1
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Morel-Letelier I, Yuen B, Kück AC, Camacho-García YE, Petersen JM, Lara M, Leray M, Eisen JA, Osvatic JT, Gros O, Wilkins LGE. Adaptations to nitrogen availability drive ecological divergence of chemosynthetic symbionts. PLoS Genet 2024; 20:e1011295. [PMID: 38820540 PMCID: PMC11168628 DOI: 10.1371/journal.pgen.1011295] [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: 11/17/2023] [Revised: 06/12/2024] [Accepted: 05/08/2024] [Indexed: 06/02/2024] Open
Abstract
Bacterial symbionts, with their shorter generation times and capacity for horizontal gene transfer (HGT), play a critical role in allowing marine organisms to cope with environmental change. The closure of the Isthmus of Panama created distinct environmental conditions in the Tropical Eastern Pacific (TEP) and Caribbean, offering a "natural experiment" for studying how closely related animals evolve and adapt under environmental change. However, the role of bacterial symbionts in this process is often overlooked. We sequenced the genomes of endosymbiotic bacteria in two sets of sister species of chemosymbiotic bivalves from the genera Codakia and Ctena (family Lucinidae) collected on either side of the Isthmus, to investigate how differing environmental conditions have influenced the selection of symbionts and their metabolic capabilities. The lucinid sister species hosted different Candidatus Thiodiazotropha symbionts and only those from the Caribbean had the genetic potential for nitrogen fixation, while those from the TEP did not. Interestingly, this nitrogen-fixing ability did not correspond to symbiont phylogeny, suggesting convergent evolution of nitrogen fixation potential under nutrient-poor conditions. Reconstructing the evolutionary history of the nifHDKT operon by including other lucinid symbiont genomes from around the world further revealed that the last common ancestor (LCA) of Ca. Thiodiazotropha lacked nif genes, and populations in oligotrophic habitats later re-acquired the nif operon through HGT from the Sedimenticola symbiont lineage. Our study suggests that HGT of the nif operon has facilitated niche diversification of the globally distributed Ca. Thiodiazotropha endolucinida species clade. It highlights the importance of nitrogen availability in driving the ecological diversification of chemosynthetic symbiont species and the role that bacterial symbionts may play in the adaptation of marine organisms to changing environmental conditions.
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Affiliation(s)
- Isidora Morel-Letelier
- Eco-Evolutionary Interactions Group, Max Planck Institute for Marine Microbiology (MPIMM), Bremen, Germany
| | - Benedict Yuen
- Eco-Evolutionary Interactions Group, Max Planck Institute for Marine Microbiology (MPIMM), Bremen, Germany
| | - A. Carlotta Kück
- Eco-Evolutionary Interactions Group, Max Planck Institute for Marine Microbiology (MPIMM), Bremen, Germany
| | - Yolanda E. Camacho-García
- Centro de Investigación en Ciencias del Mar y Limnología (CIMAR), Universidad de Costa Rica, San Pedro, San José, Costa Rica
- Centro de Investigación en Biodiversidad y Ecología Tropical (CIBET), Universidad de Costa Rica, San Pedro, San José, Costa Rica
- Escuela de Biología, Universidad de Costa Rica, San Pedro, San José, Costa Rica
| | - Jillian M. Petersen
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Minor Lara
- Diving Center Cuajiniquil, Provincia de Guanacaste, Cuajiniquil, Costa Rica
| | - Matthieu Leray
- Smithsonian Tropical Research Institute, Balboa, Ancon, Republic of Panamá
| | - Jonathan A. Eisen
- Department of Evolution and Ecology, University of California, Davis, Davis, California, United States of America
- Department of Medical Microbiology and Immunology, University of California, Davis, Davis, California, United States of America
| | - Jay T. Osvatic
- Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, Vienna, Austria
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Olivier Gros
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum National d’Histoire Naturelle, CNRS, Sorbonne Université, Université des Antilles, Pointe-à-Pitre, France
| | - Laetitia G. E. Wilkins
- Eco-Evolutionary Interactions Group, Max Planck Institute for Marine Microbiology (MPIMM), Bremen, Germany
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2
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Logares R. Decoding populations in the ocean microbiome. MICROBIOME 2024; 12:67. [PMID: 38561814 PMCID: PMC10983722 DOI: 10.1186/s40168-024-01778-0] [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: 09/27/2023] [Accepted: 02/12/2024] [Indexed: 04/04/2024]
Abstract
Understanding the characteristics and structure of populations is fundamental to comprehending ecosystem processes and evolutionary adaptations. While the study of animal and plant populations has spanned a few centuries, microbial populations have been under scientific scrutiny for a considerably shorter period. In the ocean, analyzing the genetic composition of microbial populations and their adaptations to multiple niches can yield important insights into ecosystem function and the microbiome's response to global change. However, microbial populations have remained elusive to the scientific community due to the challenges associated with isolating microorganisms in the laboratory. Today, advancements in large-scale metagenomics and metatranscriptomics facilitate the investigation of populations from many uncultured microbial species directly from their habitats. The knowledge acquired thus far reveals substantial genetic diversity among various microbial species, showcasing distinct patterns of population differentiation and adaptations, and highlighting the significant role of selection in structuring populations. In the coming years, population genomics is expected to significantly increase our understanding of the architecture and functioning of the ocean microbiome, providing insights into its vulnerability or resilience in the face of ongoing global change. Video Abstract.
