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Wang R, Meng Q, Wang X, Xiao Y, Sun R, Zhang Z, Fu Y, Di Giuseppe G, Liang A. Comparative genomic analysis of symbiotic and free-living Fluviibacter phosphoraccumulans strains provides insights into the evolutionary origins of obligate Euplotes-bacterial endosymbioses. Appl Environ Microbiol 2024; 90:e0190023. [PMID: 38334408 PMCID: PMC10952467 DOI: 10.1128/aem.01900-23] [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: 10/25/2023] [Accepted: 01/12/2024] [Indexed: 02/10/2024] Open
Abstract
Endosymbiosis is a widespread and important phenomenon requiring diverse model systems. Ciliates are a widespread group of protists that often form symbioses with diverse microorganisms. Endosymbioses between the ciliate Euplotes and heritable bacterial symbionts are common in nature, and four essential symbionts were described: Polynucleobacter necessarius, "Candidatus Protistobacter heckmanni," "Ca. Devosia symbiotica," and "Ca. Devosia euplotis." Among them, only the genus Polynucleobacter comprises very close free-living and symbiotic representatives, which makes it an excellent model for investigating symbiont replacements and recent symbioses. In this article, we characterized a novel endosymbiont inhabiting the cytoplasm of Euplotes octocarinatus and found that it is a close relative of the free-living bacterium Fluviibacter phosphoraccumulans (Betaproteobacteria and Rhodocyclales). We present the complete genome sequence and annotation of the symbiotic Fluviibacter. Comparative analyses indicate that the genome of symbiotic Fluviibacter is small in size and rich in pseudogenes when compared with free-living strains, which seems to fit the prediction for recently established endosymbionts undergoing genome erosion. Further comparative analysis revealed reduced metabolic capacities in symbiotic Fluviibacter, which implies that the symbiont relies on the host Euplotes for carbon sources, organic nitrogen and sulfur, and some cofactors. We also estimated substitution rates between symbiotic and free-living Fluviibacter pairs for 233 genes; the results showed that symbiotic Fluviibacter displays higher dN/dS mean value than free-living relatives, which suggested that genetic drift is the main driving force behind molecular evolution in endosymbionts. IMPORTANCE In the long history of symbiosis research, most studies focused mainly on organelles or bacteria within multicellular hosts. The single-celled protists receive little attention despite harboring an immense diversity of symbiotic associations with bacteria and archaea. One subgroup of the ciliate Euplotes species is strictly dependent on essential symbionts for survival and has emerged as a valuable model for understanding symbiont replacements and recent symbioses. However, almost all of our knowledge about the evolution and functions of Euplotes symbioses comes from the Euplotes-Polynucleobacter system. In this article, we report a novel essential symbiont, which also has very close free-living relatives. Genome analysis indicated that it is a recently established endosymbiont undergoing genome erosion and relies on the Euplotes host for many essential molecules. Our results provide support for the notion that essential symbionts of the ciliate Euplotes evolve from free-living progenitors in the natural water environment.
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Affiliation(s)
- Ruanlin Wang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | - Qingyao Meng
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | - Xue Wang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | - Yu Xiao
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | - Ruijuan Sun
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | - Zhiyun Zhang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | - Yuejun Fu
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | | | - Aihua Liang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
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Castelli M, Nardi T, Gammuto L, Bellinzona G, Sabaneyeva E, Potekhin A, Serra V, Petroni G, Sassera D. Host association and intracellularity evolved multiple times independently in the Rickettsiales. Nat Commun 2024; 15:1093. [PMID: 38321113 PMCID: PMC10847448 DOI: 10.1038/s41467-024-45351-7] [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: 12/14/2022] [Accepted: 01/18/2024] [Indexed: 02/08/2024] Open
Abstract
The order Rickettsiales (Alphaproteobacteria) encompasses multiple diverse lineages of host-associated bacteria, including pathogens, reproductive manipulators, and mutualists. Here, in order to understand how intracellularity and host association originated in this order, and whether they are ancestral or convergently evolved characteristics, we built a large and phylogenetically-balanced dataset that includes de novo sequenced genomes and a selection of published genomic and metagenomic assemblies. We perform detailed functional reconstructions that clearly indicates "late" and parallel evolution of obligate host-association in different Rickettsiales lineages. According to the depicted scenario, multiple independent horizontal acquisitions of transporters led to the progressive loss of biosynthesis of nucleotides, amino acids and other metabolites, producing distinct conditions of host-dependence. Each clade experienced a different pattern of evolution of the ancestral arsenal of interaction apparatuses, including development of specialised effectors involved in the lineage-specific mechanisms of host cell adhesion and/or invasion.
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Affiliation(s)
- Michele Castelli
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Tiago Nardi
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | | | - Greta Bellinzona
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Elena Sabaneyeva
- Department of Cytology and Histology, Saint Petersburg State University, Petersburg, Russia
| | - Alexey Potekhin
- Department of Microbiology, Saint Petersburg State University, Petersburg, Russia
- Research Department for Limnology, University of Innsbruck, Mondsee, Austria
| | | | | | - Davide Sassera
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy.
- IRCCS Policlinico San Matteo, Pavia, Italy.
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Song Q, Zhao F, Hou L, Miao M. Cellular interactions and evolutionary origins of endosymbiotic relationships with ciliates. THE ISME JOURNAL 2024; 18:wrae117. [PMID: 38916437 PMCID: PMC11253213 DOI: 10.1093/ismejo/wrae117] [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: 02/16/2024] [Revised: 05/26/2024] [Accepted: 06/21/2024] [Indexed: 06/26/2024]
Abstract
As unicellular predators, ciliates engage in close associations with diverse microbes, laying the foundation for the establishment of endosymbiosis. Originally heterotrophic, ciliates demonstrate the ability to acquire phototrophy by phagocytizing unicellular algae or by sequestering algal plastids. This adaptation enables them to gain photosynthate and develop resistance to unfavorable environmental conditions. The integration of acquired phototrophy with intrinsic phagotrophy results in a trophic mode known as mixotrophy. Additionally, ciliates can harbor thousands of bacteria in various intracellular regions, including the cytoplasm and nucleus, exhibiting species specificity. Under prolonged and specific selective pressure within hosts, bacterial endosymbionts evolve unique lifestyles and undergo particular reductions in metabolic activities. Investigating the research advancements in various endosymbiotic cases within ciliates will contribute to elucidate patterns in cellular interaction and unravel the evolutionary origins of complex traits.
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Affiliation(s)
- Qi Song
- Medical School, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing 100049, China
| | - Fangqing Zhao
- Medical School, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing 100049, China
- Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China
- Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, No. 1 Xiangshan Road, Hangzhou 310024, China
| | - Lina Hou
- Medical School, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing 100049, China
| | - Miao Miao
- Medical School, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing 100049, China
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4
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Wang R, Sun R, Zhang Z, Vannini C, Di Giuseppe G, Liang A. "Candidatus Euplotechlamydia quinta," a novel chlamydia-like bacterium hosted by the ciliate Euplotes octocarinatus (Ciliophora, Spirotrichea). J Eukaryot Microbiol 2023; 70:e12945. [PMID: 36039907 DOI: 10.1111/jeu.12945] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/15/2022] [Accepted: 08/24/2022] [Indexed: 11/29/2022]
Abstract
Our knowledge of ciliate endosymbiont diversity greatly expanded over the past decades due to the development of characterization methods for uncultivable bacteria. Chlamydia-like bacteria have been described as symbionts of free-living amoebae and other phylogenetically diverse eukaryotic hosts. In the present work, a systematic survey of the bacterial diversity associated with the ciliate Euplotes octocarinatus strain Zam5b-1 was performed, using metagenomic screening as well as classical full-cycle rRNA approach, and a novel chlamydial symbiont was characterized. The metagenomic screening revealed 16S rRNA gene sequences from Polynucleobacter necessarius, three previously reported accessory symbionts, and a novel chlamydia-like bacterium. Following the full-cycle rRNA approach, we obtained the full-length 16S rRNA gene sequence of this chlamydia-like bacterium and developed probes for diagnostic fluorescence in situ hybridizations. The phylogenetic analysis of the 16S rRNA gene sequences unambiguously places the new bacterium in the family Rhabdochlamydiaceae. This is the first report of chlamydia-like bacterium being found in Euplotes. Based on the obtained data, the bacterium is proposed as a new candidate genus and species: "Candidatus Euplotechlamydia quinta."
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Affiliation(s)
- Ruanlin Wang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | - Ruijuan Sun
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | - Zhiyun Zhang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
| | | | | | - Aihua Liang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China
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Li LJ, Lin C, Huang XR, An XL, Li WJ, Su JQ, Zhu YG. Characterizing potential pathogens from intracellular bacterial community of protists in wastewater treatment plants. ENVIRONMENT INTERNATIONAL 2023; 171:107723. [PMID: 36584423 DOI: 10.1016/j.envint.2022.107723] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/25/2022] [Accepted: 12/26/2022] [Indexed: 06/17/2023]
Abstract
Protists are a trophically diverse and biogeochemically significant component of water environments and are widely reported as hosts of bacteria. However, the potential role of protists in wastewater treatment plants (WWTPs) as reservoirs for human pathogens does not appear to have received adequate attention. Here, a combination of fluorescence-activated cell sorting and Illumina sequencing was applied to characterize the dynamics of the internalized bacterial community of the enriched protists from the influents and effluents of five WWTPs. The results showed that Proteobacteria (mainly Betaproteobacteria) dominate the intracellular bacterial communities of protists in both influents and effluents of WWTPs, accounting for 72.6% of the total intracellular bacterial communities. The most frequently detected genus was Sulfuricurvum in the influent samples, Chryseobacterium and Pseudomonas were most prevalent in the effluent samples. Compared with the influents, a more diverse and abundant intracellular bacterial community was observed in the effluents. Moreover, the potential intracellular bacterial pathogens were 26 times higher in effluents than in influents, with Pseudomonas fluorescens and Pseudomonas putida significantly enriched in effluents. This work provides insights into the dynamics of bacterial communities and potential pathogens harbored by protists in the influents and effluents from WWTPs, contributing to the improved evaluation of biosafety in WWTPs.
