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Zhang B, Xiao L, Lyu L, Zhao F, Miao M. Exploring the landscape of symbiotic diversity and distribution in unicellular ciliated protists. MICROBIOME 2024; 12:96. [PMID: 38790063 PMCID: PMC11127453 DOI: 10.1186/s40168-024-01809-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 04/04/2024] [Indexed: 05/26/2024]
Abstract
BACKGROUND The eukaryotic-bacterial symbiotic system plays an important role in various physiological, developmental, and evolutionary processes. However, our current understanding is largely limited to multicellular eukaryotes without adequate consideration of diverse unicellular protists, including ciliates. RESULTS To investigate the bacterial profiles associated with unicellular organisms, we collected 246 ciliate samples spanning the entire Ciliophora phylum and conducted single-cell based metagenome sequencing. This effort has yielded the most extensive collection of bacteria linked to unicellular protists to date. From this dataset, we identified 883 bacterial species capable of cohabiting with ciliates, unveiling the genomes of 116 novel bacterial cohabitants along with 7 novel archaeal cohabitants. Highlighting the intimate relationship between ciliates and their cohabitants, our study unveiled that over 90% of ciliates coexist with bacteria, with individual hosts fostering symbiotic relationships with multiple bacteria concurrently, resulting in the observation of seven distinct symbiotic patterns among bacteria. Our exploration of symbiotic mechanisms revealed the impact of host digestion on the intracellular diversity of cohabitants. Additionally, we identified the presence of eukaryotic-like proteins in bacteria as a potential contributing factor to their resistance against host digestion, thereby expanding their potential host range. CONCLUSIONS As the first large-scale analysis of prokaryotic associations with ciliate protists, this study provides a valuable resource for future research on eukaryotic-bacterial symbioses. Video Abstract.
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Affiliation(s)
- Bing Zhang
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Institute of Zoology, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China
- Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Liwen Xiao
- Institute of Zoology, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China
| | - Liping Lyu
- Key Laboratory of Evolution & Marine Biodiversity (Ministry of Education), and Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, 266003, China
| | - Fangqing Zhao
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Institute of Zoology, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China.
- Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China.
| | - Miao Miao
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Institute of Zoology, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China.
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2
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Mukherjee I, Grujčić V, Salcher MM, Znachor P, Seďa J, Devetter M, Rychtecký P, Šimek K, Shabarova T. Integrating depth-dependent protist dynamics and microbial interactions in spring succession of a freshwater reservoir. ENVIRONMENTAL MICROBIOME 2024; 19:31. [PMID: 38720385 PMCID: PMC11080224 DOI: 10.1186/s40793-024-00574-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 04/30/2024] [Indexed: 05/12/2024]
Abstract
BACKGROUND Protists are essential contributors to eukaryotic diversity and exert profound influence on carbon fluxes and energy transfer in freshwaters. Despite their significance, there is a notable gap in research on protistan dynamics, particularly in the deeper strata of temperate lakes. This study aimed to address this gap by integrating protists into the well-described spring dynamics of Římov reservoir, Czech Republic. Over a 2-month period covering transition from mixing to established stratification, we collected water samples from three reservoir depths (0.5, 10 and 30 m) with a frequency of up to three times per week. Microbial eukaryotic and prokaryotic communities were analysed using SSU rRNA gene amplicon sequencing and dominant protistan groups were enumerated by Catalysed Reporter Deposition-Fluorescence in situ Hybridization (CARD-FISH). Additionally, we collected samples for water chemistry, phyto- and zooplankton composition analyses. RESULTS Following the rapid changes in environmental and biotic parameters during spring, protistan and bacterial communities displayed swift transitions from a homogeneous community to distinct strata-specific communities. A prevalence of auto- and mixotrophic protists dominated by cryptophytes was associated with spring algal bloom-specialized bacteria in the epilimnion. In contrast, the meta- and hypolimnion showcased a development of a protist community dominated by putative parasitic Perkinsozoa, detritus or particle-associated ciliates, cercozoans, telonemids and excavate protists (Kinetoplastida), co-occurring with bacteria associated with lake snow. CONCLUSIONS Our high-resolution sampling matching the typical doubling time of microbes along with the combined microscopic and molecular approach and inclusion of all main components of the microbial food web allowed us to unveil depth-specific populations' successions and interactions in a deep lentic ecosystem.
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Affiliation(s)
- Indranil Mukherjee
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic.
| | - Vesna Grujčić
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Michaela M Salcher
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic
| | - Petr Znachor
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, 37005, Ceske Budejovice, Czech Republic
| | - Jaromír Seďa
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic
| | - Miloslav Devetter
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic
- Biology Centre of the Czech Academy of Sciences, Institute of Soil Biology and Biogeochemistry, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic
| | - Pavel Rychtecký
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic
| | - Karel Šimek
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, 37005, Ceske Budejovice, Czech Republic
| | - Tanja Shabarova
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic.
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3
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Ali M, Rice CA, Byrne AW, Paré PE, Beauvais W. Modelling dynamics between free-living amoebae and bacteria. Environ Microbiol 2024; 26:e16623. [PMID: 38715450 DOI: 10.1111/1462-2920.16623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 04/04/2024] [Indexed: 05/23/2024]
Abstract
Free-living amoebae (FLA) serve as hosts for a variety of endosymbionts, which are microorganisms that reside and multiply within the FLA. Some of these endosymbionts pose a pathogenic threat to humans, animals, or both. The symbiotic relationship with FLA not only offers these microorganisms protection but also enhances their survival outside their hosts and assists in their dispersal across diverse habitats, thereby escalating disease transmission. This review is intended to offer an exhaustive overview of the existing mathematical models that have been applied to understand the dynamics of FLA, especially concerning their interactions with bacteria. An extensive literature review was conducted across Google Scholar, PubMed, and Scopus databases to identify mathematical models that describe the dynamics of interactions between FLA and bacteria, as published in peer-reviewed scientific journals. The literature search revealed several FLA-bacteria model systems, including Pseudomonas aeruginosa, Pasteurella multocida, and Legionella spp. Although the published mathematical models account for significant system dynamics such as predator-prey relationships and non-linear growth rates, they generally overlook spatial and temporal heterogeneity in environmental conditions, such as temperature, and population diversity. Future mathematical models will need to incorporate these factors to enhance our understanding of FLA-bacteria dynamics and to provide valuable insights for future risk assessment and disease control measures.