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Affiliation(s)
- Ramiro Logares
- Institute of Marine Sciences (ICM), CSIC, Barcelona, Catalonia, 08003, Spain.
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3
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Stanojković A, Skoupý S, Johannesson H, Dvořák P. The global speciation continuum of the cyanobacterium Microcoleus. Nat Commun 2024; 15:2122. [PMID: 38459017 PMCID: PMC10923798 DOI: 10.1038/s41467-024-46459-6] [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: 07/10/2023] [Accepted: 02/27/2024] [Indexed: 03/10/2024] Open
Abstract
Speciation is a continuous process driven by genetic, geographic, and ecological barriers to gene flow. It is widely investigated in multicellular eukaryotes, yet we are only beginning to comprehend the relative importance of mechanisms driving the emergence of barriers to gene flow in microbial populations. Here, we explored the diversification of the nearly ubiquitous soil cyanobacterium Microcoleus. Our dataset consisted of 291 genomes, of which 202 strains and eight herbarium specimens were sequenced for this study. We found that Microcoleus represents a global speciation continuum of at least 12 lineages, which radiated during Eocene/Oligocene aridification and exhibit varying degrees of divergence and gene flow. The lineage divergence has been driven by selection, geographical distance, and the environment. Evidence of genetic divergence and selection was widespread across the genome, but we identified regions of exceptional differentiation containing candidate genes associated with stress response and biosynthesis of secondary metabolites.
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Affiliation(s)
- Aleksandar Stanojković
- Palacký University Olomouc, Faculty of Sciences, Department of Botany, Olomouc, Czech Republic
| | - Svatopluk Skoupý
- Palacký University Olomouc, Faculty of Sciences, Department of Botany, Olomouc, Czech Republic
| | - Hanna Johannesson
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
- The Royal Swedish Academy of Sciences, Stockholm, Sweden
| | - Petr Dvořák
- Palacký University Olomouc, Faculty of Sciences, Department of Botany, Olomouc, Czech Republic.
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4
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Labutin A, Heckel G. Genome-wide support for incipient Tula hantavirus species within a single rodent host lineage. Virus Evol 2024; 10:veae002. [PMID: 38361825 PMCID: PMC10868551 DOI: 10.1093/ve/veae002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 11/08/2023] [Accepted: 01/04/2024] [Indexed: 02/17/2024] Open
Abstract
Evolutionary divergence of viruses is most commonly driven by co-divergence with their hosts or through isolation of transmission after host shifts. It remains mostly unknown, however, whether divergent phylogenetic clades within named virus species represent functionally equivalent byproducts of high evolutionary rates or rather incipient virus species. Here, we test these alternatives with genomic data from two widespread phylogenetic clades in Tula orthohantavirus (TULV) within a single evolutionary lineage of their natural rodent host, the common vole Microtus arvalis. We examined voles from forty-two locations in the contact region between clades for TULV infection by reverse transcription (RT)-PCR. Sequencing yielded twenty-three TULV Central North and twenty-one TULV Central South genomes, which differed by 14.9-18.5 per cent at the nucleotide and 2.2-3.7 per cent at the amino acid (AA) level without evidence of recombination or reassortment between clades. Geographic cline analyses demonstrated an abrupt (<1 km wide) transition between the parapatric TULV clades in continuous landscape. This transition was located within the Central mitochondrial lineage of M. arvalis, and genomic single nucleotide polymorphisms showed gradual mixing of host populations across it. Genomic differentiation of hosts was much weaker across the TULV Central North to South transition than across the nearby hybrid zone between two evolutionary lineages in the host. We suggest that these parapatric TULV clades represent functionally distinct, incipient species, which are likely differently affected by genetic polymorphisms in the host. This highlights the potential of natural viral contact zones as systems for investigating the genetic and evolutionary factors enabling or restricting the transmission of RNA viruses.