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Affiliation(s)
- Li-Juan Li
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Chenshuo Lin
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Xin-Rong Huang
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Xin-Li An
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China
| | - Wen-Jing Li
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Jian-Qiang Su
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China
| | - Yong-Guan Zhu
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China; State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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6
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Boscaro V, Manassero V, Keeling PJ, Vannini C. Single-cell Microbiomics Unveils Distribution and Patterns of Microbial Symbioses in the Natural Environment. MICROBIAL ECOLOGY 2023; 85:307-316. [PMID: 35048168 DOI: 10.1007/s00248-021-01938-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 12/05/2021] [Indexed: 06/14/2023]
Abstract
Protist-bacteria associations are extremely common. Among them, those involving ciliates of the genus Euplotes are emerging as models for symbioses between prokaryotes and eukaryotes, and a great deal of information is available from cultured representatives of this system. Even so, as for most known microbial symbioses, data on natural populations is lacking, and their ecology remains largely unexplored; how well lab cultures represent actual diversity is untested. Here, we describe a survey on natural populations of Euplotes based on a single-cell microbiomic approach, focusing on taxa that include known endosymbionts of this ciliate. The results reveal an unexpected variability in symbiotic communities, with individual hosts of the same population harboring different sets of bacterial endosymbionts. Co-occurring Euplotes individuals of the same population can even have different essential symbionts, Polynucleobacter and "Candidatus Protistobacter," which might suggest that replacement events could be more frequent in nature than previously hypothesized. Accessory symbionts are even more variable: some showed a strong affinity for one host species, some for a sampling site, and two ("Candidatus Cyrtobacter" and "Candidatus Anadelfobacter") displayed an unusual pattern of competitive exclusion. These data represent the first insight into the prevalence and patterns of bacterial symbionts in natural populations of free-living protists.
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Affiliation(s)
- Vittorio Boscaro
- Department of Botany, University of British Columbia, Vancouver, Canada
| | | | - Patrick J Keeling
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Claudia Vannini
- Department of Biology, University of Pisa, 56126, Pisa, Italy.
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7
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The 'other' Rickettsiales: an overview of the family ' Candidatus Midichloriaceae'. Appl Environ Microbiol 2022; 88:e0243221. [PMID: 35108076 DOI: 10.1128/aem.02432-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The family 'Candidatus Midichloriaceae' constitutes the most diverse but least studied lineage within the important order of intracellular bacteria Rickettsiales. Midichloriaceae endosymbionts are found in many hosts, including terrestrial arthropods, aquatic invertebrates, and protists. Representatives of the family are not documented to be pathogenic, but some are associated with diseased fish or corals. Different genera display a range of unusual features, such as full sets of flagellar genes without visible flagella, or the ability to invade host mitochondria. Since studies on 'Ca. Midichloriaceae' tend to focus on the host, the family is rarely addressed as a unit and we therefore lack a coherent picture of its diversity. Here we provide four new midichloriaceae genomes and we survey molecular and ecological data from the entire family. Features like genome size, ecological context, and host transitions vary considerably even among closely related midichloriaceae, suggesting a high frequency of such shifts, incomplete sampling, or both. Important functional traits involved in energy metabolism, flagella and secretion systems were independently reduced multiple times with no obvious correspondence to host or habitat, corroborating the idea that many features of these 'professional symbionts' are largely independent of host identity. Finally, despite 'Ca. Midichloriaceae' being predominantly studied in ticks, our analyses show that the clade is mainly aquatic, with a few terrestrial offshoots. This highlights the importance of considering aquatic hosts, and protists in particular, when reconstructing the evolution of these endosymbionts and by extension all Rickettsiales. Importance Among endosymbiotic bacterial lineages, few are as intensely studied as Rickettsiales, which include the causative agents of spotted fever, typhus, and anaplasmosis. And yet, an important subgroup called 'Candidatus Midichloriaceae' receives little attention despite accounting for a third of the diversity of Rickettsiales and harbouring a wide range of bacteria with unique features, like the ability to infect mitochondria. Midichloriaceae are found in many hosts, from ticks to corals to unicellular protozoa, and studies on them tend to focus on the host groups. Here, for the first time since the establishment of this clade, we address the genomics, evolution, and ecology of 'Ca. Midichloriaceae' as a whole, highlighting trends and patterns, the remaining gaps in our knowledge, and its importance for the understanding of symbiotic processes in intracellular bacteria.
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8
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Fokin SI, Serra V. Bacterial Symbiosis in Ciliates (Alveolata, Ciliophora): Roads Traveled and Those Still to be Taken. J Eukaryot Microbiol 2022; 69:e12886. [PMID: 35006645 PMCID: PMC9539572 DOI: 10.1111/jeu.12886] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 11/30/2022]
Abstract
The diversity of prokaryotic symbionts in Ciliophora and other protists is fascinatingly rich; they may even include some potentially pathogenic bacteria. In this review, we summarize currently available data on biodiversity and some morphological and biological peculiarities of prokaryotic symbionts mainly within the genera Paramecium and Euplotes. Another direction of ciliate symbiology, neglected for a long time and now re‐discovered, is the study of epibionts of ciliates. This promises a variety of interesting outcomes. Last, but not least, we stress the new technologies, such as next generation sequencing and the use of genomics data, which all can clarify many new aspects of relevance. For this reason, a brief overview of achievements in genomic studies on ciliate's symbionts is provided. Summing up the results of numerous scientific contributions, we systematically update current knowledge and outline the prospects as to how symbiology of Ciliophora may develop in the near future.
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Affiliation(s)
- Sergei I Fokin
- University of Pisa, Pisa, Italy.,St. Petersburg State University, St. Petersburg, Russia
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9
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Serra V, Gammuto L, Nitla V, Castelli M, Lanzoni O, Sassera D, Bandi C, Sandeep BV, Verni F, Modeo L, Petroni G. Morphology, ultrastructure, genomics, and phylogeny of Euplotes vanleeuwenhoeki sp. nov. and its ultra-reduced endosymbiont "Candidatus Pinguicoccus supinus" sp. nov. Sci Rep 2020; 10:20311. [PMID: 33219271 PMCID: PMC7679464 DOI: 10.1038/s41598-020-76348-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 09/30/2020] [Indexed: 01/30/2023] Open
Abstract
Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics and, more recently, on evolutionary relationships. With the birth of novel genomics/bioinformatics techniques and the increasing interest in microbiome studies, a further advance of taxonomic discipline appears not only possible but highly desirable. The present work proposes a new approach to modern taxonomy, consisting in the inclusion of novel descriptors in the organism characterization: (1) the presence of associated microorganisms (e.g.: symbionts, microbiome), (2) the mitochondrial genome of the host, (3) the symbiont genome. This approach aims to provide a deeper comprehension of the evolutionary/ecological dimensions of organisms since their very first description. Particularly interesting, are those complexes formed by the host plus associated microorganisms, that in the present study we refer to as "holobionts". We illustrate this approach through the description of the ciliate Euplotes vanleeuwenhoeki sp. nov. and its bacterial endosymbiont "Candidatus Pinguicoccus supinus" gen. nov., sp. nov. The endosymbiont possesses an extremely reduced genome (~ 163 kbp); intriguingly, this suggests a high integration between host and symbiont.
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Affiliation(s)
- Valentina Serra
- Department of Biology, University of Pisa, Via Volta 4/6, 56126, Pisa, Italy
| | - Leandro Gammuto
- Department of Biology, University of Pisa, Via Volta 4/6, 56126, Pisa, Italy
| | - Venkatamahesh Nitla
- Department of Biology, University of Pisa, Via Volta 4/6, 56126, Pisa, Italy
| | - Michele Castelli
- Department of Biosciences, Romeo and Enrica Invernizzi Pediatric Research Center, University of Milan, Milan, Italy
- Department of Biology and Biotechnology "Lazzaro Spallanzani", Pavia University, Pavia, Italy
| | - Olivia Lanzoni
- Department of Biology, University of Pisa, Via Volta 4/6, 56126, Pisa, Italy
| | - Davide Sassera
- Department of Biology and Biotechnology "Lazzaro Spallanzani", Pavia University, Pavia, Italy
| | - Claudio Bandi
- Department of Biosciences, Romeo and Enrica Invernizzi Pediatric Research Center, University of Milan, Milan, Italy
| | | | - Franco Verni
- Department of Biology, University of Pisa, Via Volta 4/6, 56126, Pisa, Italy
| | - Letizia Modeo
- Department of Biology, University of Pisa, Via Volta 4/6, 56126, Pisa, Italy.
- CIME, Centro Interdipartimentale di Microscopia Elettronica, Università di Pisa, Pisa, Italy.
- CISUP, Centro per l'Integrazione della Strumentazione dell'Università di Pisa, Pisa, India.
| | - Giulio Petroni
- Department of Biology, University of Pisa, Via Volta 4/6, 56126, Pisa, Italy.
- CIME, Centro Interdipartimentale di Microscopia Elettronica, Università di Pisa, Pisa, Italy.
- CISUP, Centro per l'Integrazione della Strumentazione dell'Università di Pisa, Pisa, India.
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Oren A, Garrity GM, Parker CT, Chuvochina M, Trujillo ME. Lists of names of prokaryotic Candidatus taxa. Int J Syst Evol Microbiol 2020; 70:3956-4042. [DOI: 10.1099/ijsem.0.003789] [Citation(s) in RCA: 782] [Impact Index Per Article: 195.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We here present annotated lists of names of Candidatus taxa of prokaryotes with ranks between subspecies and class, proposed between the mid-1990s, when the provisional status of Candidatus taxa was first established, and the end of 2018. Where necessary, corrected names are proposed that comply with the current provisions of the International Code of Nomenclature of Prokaryotes and its Orthography appendix. These lists, as well as updated lists of newly published names of Candidatus taxa with additions and corrections to the current lists to be published periodically in the International Journal of Systematic and Evolutionary Microbiology, may serve as the basis for the valid publication of the Candidatus names if and when the current proposals to expand the type material for naming of prokaryotes to also include gene sequences of yet-uncultivated taxa is accepted by the International Committee on Systematics of Prokaryotes.
