectosymbiont for nutrition. Analysis of the host's gene expression provided evidence that it could offer intermediates for the ectosymbiont to complete its TCA cycle and some amino acid synthesis pathways using exosomes, and its phagosomes, endosomes, and lysosomes might be involved in harvesting nutrients from the symbionts. Overall, our study prompts us to rethink the intimacy between the hosts and ectosymbionts in Bivalvia and the evolution of chemosymbiosis in general.
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Affiliation(s)
- Yi-Tao Lin
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, 999077, China
| | - Jack Chi-Ho Ip
- Science Unit, Lingnan University, Hong Kong SAR, 999077, China
| | - Xing He
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Zhao-Ming Gao
- Deep-sea Science Division, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China
| | - Maeva Perez
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, 999077, China
| | - Ting Xu
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong SAR, 999077, China
| | - Jin Sun
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Pei-Yuan Qian
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong SAR, 999077, China
| | - Jian-Wen Qiu
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, 999077, China
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Li Y, He X, Lin Y, Li YX, Kamenev GM, Li J, Qiu JW, Sun J. Reduced chemosymbiont genome in the methane seep thyasirid and the cooperated metabolisms in the holobiont under anaerobic sediment. Mol Ecol Resour 2023; 23:1853-1867. [PMID: 37486074 DOI: 10.1111/1755-0998.13846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/16/2023] [Accepted: 07/11/2023] [Indexed: 07/25/2023]
Abstract
Previous studies have deciphered the genomic basis of host-symbiont metabolic complementarity in vestimentiferans, bathymodioline mussels, vesicomyid clams and Alviniconcha snails, yet little is known about the chemosynthetic symbiosis in Thyasiridae-a family of Bivalvia regarded as an excellent model in chemosymbiosis research due to their wide distribution in both deep-sea and shallow-water habitats. We report the first circular thyasirid symbiont genome, named Candidatus Ruthturnera sp. Tsphm01, with a size of 1.53 Mb, 1521 coding genes and 100% completeness. Compared to its free-living relatives, Ca. Ruthturnera sp. Tsphm01 genome is reduced, lacking components for chemotaxis, citric acid cycle and de novo biosynthesis of small molecules (e.g. amino acids and cofactors), indicating it is likely an obligate intracellular symbiont. Nevertheless, the symbiont retains complete genomic components of sulphur oxidation and assimilation of inorganic carbon, and these systems were highly and actively expressed. Moreover, the symbiont appears well-adapted to anoxic environment, including capable of anaerobic respiration (i.e. reductions of DMSO and nitrate) and possession of a low oxygen-adapted type of cytochrome c oxidase. Analysis of the host transcriptome revealed its metabolic complementarity to the incomplete metabolic pathways of the symbiont and the acquisition of nutrients from the symbiont via phagocytosis and exosome. By providing the first complete genome of reduced size in a thyasirid symbiont, this study enhances our understanding of the diversity of symbiosis that has enabled bivalves to thrive in chemosynthetic habitats. The resources will be widely used in phylogenetic, geographic and evolutionary studies of chemosynthetic bacteria and bivalves.