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Affiliation(s)
- Anton Labutin
- Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, Bern 3012, Switzerland
| | - Gerald Heckel
- Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, Bern 3012, Switzerland
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5
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Power JF, Carere CR, Welford HE, Hudson DT, Lee KC, Moreau JW, Ettema TJG, Reysenbach AL, Lee CK, Colman DR, Boyd ES, Morgan XC, McDonald IR, Craig Cary S, Stott MB. A genus in the bacterial phylum Aquificota appears to be endemic to Aotearoa-New Zealand. Nat Commun 2024; 15:179. [PMID: 38167814 PMCID: PMC10762115 DOI: 10.1038/s41467-023-43960-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 11/24/2023] [Indexed: 01/05/2024] Open
Abstract
Allopatric speciation has been difficult to examine among microorganisms, with prior reports of endemism restricted to sub-genus level taxa. Previous microbial community analysis via 16S rRNA gene sequencing of 925 geothermal springs from the Taupō Volcanic Zone (TVZ), Aotearoa-New Zealand, revealed widespread distribution and abundance of a single bacterial genus across 686 of these ecosystems (pH 1.2-9.6 and 17.4-99.8 °C). Here, we present evidence to suggest that this genus, Venenivibrio (phylum Aquificota), is endemic to Aotearoa-New Zealand. A specific environmental niche that increases habitat isolation was identified, with maximal read abundance of Venenivibrio occurring at pH 4-6, 50-70 °C, and low oxidation-reduction potentials. This was further highlighted by genomic and culture-based analyses of the only characterised species for the genus, Venenivibrio stagnispumantis CP.B2T, which confirmed a chemolithoautotrophic metabolism dependent on hydrogen oxidation. While similarity between Venenivibrio populations illustrated that dispersal is not limited across the TVZ, extensive amplicon, metagenomic, and phylogenomic analyses of global microbial communities from DNA sequence databases indicates Venenivibrio is geographically restricted to the Aotearoa-New Zealand archipelago. We conclude that geographic isolation, complemented by physicochemical constraints, has resulted in the establishment of an endemic bacterial genus.
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Affiliation(s)
- Jean F Power
- Thermophile Research Unit, Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, 3240, Aotearoa New Zealand
| | - Carlo R Carere
- Te Tari Pūhanga Tukanga Matū | Department of Chemical and Process Engineering, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, 8140, Aotearoa New Zealand
| | - Holly E Welford
- Te Kura Pūtaiao Koiora | School of Biological Sciences, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, 8140, Aotearoa New Zealand
| | - Daniel T Hudson
- Te Tari Moromoroiti me te Ārai Mate | Department of Microbiology and Immunology, Te Whare Wānanga o Ōtākou | University of Otago, Dunedin, 9054, Aotearoa New Zealand
| | - Kevin C Lee
- Te Kura Pūtaiao | School of Science, Te Wānanga Aronui o Tāmaki Makau Rau | Auckland University of Technology, Auckland, 1010, Aotearoa New Zealand
| | - John W Moreau
- School of Geographical & Earth Sciences, University of Glasgow, Glasgow, G12 8RZ, UK
| | - Thijs J G Ettema
- Laboratory of Microbiology, Wageningen University & Research, 6708, WE, Wageningen, the Netherlands
| | | | - Charles K Lee
- Thermophile Research Unit, Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, 3240, Aotearoa New Zealand
| | - Daniel R Colman
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, 59717, USA
| | - Eric S Boyd
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, 59717, USA
| | - Xochitl C Morgan
- Te Tari Moromoroiti me te Ārai Mate | Department of Microbiology and Immunology, Te Whare Wānanga o Ōtākou | University of Otago, Dunedin, 9054, Aotearoa New Zealand
- Department of Biostatistics, Harvard T. H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Ian R McDonald
- Thermophile Research Unit, Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, 3240, Aotearoa New Zealand
| | - S Craig Cary
- Thermophile Research Unit, Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, 3240, Aotearoa New Zealand.
| | - Matthew B Stott
- Te Kura Pūtaiao Koiora | School of Biological Sciences, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, 8140, Aotearoa New Zealand.