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Affiliation(s)
- Marwa Ali
- Comparative Pathobiology Department, Purdue Veterinary Medicine, Purdue University, West Lafayette, Indiana, USA
| | - Christopher A Rice
- Comparative Pathobiology Department, Purdue Veterinary Medicine, Purdue University, West Lafayette, Indiana, USA
- Purdue Institute for Drug Discovery (PIDD), Purdue University, West Lafayette, Indiana, USA
- Purdue Institute of Inflammation, Immunology and Infectious Disease (PI4D), Purdue University, West Lafayette, Indiana, USA
- Regenstrief Center for Healthcare Engineering (RHCE), Purdue University, West Lafayette, Indiana, USA
| | - Andrew W Byrne
- One Health Scientific Support Unit, National Disease Control Centre, Agriculture House, Dublin, Ireland
| | - Philip E Paré
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Wendy Beauvais
- Comparative Pathobiology Department, Purdue Veterinary Medicine, Purdue University, West Lafayette, Indiana, USA
- Purdue Institute of Inflammation, Immunology and Infectious Disease (PI4D), Purdue University, West Lafayette, Indiana, USA
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4
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Bergman O, Be'eri-Shlevin Y, Ninio S. Sodium levels and grazing pressure shape natural communities of the intracellular pathogen Legionella. MICROBIOME 2023; 11:167. [PMID: 37518067 PMCID: PMC10388490 DOI: 10.1186/s40168-023-01611-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 06/30/2023] [Indexed: 08/01/2023]
Abstract
BACKGROUND Legionella are parasites of freshwater protozoa, responsible for Legionellosis. Legionella can be found in a variety of aquatic environments, including rivers, lakes, and springs, as well as in engineered water systems where they can potentially lead to human disease outbarks. Legionella are considered to be predominantly freshwater organisms with a limited ability to proliferate in saline environments. Exposure of Legionella to high sodium concentrations inhibits growth and virulence of laboratory strains, particularly under elevated temperatures. Nonetheless, Legionella have been identified in some saline environments where they likely interact with various protozoan hosts. In this work, we examine how these selection pressures, sodium and grazing, help shape Legionella ecology within natural environments. Utilizing Legionella-specific primers targeting a variable region of the Legionella 16S rRNA gene, we characterized Legionella abundance, diversity, and community composition in natural spring clusters of varying sodium concentrations, focusing on high sodium concentrations and elevated temperatures. RESULTS We observed the highest abundance of Legionella in spring clusters of high salinity, particularly in combination with elevated temperatures. Legionella abundance was strongly related to sodium concentrations. The Legionella community structure in saline environments was characterized by relatively low diversity, compared to spring clusters of lower salinity. The community composition in high salinity was characterized by few dominant Legionella genotypes, not related to previously described species. Protozoan microbial community structure and composition patterns resembled those of Legionella, suggesting a common response to similar selection pressures. We examined Legionella co-occurrence with potential protozoan hosts and found associations with Ciliophora and Amoebozoa representatives. CONCLUSIONS Our results indicate that selection forces in saline environments favor a small yet dominant group of Legionella species that are not closely related to known species. These novel environmental genotypes interact with various protozoan hosts, under environmental conditions of high salinity. Our findings suggest that alternative survival mechanisms are utilized by these species, representing mechanisms distinct from those of well-studied laboratory strains. Our study demonstrate how salinity can shape communities of opportunistic pathogens and their hosts, in natural environments, shedding light on evolutionary forces acting within these complex environments. Video Abstract.
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Affiliation(s)
- Oded Bergman
- Kinneret Limnological Laboratory (KLL), Israel Oceanographic and Limnological Research (IOLR), P.O. Box 447, 49500, Migdal, Israel
| | - Yaron Be'eri-Shlevin
- Kinneret Limnological Laboratory (KLL), Israel Oceanographic and Limnological Research (IOLR), P.O. Box 447, 49500, Migdal, Israel
| | - Shira Ninio
- Kinneret Limnological Laboratory (KLL), Israel Oceanographic and Limnological Research (IOLR), P.O. Box 447, 49500, Migdal, Israel.
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5
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Nisar MA, Ros KE, Brown MH, Bentham R, Best G, Xi J, Hinds J, Whiley H. Stagnation arising through intermittent usage is associated with increased viable but non culturable Legionella and amoeba hosts in a hospital water system. Front Cell Infect Microbiol 2023; 13:1190631. [PMID: 37351181 PMCID: PMC10282743 DOI: 10.3389/fcimb.2023.1190631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 05/18/2023] [Indexed: 06/24/2023] Open
Abstract
Hospital water systems are a significant source of Legionella, resulting in the potentially fatal Legionnaires' disease. One of the biggest challenges for Legionella management within these systems is that under unfavorable conditions Legionella transforms itself into a viable but non culturable (VBNC) state that cannot be detected using the standard methods. This study used a novel method (flow cytometry-cell sorting and qPCR [VFC+qPCR] assay) concurrently with the standard detection methods to examine the effect of temporary water stagnation, on Legionella spp. and microbial communities present in a hospital water system. Water samples were also analyzed for amoebae using culture and Vermamoeba vermiformis and Acanthamoeba specific qPCR. The water temperature, number and duration of water flow events for the hand basins and showers sampled was measured using the Enware Smart Flow® monitoring system. qPCR analysis demonstrated that 21.8% samples were positive for Legionella spp., 21% for L. pneumophila, 40.9% for V. vermiformis and 4.2% for Acanthamoeba. All samples that were Legionella spp. positive using qPCR (22%) were also positive for VBNC Legionella spp.; however, only 2.5% of samples were positive for culturable Legionella spp. 18.1% of the samples were positive for free-living amoebae (FLA) using culture. All samples positive for Legionella spp. were also positive for FLA. Samples with a high heterotrophic plate count (HPC ≥ 5 × 103 CFU/L) were also significantly associated with high concentrations of Legionella spp. DNA, VBNC Legionella spp./L. pneumophila (p < 0.01) and V. vermiformis (p < 0.05). Temporary water stagnation arising through intermittent usage (< 2 hours of usage per month) significantly (p < 0.01) increased the amount of Legionella spp. DNA, VBNC Legionella spp./L. pneumophila, and V. vermiformis; however, it did not significantly impact the HPC load. In contrast to stagnation, no relationship was observed between the microbes and water temperature. In conclusion, Legionella spp. (DNA and VBNC) was associated with V. vermiformis, heterotrophic bacteria, and stagnation occurring through intermittent usage. This is the first study to monitor VBNC Legionella spp. within a hospital water system. The high percentage of false negative Legionella spp. results provided by the culture method supports the use of either qPCR or VFC+qPCR to monitor Legionella spp. contamination within hospital water systems.
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Affiliation(s)
- Muhammad Atif Nisar
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Kirstin E. Ros
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Melissa H. Brown
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
- Australian Research Council Training Centre for Biofilm Research and Innovation, Flinders University, Bedford Park, SA, Australia
| | - Richard Bentham
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Giles Best
- College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
- Flow Cytometry Facility, Flinders University, Bedford Park, SA, Australia
| | - James Xi
- Enware Australia Pty Ltd., Caringbah, NSW, Australia
| | - Jason Hinds
- Enware Australia Pty Ltd., Caringbah, NSW, Australia
| | - Harriet Whiley
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
- Australian Research Council Training Centre for Biofilm Research and Innovation, Flinders University, Bedford Park, SA, Australia
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6
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Kodama Y, Fujishima M. Role of host ciliate Paramecium bursaria mitochondria and trichocysts for symbiotic Chlorella variabilis attachment beneath the host cell cortex. FEMS Microbiol Lett 2023; 370:fnad088. [PMID: 37660246 DOI: 10.1093/femsle/fnad088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 08/08/2023] [Accepted: 08/25/2023] [Indexed: 09/04/2023] Open
Abstract
Symbiotic Chlorella variabilis is encased in the perialgal vacuole (PV) membrane of ciliate Paramecium bursaria. The PV membrane is stably anchored below the host cell cortex by adhesion to host mitochondria. Host trichocysts, which are defensive organelles against predators, are present in the mitochondria and PV membrane vicinity. The mechanism by which PV attaches beneath the host cell cortex remains unknown. When P. bursaria is centrifuged at high speed, the symbiotic algae are displaced from the host cell cortex and concentrate at the posterior end. When centrifugation is stopped, the dislocated algae reattach beneath the host cell cortex with fast cytoplasmic streaming. The densities of mitochondria and trichocysts before and after centrifugation were compared using indirect immunofluorescence microscopy with monoclonal antibodies. Almost all trichocysts were shed by high-speed centrifugation, but dislocated algae could reattach even in the absence of trichocysts. In contrast, host mitochondria were unaffected in localization and number, and the dislocated algae also reattached. These findings suggest trichocysts are unnecessary for algal relocalization and that mitochondria are colocalized with the algae. However, many mitochondria were also present in the cell's anterior region without symbiotic algae. Therefore, not all areas with mitochondria contained algae, but there was an algal localization bias within the host cell.