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Affiliation(s)
- Aharon Oren
- The Institute of Life Sciences, The Hebrew University of Jerusalem, The Edmond J. Safra Campus, 9190401 Jerusalem, Israel
| | - George M. Garrity
- NamesforLife, LLC, PO Box 769, Okemos MI 48805-0769, USA
- Department of Microbiology & Molecular Genetics, Biomedical Physical Sciences, Michigan State University, East Lansing, MI 48824-4320, USA
| | | | - Maria Chuvochina
- Australian Centre for Ecogenomics, University of Queensland, St. Lucia QLD 4072, Brisbane, Australia
| | - Martha E. Trujillo
- Departamento de Microbiología y Genética, Campus Miguel de Unamuno, Universidad de Salamanca, 37007, Salamanca, Spain
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11
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Castelli M, Sabaneyeva E, Lanzoni O, Lebedeva N, Floriano AM, Gaiarsa S, Benken K, Modeo L, Bandi C, Potekhin A, Sassera D, Petroni G. Deianiraea, an extracellular bacterium associated with the ciliate Paramecium, suggests an alternative scenario for the evolution of Rickettsiales. THE ISME JOURNAL 2019; 13:2280-2294. [PMID: 31073215 PMCID: PMC6776064 DOI: 10.1038/s41396-019-0433-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/19/2019] [Accepted: 04/10/2019] [Indexed: 12/28/2022]
Abstract
Rickettsiales are a lineage of obligate intracellular Alphaproteobacteria, encompassing important human pathogens, manipulators of host reproduction, and mutualists. Here we report the discovery of a novel Rickettsiales bacterium associated with Paramecium, displaying a unique extracellular lifestyle, including the ability to replicate outside host cells. Genomic analyses show that the bacterium possesses a higher capability to synthesise amino acids, compared to all investigated Rickettsiales. Considering these observations, phylogenetic and phylogenomic reconstructions, and re-evaluating the different means of interaction of Rickettsiales bacteria with eukaryotic cells, we propose an alternative scenario for the evolution of intracellularity in Rickettsiales. According to our reconstruction, the Rickettsiales ancestor would have been an extracellular and metabolically versatile bacterium, while obligate intracellularity would have evolved later, in parallel and independently, in different sub-lineages. The proposed new scenario could impact on the open debate on the lifestyle of the last common ancestor of mitochondria within Alphaproteobacteria.
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Affiliation(s)
- Michele Castelli
- Centro Romeo ed Enrica Invernizzi Ricerca Pediatrica, Dipartimento di Bioscienze, Università degli studi di Milano, Milan, Italy
| | - Elena Sabaneyeva
- Department of Cytology and Histology, Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia
| | - Olivia Lanzoni
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
| | - Natalia Lebedeva
- Centre of Core Facilities "Culture Collections of Microorganisms", Saint Petersburg State University, Saint Petersburg, Russia
| | - Anna Maria Floriano
- Dipartimento di Biologia e Biotecnologie, Università degli studi di Pavia, Pavia, Italy
| | - Stefano Gaiarsa
- Dipartimento di Biologia e Biotecnologie, Università degli studi di Pavia, Pavia, Italy
- UOC Microbiologia e Virologia, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Konstantin Benken
- Core Facility Center for Microscopy and Microanalysis, Saint Petersburg State University, Saint Petersburg, Russia
| | - Letizia Modeo
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
| | - Claudio Bandi
- Centro Romeo ed Enrica Invernizzi Ricerca Pediatrica, Dipartimento di Bioscienze, Università degli studi di Milano, Milan, Italy
| | - Alexey Potekhin
- Department of Microbiology, Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia
| | - Davide Sassera
- Dipartimento di Biologia e Biotecnologie, Università degli studi di Pavia, Pavia, Italy.
| | - Giulio Petroni
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy.
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12
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Boscaro V, Husnik F, Vannini C, Keeling PJ. Symbionts of the ciliate Euplotes: diversity, patterns and potential as models for bacteria-eukaryote endosymbioses. Proc Biol Sci 2019; 286:20190693. [PMID: 31311477 PMCID: PMC6661354 DOI: 10.1098/rspb.2019.0693] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 06/26/2019] [Indexed: 12/21/2022] Open
Abstract
Endosymbioses between bacteria and eukaryotes are enormously important in ecology and evolution, and as such are intensely studied. Despite this, the range of investigated hosts is narrow in the context of the whole eukaryotic tree of life: most of the information pertains to animal hosts, while most of the diversity is found in unicellular protists. A prominent case study is the ciliate Euplotes, which has repeatedly taken up the bacterium Polynucleobacter from the environment, triggering its transformation into obligate endosymbiont. This multiple origin makes the relationship an excellent model to understand recent symbioses, but Euplotes may host bacteria other than Polynucleobacter, and a more detailed knowledge of these additional interactions is needed in order to correctly interpret the system. Here, we present the first systematic survey of Euplotes endosymbionts, adopting a classical as well as a metagenomic approach, and review the state of knowledge. The emerging picture is indeed quite complex, with some Euplotes harbouring rich, stable prokaryotic communities not unlike those of multicellular animals. We provide insights into the distribution, evolution and diversity of these symbionts (including the establishment of six novel bacterial taxa), and outline differences and similarities with the most well-understood group of eukaryotic hosts: insects.
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Affiliation(s)
- Vittorio Boscaro
- Department of Botany, University of British Columbia, British Columbia, Canada
| | - Filip Husnik
- Department of Botany, University of British Columbia, British Columbia, Canada
| | | | - Patrick J. Keeling
- Department of Botany, University of British Columbia, British Columbia, Canada
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13
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Chiellini C, Pasqualetti C, Lanzoni O, Fagorzi C, Bazzocchi C, Fani R, Petroni G, Modeo L. Harmful Effect of Rheinheimera sp. EpRS3 ( Gammaproteobacteria) Against the Protist Euplotes aediculatus (Ciliophora, Spirotrichea): Insights Into the Ecological Role of Antimicrobial Compounds From Environmental Bacterial Strains. Front Microbiol 2019; 10:510. [PMID: 31001206 PMCID: PMC6457097 DOI: 10.3389/fmicb.2019.00510] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 02/27/2019] [Indexed: 01/24/2023] Open
Abstract
Rheinheimera sp. strain EpRS3, isolated from the rhizosphere of Echinacea purpurea, is already known for its ability to produce antibacterial compounds. By use of culture experiments, we verified and demonstrated its harmful effect against the ciliated protist Euplotes aediculatus (strain EASCc1), which by FISH experiments resulted to harbor in its cytoplasm the obligate bacterial endosymbiont Polynucleobacter necessarius (Betaproteobacteria) and the secondary endosymbiont "Candidatus Nebulobacter yamunensis" (Gammaproteobacteria). In culture experiments, the number of ciliates treated both with liquid broth bacteria-free (Supernatant treatment) and bacteria plus medium (Tq treatment), decreases with respect to control cells, with complete disappearance of ciliates within 6 h after Tq treatment. Results suggest that Rheinheimera sp. EpRS3 produces and releases in liquid culture one or more bioactive molecules affecting E. aediculatus survival. TEM analysis of control (not treated) ciliates allowed to morphologically characterize both kind of E. aediculatus endosymbionts. In treated ciliates, collected soon after the arising of cell suffering leading to death, TEM observations revealed some ultrastructural damages, indicating that P. necessarius endosymbionts went into degradation and vacuolization after both Supernatant and Tq treatments. Additionally, TEM investigation showed that when the ciliate culture was inoculated with Tq treatment, both a notable decrease of P. necessarius number and an increase of damaged and degraded mitochondria occur. FISH experiments performed on treated ciliates confirmed TEM results and, by means of the specific probe herein designed, disclosed the presence of Rheinheimera sp. EpRS3 both inside phagosomes and free in cytoplasm in ciliates after Tq treatment. This finding suggests a putative ability of Rheinheimera sp. EpRS3 to reintroduce itself in the environment avoiding ciliate digestion.
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Affiliation(s)
| | | | | | - Camilla Fagorzi
- Department of Biology, University of Florence, Florence, Italy
| | - Chiara Bazzocchi
- Department of Veterinary Medicine, University of Milan, Milan, Italy
| | - Renato Fani
- Department of Biology, University of Florence, Florence, Italy
| | | | - Letizia Modeo
- Department of Biology, University of Pisa, Pisa, Italy
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14
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Boscaro V, Fokin SI, Petroni G, Verni F, Keeling PJ, Vannini C. Symbiont replacement between bacteria of different classes reveals additional layers of complexity in the evolution of symbiosis in the ciliate Euplotes. Protist 2017; 169:43-52. [PMID: 29414319 DOI: 10.1016/j.protis.2017.12.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 12/08/2017] [Accepted: 12/12/2017] [Indexed: 11/25/2022]
Abstract
Symbiosis is a diverse and complex phenomenon requiring diverse model systems. The obligate relationship between a monophyletic group of Euplotes species ("clade B") and the betaproteobacteria Polynucleobacter and "Candidatus Protistobacter" is among the best-studied in ciliates, and provides a framework to investigate symbiont replacements. Several other Euplotes-bacteria relationships exist but are less understood, such as the co-dependent symbiosis between Euplotes magnicirratus (which belongs to "clade A") and the alphaproteobacterium "Candidatus Devosia euplotis". Here we describe a new Devosia inhabiting the cytoplasm of a strain of Euplotes harpa, a clade B species that usually depends on Polynucleobacter for survival. The novel bacterial species, "Candidatus Devosia symbiotica", is closely related to the symbiont of E. magnicirratus, casting a different light on the history of bacteria colonizing ciliates of this genus. The two Devosia species may have become symbionts independently or as the result of a symbiont exchange between hosts, in either case replacing a previous essential bacterium in E. harpa. Alternatively, both may be remnants of an ancient symbiotic relationship between Euplotes and Devosia, in which case Polynucleobacter and "Ca. Protistobacter" are recent invaders. Either way, symbiont replacement between bacteria belonging to different classes must be evoked to explain this fascinating system.