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6
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Haider D, Hall MW, LaRoche J, Beiko RG. Mock microbial community meta-analysis using different trimming of amplicon read lengths. Environ Microbiol 2024; 26:e16566. [PMID: 38149467 DOI: 10.1111/1462-2920.16566] [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: 06/18/2023] [Accepted: 12/12/2023] [Indexed: 12/28/2023]
Abstract
Trimming of sequencing reads is a pre-processing step that aims to discard sequence segments such as primers, adapters and low quality nucleotides that will interfere with clustering and classification steps. We evaluated the impact of trimming length of paired-end 16S and 18S rRNA amplicon reads on the ability to reconstruct the taxonomic composition and relative abundances of communities with a known composition in both even and uneven proportions. We found that maximizing read retention maximizes recall but reduces precision by increasing false positives. The presence of expected taxa was accurately predicted across broad trim length ranges but recovering original relative proportions remains a difficult challenge. We show that parameters that maximize taxonomic recovery do not simultaneously maximize relative abundance accuracy. Trim length represents one of several experimental parameters that have non-uniform impact across microbial clades, making it a difficult parameter to optimize. This study offers insights, guidelines, and helps researchers assess the significance of their decisions when trimming raw reads in a microbiome analysis based on overlapping or non-overlapping paired-end amplicons.
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Affiliation(s)
- Diana Haider
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Faculty of Computer Science, Dalhousie University, Halifax, Nova Scotia, Canada
- Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Michael W Hall
- Faculty of Computer Science, Dalhousie University, Halifax, Nova Scotia, Canada
- Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Julie LaRoche
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Robert G Beiko
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia, Canada
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7
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Pold G, Bonilla-Rosso G, Saghaï A, Strous M, Jones CM, Hallin S. Phylogenetics and environmental distribution of nitric oxide-forming nitrite reductases reveal their distinct functional and ecological roles. ISME COMMUNICATIONS 2024; 4:ycae020. [PMID: 38584645 PMCID: PMC10999283 DOI: 10.1093/ismeco/ycae020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/16/2024] [Accepted: 01/29/2024] [Indexed: 04/09/2024]
Abstract
The two evolutionarily unrelated nitric oxide-producing nitrite reductases, NirK and NirS, are best known for their redundant role in denitrification. They are also often found in organisms that do not perform denitrification. To assess the functional roles of the two enzymes and to address the sequence and structural variation within each, we reconstructed robust phylogenies of both proteins with sequences recovered from 6973 isolate and metagenome-assembled genomes and identified 32 well-supported clades of structurally distinct protein lineages. We then inferred the potential niche of each clade by considering other functional genes of the organisms carrying them as well as the relative abundances of each nir gene in 4082 environmental metagenomes across diverse aquatic, terrestrial, host-associated, and engineered biomes. We demonstrate that Nir phylogenies recapitulate ecology distinctly from the corresponding organismal phylogeny. While some clades of the nitrite reductase were equally prevalent across biomes, others had more restricted ranges. Nitrifiers make up a sizeable proportion of the nitrite-reducing community, especially for NirK in marine waters and dry soils. Furthermore, the two reductases showed distinct associations with genes involved in oxidizing and reducing other compounds, indicating that the NirS and NirK activities may be linked to different elemental cycles. Accordingly, the relative abundance and diversity of NirS versus NirK vary between biomes. Our results show the divergent ecological roles NirK and NirS-encoding organisms may play in the environment and provide a phylogenetic framework to distinguish the traits associated with organisms encoding the different lineages of nitrite reductases.