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Affiliation(s)
- Yuuki Kodama
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu-cho, Matsue-shi, Shimane 690-8504, Japan
| | - Masahiro Fujishima
- Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8512, Japan
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7
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Scheithauer L, Karagöz MS, Mayer BE, Steinert M. Protein sociology of ProA, Mip and other secreted virulence factors at the Legionella pneumophila surface. Front Cell Infect Microbiol 2023; 13:1140688. [PMID: 36936764 PMCID: PMC10017501 DOI: 10.3389/fcimb.2023.1140688] [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: 01/09/2023] [Accepted: 02/17/2023] [Indexed: 03/06/2023] Open
Abstract
The pathogenicity of L. pneumophila, the causative agent of Legionnaires' disease, depends on an arsenal of interacting proteins. Here we describe how surface-associated and secreted virulence factors of this pathogen interact with each other or target extra- and intracellular host proteins resulting in host cell manipulation and tissue colonization. Since progress of computational methods like AlphaFold, molecular dynamics simulation, and docking allows to predict, analyze and evaluate experimental proteomic and interactomic data, we describe how the combination of these approaches generated new insights into the multifaceted "protein sociology" of the zinc metalloprotease ProA and the peptidyl-prolyl cis/trans isomerase Mip (macrophage infectivity potentiator). Both virulence factors of L. pneumophila interact with numerous proteins including bacterial flagellin (FlaA) and host collagen, and play important roles in virulence regulation, host tissue degradation and immune evasion. The recent progress in protein-ligand analyses of virulence factors suggests that machine learning will also have a beneficial impact in early stages of drug discovery.
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Affiliation(s)
- Lina Scheithauer
- Institut für Mikrobiologie, Technische Universität Braunschweig, Braunschweig, Germany
| | - Mustafa Safa Karagöz
- Institut für Mikrobiologie, Technische Universität Braunschweig, Braunschweig, Germany
| | - Benjamin E. Mayer
- Computational Biology & Simulation, Technische Universität Darmstadt, Darmstadt, Germany
| | - Michael Steinert
- Institut für Mikrobiologie, Technische Universität Braunschweig, Braunschweig, Germany
- *Correspondence: Michael Steinert,
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8
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Characterization of a Pseudokeronopsis Strain (Ciliophora, Urostylida) and Its Bacterial Endosymbiont “Candidatus Trichorickettsia” (Alphaproteobacteria, Rickettsiales). DIVERSITY 2022. [DOI: 10.3390/d14121032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Symbiotic associations between bacteria and ciliate protists are rather common. In particular, several cases were reported involving bacteria of the alphaproteobacterial lineage Rickettsiales, but the diversity, features, and interactions in these associations are still poorly understood. In this work, we characterized a novel ciliate protist strain originating from Brazil and its associated Rickettsiales endosymbiont by means of live and ultrastructural observations, as well as molecular phylogeny. Though with few morphological peculiarities, the ciliate was found to be phylogenetically affiliated with Pseudokeronopsis erythrina, a euryhaline species, which is consistent with its origin from a lagoon with significant spatial and seasonal salinity variations. The bacterial symbiont was assigned to “Candidatus Trichorickettsia mobilis subsp. hyperinfectiva”, being the first documented case of a Rickettsiales associated with urostylid ciliates. It resided in the host cytoplasm and bore flagella, similarly to many, but not all, conspecifics in other host species. These findings highlight the ability of “Candidatus Trichorickettsia” to infect multiple distinct host species and underline the importance of further studies on this system, in particular on flagella and their regulation, from a functional and also an evolutionary perspective, considering the phylogenetic proximity with the well-studied and non-flagellated Rickettsia.
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9
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Nisar MA, Ross KE, Brown MH, Bentham R, Hinds J, Whiley H. Molecular screening and characterization of Legionella pneumophila associated free-living amoebae in domestic and hospital water systems. WATER RESEARCH 2022; 226:119238. [PMID: 36270142 DOI: 10.1016/j.watres.2022.119238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 10/05/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Free-living amoebae are ubiquitous in the environment and cause both opportunistic and non-opportunistic infections in humans. Some genera of amoebae are natural reservoirs of opportunistic plumbing pathogens, such as Legionella pneumophila. In this study, the presence of free-living amoebae and Legionella was investigated in 140 water and biofilm samples collected from Australian domestic (n = 68) and hospital water systems (n = 72). Each sample was screened in parallel using molecular and culture-based methods. Direct quantitative polymerase chain reaction (qPCR) assays showed that 41% samples were positive for Legionella, 33% for L. pneumophila, 11% for Acanthamoeba, and 55% for Vermamoeba vermiformis gene markers. Only 7% of samples contained culturable L. pneumophila serogroup (sg)1, L. pneumophila sg2-14, and non-pneumophila Legionella. In total, 69% of samples were positive for free-living amoebae using any method. Standard culturing found that 41% of the samples were positive for amoeba (either Acanthamoeba, Allovahlkampfia, Stenamoeba, or V. vermiformis). V. vermiformis showed the highest overall frequency of occurrence. Acanthamoeba and V. vermiformis isolates demonstrated high thermotolerance and osmotolerance and strong broad spectrum bacteriogenic activity against Gram-negative and Gram-positive bacteria. Importantly, all Legionella positive samples were also positive for amoeba, and this co-occurrence was statistically significant (p < 0.05). According to qPCR and fluorescence in situ hybridization, V. vermiformis and Allovahlkampfia harboured intracellular L. pneumophila. To our knowledge, this is the first time Allovahlkampfia and Stenamoeba have been demonstrated as hosts of L. pneumophila in potable water. These results demonstrate the importance of amoebae in engineered water systems, both as a pathogen and as a reservoir of Legionella. The high frequency of gymnamoebae detected in this study from Australian engineered water systems identifies an issue of significant public health concern. Future water management protocols should incorporate treatments strategies to control amoebae to reduce the risk to end users.
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Affiliation(s)
- Muhammad Atif Nisar
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Kirstin E Ross
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Melissa H Brown
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Richard Bentham
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Jason Hinds
- Enware Australia Pty Ltd, Caringbah, NSW, Australia
| | - Harriet Whiley
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia.
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10
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Matsumoto S, Watanabe K, Imamura A, Tachibana M, Shimizu T, Watarai M. Comparative Analysis Between Paramecium Strains with Different Syngens Using the RAPD Method. MICROBIAL ECOLOGY 2022; 84:594-602. [PMID: 34522990 DOI: 10.1007/s00248-021-01864-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 09/03/2021] [Indexed: 06/13/2023]
Abstract
Paramecium spp. are a genus of free-living protists that live mainly in freshwater environments. They are ciliates with high motility and phagocytosis and have been used to analyze cell motility and as a host model for pathogens. Besides such biological characteristics, apart from the usual morphological and genetic classification of species, the existence of taxonomies (such as syngens) and mating types related to Paramecium's unique reproduction is known. In this study, we attempted to develop a simple method to identify Paramecium strains, which are difficult to distinguish morphologically, using random amplified polymorphic DNA (RAPD) analysis. Consequently, we can observe strain-specific band patterns. We also confirm that the presence of endosymbiotic Chlorella cells affects the band pattern of P. bursaria. Furthermore, the results of the RAPD analysis using several P. caudatum strains with different syngens show that it is possible to detect a band specific to a certain syngen. By improving the reaction conditions and random primers, based on the results of this study, RAPD analysis can be applied to the identification of Paramecium strains and their syngen confirmation tests.