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Affiliation(s)
- Vittorio Boscaro
- University of Pisa, Department of Biology, Italy; University of British Columbia, Department of Botany, Canada
| | - Sergei I Fokin
- University of Pisa, Department of Biology, Italy; St.-Petersburg State University, Department of Invertebrate Zoology, Russia
| | | | - Franco Verni
- University of Pisa, Department of Biology, Italy
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15
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Galeotti M, Manzano M, Beraldo P, Bulfon C, Rossi G, Volpatti D, Magi GE. Ultrastructural and biomolecular detection of Rickettsiales-like organisms in tissues of rainbow trout with Red Mark Syndrome. JOURNAL OF FISH DISEASES 2017; 40:907-917. [PMID: 27882570 DOI: 10.1111/jfd.12571] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 09/21/2016] [Accepted: 09/22/2016] [Indexed: 06/06/2023]
Abstract
Red mark syndrome (RMS) and US strawberry disease (US SD) are skin disorders affecting rainbow trout farmed in Europe and USA. The disease etiology has not yet been established. In spite of specific investigations, identifying Rickettsia-like organism (RLO)- and Midichloria-like organism (MLO)-related DNA in affected individuals, these pathogens have never been observed. We performed histological, ultrastructural and biomolecular analysis on skin and spleen samples of trout with RMS. Examination by TEM revealed the presence of intracytoplasmic microorganisms resembling Rickettsiales within macrophages, fibroblasts and erythrocytes. The microorganisms were oval or short rod shaped (400-800 nm in length and 100-200 nm in width) and often showed a cell wall similar to Gram-negative bacteria. PCR analysis for Rickettsiales supported these findings: 53% of affected trout were positive by both PCR and TEM The primers RiFCfw-RiFCrev were used to anneal both the RLO 16S DNA sequence and the MLO 16S DNA sequence. For this reason, and in agreement with previous studies confirming the presence of Rickettsiales-related DNA in trout with RMS, we assume that TEM detected microorganisms morphologically consistent with bacteria belonging to Rickettsiales order and could be considered as possible causative agents of RMS.
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Affiliation(s)
- M Galeotti
- Department of Agricultural, Food, Environmental and Animal Science, Veterinary Pathology Section and Microbiology Section, University of Udine, Udine, Italy
| | - M Manzano
- Department of Agricultural, Food, Environmental and Animal Science, Veterinary Pathology Section and Microbiology Section, University of Udine, Udine, Italy
| | - P Beraldo
- Department of Agricultural, Food, Environmental and Animal Science, Veterinary Pathology Section and Microbiology Section, University of Udine, Udine, Italy
| | - C Bulfon
- Department of Agricultural, Food, Environmental and Animal Science, Veterinary Pathology Section and Microbiology Section, University of Udine, Udine, Italy
| | - G Rossi
- School of Biosciences and Veterinary Medicine, University of Camerino, Matelica, Italy
| | - D Volpatti
- Department of Agricultural, Food, Environmental and Animal Science, Veterinary Pathology Section and Microbiology Section, University of Udine, Udine, Italy
| | - G E Magi
- School of Biosciences and Veterinary Medicine, University of Camerino, Matelica, Italy
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16
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Mukhacheva TA, Kovalev SY. Bacteria of the Family 'Candidatus Midichloriaceae' in Sympatric Zones of Ixodes Ticks: Genetic Evidence for Vertical Transmission. MICROBIAL ECOLOGY 2017; 74:185-193. [PMID: 28091705 DOI: 10.1007/s00248-017-0932-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 01/04/2017] [Indexed: 06/06/2023]
Abstract
Ixodes ticks transmit infectious agents and also harbor their own parasites and symbionts. The presumptive endosymbiont of Ixodes ricinus, 'Candidatus Midichloria mitochondrii', has a unique ability to invade mitochondria within tick ovarian cells and is transovarially transmitted with 100% efficiency. A closely related bacterium, provisionally named Montezuma (now 'Candidatus Lariskella arthropodarum'), was isolated from the Ixodes persulcatus ticks and human blood in 2004 as well as from Ixodes pavlovskyi in 2015. These microorganisms belong to the family 'Candidatus Midichloriaceae fam. nov.' and were detected not only in tick salivary glands, but also in animal blood. Nevertheless, the relative importance of vertical and horizontal routes for their transmission or maintenance in natural tick populations remains unclear. We analyzed the prevalence of L. arthropodarum and M. mitochondrii in two sympatric zones, where I. persulcatus/I. ricinus and I. persulcatus/I. pavlovskyi cohabit and produce interspecific hybrids. A specificity of the associations of L. arthropodarum with I. persulcatus (100%) and M. mitochondrii with I. ricinus (96.2%) was observed in the sympatric zone in Estonia, possibly showing poor contribution of the horizontal route to the overall prevalence of endosymbionts. L. arthropodarum was observed probably multiplying in I. pavlovskyi and also subjected to transovarial transmission, but much less efficiently compared to I. persulcatus. We revealed two new genetic variants of the rrl-rrf intergenic spacer of L. arthropodarum isolated from I. pavlovskyi ticks that possibly could indicate an ongoing process of adaptation of the microorganism to a new host species.
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Affiliation(s)
- Tatyana A Mukhacheva
- Laboratory of Molecular Genetics, Department of Biology, Ural Federal University, Lenin Avenue 51, Yekaterinburg, 620000, Russia
| | - Sergey Y Kovalev
- Laboratory of Molecular Genetics, Department of Biology, Ural Federal University, Lenin Avenue 51, Yekaterinburg, 620000, Russia.
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17
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Zaila KE, Doak TG, Ellerbrock H, Tung CH, Martins ML, Kolbin D, Yao MC, Cassidy-Hanley DM, Clark TG, Chang WJ. Diversity and Universality of Endosymbiotic Rickettsia in the Fish Parasite Ichthyophthirius multifiliis. Front Microbiol 2017; 8:189. [PMID: 28232825 PMCID: PMC5299013 DOI: 10.3389/fmicb.2017.00189] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 01/25/2017] [Indexed: 01/04/2023] Open
Abstract
Although the presence of endosymbiotic rickettsial bacteria, specifically Candidatus Megaira, has been reported in diverse habitats and a wide range of eukaryotic hosts, it remains unclear how broadly Ca. Megaira are distributed in a single host species. In this study we seek to address whether Ca. Megaira are present in most, if not all isolates, of the parasitic ciliate Ichthyophthirius multifiliis. Conserved regions of bacterial 16S rRNA genes were either PCR amplified, or assembled from deep sequencing data, from 18 isolates/populations of I. multifiliis sampled worldwide (Brazil, Taiwan, and USA). We found that rickettsial rRNA sequences belonging to three out of four Ca. Megaira subclades could be consistently detected in all I. multifiliis samples. I. multifiliis collected from local fish farms tend to be inhabited by the same subclade of Ca. Megaira, whereas those derived from pet fish are often inhabited by more than one subclade of Ca. Megaira. Distributions of Ca. Megaira in I. multifiliis thus better reflect the travel history, but not the phylogeny, of I. multifiliis. In summary, our results suggest that I. multifiliis may be dependent on this endosymbiotic relationship, and the association between Ca. Megaira and I. multifiliis is more diverse than previously thought.
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Affiliation(s)
| | - Thomas G. Doak
- Department of Biology, Indiana University, BloomingtonIN, USA
- National Center for Genome Analysis Support, Indiana University, BloomingtonIN, USA
| | | | - Che-Huang Tung
- Department of Aquatic Biosciences, National Chyai UniversityChyai City, Taiwan
| | - Mauricio L. Martins
- Departamento de Aquicultura, Centro de Ciências Agrárias, Universidade Federal de Santa CatarinaFlorianópolis, Brazil
| | - Daniel Kolbin
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, IthacaNY, USA
| | - Meng-Chao Yao
- Institute of Molecular Biology, Academia SinicaTaipei, Taiwan
| | - Donna M. Cassidy-Hanley
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, IthacaNY, USA
| | - Theodore G. Clark
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, IthacaNY, USA
| | - Wei-Jen Chang
- Department of Biology, Hamilton College, ClintonNY, USA
- Institute of Molecular Biology, Academia SinicaTaipei, Taiwan
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18
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Disentangling the Taxonomy of Rickettsiales and Description of Two Novel Symbionts ("Candidatus Bealeia paramacronuclearis" and "Candidatus Fokinia cryptica") Sharing the Cytoplasm of the Ciliate Protist Paramecium biaurelia. Appl Environ Microbiol 2016; 82:7236-7247. [PMID: 27742680 PMCID: PMC5118934 DOI: 10.1128/aem.02284-16] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/06/2016] [Indexed: 11/20/2022] Open
Abstract
In the past 10 years, the number of endosymbionts described within the bacterial order Rickettsiales has constantly grown. Since 2006, 18 novel Rickettsiales genera inhabiting protists, such as ciliates and amoebae, have been described. In this work, we characterize two novel bacterial endosymbionts from Paramecium collected near Bloomington, IN. Both endosymbiotic species inhabit the cytoplasm of the same host. The Gram-negative bacterium “Candidatus Bealeia paramacronuclearis” occurs in clumps and is frequently associated with the host macronucleus. With its electron-dense cytoplasm and a distinct halo surrounding the cell, it is easily distinguishable from the second smaller symbiont, “Candidatus Fokinia cryptica,” whose cytoplasm is electron lucid, lacks a halo, and is always surrounded by a symbiontophorous vacuole. For molecular characterization, the small-subunit rRNA genes were sequenced and used for taxonomic assignment as well as the design of species-specific oligonucleotide probes. Phylogenetic analyses revealed that “Candidatus Bealeia paramacronuclearis” clusters with the so-called “basal” Rickettsiales, and “Candidatus Fokinia cryptica” belongs to “Candidatus Midichloriaceae.” We obtained tree topologies showing a separation of Rickettsiales into at least two groups: one represented by the families Rickettsiaceae, Anaplasmataceae, and “Candidatus Midichloriaceae” (RAM clade), and the other represented by “basal Rickettsiales,” including “Candidatus Bealeia paramacronuclearis.” Therefore, and in accordance with recent publications, we propose to limit the order Rickettsiales to the RAM clade and to raise “basal Rickettsiales” to an independent order, Holosporales ord. nov., inside Alphaproteobacteria, which presently includes four family-level clades. Additionally, we define the family “Candidatus Hepatincolaceae” and redefine the family Holosporaceae. IMPORTANCE In this paper, we provide the characterization of two novel bacterial symbionts inhabiting the same Paramecium host (Ciliophora, Alveolata). Both symbionts belong to “traditional” Rickettsiales, one representing a new species of the genus “Candidatus Fokinia” (“Candidatus Midichloriaceae”), and the other representing a new genus of a “basal” Rickettsiales. According to newly characterized sequences and to a critical revision of recent literature, we propose a taxonomic reorganization of “traditional” Rickettsiales that we split into two orders: Rickettsiales sensu stricto and Holosporales ord. nov. This work represents a critical revision, including new records of a group of symbionts frequently occurring in protists and whose biodiversity is still largely underestimated.