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Affiliation(s)
- Yunlong Li
- Institute of Evolution & Marine Biodiversity, Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China
- Laoshan Laboratory, Qingdao, China
| | - Xing He
- Institute of Evolution & Marine Biodiversity, Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China
- Laoshan Laboratory, Qingdao, China
| | - Yuxuan Lin
- Department of Ocean Science, Hong Kong University of Science and Technology, Hong Kong, China
| | - Yi-Xuan Li
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Gennady M Kamenev
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russian Federation
| | - Jiying Li
- Department of Ocean Science, Hong Kong University of Science and Technology, Hong Kong, China
| | - Jian-Wen Qiu
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Jin Sun
- Institute of Evolution & Marine Biodiversity, Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China
- Laoshan Laboratory, Qingdao, China
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Breusing C, Xiao Y, Russell SL, Corbett-Detig RB, Li S, Sun J, Chen C, Lan Y, Qian PY, Beinart RA. Ecological differences among hydrothermal vent symbioses may drive contrasting patterns of symbiont population differentiation. mSystems 2023; 8:e0028423. [PMID: 37493648 PMCID: PMC10469979 DOI: 10.1128/msystems.00284-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 06/13/2023] [Indexed: 07/27/2023] Open
Abstract
The intra-host composition of horizontally transmitted microbial symbionts can vary across host populations due to interactive effects of host genetics, environmental, and geographic factors. While adaptation to local habitat conditions can drive geographic subdivision of symbiont strains, it is unknown how differences in ecological characteristics among host-symbiont associations influence the genomic structure of symbiont populations. To address this question, we sequenced metagenomes of different populations of the deep-sea mussel Bathymodiolus septemdierum, which are common at Western Pacific deep-sea hydrothermal vents and show characteristic patterns of niche partitioning with sympatric gastropod symbioses. Bathymodiolus septemdierum lives in close symbiotic relationship with sulfur-oxidizing chemosynthetic bacteria but supplements its symbiotrophic diet through filter-feeding, enabling it to occupy ecological niches with little exposure to geochemical reductants. Our analyses indicate that symbiont populations associated with B. septemdierum show structuring by geographic location, but that the dominant symbiont strain is uncorrelated with vent site. These patterns are in contrast to co-occurring Alviniconcha and Ifremeria gastropod symbioses that exhibit greater symbiont nutritional dependence and occupy habitats with higher spatial variability in environmental conditions. Our results suggest that relative habitat homogeneity combined with sufficient symbiont dispersal and genomic mixing might promote persistence of similar symbiont strains across geographic locations, while mixotrophy might decrease selective pressures on the host to affiliate with locally adapted symbiont strains. Overall, these data contribute to our understanding of the potential mechanisms influencing symbiont population structure across a spectrum of marine microbial symbioses that occupy contrasting ecological niches. IMPORTANCE Beneficial relationships between animals and microbial organisms (symbionts) are ubiquitous in nature. In the ocean, microbial symbionts are typically acquired from the environment and their composition across geographic locations is often shaped by adaptation to local habitat conditions. However, it is currently unknown how generalizable these patterns are across symbiotic systems that have contrasting ecological characteristics. To address this question, we compared symbiont population structure between deep-sea hydrothermal vent mussels and co-occurring but ecologically distinct snail species. Our analyses show that mussel symbiont populations are less partitioned by geography and do not demonstrate evidence for environmental adaptation. We posit that the mussel's mixotrophic feeding mode may lower its need to affiliate with locally adapted symbiont strains, while microhabitat stability and symbiont genomic mixing likely favors persistence of symbiont strains across geographic locations. Altogether, these findings further our understanding of the mechanisms shaping symbiont population structure in marine environmentally transmitted symbioses.