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Affiliation(s)
- Grace Pold
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
| | - Germán Bonilla-Rosso
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
| | - Aurélien Saghaï
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
| | - Marc Strous
- Department of Earth, Energy, and Environment, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
| | - Christopher M Jones
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
| | - Sara Hallin
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
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8
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Joglekar P, Conlan S, Lee-Lin SQ, Deming C, Kashaf SS, Kong HH, Segre JA. Integrated genomic and functional analyses of human skin-associated Staphylococcus reveal extensive inter- and intra-species diversity. Proc Natl Acad Sci U S A 2023; 120:e2310585120. [PMID: 37956283 PMCID: PMC10666031 DOI: 10.1073/pnas.2310585120] [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: 07/04/2023] [Accepted: 10/11/2023] [Indexed: 11/15/2023] Open
Abstract
Human skin is stably colonized by a distinct microbiota that functions together with epidermal cells to maintain a protective physical barrier. Staphylococcus, a prominent genus of the skin microbiota, participates in colonization resistance, tissue repair, and host immune regulation in strain-specific manners. To unlock the potential of engineering skin microbial communities, we aim to characterize the diversity of this genus within the context of the skin environment. We reanalyzed an extant 16S rRNA amplicon dataset obtained from distinct body sites of healthy volunteers, providing a detailed biogeographic depiction of staphylococcal species that colonize our skin. S. epidermidis, S. capitis, and S. hominis were the most abundant staphylococcal species present in all volunteers and were detected at all body sites. Pan-genome analysis of isolates from these three species revealed that the genus-core was dominated by central metabolism genes. Species-restricted-core genes encoded known host colonization functions. The majority (~68%) of genes were detected only in a fraction of isolate genomes, underscoring the immense strain-specific gene diversity. Conspecific genomes grouped into phylogenetic clades, exhibiting body site preference. Each clade was enriched for distinct gene sets that are potentially involved in site tropism. Finally, we conducted gene expression studies of select isolates showing variable growth phenotypes in skin-like medium. In vitro expression revealed extensive intra- and inter-species gene expression variation, substantially expanding the functional diversification within each species. Our study provides an important resource for future ecological and translational studies to examine the role of shared and strain-specific staphylococcal genes within the skin environment.
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Affiliation(s)
- Payal Joglekar
- Microbial Genomics Section, Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD20892
| | - Sean Conlan
- Microbial Genomics Section, Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD20892
| | - Shih-Queen Lee-Lin
- Microbial Genomics Section, Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD20892
| | - Clay Deming
- Microbial Genomics Section, Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD20892
| | - Sara Saheb Kashaf
- Microbial Genomics Section, Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD20892
| | | | - Heidi H. Kong
- Cutaneous Microbiome and Inflammation Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD20892
| | - Julia A. Segre
- Microbial Genomics Section, Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD20892
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9
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Joglekar P, Conlan S, Lee-Lin SQ, Deming C, Kashaf SS, Kong HH, Segre JA. Integrated genomic and functional analyses of human skin-associated Staphylococcus reveals extensive inter- and intra-species diversity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.22.546190. [PMID: 37503282 PMCID: PMC10370188 DOI: 10.1101/2023.06.22.546190] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Human skin is stably colonized by a distinct microbiota that functions together with epidermal cells to maintain a protective physical barrier. Staphylococcus, a prominent genus of the skin microbiota, participates in colonization resistance, tissue repair, and host immune regulation in strain specific manners. To unlock the potential of engineering skin microbial communities, we aim to fully characterize the functional diversity of this genus within the context of the skin environment. We conducted metagenome and pan-genome analyses of isolates obtained from distinct body sites of healthy volunteers, providing a detailed biogeographic depiction of staphylococcal species that colonize our skin. S. epidermidis, S. capitis, and S. hominis were the most abundant species present in all volunteers and were detected at all body sites. Pan-genome analysis of these three species revealed that the genus-core was dominated by central metabolism genes. Species-specific core genes were enriched in host colonization functions. The majority (~68%) of genes were detected only in a fraction of isolate genomes, underscoring the immense strain-specific gene diversity. Conspecific genomes grouped into phylogenetic clades, exhibiting body site preference. Each clade was enriched for distinct gene-sets that are potentially involved in site tropism. Finally, we conducted gene expression studies of select isolates showing variable growth phenotypes in skin-like medium. In vitro expression revealed extensive intra- and inter-species gene expression variation, substantially expanding the functional diversification within each species. Our study provides an important resource for future ecological and translational studies to examine the role of shared and strain-specific staphylococcal genes within the skin environment.