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Affiliation(s)
- Sonoko Matsumoto
- Joint Graduate School of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Kenta Watanabe
- Joint Graduate School of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Akiko Imamura
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Masato Tachibana
- National BioResource Project Paramecium, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Takashi Shimizu
- Joint Graduate School of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Masahisa Watarai
- Joint Graduate School of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan.
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan.
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11
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Matsumoto S, Watanabe K, Kiyota H, Tachibana M, Shimizu T, Watarai M. Distinction of Paramecium strains by a combination method of RAPD analysis and multiplex PCR. PLoS One 2022; 17:e0265139. [PMID: 35275953 PMCID: PMC8916638 DOI: 10.1371/journal.pone.0265139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/23/2022] [Indexed: 12/20/2022] Open
Abstract
Paramecium is employed as a valuable model organism in various research fields since a large number of strains with different characteristics of size, morphology, degree of aging, and type of conjugation can be obtained. It is necessary to determine a method for the classification and simple identification of strains to increase their utility as a research tool. This study attempted to establish a polymerase chain reaction (PCR)-based method to differentiate strains of the same species. Genomic DNA was purified from several strains of P. caudatum, P. tetraurelia, and P. bursaria used for comparison by the random amplified polymorphic DNA (RAPD)-PCR method. In P. tetraurelia and P. bursaria, it was sufficiently possible to distinguish specific strains depending on the pattern of random primers and amplification characteristics. For the classification of P. caudatum, based on the sequence data obtained by RAPD-PCR analysis, 5 specific primer sets were designed and a multiplex PCR method was developed. The comparative analysis of 2 standard strains, 12 recommended strains, and 12 other strains of P. caudatum provided by the National BioResource Project was conducted, and specific strains were identified. This multiplex PCR method would be an effective tool for the simple identification of environmental isolates or the management of Paramecium strains.
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Affiliation(s)
- Sonoko Matsumoto
- Joint Graduate School of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Kenta Watanabe
- Joint Graduate School of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Hiroko Kiyota
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Masato Tachibana
- Joint Faculty of Veterinary Medicine, National BioResource Project Paramecium, Yamaguchi University, Yamaguchi, Japan
| | - Takashi Shimizu
- Joint Graduate School of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Masahisa Watarai
- Joint Graduate School of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
- * E-mail:
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12
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Watanabe K, Motonaga A, Tachibana M, Shimizu T, Watarai M. Francisella novicida can utilize Paramecium bursaria as its potential host. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:50-59. [PMID: 34845838 DOI: 10.1111/1758-2229.13029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 06/13/2023]
Abstract
Francisella novicida is a facultative intracellular pathogen and the causative agent of tularemia. Although cases of infection caused by exposure to contaminated water have been reported, its natural host and ecology in the environment remain unclear. In this study, we investigated in vitro the possibility that Paramecium bursaria may be a useful tool as a protist host model of F. novicida. Experimental infection with F. novicida resulted in a stable intracellular relationship within P. bursaria. This symbiotic intracellular relationship was not observed in experimental infections with other Francisella species and Legionella pneumophila. We found that F. novicida showed similar behaviour to that of the eukaryotic endosymbiont of P. bursaria, the green algae Chlorella, in the internalization process. In addition, stable intracellular localization of F. novicida was possible only when Chlorella was not present. Although we investigated the type VI secretion system of F. novicida as a candidate for the bacterial factor, we found that it was not involved in the establishment of an intracellular relationship with P. bursaria. These results suggested that P. bursaria is potentially a protist host model for F. novicida and may be a useful tool for understanding the relationship between protist hosts and their symbionts.
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Affiliation(s)
- Kenta Watanabe
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Akane Motonaga
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Masato Tachibana
- National BioResource Project Paramecium, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Takashi Shimizu
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Masahisa Watarai
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
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13
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Kawashiro A, Okubo T, Nakamura S, Thapa J, Miyake M, Yamaguchi H. Wild ciliates differ in susceptibility to Legionella pneumophila JR32. MICROBIOLOGY-SGM 2021; 167. [PMID: 34402779 DOI: 10.1099/mic.0.001078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We investigated how Legionella pneumophila (Lp) JR32 interacts with Anteglaucoma CS11A and Colpoda E6, two ciliates that we isolated from sewage and sink trap sludge, respectively, using a handmade maze device containing a 96-well crafting plate. Our 18S rDNA-based phylogenetic analysis showed that Anteglaucoma CS11A and Colpoda E6 formed distinct clades. Scanning electron microscopy showed that Anteglaucoma CS11A had a bigger-sized body than Colpoda E6 and, unlike Tetrahymena IB (the reference strain), neither ciliate produced pellets, which are extracellular vacuoles. Fluorescence microscopic observations revealed that although the intake amounts differed, all three ciliates rapidly ingested LpJR32 regardless of the presence or absence of the icm/dot virulence genes, indicating that they all interacted with LpJR32. In co-cultures with Anteglaucoma CS11A, the LpJR32 levels were maintained but fell dramatically when the co-culture contained the LpJR32 icm/dot deletion mutant instead. Anteglaucoma CS11A died within 2 days of co-culture with LpJR32, but survived co-culture with the deletion mutant. In co-cultures with Colpoda E6, LpJR32 levels were maintained but temporarily decreased independently of the virulence gene. Concurrently, the Colpoda E6 ciliates survived by forming cysts, which may enable them to resist harsh environments, and by diminishing the sensitivity of trophozoites to Lp. In the Tetrahymena IB co-cultures with LpJR32 or Δicm/dot, the Lp levels were maintained, albeit with temporal decreases, and the Tetrahymena IB levels were also maintained. We conclude that unlike Tetrahymena IB with pellet production, Anteglaucoma CS11A can be killed by LpJR32 infection, and Colpoda E6 can resist LpJR32 infection through cyst formation and the low sensitivity of trophozoites to Lp. Thus, the two ciliates that we isolated had different susceptibilities to LpJR32 infection.
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Affiliation(s)
- Airi Kawashiro
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Torahiko Okubo
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Shinji Nakamura
- Division of Biomedical Imaging Research, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Jeewan Thapa
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.,Division of Bioresources Research Center for Zoonosis Control, Hokkaido University, Hokkaido, Sapporo, Japan
| | - Masaki Miyake
- Laboratory of Microbiology and Immunology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Hiroyuki Yamaguchi
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
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14
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Chasing Waterborne Pathogens in Antarctic Human-Made and Natural Environments, with Special Reference to Legionella spp. Appl Environ Microbiol 2021; 87:AEM.02247-20. [PMID: 33097517 DOI: 10.1128/aem.02247-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 10/18/2020] [Indexed: 12/21/2022] Open
Abstract
Waterborne pathogenic diseases are public health issues, especially for people staying in remote environments, such as Antarctica. After repeated detection of Legionella by PCR from the shower room of Syowa Station, the Japanese Antarctic research station, we wanted to understand the occurrence of waterborne pathogens, especially Legionella, in the station and their potential sources. In this study, we analyzed water and biofilm samples collected from the water facilities of Syowa Station, as well as water samples from surrounding glacier lakes, by 16S rRNA gene-based amplicon sequencing. For Legionella spp., we further attempted to obtain a detailed community structure by using genus-specific primers. The results showed that potentially pathogenic genera were mostly localized in the station, while Legionella spp., Pseudomonas spp., and Mycobacterium spp. were also widely distributed in lakes. Genus-specific analysis of Legionella spp. within the lake environments confirmed the presence of diverse Legionella amplicon sequence variants (ASVs) that were distinctly different from the Legionella ASVs detected in the station. The majority of the Legionella ASVs inhabiting Antarctic lake habitats were phylogenetically distinct from known Legionella species, whereas the ASVs detected in the human-made station tended to contain ASVs highly similar to well-described mesophilic species with human pathogenicity. These data suggest that unexpected Legionella diversity exists in remote Antarctic cold environments and that environmental differences (e.g., temperature) in and around the station affect the community structure.IMPORTANCE We comprehensively examined the localization of potential waterborne pathogens in the Antarctic human-made and natural aquatic environment with special focus on Legionella spp. Some potential pathogenic genera were detected with low relative abundance in the natural environment, but most detections of these genera occurred in the station. Through detailed community analysis of Legionella spp., we revealed that a variety of Legionella spp. was widely distributed in the Antarctic environment and that they were phylogenetically distinct from the described species. This fact indicates that there are still diverse unknown Legionella spp. in Antarctica, and this genus encompasses a greater variety of species in low-temperature environments than is currently known. In contrast, amplicon sequence variants closely related to known Legionella spp. with reported pathogenicity were almost solely localized in the station, suggesting that human-made environments alter the Legionella community.