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19
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Serra V, Fokin SI, Castelli M, Basuri CK, Nitla V, Verni F, Sandeep BV, Kalavati C, Petroni G. " Candidatus Gortzia shahrazadis", a Novel Endosymbiont of Paramecium multimicronucleatum and a Revision of the Biogeographical Distribution of Holospora-Like Bacteria. Front Microbiol 2016; 7:1704. [PMID: 27867371 PMCID: PMC5095128 DOI: 10.3389/fmicb.2016.01704] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 10/12/2016] [Indexed: 11/13/2022] Open
Abstract
Holospora spp. and "Candidatus Gortzia infectiva", known as Holospora-like bacteria (HLB), are commonly found as nuclear endosymbionts of ciliates, especially the Paramecium genus. HLB are related by phylogenetic relationships, morphological features, and life-cycles, which involve two alternating morphotypes: reproductive and infectious forms (RF, IF). In this paper we describe a novel species belonging to the "Ca. Gortzia" genus, detected in P. multimicronucleatum, a ciliate for which infection by an HLB has not been reported, discovered in India. This novel endosymbiont shows unusual and surprising features with respect to other HLB, such as large variations in IF morphology and the occasional ability to reproduce in the host cytoplasm. We propose the name of "Candidatus Gortzia shahrazadis" for this novel HLB. Moreover, we report two additional species of HLB from Indian Paramecium populations: "Ca. Gortzia infectiva" (from P. jenningsi), and H. obtusa (from P. caudatum); the latter is the first record of Holospora from a tropical country. Although tropical, we retrieved H. obtusa at an elevation of 706 m corresponding to a moderate climate not unlike conditions where Holospora are normally found, suggesting the genus Holospora does exist in tropical countries, but restricted to higher elevations.
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Affiliation(s)
| | - Sergei I Fokin
- Department of Biology, University of PisaPisa, Italy; Department of Invertebrate Zoology, Saint Petersburg State UniversitySaint Petersburg, Russia
| | - Michele Castelli
- Department of Biology, University of PisaPisa, Italy; Department of Veterinary Medicine, University of MilanMilan, Italy
| | - Charan K Basuri
- Department of Zoology, Andhra University Visakhapatnam, India
| | | | - Franco Verni
- Department of Biology, University of Pisa Pisa, Italy
| | - Bhagavatula V Sandeep
- Department of Zoology, Andhra UniversityVisakhapatnam, India; Department of Biotechnology, Andhra UniversityVisakhapatnam, India
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20
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Cafiso A, Bazzocchi C, De Marco L, Opara MN, Sassera D, Plantard O. Molecular screening for Midichloria in hard and soft ticks reveals variable prevalence levels and bacterial loads in different tick species. Ticks Tick Borne Dis 2016; 7:1186-1192. [PMID: 27521265 DOI: 10.1016/j.ttbdis.2016.07.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/01/2016] [Accepted: 07/31/2016] [Indexed: 11/26/2022]
Abstract
Candidatus Midichloria mitochondrii, symbiont of the sheep tick Ixodes ricinus, was the first described member of the family Candidatus Midichloriaceae, order Rickettsiales. Recent reports are expanding our view of this family, now including numerous bacteria of great biological and medical interest, indicating a widespread distribution with an increasing range of hosts, with ticks being strongly represented. Here we present a molecular screening of 17 tick species, detecting and quantifying bacteria of the family Midichloriaceae in seven of them, including the first report of a representative of this family in a soft tick species (Argasidae), Ornithodoros maritimus. Based on sequence identity and phylogenetic analysis we propose that all these bacterial symbionts of ticks could be members of the genus Midichloria. The performed screening highlights different prevalence levels and variable bacterial loads in different tick species including one, Ixodes aulacodi, where the bacterium is present in all examined individuals, like in I. ricinus. This result prompts us to hypothesize different roles of Midichloria bacteria in different tick species.
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Affiliation(s)
- Alessandra Cafiso
- Department of Veterinary Medicine, University of Milan, Via Celoria 10, 20133 Milan, Italy
| | - Chiara Bazzocchi
- Department of Veterinary Medicine, University of Milan, Via Celoria 10, 20133 Milan, Italy; Joint Research Center for Epidemiology and Molecular Surveillance of Infections, University of Milan, 20133 Milan, Italy
| | - Leone De Marco
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy; School of Bioscience and Veterinary Medicine, University of Camerino, Via Gentile III Da Varano, 62032 Camerino, Italy
| | - Maxwell N Opara
- Department of Parasitology and Entomology, Faculty of Veterinary Medicine, University of Abuja, PMB 117, FCT Nigeria
| | - Davide Sassera
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy.
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21
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Yang A, Narechania A, Kim E. Rickettsial endosymbiont in the "early-diverging" streptophyte green alga Mesostigma viride. JOURNAL OF PHYCOLOGY 2016; 52:219-229. [PMID: 27037587 DOI: 10.1111/jpy.12385] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 11/20/2015] [Indexed: 06/05/2023]
Abstract
A bacterial endosymbiont was unexpectedly found in the "axenic" culture strain of the streptophyte green alga Mesostigma viride (NIES-995). Phylogenetic analyses based on 16S rRNA gene sequences showed that the symbiont belongs to the order Rickettsiales, specifically to the recently designated clade "Candidatus Megaira," which is closely related to the well-known Rickettsia clade. Rickettsiales bacteria of the "Ca. Megaira" clade are found in a taxonomically diverse array of eukaryotic hosts, including chlorophycean green algae, several ciliate species, and invertebrates such as Hydra. Transmission electron microscopy, fluorescence in situ hybridi-zation, and SYBR Green I staining experiments revealed that the endosymbiont of M. viride NIES-995 is rod shaped, typically occurs in clusters, and is surrounded by a halo-like structure, presumably formed by secretory substances from the bacterium. Two additional M. viride strains (NIES-296 and NIES-475), but not SAG50-1, were found to house the rickettsial endosymbiont. Analyses of strain NIES-995 transcriptome data indicated the presence of at least 91 transcriptionally active genes of symbiont origins. These include genes for surface proteins (e.g., rOmpB) that are known to play key roles in bacterial attachment onto host eukaryotes in related Rickettsia species. The assembled M. viride transcriptome includes transcripts that code for a suite of predicted algal-derived proteins, such as Ku70, WASH, SCAR, and CDC42, which may be important in the formation of the algal-rickettsial association.
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Affiliation(s)
- Ashley Yang
- Sackler Institute for Comparative Genomics, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024, USA
| | - Apurva Narechania
- Sackler Institute for Comparative Genomics, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024, USA
| | - Eunsoo Kim
- Sackler Institute for Comparative Genomics, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024, USA
- Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024, USA
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22
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Senra MVX, Dias RJP, Castelli M, Silva-Neto ID, Verni F, Soares CAG, Petroni G. A House for Two--Double Bacterial Infection in Euplotes woodruffi Sq1 (Ciliophora, Euplotia) Sampled in Southeastern Brazil. MICROBIAL ECOLOGY 2016; 71:505-517. [PMID: 26381539 DOI: 10.1007/s00248-015-0668-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 08/28/2015] [Indexed: 06/05/2023]
Abstract
Several ciliated protists form symbiotic associations with a diversity of microorganisms, leading to drastic impact on their ecology and evolution. In this work, two Euplotes spp. sampled in Rio de Janeiro, Brazil, were identified based on morphological and molecular features as Euplotes woodruffi strain Sq1 and E. encysticus strain Sq2 and investigated for the presence of endosymbionts. While E. woodruffi Sq1 stably hosts two bacterial populations, namely Polynucleobacter necessarius (Betaproteobacteria) and a new member of the family "Candidatus Midichloriaceae" (Alphaproteobacteria, Rickettsiales), here described as "Candidatus Bandiella woodruffii," branching with a broad host range bacterial group found in association with cnidarians, sponges, euglenoids, and some arthropods; in E. encysticus Sq2 no symbiotic bacterium could be detected. The dispersion ability of this novel bacterium was tested by co-incubating E. woodruffi Sq1 with three different ciliate species. Among the tested strains "Ca. B. woodruffii" could only be detected in association with E. encysticus Sq2 with a prevalence of 20 % after 1 week and 40 % after 2 weeks, maintaining this level for up to 6 months. Nevertheless, this apparent in vitro association was abolished when E. woodruffi Sq1 donor was removed from the microcosm, suggesting that this bacterium has the capacity for at least a short-term survival outside its natural host and the aptitude to ephemerally interact with other organisms. Together, these findings strongly suggest the need for more detailed investigations to evaluate the host range for "Ca. B. woodruffii" and any possible pathogenic effect of this bacterium on other organisms including humans.
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Affiliation(s)
- Marcus V X Senra
- Departamento de Genética, Universidade Federal do Rio de Janeiro, UFRJ, Av. Carlos Chagas Filho 373 - CCS A2-120, Rio de Janeiro, 21.944-970, Brazil
- Departamento de Zoologia, Universidade Federal de Juiz de Fora, UFJF, Rio de Janeiro, Brazil
| | - Roberto J P Dias
- Departamento de Zoologia, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro, Brazil
- Departamento de Zoologia, Universidade Federal de Juiz de Fora, UFJF, Rio de Janeiro, Brazil
| | - Michele Castelli
- Department of Biology, University of Pisa, via A. Volta 4/6, Pisa, 56126, Italy
| | - Inácio D Silva-Neto
- Departamento de Zoologia, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro, Brazil
| | - Franco Verni
- Department of Biology, University of Pisa, via A. Volta 4/6, Pisa, 56126, Italy
| | - Carlos A G Soares
- Departamento de Genética, Universidade Federal do Rio de Janeiro, UFRJ, Av. Carlos Chagas Filho 373 - CCS A2-120, Rio de Janeiro, 21.944-970, Brazil.
| | - Giulio Petroni
- Department of Biology, University of Pisa, via A. Volta 4/6, Pisa, 56126, Italy.