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Affiliation(s)
- Payal Joglekar
- Microbial Genomics Section, Translational and Functional Genomics Branch, NHGRI, NIH, Bethesda, Maryland, USA
| | - Sean Conlan
- Microbial Genomics Section, Translational and Functional Genomics Branch, NHGRI, NIH, Bethesda, Maryland, USA
| | - Shih-Queen Lee-Lin
- Microbial Genomics Section, Translational and Functional Genomics Branch, NHGRI, NIH, Bethesda, Maryland, USA
| | - Clay Deming
- Microbial Genomics Section, Translational and Functional Genomics Branch, NHGRI, NIH, Bethesda, Maryland, USA
| | - Sara Saheb Kashaf
- Microbial Genomics Section, Translational and Functional Genomics Branch, NHGRI, NIH, Bethesda, Maryland, USA
| | | | - Heidi H. Kong
- Cutaneous Microbiome and Inflammation Section, NIAMS, NIH, Bethesda, Maryland, USA
| | - Julia A. Segre
- Microbial Genomics Section, Translational and Functional Genomics Branch, NHGRI, NIH, Bethesda, Maryland, USA
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10
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Kamptonema animale (Microcoleaceae), terrestrial cyanobacterium colonizing geoglossoid fungi (Central Slovakia). Biologia (Bratisl) 2023. [DOI: 10.1007/s11756-023-01367-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
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11
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Strachan CR, Yu XA, Neubauer V, Mueller AJ, Wagner M, Zebeli Q, Selberherr E, Polz MF. Differential carbon utilization enables co-existence of recently speciated Campylobacteraceae in the cow rumen epithelial microbiome. Nat Microbiol 2023; 8:309-320. [PMID: 36635570 PMCID: PMC9894753 DOI: 10.1038/s41564-022-01300-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 12/05/2022] [Indexed: 01/14/2023]
Abstract
The activities of different microbes in the cow rumen have been shown to modulate the host's ability to utilize plant biomass, while the host-rumen interface has received little attention. As datasets collected worldwide have pointed to Campylobacteraceae as particularly abundant members of the rumen epithelial microbiome, we targeted this group in a subset of seven cows with meta- and isolate genome analysis. We show that the dominant Campylobacteraceae lineage has recently speciated into two populations that were structured by genome-wide selective sweeps followed by population-specific gene import and recombination. These processes led to differences in gene expression and enzyme domain composition that correspond to the ability to utilize acetate, the main carbon source for the host, at the cost of inhibition by propionate. This trade-off in competitive ability further manifests itself in differential dynamics of the two populations in vivo. By exploring population-level adaptations that otherwise remain cryptic in culture-independent analyses, our results highlight how recent evolutionary dynamics can shape key functional roles in the rumen microbiome.
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Affiliation(s)
- Cameron R Strachan
- Institute of Food Safety, Food Technology and Veterinary Public Health, Department for Farm Animals and Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
- Austrian Competence Centre for Feed and Food Quality, Safety and Innovation FFoQSI GmbH, Tulln, Austria
| | - Xiaoqian A Yu
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Viktoria Neubauer
- Institute of Food Safety, Food Technology and Veterinary Public Health, Department for Farm Animals and Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
- Austrian Competence Centre for Feed and Food Quality, Safety and Innovation FFoQSI GmbH, Tulln, Austria
| | - Anna J Mueller
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
- University of Vienna, Doctoral School in Microbiology and Environmental Science, Vienna, Austria
| | - Martin Wagner
- Institute of Food Safety, Food Technology and Veterinary Public Health, Department for Farm Animals and Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
- Austrian Competence Centre for Feed and Food Quality, Safety and Innovation FFoQSI GmbH, Tulln, Austria
| | - Qendrim Zebeli
- Institute of Animal Nutrition and Functional Plant Compounds, Department for Farm Animals and Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
- Christian Doppler Laboratory for Innovative Gut Health Concepts of Livestock, Vienna, Austria
| | - Evelyne Selberherr
- Institute of Food Safety, Food Technology and Veterinary Public Health, Department for Farm Animals and Public Health, University of Veterinary Medicine Vienna, Vienna, Austria.
| | - Martin F Polz
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.