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15
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Watanabe K, Higuchi Y, Shimmura M, Tachibana M, Fujishima M, Shimizu T, Watarai M. Peculiar Paramecium Hosts Fail to Establish a Stable Intracellular Relationship With Legionella pneumophila. Front Microbiol 2020; 11:596731. [PMID: 33193278 PMCID: PMC7644925 DOI: 10.3389/fmicb.2020.596731] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/06/2020] [Indexed: 12/29/2022] Open
Abstract
Legionella pneumophila, an intracellular human pathogen, establishes intracellular relationships with several protist hosts, including Paramecium caudatum. L. pneumophila can escape the normal digestion process and establish intracellular relationships in Paramecium. In this study, we identify new Paramecium strains that significantly reduce the number of L. pneumophila during infection. As a result, stable intracellular relationships between L. pneumophila and these Paramecium strains were not observed. These digestion-type Paramecium also showed high efficiency for Escherichia coli elimination compared to other strains of Paramecium. These results suggest that the digestion-type strains identified have high non-specific digestion activity. Although we evaluated the maturation process of Legionella-containing vacuoles (LCVs) in the Paramecium strains using LysoTracker, there were no discriminative changes in these LCVs compared to other Paramecium strains. Detailed understanding of the mechanisms of high digestion efficiency in these strains could be applied to water purification technologies and L. pneumophila elimination from environmental water.
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Affiliation(s)
- Kenta Watanabe
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Yusei Higuchi
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Mizuki Shimmura
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Masato Tachibana
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan.,Joint Faculty of Veterinary Medicine, Laboratory of National BioResource Project Paramecium, Yamaguchi University, Yamaguchi, Japan.,Department of Research Infrastructure, National BioResource Project of Japan Agency for Medical Research and Development, Tokyo, Japan
| | - Masahiro Fujishima
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan.,Joint Faculty of Veterinary Medicine, Laboratory of National BioResource Project Paramecium, Yamaguchi University, Yamaguchi, Japan.,Department of Research Infrastructure, National BioResource Project of Japan Agency for Medical Research and Development, Tokyo, Japan
| | - Takashi Shimizu
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Masahisa Watarai
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
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16
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“Candidatus Mystax nordicus” Aggregates with Mitochondria of Its Host, the Ciliate Paramecium nephridiatum. DIVERSITY 2020. [DOI: 10.3390/d12060251] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Extensive search for new endosymbiotic systems in ciliates occasionally reverts us to the endosymbiotic bacteria described in the pre-molecular biology era and, hence, lacking molecular characterization. A pool of these endosymbionts has been referred to as a hidden bacterial biodiversity from the past. Here, we provide a description of one of such endosymbionts, retrieved from the ciliate Paramecium nephridiatum. This curve-shaped endosymbiont (CS), which shared the host cytoplasm with recently described “Candidatus Megaira venefica”, was found in the same host and in the same geographic location as one of the formerly reported endosymbiotic bacteria and demonstrated similar morphology. Based on morphological data obtained with DIC, TEM and AFM and molecular characterization by means of sequencing 16S rRNA gene, we propose a novel genus, “Candidatus Mystax”, with a single species “Ca. Mystax nordicus”. Phylogenetic analysis placed this species in Holosporales, among Holospora-like bacteria. Contrary to all Holospora species and many other Holospora-like bacteria, such as “Candidatus Gortzia”, “Candidatus Paraholospora” or “Candidatus Hafkinia”, “Ca. Mystax nordicus” was never observed inside the host nucleus. “Ca. Mystax nordicus” lacked infectivity and killer effect. The striking peculiarity of this endosymbiont was its ability to form aggregates with the host mitochondria, which distinguishes it from Holospora and Holospora-like bacteria inhabiting paramecia.
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17
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Nisar MA, Ross KE, Brown MH, Bentham R, Whiley H. Legionella pneumophila and Protozoan Hosts: Implications for the Control of Hospital and Potable Water Systems. Pathogens 2020; 9:pathogens9040286. [PMID: 32326561 PMCID: PMC7238060 DOI: 10.3390/pathogens9040286] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 12/12/2022] Open
Abstract
Legionella pneumophila is an opportunistic waterborne pathogen of public health concern. It is the causative agent of Legionnaires’ disease (LD) and Pontiac fever and is ubiquitous in manufactured water systems, where protozoan hosts and complex microbial communities provide protection from disinfection procedures. This review collates the literature describing interactions between L. pneumophila and protozoan hosts in hospital and municipal potable water distribution systems. The effectiveness of currently available water disinfection protocols to control L. pneumophila and its protozoan hosts is explored. The studies identified in this systematic literature review demonstrated the failure of common disinfection procedures to achieve long term elimination of L. pneumophila and protozoan hosts from potable water. It has been demonstrated that protozoan hosts facilitate the intracellular replication and packaging of viable L. pneumophila in infectious vesicles; whereas, cyst-forming protozoans provide protection from prolonged environmental stress. Disinfection procedures and protozoan hosts also facilitate biogenesis of viable but non-culturable (VBNC) L. pneumophila which have been shown to be highly resistant to many water disinfection protocols. In conclusion, a better understanding of L. pneumophila-protozoan interactions and the structure of complex microbial biofilms is required for the improved management of L. pneumophila and the prevention of LD.
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18
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Lanzoni O, Plotnikov A, Khlopko Y, Munz G, Petroni G, Potekhin A. The core microbiome of sessile ciliate Stentor coeruleus is not shaped by the environment. Sci Rep 2019; 9:11356. [PMID: 31388025 PMCID: PMC6684585 DOI: 10.1038/s41598-019-47701-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 07/22/2019] [Indexed: 12/29/2022] Open
Abstract
Microbiomes of multicellular organisms are one of the hottest topics in microbiology and physiology, while only few studies addressed bacterial communities associated with protists. Protists are widespread in all environments and can be colonized by plethora of different bacteria, including also human pathogens. The aim of this study was to characterize the prokaryotic community associated with the sessile ciliate Stentor coeruleus. 16S rRNA gene metabarcoding was performed on single cells of S. coeruleus and on their environment, water from the sewage stream. Our results showed that the prokaryotic community composition differed significantly between Stentor cells and their environment. The core microbiome common for all ciliate specimens analyzed could be defined, and it was composed mainly by representatives of bacterial genera which include also potential human pathogens and commensals, such as Neisseria, Streptococcus, Capnocytophaga, Porphyromonas. Numerous 16S rRNA gene contigs belonged to endosymbiont “Candidatus Megaira polyxenophila”. Our data suggest that each ciliate cell can be considered as an ecological microniche harboring diverse prokaryotic organisms. Possible benefits for persistence and transmission in nature for bacteria associated with protists are discussed. Our results support the hypothesis that ciliates attract potentially pathogenic bacteria and play the role of natural reservoirs for them.