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23
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Szokoli F, Sabaneyeva E, Castelli M, Krenek S, Schrallhammer M, Soares CAG, da Silva-Neto ID, Berendonk TU, Petroni G. "Candidatus Fokinia solitaria", a Novel "Stand-Alone" Symbiotic Lineage of Midichloriaceae (Rickettsiales). PLoS One 2016; 11:e0145743. [PMID: 26731731 PMCID: PMC4701390 DOI: 10.1371/journal.pone.0145743] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/08/2015] [Indexed: 12/26/2022] Open
Abstract
Recently, the family Midichloriaceae has been described within the bacterial order Rickettsiales. It includes a variety of bacterial endosymbionts detected in different metazoan host species belonging to Placozoa, Cnidaria, Arthropoda and Vertebrata. Representatives of Midichloriaceae are also considered possible etiological agents of certain animal diseases. Midichloriaceae have been found also in protists like ciliates and amoebae. The present work describes a new bacterial endosymbiont, "Candidatus Fokinia solitaria", retrieved from three different strains of a novel Paramecium species isolated from a wastewater treatment plant in Rio de Janeiro (Brazil). Symbionts were characterized through the full-cycle rRNA approach: SSU rRNA gene sequencing and fluorescence in situ hybridization (FISH) with three species-specific oligonucleotide probes. In electron micrographs, the tiny rod-shaped endosymbionts (1.2 x 0.25-0.35 μm in size) were not surrounded by a symbiontophorous vacuole and were located in the peripheral host cytoplasm, stratified in the host cortex in between the trichocysts or just below them. Frequently, they occurred inside autolysosomes. Phylogenetic analyses of Midichloriaceae apparently show different evolutionary pathways within the family. Some genera, such as "Ca. Midichloria" and "Ca. Lariskella", have been retrieved frequently and independently in different hosts and environmental surveys. On the contrary, others, such as Lyticum, "Ca. Anadelfobacter", "Ca. Defluviella" and the presently described "Ca. Fokinia solitaria", have been found only occasionally and associated to specific host species. These last are the only representatives in their own branches thus far. Present data do not allow to infer whether these genera, which we named "stand-alone lineages", are an indication of poorly sampled organisms, thus underrepresented in GenBank, or represent fast evolving, highly adapted evolutionary lineages.
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Affiliation(s)
- Franziska Szokoli
- Institut für Hydrobiologie, Technische Universität Dresden, Dresden, Germany
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
| | - Elena Sabaneyeva
- Department of Cytology and Histology, St. Petersburg State University, St. Petersburg, Russia
| | | | - Sascha Krenek
- Institut für Hydrobiologie, Technische Universität Dresden, Dresden, Germany
| | - Martina Schrallhammer
- Mikrobiologie, Biologisches Institut II, Albert-Ludwigs Universität Freiburg, Freiburg, Germany
| | - Carlos A. G. Soares
- Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Thomas U. Berendonk
- Institut für Hydrobiologie, Technische Universität Dresden, Dresden, Germany
| | - Giulio Petroni
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
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"Candidatus Finniella" (Rickettsiales, Alphaproteobacteria), Novel Endosymbionts of Viridiraptorid Amoeboflagellates (Cercozoa, Rhizaria). Appl Environ Microbiol 2015; 82:659-70. [PMID: 26567303 DOI: 10.1128/aem.02680-15] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 11/08/2015] [Indexed: 11/20/2022] Open
Abstract
The Rickettsiales (Alphaproteobacteria) are obligate intracellular bacteria that colonize a wide range of eukaryotic hosts, including diverse metazoa and protists. Here, we characterize rickettsial endosymbionts discovered in the cytoplasm of the algivorous amoeboflagellates Viridiraptor invadens and Orciraptor agilis (Viridiraptoridae, Cercozoa, Rhizaria), supplying evidence of free-living, phagotrophic members of the Cercozoa serving as hosts for Rickettsiales. According to 16S rRNA gene phylogenies, the bacteria represent two closely related but distinct genotypes within a deep-branching rickettsial clade, which contains the genera "Candidatus Odyssella," "Candidatus Paracaedibacter," and "Candidatus Captivus." Using the full-cycle rRNA approach, we detected the novel bacteria in four of nine viridiraptorid strains tested. Furthermore, two specific oligonucleotide probes with a single-nucleotide-difference discriminated both bacterial genotypes by fluorescence in situ hybridization (FISH). We establish the candidate species "Candidatus Finniella inopinata" (found in Viridiraptor invadens) and "Candidatus Finniella lucida" (found in Orciraptor agilis) for the novel bacteria and propose a new, provisional family of Rickettsiales, "Candidatus Paracaedibacteraceae."
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25
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Schulz F, Martijn J, Wascher F, Lagkouvardos I, Kostanjšek R, Ettema TJG, Horn M. A Rickettsiales symbiont of amoebae with ancient features. Environ Microbiol 2015; 18:2326-42. [PMID: 25908022 DOI: 10.1111/1462-2920.12881] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 03/03/2015] [Accepted: 03/16/2015] [Indexed: 11/28/2022]
Abstract
The Rickettsiae comprise intracellular bacterial symbionts and pathogens infecting diverse eukaryotes. Here, we provide a detailed characterization of 'Candidatus Jidaibacter acanthamoeba', a rickettsial symbiont of Acanthamoeba. The bacterium establishes the infection in its amoeba host within 2 h where it replicates within vacuoles. Higher bacterial loads and accelerated spread of infection at elevated temperatures were observed. The infection had a negative impact on host growth rate, although no increased levels of host cell lysis were seen. Phylogenomic analysis identified this bacterium as member of the Midichloriaceae. Its 2.4 Mb genome represents the largest among Rickettsiales and is characterized by a moderate degree of pseudogenization and a high coding density. We found an unusually large number of genes encoding proteins with eukaryotic-like domains such as ankyrins, leucine-rich repeats and tetratricopeptide repeats, which likely function in host interaction. There are a total of three divergent, independently acquired type IV secretion systems, and 35 flagellar genes representing the most complete set found in an obligate intracellular Alphaproteobacterium. The deeply branching phylogenetic position of 'Candidatus Jidaibacter acanthamoeba' together with its ancient features place it closely to the rickettsial ancestor and helps to better understand the transition from a free-living to an intracellular lifestyle.
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Affiliation(s)
- Frederik Schulz
- Department of Microbiology and Ecosystem Science, University of Vienna, Althanstraße 14, Vienna, Austria
| | - Joran Martijn
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Husargatan 3, Uppsala, Sweden
| | - Florian Wascher
- Department of Microbiology and Ecosystem Science, University of Vienna, Althanstraße 14, Vienna, Austria
| | - Ilias Lagkouvardos
- Department of Microbiology and Ecosystem Science, University of Vienna, Althanstraße 14, Vienna, Austria
| | - Rok Kostanjšek
- Department of Biology, University of Ljubljana, Večna pot 111, Ljubljana, Slovenia
| | - Thijs J G Ettema
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Husargatan 3, Uppsala, Sweden
| | - Matthias Horn
- Department of Microbiology and Ecosystem Science, University of Vienna, Althanstraße 14, Vienna, Austria
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Complete Genome Sequence of the Endosymbiont of Acanthamoeba Strain UWC8, an Amoeba Endosymbiont Belonging to the "Candidatus Midichloriaceae" Family in Rickettsiales. GENOME ANNOUNCEMENTS 2014; 2:2/4/e00791-14. [PMID: 25103769 PMCID: PMC4125780 DOI: 10.1128/genomea.00791-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The endosymbiont of Acanthamoeba strain UWC8 is an obligate amoeba endosymbiont belonging to the family of “Candidatus Midichloriaceae” in Rickettsiales. We report here the complete genome sequence of this bacterium, which should catalyze future studies of amoeba-symbiont interactions.
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Flagellar movement in two bacteria of the family rickettsiaceae: a re-evaluation of motility in an evolutionary perspective. PLoS One 2014; 9:e87718. [PMID: 24505307 PMCID: PMC3914857 DOI: 10.1371/journal.pone.0087718] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 01/02/2014] [Indexed: 01/22/2023] Open
Abstract
Bacteria of the family Rickettsiaceae have always been largely studied not only for their importance in the medical field, but also as model systems in evolutionary biology. In fact, they share a recent common ancestor with mitochondria. The most studied species, belonging to genera Rickettsia and Orientia, are hosted by terrestrial arthropods and include many human pathogens. Nevertheless, recent findings show that a large part of Rickettsiaceae biodiversity actually resides outside the group of well-known pathogenic bacteria. Collecting data on these recently described non-conventional members of the family is crucial in order to gain information on ancestral features of the whole group. Although bacteria of the family Rickettsiaceae, and of the whole order Rickettsiales, are formally described as non-flagellated prokaryotes, some recent findings renewed the debate about this feature. In this paper we report the first finding of members of the family displaying numerous flagella and active movement inside their host cells. These two new taxa are hosted in aquatic environments by protist ciliates and are described here by means of ultrastructural and molecular characterization. Data here reported suggest that the ancestor of Rickettsiales displayed flagellar movement and re-evaluate the hypothesis that motility played a key-role in the origin of mitochondria. Moreover, our study highlights that the aquatic environment represents a well exploited habitat for bacteria of the family Rickettsiaceae. Our results encourage a deep re-consideration of ecological and morphological traits of the family and of the whole order.
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Boscaro V, Schrallhammer M, Benken KA, Krenek S, Szokoli F, Berendonk TU, Schweikert M, Verni F, Sabaneyeva EV, Petroni G. Rediscovering the genus Lyticum, multiflagellated symbionts of the order Rickettsiales. Sci Rep 2013; 3:3305. [PMID: 24264310 PMCID: PMC3837311 DOI: 10.1038/srep03305] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 10/21/2013] [Indexed: 11/09/2022] Open
Abstract
Among the bacterial symbionts harbored by the model organism Paramecium, many still lack a recent investigation that includes a molecular characterization. The genus Lyticum consists of two species of large-sized bacteria displaying numerous flagella, despite their inability to move inside their hosts' cytoplasm. We present a multidisciplinary redescription of both species, using the deposited type strains as well as newly collected material. On the basis of 16S rRNA gene sequences, we assigned Lyticum to the order Rickettsiales, that is intensely studied because of its pathogenic representatives and its position as the extant group most closely related to the mitochondrial ancestor. We provide conclusive proofs that at least some Rickettsiales possess actual flagella, a feature that has been recently predicted from genomic data but never confirmed. We give support to the hypothesis that the mitochondrial ancestor could have been flagellated, and provide the basis for further studies on these ciliate endosymbionts.