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Affiliation(s)
- Corinna Breusing
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Yao Xiao
- Department of Ocean Science, Division of Life Science and Hong Kong Branch of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Hong Kong, China
- The Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Nansha, Guangzhou, China
| | - Shelbi L. Russell
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, California, USA
| | - Russell B. Corbett-Detig
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, California, USA
| | - Sixuan Li
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Jin Sun
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, China
| | - Chong Chen
- X-STAR, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
| | - Yi Lan
- Department of Ocean Science, Division of Life Science and Hong Kong Branch of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Hong Kong, China
- The Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Nansha, Guangzhou, China
| | - Pei-Yuan Qian
- Department of Ocean Science, Division of Life Science and Hong Kong Branch of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Hong Kong, China
- The Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Nansha, Guangzhou, China
| | - Roxanne A. Beinart
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
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Hyams Y, Rubin-Blum M, Rosner A, Brodsky L, Rinkevich Y, Rinkevich B. Physiological changes during torpor favor association with Endozoicomonas endosymbionts in the urochordate Botrylloides leachii. Front Microbiol 2023; 14:1072053. [PMID: 37323901 PMCID: PMC10264598 DOI: 10.3389/fmicb.2023.1072053] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 05/02/2023] [Indexed: 06/17/2023] Open
Abstract
Environmental perturbations evoke down-regulation of metabolism in some multicellular organisms, leading to dormancy, or torpor. Colonies of the urochordate Botrylloides leachii enter torpor in response to changes in seawater temperature and may survive for months as small vasculature remnants that lack feeding and reproductive organs but possess torpor-specific microbiota. Upon returning to milder conditions, the colonies rapidly restore their original morphology, cytology and functionality while harboring re-occurring microbiota, a phenomenon that has not been described in detail to date. Here we investigated the stability of B. leachii microbiome and its functionality in active and dormant colonies, using microscopy, qPCR, in situ hybridization, genomics and transcriptomics. A novel lineage of Endozoicomonas, proposed here as Candidatus Endozoicomonas endoleachii, was dominant in torpor animals (53-79% read abundance), and potentially occupied specific hemocytes found only in torpid animals. Functional analysis of the metagenome-assembled genome and genome-targeted transcriptomics revealed that Endozoicomonas can use various cellular substrates, like amino acids and sugars, potentially producing biotin and thiamine, but also expressing various features involved in autocatalytic symbiosis. Our study suggests that the microbiome can be linked to the metabolic and physiological states of the host, B. leachii, introducing a model organism for the study of symbioses during drastic physiological changes, such as torpor.
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Affiliation(s)
- Yosef Hyams
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Maxim Rubin-Blum
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel
| | - Amalia Rosner
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel
| | - Leonid Brodsky
- Tauber Bioinformatics Research Center, University of Haifa, Haifa, Israel
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Yuval Rinkevich
- Comprehensive Pneumology Center, Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
| | - Baruch Rinkevich
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel
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Zvi-Kedem T, Vintila S, Kleiner M, Tchernov D, Rubin-Blum M. Metabolic handoffs between multiple symbionts may benefit the deep-sea bathymodioline mussels. ISME COMMUNICATIONS 2023; 3:48. [PMID: 37210404 PMCID: PMC10199937 DOI: 10.1038/s43705-023-00254-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 04/25/2023] [Accepted: 05/11/2023] [Indexed: 05/22/2023]
Abstract
Bathymodioline mussels rely on thiotrophic and/or methanotrophic chemosynthetic symbionts for nutrition, yet, secondary heterotrophic symbionts are often present and play an unknown role in the fitness of the organism. The bathymodioline Idas mussels that thrive in gas seeps and on sunken wood in the Mediterranean Sea and the Atlantic Ocean, host at least six symbiont lineages that often co-occur. These lineages include the primary symbionts chemosynthetic methane- and sulfur-oxidizing gammaproteobacteria, and the secondary symbionts, Methylophagaceae, Nitrincolaceae and Flavobacteriaceae, whose physiology and metabolism are obscure. Little is known about if and how these symbionts interact or exchange metabolites. Here we curated metagenome-assembled genomes of Idas modiolaeformis symbionts and used genome-centered metatranscriptomics and metaproteomics to assess key symbiont functions. The Methylophagaceae symbiont is a methylotrophic autotroph, as it encoded and expressed the ribulose monophosphate and Calvin-Benson-Bassham cycle enzymes, particularly RuBisCO. The Nitrincolaceae ASP10-02a symbiont likely fuels its metabolism with nitrogen-rich macromolecules and may provide the holobiont with vitamin B12. The Urechidicola (Flavobacteriaceae) symbionts likely degrade glycans and may remove NO. Our findings indicate that these flexible associations allow for expanding the range of substrates and environmental niches, via new metabolic functions and handoffs.