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Affiliation(s)
| | - Andrey Plotnikov
- Center of Shared Scientific Equipment, Institute for Cellular and Intracellular Symbiosis, Ural Division of RAS, Orenburg, Russia
| | - Yuri Khlopko
- Center of Shared Scientific Equipment, Institute for Cellular and Intracellular Symbiosis, Ural Division of RAS, Orenburg, Russia
| | - Giulio Munz
- Department of Civil and Environmental Engineering, University of Florence, Florence, Italy
| | | | - Alexey Potekhin
- Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia.
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19
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Plotnikov AO, Balkin AS, Gogoleva NE, Lanzoni O, Khlopko YA, Cherkasov SV, Potekhin AA. High-Throughput Sequencing of the 16S rRNA Gene as a Survey to Analyze the Microbiomes of Free-Living Ciliates Paramecium. MICROBIAL ECOLOGY 2019; 78:286-298. [PMID: 30661111 DOI: 10.1007/s00248-019-01321-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
Ciliates are the largest group of ubiquitous aquatic bacterivorous protists, and many species are easily cultivated. However, only few studies reported prokaryotic communities naturally associated with ciliate cells. Herein, we analyzed the microbiome composition of several strains of Paramecium (Ciliophora) originating from different locations and belonging to two morpho-species by high-throughput sequencing (HTS) of the 16S rRNA gene. Possible reasons of HTS results bias were addressed comparing DNA libraries obtained using different primers and different number of ciliate cells. Microbiomes associated with ciliates and their environments were always significantly different by prokaryotic taxonomic composition and bacterial richness. There were also pronounced differences between Paramecium strains. Interestingly, potentially pathogenic bacteria were revealed in Paramecium microbiomes.
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Affiliation(s)
- Andrey O Plotnikov
- "Persistence of microorganisms" Center of Shared Scientific Equipment, Institute for Cellular and Intracellular Symbiosis UrB RAS, Orenburg, Russia.
| | - Alexander S Balkin
- "Persistence of microorganisms" Center of Shared Scientific Equipment, Institute for Cellular and Intracellular Symbiosis UrB RAS, Orenburg, Russia
| | - Natalia E Gogoleva
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre of Russian Academy of Sciences, Kazan, Russia
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
| | | | - Yuri A Khlopko
- "Persistence of microorganisms" Center of Shared Scientific Equipment, Institute for Cellular and Intracellular Symbiosis UrB RAS, Orenburg, Russia
| | - Sergey V Cherkasov
- Laboratory of biomedical technologies, Institute for Cellular and Intracellular Symbiosis UrB RAS, Orenburg, Russia
| | - Alexey A Potekhin
- Department of Microbiology, Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia
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20
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Watanabe K, Suzuki H, Nishida T, Mishima M, Tachibana M, Fujishima M, Shimizu T, Watarai M. Identification of novel Legionella genes required for endosymbiosis in Paramecium based on comparative genome analysis with Holospora spp. FEMS Microbiol Ecol 2019; 94:5074368. [PMID: 30124811 DOI: 10.1093/femsec/fiy162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 08/11/2018] [Indexed: 12/20/2022] Open
Abstract
The relationship between Legionella and protist hosts has a huge impact when considering the infectious risk in humans because it facilitates the long-term replication and survival of Legionella in the environment. The ciliate Paramecium is considered to be a protist host for Legionella in natural environments, but the details of their endosymbiosis are largely unknown. In this study, we determined candidate Legionella pneumophila genes that are likely to be involved in the establishment of endosymbiosis in Paramecium caudatum by comparing the genomes of Legionella spp. and Holospora spp. that are obligate endosymbiotic bacteria in Paramecium spp. Among the candidate genes, each single deletion mutant for five genes (lpg0492, lpg0522, lpg0523, lpg2141 and lpg2398) failed to establish endosymbiosis in P. caudatum despite showing intracellular growth in human macrophages. The mutants exhibited no characteristic changes in terms of their morphology, multiplication rate or capacity for modulating the phagosomes in which they were contained, but their resistance to lysozyme decreased significantly. This study provides insights into novel factors required by L. pneumophila for endosymbiosis in P. caudatum, and suggests that endosymbiotic organisms within conspecific hosts may have shared genes related to effective endosymbiosis establishment.
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Affiliation(s)
- Kenta Watanabe
- The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.,Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Haruo Suzuki
- Institute for Advanced Biosciences, Keio University, 5322 Endo, Fujisawa, Kanagawa 252-0882, Japan
| | - Takashi Nishida
- The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Manami Mishima
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Masato Tachibana
- Graduate School of Medicine, Dentistry and Pharmaceutical Science, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Masahiro Fujishima
- Department of Sciences, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.,Department of Research Infrastructure, National BioResource Project of Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo 100-0004, Japan
| | - Takashi Shimizu
- The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.,Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Masahisa Watarai
- The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.,Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
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21
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Flores E, Thompson L, Sirisaengtaksin N, Nguyen AT, Ballard A, Krachler AM. Using the Protozoan Paramecium caudatum as a Vehicle for Food-borne Infections in Zebrafish Larvae. J Vis Exp 2019. [PMID: 30663701 DOI: 10.3791/58949] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Due to their transparency, genetic tractability, and ease of maintenance, zebrafish (Danio rerio) have become a widely-used vertebrate model for infectious diseases. Larval zebrafish naturally prey on the unicellular protozoan Paramecium caudatum. This protocol describes the use of P. caudatum as a vehicle for food-borne infection in larval zebrafish. P. caudatum internalize a wide range of bacteria and bacterial cells remain viable for several hours. Zebrafish then prey on P. caudatum, the bacterial load is released in the foregut upon digestion of the paramecium vehicle, and the bacteria colonize the intestinal tract. The protocol includes a detailed description of paramecia maintenance, loading with bacteria, determination of bacterial degradation and dose, as well as infection of zebrafish by feeding with paramecia. The advantage of using this method of food-borne infection is that it closely mimics the mode of infection observed in human disease, leads to more robust colonization compared to immersion protocols, and allows the study of a wide range of pathogens. Food-borne infection in the zebrafish model can be used to investigate bacterial gene expression within the host, host-pathogen interactions, and hallmarks of pathogenicity including bacterial burden, localization, dissemination and morbidity.
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Affiliation(s)
- Erika Flores
- McGovern Medical School, Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston
| | - Laurel Thompson
- McGovern Medical School, Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston
| | - Natalie Sirisaengtaksin
- McGovern Medical School, Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston
| | - Anh Trinh Nguyen
- McGovern Medical School, Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston
| | - Abigail Ballard
- McGovern Medical School, Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston
| | - Anne-Marie Krachler
- McGovern Medical School, Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston;
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22
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Abstract
Within the human host, Legionella pneumophila replicates within alveolar macrophages, leading to pneumonia. However, L. pneumophila is an aquatic generalist pathogen that replicates within a wide variety of protist hosts, including amoebozoa, percolozoa, and ciliophora. The intracellular lifestyles of L. pneumophila within the two evolutionarily distant hosts macrophages and protists are remarkably similar. Coevolution with numerous protist hosts has shaped plasticity of the genome of L. pneumophila, which harbors numerous proteins encoded by genes acquired from primitive eukaryotic hosts through interkingdom horizontal gene transfer. The Dot/Icm type IVb translocation system translocates ∼6,000 effectors among Legionella species and >320 effector proteins in L. pneumophila into host cells to modulate a plethora of cellular processes to create proliferative niches. Since many of the effectors have likely evolved to modulate cellular processes of primitive eukaryotic hosts, it is not surprising that most of the effectors do not contribute to intracellular growth within human macrophages. Some of the effectors may modulate highly conserved eukaryotic processes, while others may target protist-specific processes that are absent in mammals. The lack of studies to determine the role of the effectors in adaptation of L. pneumophila to various protists has hampered the progress to determine the function of most of these effectors, which are routinely studied in mouse or human macrophages. Since many protists restrict L. pneumophila, utilization of such hosts can also be instrumental in deciphering the mechanisms of failure of L. pneumophila to overcome restriction of certain protist hosts. Here, we review the interaction of L. pneumophila with its permissive and restrictive protist environmental hosts and outline the accomplishments as well as gaps in our knowledge of L. pneumophila-protist host interaction and L. pneumophila's evolution to become a human pathogen.