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29
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Gong J, Qing Y, Guo X, Warren A. "Candidatus Sonnebornia yantaiensis", a member of candidate division OD1, as intracellular bacteria of the ciliated protist Paramecium bursaria (Ciliophora, Oligohymenophorea). Syst Appl Microbiol 2013; 37:35-41. [PMID: 24231291 DOI: 10.1016/j.syapm.2013.08.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Revised: 08/29/2013] [Accepted: 08/30/2013] [Indexed: 10/26/2022]
Abstract
An intracellular bacterium was discovered in an isolate of Paramecium bursaria from a freshwater pond in Yantai, China. The bacteria were abundant and exclusively found in the cytoplasm of the host which, along with the green alga Chlorella, formed a three-partner consortium that could survive in pure water for at least one week. Cloning, sequencing and phylogenetic analysis of the bacterial 16S rRNA gene showed that the bacterium belonged to the uncultured candidate division OD1, which usually forms part of the rare biosphere. Transmission electron microscopy and fluorescence in situ hybridization (FISH) with specific probes showed that the bacteria were usually located close to the perialgal membranes of endosymbiotic Chlorella cells, and occasionally irregularly distributed throughout the host cytoplasm. The name "Candidatus Sonnebornia yantaiensis" gen. nov., sp. nov. is proposed for the new bacterium. A strongly supported monophyletic subclade, OD1-p, which included the new species, was recognized and this study highlights that protists can be important hosts for rare bacterial taxa.
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Affiliation(s)
- Jun Gong
- Microbial Ecology Group, Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China; College of Life Sciences, South China Normal University, Guangzhou 510631, China.
| | - Yao Qing
- Microbial Ecology Group, Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China; College of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Xiaohong Guo
- Microbial Ecology Group, Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Alan Warren
- Department of Life Sciences, Natural History Museum, London SW7 5BD, United Kingdom
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30
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Driscoll T, Gillespie JJ, Nordberg EK, Azad AF, Sobral BW. Bacterial DNA sifted from the Trichoplax adhaerens (Animalia: Placozoa) genome project reveals a putative rickettsial endosymbiont. Genome Biol Evol 2013; 5:621-45. [PMID: 23475938 PMCID: PMC3641634 DOI: 10.1093/gbe/evt036] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Eukaryotic genome sequencing projects often yield bacterial DNA sequences, data typically considered as microbial contamination. However, these sequences may also indicate either symbiont genes or lateral gene transfer (LGT) to host genomes. These bacterial sequences can provide clues about eukaryote-microbe interactions. Here, we used the genome of the primitive animal Trichoplax adhaerens (Metazoa: Placozoa), which is known to harbor an uncharacterized Gram-negative endosymbiont, to search for the presence of bacterial DNA sequences. Bioinformatic and phylogenomic analyses of extracted data from the genome assembly (181 bacterial coding sequences [CDS]) and trace read archive (16S rDNA) revealed a dominant proteobacterial profile strongly skewed to Rickettsiales (Alphaproteobacteria) genomes. By way of phylogenetic analysis of 16S rDNA and 113 proteins conserved across proteobacterial genomes, as well as identification of 27 rickettsial signature genes, we propose a Rickettsiales endosymbiont of T. adhaerens (RETA). The majority (93%) of the identified bacterial CDS belongs to small scaffolds containing prokaryotic-like genes; however, 12 CDS were identified on large scaffolds comprised of eukaryotic-like genes, suggesting that T. adhaerens might have recently acquired bacterial genes. These putative LGTs may coincide with the placozoan's aquatic niche and symbiosis with RETA. This work underscores the rich, and relatively untapped, resource of eukaryotic genome projects for harboring data pertinent to host-microbial interactions. The nature of unknown (or poorly characterized) bacterial species may only emerge via analysis of host genome sequencing projects, particularly if these species are resistant to cell culturing, as are many obligate intracellular microbes. Our work provides methodological insight for such an approach.
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Affiliation(s)
- Timothy Driscoll
- Virginia Bioinformatics Institute at Virginia Polytechnic Institute and State University, USA
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31
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"Candidatus Midichloriaceae" fam. nov. (Rickettsiales), an ecologically widespread clade of intracellular alphaproteobacteria. Appl Environ Microbiol 2013; 79:3241-8. [PMID: 23503305 DOI: 10.1128/aem.03971-12] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
"Candidatus Midichloria mitochondrii" is an intramitochondrial bacterium of the order Rickettsiales associated with the sheep tick Ixodes ricinus. Bacteria phylogenetically related to "Ca. Midichloria mitochondrii" (midichloria and like organisms [MALOs]) have been shown to be associated with a wide range of hosts, from amoebae to a variety of animals, including humans. Despite numerous studies focused on specific members of the MALO group, no comprehensive phylogenetic and statistical analyses have so far been performed on the group as a whole. Here, we present a multidisciplinary investigation based on 16S rRNA gene sequences using both phylogenetic and statistical methods, thereby analyzing MALOs in the overall framework of the Rickettsiales. This study revealed that (i) MALOs form a monophyletic group; (ii) the MALO group is structured into distinct subgroups, verifying current genera as significant evolutionary units and identifying several subclades that could represent novel genera; (iii) the MALO group ranks at the level of described Rickettsiales families, leading to the proposal of the novel family "Candidatus Midichloriaceae." In addition, based on the phylogenetic trees generated, we present an evolutionary scenario to interpret the distribution and life history transitions of these microorganisms associated with highly divergent eukaryotic hosts: we suggest that aquatic/environmental protista have acted as evolutionary reservoirs for members of this novel family, from which one or more lineages with the capacity of infecting metazoa have evolved.
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32
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Boscaro V, Petroni G, Ristori A, Verni F, Vannini C. "Candidatus Defluviella procrastinata" and "Candidatus Cyrtobacter zanobii", two novel ciliate endosymbionts belonging to the "Midichloria clade". MICROBIAL ECOLOGY 2013; 65:302-310. [PMID: 23296446 DOI: 10.1007/s00248-012-0170-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 12/17/2012] [Indexed: 06/01/2023]
Abstract
The "Midichloria clade" is a recently discovered but well-established evolutionary lineage clustering inside the order Rickettsiales (Alphaproteobacteria). Not much is known about the biology of these organisms. The best characterized ones are endocellular symbionts of very different eukaryotic hosts, ranging from arthropods to protists. "Candidatus Midichloria mitochondrii", the most studied organism of the group, is an interesting object of study because of its unique capability to infect metazoans' mitochondria and the presence of flagellar genes in its genome. With this work, we aim at increasing the knowledge on the biodiversity and phylogeny of the "Midichloria group". We characterized according to the "full cycle rRNA approach" two novel endosymbionts of ciliated protozoa, i.e. Paramecium nephridiatum and Euplotes aediculatus. According to the nomenclatural rules for uncultivated prokaryotes, we established the novel taxa "Candidatus Defluviella procrastinata" and "Candidatus Cyrtobacter zanobii" for the two bacterial symbionts. Our phylogenetic analysis based on 16S rRNA gene sequences confirms that the evolutionary histories of "Midichloria clade" representatives and of their hosts are very different. This suggests that the symbiotic processes arose many times independently, perhaps through ways of transmission still not described in Rickettsiales.
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Affiliation(s)
- Vittorio Boscaro
- Biology Department, Protistology-Zoology Unit, University of Pisa, Pisa, Italy
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Boscaro V, Fokin SI, Schrallhammer M, Schweikert M, Petroni G. Revised systematics of Holospora-like bacteria and characterization of "Candidatus Gortzia infectiva", a novel macronuclear symbiont of Paramecium jenningsi. MICROBIAL ECOLOGY 2013; 65:255-267. [PMID: 22940732 DOI: 10.1007/s00248-012-0110-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 08/07/2012] [Indexed: 06/01/2023]
Abstract
The genus Holospora (Rickettsiales) includes highly infectious nuclear symbionts of the ciliate Paramecium with unique morphology and life cycle. To date, nine species have been described, but a molecular characterization is lacking for most of them. In this study, we have characterized a novel Holospora-like bacterium (HLB) living in the macronuclei of a Paramecium jenningsi population. This bacterium was morphologically and ultrastructurally investigated in detail, and its life cycle and infection capabilities were described. We also obtained its 16S rRNA gene sequence and developed a specific probe for fluorescence in situ hybridization experiments. A new taxon, "Candidatus Gortzia infectiva", was established for this HLB according to its unique characteristics and the relatively low DNA sequence similarities shared with other bacteria. The phylogeny of the order Rickettsiales based on 16S rRNA gene sequences has been inferred, adding to the available data the sequence of the novel bacterium and those of two Holospora species (Holospora obtusa and Holospora undulata) characterized for the purpose. Our phylogenetic analysis provided molecular support for the monophyly of HLBs and showed a possible pattern of evolution for some of their features. We suggested to classify inside the family Holosporaceae only HLBs, excluding other more distantly related and phenotypically different Paramecium endosymbionts.
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Affiliation(s)
- Vittorio Boscaro
- Biology Department, Protistology-Zoology Unit, University of Pisa, Via A. Volta 4, 56126 Pisa, Italy
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"Candidatus Hepatobacter penaei," an intracellular pathogenic enteric bacterium in the hepatopancreas of the marine shrimp Penaeus vannamei (Crustacea: Decapoda). Appl Environ Microbiol 2012; 79:1407-9. [PMID: 23241970 DOI: 10.1128/aem.02425-12] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacteria that cause necrotizing hepatopancreatitis in Penaeus vannamei adversely affect penaeid shrimp cultured in the western hemisphere. 16S rRNA and gyrase B gene analyses determined the taxonomic position of these bacteria. The name "Candidatus Hepatobacter penaei" is proposed for these pathogenic bacteria, which are members of the Rickettsiales order.
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35
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Williams-Newkirk AJ, Rowe LA, Mixson-Hayden TR, Dasch GA. Presence, genetic variability, and potential significance of "Candidatus Midichloria mitochondrii" in the lone star tick Amblyomma americanum. EXPERIMENTAL & APPLIED ACAROLOGY 2012; 58:291-300. [PMID: 22678102 PMCID: PMC5730336 DOI: 10.1007/s10493-012-9582-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 05/19/2012] [Indexed: 06/01/2023]
Abstract
We used next generation sequencing to detect the bacterium "Candidatus Midichloria mitochondrii" for the first time in lone star ticks (Amblyomma americanum) from the eastern United States. 177 individuals and 11 tick pools from seven sites in four states were tested by pyrosequencing with barcoded 16S rRNA gene eubacterial primers targeting variable regions 5-3. Average infection prevalence was 0.15 across all surveyed populations (range 0-0.29) and only the site with the smallest sample size (n = 5) was negative. Three genotypes differing by 2.6-4.1 % in a 271 bp region of 16S rRNA gene were identified. Two variants co-occurred in sites in North Carolina and New York, but were not observed in the same tick at those sites. The third genotype was found only in Georgia. Phylogenetic analysis of this fragment indicated that the three variants are more closely related to "Candidatus Midichloria mitochondrii" genotypes from other tick species than to each other. This variation suggests that multiple independent introductions occurred in A. americanum which may provide insight into bacterial spread within its ecosystem and parasitism on this tick. Whether the presence of this bacterium affects acquisition or maintenance of other pathogens and symbionts in A. americanum or the survival, biology and evolution of the tick itself is unknown.