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Affiliation(s)
- Tal Zvi-Kedem
- Biology Department, National Institute of Oceanography, Israel Oceanographic and Limnological Research (IOLR), Haifa, 3108000, Israel
- Morris Kahn Marine Research Station, Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, 3498838, Israel
| | - Simina Vintila
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Manuel Kleiner
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Dan Tchernov
- Morris Kahn Marine Research Station, Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, 3498838, Israel
| | - Maxim Rubin-Blum
- Biology Department, National Institute of Oceanography, Israel Oceanographic and Limnological Research (IOLR), Haifa, 3108000, Israel.
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A regulatory hydrogenase gene cluster observed in the thioautotrophic symbiont of Bathymodiolus mussel in the East Pacific Rise. Sci Rep 2022; 12:22232. [PMID: 36564432 PMCID: PMC9789115 DOI: 10.1038/s41598-022-26669-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
The mytilid mussel Bathymodiolus thermophilus lives in the deep-sea hydrothermal vent regions due to its relationship with chemosynthetic symbiotic bacteria. It is well established that symbionts reside in the gill bacteriocytes of the mussel and can utilize hydrogen sulfide, methane, and hydrogen from the surrounding environment. However, it is observed that some mussel symbionts either possess or lack genes for hydrogen metabolism within the single-ribotype population and host mussel species level. Here, we found a hydrogenase cluster consisting of additional H2-sensing hydrogenase subunits in a complete genome of B. thermophilus symbiont sampled from an individual mussel from the East Pacific Rise (EPR9N). Also, we found methylated regions sparsely distributed throughout the EPR9N genome, mainly in the transposase regions and densely present in the rRNA gene regions. CRISPR diversity analysis confirmed that this genome originated from a single symbiont strain. Furthermore, from the comparative analysis, we observed variation in genome size, gene content, and genome re-arrangements across individual hosts suggesting multiple symbiont strains can associate with B. thermophilus. The ability to acquire locally adaptive various symbiotic strains may serve as an effective mechanism for successfully colonizing different chemosynthetic environments across the global oceans by host mussels.
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Perez M, Breusing C, Angers B, Beinart RA, Won YJ, Young CR. Divergent paths in the evolutionary history of maternally transmitted clam symbionts. Proc Biol Sci 2022; 289:20212137. [PMID: 35259985 PMCID: PMC8905170 DOI: 10.1098/rspb.2021.2137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Vertical transmission of bacterial endosymbionts is accompanied by virtually irreversible gene loss that results in a progressive reduction in genome size. While the evolutionary processes of genome reduction have been well described in some terrestrial symbioses, they are less understood in marine systems where vertical transmission is rarely observed. The association between deep-sea vesicomyid clams and chemosynthetic Gammaproteobacteria is one example of maternally inherited symbioses in the ocean. Here, we assessed the contributions of drift, recombination and selection to genome evolution in two extant vesicomyid symbiont clades by comparing 15 representative symbiont genomes (1.017-1.586 Mb) to those of closely related bacteria and the hosts' mitochondria. Our analyses suggest that drift is a significant force driving genome evolution in vesicomyid symbionts, though selection and interspecific recombination appear to be critical for maintaining symbiont functional integrity and creating divergent patterns of gene conservation. Notably, the two symbiont clades possess putative functional differences in sulfide physiology, anaerobic respiration and dependency on environmental vitamin B12, which probably reflect adaptations to different ecological habitats available to each symbiont group. Overall, these results contribute to our understanding of the eco-evolutionary processes shaping reductive genome evolution in vertically transmitted symbioses.
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Affiliation(s)
- Maëva Perez
- Department of Biological Sciences, Université de Montréal, Montreal, Canada
| | - Corinna Breusing
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
| | - Bernard Angers
- Department of Biological Sciences, Université de Montréal, Montreal, Canada
| | - Roxanne A Beinart
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
| | - Yong-Jin Won
- Division of EcoScience, Ewha Womans University, Seoul, South Korea
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