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Affiliation(s)
- Ashley Best
- Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, Kentucky, USA
| | - Yousef Abu Kwaik
- Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, Kentucky, USA
- Center for Predictive Medicine, University of Louisville, Louisville, Kentucky, USA
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Nishida T, Hara N, Watanabe K, Shimizu T, Fujishima M, Watarai M. Crucial Role of Legionella pneumophila TolC in the Inhibition of Cellular Trafficking in the Protistan Host Paramecium tetraurelia. Front Microbiol 2018; 9:800. [PMID: 29743879 PMCID: PMC5930787 DOI: 10.3389/fmicb.2018.00800] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 04/10/2018] [Indexed: 12/14/2022] Open
Abstract
Legionella pneumophila is a facultative intracellular Gram-negative bacterium, which is a major causative agent of Legionnaires’ disease. In the environment, this bacterium survives in free-living protists such as amoebae and Tetrahymena. The association of L. pneumophila and protists leads to the replication and spread of this bacterium. Thus, from a public health perspective, their association can enhance the risk of L. pneumophila infection for humans. Paramecium spp. are candidates of natural hosts of L. pneumophila, but their detailed relationships remain unclear. In the present study, we used an environmental strain, L. pneumophila Ofk308 (Ofk308) and Paramecium tetraurelia st110-1a to reveal the relationship between L. pneumophila and Paramecium spp. Ofk308 was cytotoxic to P. tetraurelia in an infection-dependent manner. We focused on TolC, a component of the type I secretion system, which is a virulence factor of L. pneumophila toward protists and found that cytotoxicity was dependent on TolC but not on other T1SS components. Further, the number of bacteria in P. tetraurelia was not associated with cytotoxicity and TolC was not involved in the mechanism of resistance against the digestion of P. tetraurelia in Ofk308. We used a LysoTracker to evaluate the maturation process of P. tetraurelia phagosomes containing Ofk308. We found that there was no difference between Ofk308 and the tolC-deletion mutant. To assess the phagocytic activity of P. tetraurelia, Texas Red-conjugated dextran-uptake assays were performed. Ofk308 inhibited phagosome formation by P. tetraurelia through a TolC-dependent mechanism. Further, we evaluated the excretion of Legionella-containing vacuoles from P. tetraurelia. We found that P. tetraurelia failed to excrete undigested Ofk308 and that Ofk308 remained within cells through a TolC-dependent mechanism. Our results suggest that TolC is essential for L. pneumophila to remain within Paramecium cells and to show cytotoxicity. Because of the high mobility and high cell division rate of Paramecium spp., living with Paramecium spp. would be beneficial for L. pneumophila to expand its habitat. To control Legionaries’ disease, understanding the ecology of L. pneumophila in the environment is essential.
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Affiliation(s)
- Takashi Nishida
- The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Naho Hara
- The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Kenta Watanabe
- The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Takashi Shimizu
- The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Masahiro Fujishima
- Department of Sciences, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan.,National BioResource Project, Japan Agency for Medical Research and Development, Tokyo, Japan
| | - Masahisa Watarai
- The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
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24
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Gomaa F, Gersh M, Cavanaugh CM. Diverse Legionella-Like Bacteria Associated with Testate Amoebae of the Genus Arcella (Arcellinida: Amoebozoa). J Eukaryot Microbiol 2018; 65:661-668. [PMID: 29443446 DOI: 10.1111/jeu.12511] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 01/03/2018] [Accepted: 02/03/2018] [Indexed: 12/11/2022]
Abstract
Diverse species of Legionella and Legionella-like amoebal pathogens (LLAPs) have been identified as intracellular bacteria in many amoeboid protists. There are, however, other amoeboid groups such as testate amoeba for which we know little about their potential to host such bacteria. In this study, we assessed the occurrence and diversity of Legionella spp. in cultures and environmental isolates of freshwater arcellinid testate amoebae species, Arcella hemispherica, Arcella intermedia, and Arcella vulgaris, via 16S rRNA gene sequence analyses and fluorescent in situ hybridization (FISH). Analysis of the 16S rRNA gene sequences indicated that A. hemispherica, A. intermedia, and A. vulgaris host Legionella-like bacteria with 94-98% identity to other Legionella spp. based on NCBI BLAST search. Phylogenetic analysis placed Legionella-like Arcella-associated bacteria (LLAB) in three different clusters within a tree containing all other members of Legionella and LLAPs. The intracellular localization of the Legionella within Arcella hosts was confirmed using FISH with a Legionella-specific probe. This study demonstrates that the host range of Legionella and Legionella-like bacteria in the Amoebozoa extends beyond members of "naked" amoebae species, with members of the testate amoebae potentially serving an ecological role in the dispersal, protection, and replication of Legionella spp. in natural environments.
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Affiliation(s)
- Fatma Gomaa
- Department of Organismic and Evolutionary Biology, Biological Laboratory, Harvard University, Cambridge, Massachusetts, 02138, USA
| | - Maxim Gersh
- Department of Organismic and Evolutionary Biology, Biological Laboratory, Harvard University, Cambridge, Massachusetts, 02138, USA
| | - Colleen M Cavanaugh
- Department of Organismic and Evolutionary Biology, Biological Laboratory, Harvard University, Cambridge, Massachusetts, 02138, USA
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25
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Sabaneyeva E, Castelli M, Szokoli F, Benken K, Lebedeva N, Salvetti A, Schweikert M, Fokin S, Petroni G. Host and symbiont intraspecific variability: The case of Paramecium calkinsi and "Candidatus Trichorickettsia mobilis". Eur J Protistol 2017; 62:79-94. [PMID: 29287245 DOI: 10.1016/j.ejop.2017.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Revised: 10/17/2017] [Accepted: 12/04/2017] [Indexed: 01/08/2023]
Abstract
Newly isolated strains of the ciliate Paramecium calkinsi and their cytoplasmic bacterial endosymbionts were characterized by a multidisciplinary approach, including live observation, ultrastructural investigation, and molecular analysis. Despite morphological resemblance, the characterized P. calkinsi strains showed a significant molecular divergence compared to conspecifics, possibly hinting for a cryptic speciation. The endosymbionts were clearly found to be affiliated to the species "Candidatus Trichorickettsia mobilis" (Rickettsiales, Rickettsiaceae), currently encompassing only bacteria retrieved in an obligate intracellular association with other ciliates. However, a relatively high degree of intraspecific divergence was observed as well, thus it was possible to split "Candidatus Trichorickettsia" into three subspecies, one of which represented so far only by the newly characterized endosymbionts of P. calkinsi. Other features distinguished the members of each different subspecies. In particular, the endosymbionts of P. calkinsi resided in the cytoplasm and possessed numerous peritrichous flagella, although no motility was evidenced, whereas their conspecifics in other hosts were either cytoplasmic and devoid of flagella, or macronuclear, displaying flagellar-driven motility. Moreover, contrarily to previously analyzed "Candidatus Trichorickettsia" hosts, infected P. calkinsi cells frequently became amicronucleate and demonstrated abnormal cell division, eventually leading to decline of the laboratory culture.