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Kuo RC, Lin S. Ectobiotic and endobiotic bacteria associated with Eutreptiella sp. isolated from Long Island Sound. Protist 2012; 164:60-74. [PMID: 23107230 DOI: 10.1016/j.protis.2012.08.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 08/25/2012] [Accepted: 08/26/2012] [Indexed: 02/07/2023]
Abstract
Diversity and functional association of bacteria with Eutreptiella sp. was investigated. 16S rDNA analysis of ectobiotic bacteria revealed various lineages of Alphaproteobacteria and abundant Gammaproteobacteria, specifically Marinobacter. Antibiotic treatment yielded axenic cultures, and experiments based on them indicated that ectobiotic bacteria likely provide vitamin B(12) and other growth-enhancing factors for the alga. Further, DAPI staining and transmission electron microscopy revealed endobiotic bacteria in the cytoplasm of algal cells. 16S rDNA analysis showed that the bacteria belonged to one species that was most closely related to Rickettsiales endosymbionts of other organisms and phylogenetically affiliated with a new group of aquatic Rickettsiales. Observations from a diel experiment indicated that the endobiotic bacteria reproduced asynchronously with Eutreptiella sp. and had no adverse effects on lipid production (bioenergetics) or growth of the host alga. Our study reveals a diverse microbiome associated with this euglenoid alga, offering a system for studying the roles of algae-bacteria associations.
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Affiliation(s)
- Rita C Kuo
- Department of Marine Sciences, University of Connecticut, Groton, CT 06340, USA
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37
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Boscaro V, Vannini C, Fokin SI, Verni F, Petroni G. Characterization of “Candidatus Nebulobacter yamunensis” from the cytoplasm of Euplotes aediculatus (Ciliophora, Spirotrichea) and emended description of the family Francisellaceae. Syst Appl Microbiol 2012; 35:432-40. [DOI: 10.1016/j.syapm.2012.07.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 07/02/2012] [Accepted: 07/26/2012] [Indexed: 12/31/2022]
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38
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Dziallas C, Allgaier M, Monaghan MT, Grossart HP. Act together-implications of symbioses in aquatic ciliates. Front Microbiol 2012; 3:288. [PMID: 22891065 PMCID: PMC3413206 DOI: 10.3389/fmicb.2012.00288] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/22/2012] [Indexed: 02/01/2023] Open
Abstract
Mutual interactions in the form of symbioses can increase the fitness of organisms and provide them with the capacity to occupy new ecological niches. The formation of obligate symbioses allows for rapid evolution of new life forms including multitrophic consortia. Microbes are important components of many known endosymbioses and their short generation times and strong potential for genetic exchange may be important drivers of speciation. Hosts provide endo- and ectosymbionts with stable, nutrient-rich environments, and protection from grazers. This is of particular importance in aquatic ecosystems, which are often highly variable, harsh, and nutrient-deficient habitats. It is therefore not surprising that symbioses are widespread in both marine and freshwater environments. Symbioses in aquatic ciliates are good model systems for exploring symbiont-host interactions. Many ciliate species are globally distributed and have been intensively studied in the context of plastid evolution. Their relatively large cell size offers an ideal habitat for numerous microorganisms with different functional traits including commensalism and parasitism. Phagocytosis facilitates the formation of symbiotic relationships, particularly since some ingested microorganisms can escape the digestion. For example, photoautotrophic algae and methanogens represent endosymbionts that greatly extend the biogeochemical functions of their hosts. Consequently, symbiotic relationships between protists and prokaryotes are widespread and often result in new ecological functions of the symbiotic communities. This enables ciliates to thrive under a wide range of environmental conditions including ultraoligotrophic or anoxic habitats. We summarize the current understanding of this exciting research topic to identify the many areas in which knowledge is lacking and to stimulate future research by providing an overview on new methodologies and by formulating a number of emerging questions in this field.
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Affiliation(s)
- Claudia Dziallas
- Marine Biological Section, University of CopenhagenHelsingør, Denmark
| | - Martin Allgaier
- Department of Limnology of Stratified Lakes, Leibniz-Institute of Freshwater Ecology and Inland FisheriesStechlin, Germany
- Berlin Center for Genomics in Biodiversity ResearchBerlin, Germany
| | - Michael T. Monaghan
- Department of Limnology of Shallow Lakes and Lowland Rivers, Leibniz-Institute of Freshwater Ecology and Inland FisheriesBerlin, Germany
| | - Hans-Peter Grossart
- Department of Limnology of Stratified Lakes, Leibniz-Institute of Freshwater Ecology and Inland FisheriesStechlin, Germany
- Institute for Biochemistry and Biology, Potsdam UniversityPotsdam, Germany
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Fokin SI. Frequency and biodiversity of symbionts in representatives of the main classes of Ciliophora. Eur J Protistol 2012; 48:138-48. [DOI: 10.1016/j.ejop.2011.12.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 12/15/2011] [Accepted: 12/16/2011] [Indexed: 10/28/2022]
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40
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Vannini C, Ferrantini F, Ristori A, Verni F, Petroni G. Betaproteobacterial symbionts of the ciliate Euplotes: origin and tangled evolutionary path of an obligate microbial association. Environ Microbiol 2012; 14:2553-63. [PMID: 22533449 DOI: 10.1111/j.1462-2920.2012.02760.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The Polynucleobacter-Euplotes association is an obligatory symbiotic system between a monophyletic group of ciliate species belonging to the genus Euplotes and bacteria of the species Polynucleobacter necessarius (Betaproteobacteria). Both organisms are unable to survive independently. Several studies revealed the existence of free-living populations of Polynucleobacter bacteria which are phylogenetically closely related to the endosymbiotic ones, but never share associations with Euplotes in the natural environment. Hence, following the most parsimonious explanation on the origin of the association, this symbiosis should represent a synapomorphic character for the hosts' clade. Nevertheless, phylogenetic analyses performed on an increased number of strains here presented suggest that Euplotes species, during their evolution, recruited Polynucleobacter bacteria as symbionts more than once. Moreover, in three cases, we observed different bacteria as obligate symbionts. These symbionts are the first characterized representatives of a phylogenetic lineage branching in a basal position with respect to the genus Polynucleobacter. The hypothesis that the original obligate symbionts belonged to this newly discovered clade and that, only subsequently, in most cases they have been replaced by Polynucleobacter bacteria recruited from the environment is proposed and discussed. The evolutionary path of this association seems anyway to have been more complex than so far supposed.
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Sassera D, Lo N, Epis S, D'Auria G, Montagna M, Comandatore F, Horner D, Peretó J, Luciano AM, Franciosi F, Ferri E, Crotti E, Bazzocchi C, Daffonchio D, Sacchi L, Moya A, Latorre A, Bandi C. Phylogenomic evidence for the presence of a flagellum and cbb(3) oxidase in the free-living mitochondrial ancestor. Mol Biol Evol 2011; 28:3285-96. [PMID: 21690562 DOI: 10.1093/molbev/msr159] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The initiation of the intracellular symbiosis that would give rise to mitochondria and eukaryotes was a major event in the history of life on earth. Hypotheses to explain eukaryogenesis fall into two broad and competing categories: those proposing that the host was a phagocytotic proto-eukaryote that preyed upon the free-living mitochondrial ancestor (hereafter FMA), and those proposing that the host was an archaebacterium that engaged in syntrophy with the FMA. Of key importance to these hypotheses are whether the FMA was motile or nonmotile, and the atmospheric conditions under which the FMA thrived. Reconstructions of the FMA based on genome content of Rickettsiales representatives-generally considered to be the closest living relatives of mitochondria-indicate that it was nonmotile and aerobic. We have sequenced the genome of Candidatus Midichloria mitochondrii, a novel and phylogenetically divergent member of the Rickettsiales. We found that it possesses unique gene sets found in no other Rickettsiales, including 26 genes associated with flagellar assembly, and a cbb(3)-type cytochrome oxidase. Phylogenomic analyses show that these genes were inherited in a vertical fashion from an ancestral α-proteobacterium, and indicate that the FMA possessed a flagellum, and could undergo oxidative phosphorylation under both aerobic and microoxic conditions. These results indicate that the FMA played a more active and potentially parasitic role in eukaryogenesis than currently appreciated and provide an explanation for how the symbiosis could have evolved under low levels of oxygen.
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Affiliation(s)
- Davide Sassera
- Dipartimento di Patologia Animale, Igiene e Sanità Pubblica Veterinaria, Università degli Studi di Milano, Milano, Italy
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Schrallhammer M, Schweikert M, Vallesi A, Verni F, Petroni G. Detection of a novel subspecies of Francisella noatunensis as endosymbiont of the ciliate Euplotes raikovi. MICROBIAL ECOLOGY 2011; 61:455-464. [PMID: 21110016 DOI: 10.1007/s00248-010-9772-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 11/04/2010] [Indexed: 05/30/2023]
Abstract
Francisella are facultative intracellular bacteria causing severe disease in a broad range of animals. Two species are notable: Francisella tularensis, the causative organism of tularemia and a putative warfare agent, and Francisella noatunensis, an emerging fish pathogen causing significant losses in wild and farmed fish. Although various aspects of Francisella biology have been intensively studied, their natural reservoir in periods between massive outbreaks remains mysterious. Protists have been suspected to serve as a disguised vector of Francisella and co-culturing attempts demonstrate that some species are able to survive and multiply within protozoan cells. Here, we report the first finding of a natural occurrence of Francisella sp. as a protist endosymbiont. By molecular and morphological approaches, we identified intracellular bacteria localized in a strain of the marine ciliate Euplotes raikovi, isolated from the coast of Adriatic Sea. Phylogenetic analysis placed these endosymbionts within the genus Francisella, in close but distinct association with F. noatunensis. We suggest the establishment of a novel subspecies within F. noatunensis and propose the cytoplasmatic endosymbiont of E. raikovi as "Candidatus F. noatunensis subsp. endociliophora" subsp. nov.
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Affiliation(s)
- Martina Schrallhammer
- Dipartimento di Biologia, Università di Pisa, Via A Volta 4/6, IT-56126 Pisa, Italy.
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