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Affiliation(s)
- E Sabaneyeva
- Department of Cytology and Histology, St. Petersburg State University, Russian Federation.
| | - M Castelli
- Department of Veterinary Medicine, University of Milan, Italy; Department of Biosciences, University of Milan, Italy
| | - F Szokoli
- Dipartimento di Biologia, Università di Pisa, Italy; Institut für Hydrobiologie, Technische Universität Dresden, Germany
| | - K Benken
- Core Facility Center for Microscopy and Microanalysis, St. Petersburg State University, Russian Federation
| | - N Lebedeva
- Core Facility Center for Cultivation of Microorganisms, St. Petersburg State University, Russian Federation
| | - A Salvetti
- Dipartimento di Medicina Clinica e Sperimentale, Università di Pisa, Italy
| | - M Schweikert
- Institut of Biomaterials and Biomolecular Systems, Stuttgart University, Germany
| | - S Fokin
- Dipartimento di Biologia, Università di Pisa, Italy; Department of Invertebrate Zoology, St. Petersburg State University, Russian Federation
| | - G Petroni
- Dipartimento di Biologia, Università di Pisa, Italy.
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26
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Boamah DK, Zhou G, Ensminger AW, O'Connor TJ. From Many Hosts, One Accidental Pathogen: The Diverse Protozoan Hosts of Legionella. Front Cell Infect Microbiol 2017; 7:477. [PMID: 29250488 PMCID: PMC5714891 DOI: 10.3389/fcimb.2017.00477] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 10/31/2017] [Indexed: 01/03/2023] Open
Abstract
The 1976 outbreak of Legionnaires' disease led to the discovery of the intracellular bacterial pathogen Legionella pneumophila. Given their impact on human health, Legionella species and the mechanisms responsible for their replication within host cells are often studied in alveolar macrophages, the primary human cell type associated with disease. Despite the potential severity of individual cases of disease, Legionella are not spread from person-to-person. Thus, from the pathogen's perspective, interactions with human cells are accidents of time and space—evolutionary dead ends with no impact on Legionella's long-term survival or pathogenic trajectory. To understand Legionella as a pathogen is to understand its interaction with its natural hosts: the polyphyletic protozoa, a group of unicellular eukaryotes with a staggering amount of evolutionary diversity. While much remains to be understood about these enigmatic hosts, we summarize the current state of knowledge concerning Legionella's natural host range, the diversity of Legionella-protozoa interactions, the factors influencing these interactions, the importance of avoiding the generalization of protozoan-bacterial interactions based on a limited number of model hosts and the central role of protozoa to the biology, evolution, and persistence of Legionella in the environment.
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Affiliation(s)
- David K Boamah
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Guangqi Zhou
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Alexander W Ensminger
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Public Health Ontario, Toronto, ON, Canada
| | - Tamara J O'Connor
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Zebrafish ( Danio rerio) as a Vertebrate Model Host To Study Colonization, Pathogenesis, and Transmission of Foodborne Escherichia coli O157. mSphere 2017; 2:mSphere00365-17. [PMID: 28959735 PMCID: PMC5607324 DOI: 10.1128/mspheredirect.00365-17] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 09/05/2017] [Indexed: 12/12/2022] Open
Abstract
Foodborne infections with enterohemorrhagic Escherichia coli (EHEC) are a major cause of diarrheal illness in humans and can lead to severe complications such as hemolytic uremic syndrome. Cattle and other ruminants are the main reservoir of EHEC, which enters the food chain through contaminated meat, dairy, or vegetables. Here, we describe the establishment of a vertebrate model for foodborne EHEC infection, using larval zebrafish (Danio rerio) as a host and the protozoan prey Paramecium caudatum as a vehicle. We follow pathogen release from the vehicle, intestinal colonization, microbe-host interactions, and microbial gene induction within a live vertebrate host, in real time, throughout the course of infection. We demonstrate that foodborne EHEC colonizes the gastrointestinal tract faster and establishes a higher burden than waterborne infection. Expression of the locus of enterocyte effacement (LEE), a key EHEC virulence factor, was observed early during infection, mainly at sites that experience fluid shear, and required tight control to enable successful host colonization. EHEC infection led to strain- and LEE-dependent mortality in the zebrafish host. Despite the presence of the endogenous microbiota limiting EHEC colonization levels, EHEC colonization and virulence can be studied either under gnotobiotic conditions or against the backdrop of an endogenous (and variable) host microbiota. Finally, we show that the model can be used for investigation of factors affecting shedding and transmission of bacteria to naive hosts. Overall, this constitutes a useful model, which ideally complements the strengths of existing EHEC vertebrate models. IMPORTANCE Enterohemorrhagic Escherichia coli (EHEC) is a foodborne pathogen which can cause diarrhea, vomiting, and, in some cases, severe complications such as kidney failure in humans. Up to 30% of cattle are colonized with EHEC, which can enter the food chain through contaminated meat, dairy, and vegetables. In order to control infections and stop transmission, it is important to understand what factors allow EHEC to colonize its hosts, cause virulence, and aid transmission. Since this cannot be systematically studied in humans, it is important to develop animal models of infection and transmission. We developed a model which allows us to study foodborne infection in zebrafish, a vertebrate host that is transparent and genetically tractable. Our results show that foodborne infection is more efficient than waterborne infection and that the locus of enterocyte effacement is a key virulence determinant in the zebrafish model. It is induced early during infection, and loss of tight LEE regulation leads to a decreased bacterial burden and decreased host mortality. Overall, the zebrafish model allows us to study foodborne infection, including pathogen release from the food vehicle and gene regulation and its context of host-microbe interactions, as well as environmental shedding and transmission to naive hosts.
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28
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Evolution of biosynthetic diversity. Biochem J 2017; 474:2277-2299. [DOI: 10.1042/bcj20160823] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 04/20/2017] [Accepted: 04/24/2017] [Indexed: 12/16/2022]
Abstract
Since the emergence of the last common ancestor from which all extant life evolved, the metabolite repertoire of cells has increased and diversified. Not only has the metabolite cosmos expanded, but the ways in which the same metabolites are made have diversified. Enzymes catalyzing the same reaction have evolved independently from different protein folds; the same protein fold can produce enzymes recognizing different substrates, and enzymes performing different chemistries. Genes encoding useful enzymes can be transferred between organisms and even between the major domains of life. Organisms that live in metabolite-rich environments sometimes lose the pathways that produce those same metabolites. Fusion of different protein domains results in enzymes with novel properties. This review will consider the major evolutionary mechanisms that generate biosynthetic diversity: gene duplication (and gene loss), horizontal and endosymbiotic gene transfer, and gene fusion. It will also discuss mechanisms that lead to convergence as well as divergence. To illustrate these mechanisms, one of the original metabolisms present in the last universal common ancestor will be employed: polyamine metabolism, which is essential for the growth and cell proliferation of archaea and eukaryotes, and many bacteria.
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Nishida T, Watanabe K, Tachibana M, Shimizu T, Watarai M. Characterization of the cryptic plasmid pOfk55 from Legionella pneumophila and construction of a pOfk55-derived shuttle vector. Plasmid 2017; 90:30-37. [DOI: 10.1016/j.plasmid.2017.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/21/2017] [Accepted: 02/27/2017] [Indexed: 11/29/2022]
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