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12
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Stanojković A, Skoupý S, Škaloud P, Dvořák P. High genomic differentiation and limited gene flow indicate recent cryptic speciation within the genus Laspinema (cyanobacteria). Front Microbiol 2022; 13:977454. [PMID: 36160208 PMCID: PMC9500459 DOI: 10.3389/fmicb.2022.977454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/15/2022] [Indexed: 11/18/2022] Open
Abstract
The sympatric occurrence of closely related lineages displaying conserved morphological and ecological traits is often characteristic of free-living microbes. Gene flow, recombination, selection, and mutations govern the genetic variability between these cryptic lineages and drive their differentiation. However, sequencing conservative molecular markers (e.g., 16S rRNA) coupled with insufficient population-level sampling hindered the study of intra-species genetic diversity and speciation in cyanobacteria. We used phylogenomics and a population genomic approach to investigate the extent of local genomic diversity and the mechanisms underlying sympatric speciation of Laspinema thermale. We found two cryptic lineages of Laspinema. The lineages were highly genetically diverse, with recombination occurring more frequently within than between them. That suggests the existence of a barrier to gene flow, which further maintains divergence. Genomic regions of high population differentiation harbored genes associated with possible adaptations to high/low light conditions and stress stimuli, although with a weak diversifying selection. Overall, the diversification of Laspinema species might have been affected by both genomic and ecological processes.
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Affiliation(s)
| | - Svatopluk Skoupý
- Department of Botany, Faculty of Science, Palacký University Olomouc, Olomouc, Czechia
| | - Pavel Škaloud
- Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czechia
| | - Petr Dvořák
- Department of Botany, Faculty of Science, Palacký University Olomouc, Olomouc, Czechia
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13
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Relevance of prokaryotic subspecies in the age of genomics. New Microbes New Infect 2022; 48:101024. [PMID: 36176539 PMCID: PMC9513812 DOI: 10.1016/j.nmni.2022.101024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 08/13/2022] [Accepted: 08/22/2022] [Indexed: 11/20/2022] Open
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Coastal Transient Niches Shape the Microdiversity Pattern of a Bacterioplankton Population with Reduced Genomes. mBio 2022; 13:e0057122. [PMID: 35880883 PMCID: PMC9426536 DOI: 10.1128/mbio.00571-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Globally dominant marine bacterioplankton lineages are often limited in metabolic versatility, owing to their extensive genome reductions, and thus cannot take advantage of transient nutrient patches. It is therefore perplexing how the nutrient-poor bulk seawater sustains the pelagic streamlined lineages, each containing numerous populations. Here, we sequenced the genomes of 33 isolates of the recently discovered CHUG lineage (~2.6 Mbp), which have some of the smallest genomes in the globally abundant Roseobacter group (commonly over 4 Mbp). These genome-reduced bacteria were isolated from a transient habitat: seawater surrounding the brown alga, Sargassum hemiphyllum. Population genomic analyses showed that: (i) these isolates, despite sharing identical 16S rRNA genes, were differentiated into several genetically isolated populations through successive speciation events; (ii) only the first speciation event led to the genetic separation of both core and accessory genomes; and (iii) populations resulting from this event are differentiated at many loci involved in carbon utilization and oxygen respiration, corroborated by BiOLOG phenotype microarray assays and oxygen uptake kinetics experiments, respectively. These differentiated traits match well with the dynamic nature of the macroalgal seawater, in which the quantity and quality of carbon sources and the concentration of oxygen likely vary spatially and temporally, though other habitats, like fresh organic aggregates, cannot be ruled out. Our study implies that transient habitats in the overall nutrient-poor ocean can shape the microdiversity and population structure of genome-reduced bacterioplankton lineages.
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15
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Habitat Adaptation Drives Speciation of a Streptomyces Species with Distinct Habitats and Disparate Geographic Origins. mBio 2022; 13:e0278121. [PMID: 35012331 PMCID: PMC8749437 DOI: 10.1128/mbio.02781-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Microbial diversification is driven by geographic and ecological factors, but how the relative importance of these factors varies among species, geographic scales, and habitats remains unclear. Streptomyces, a genus of antibiotic-producing, spore-forming, and widespread bacteria, offers a robust model for identifying the processes underlying population differentiation. We examined the population structure of 37 Streptomyces olivaceus strains isolated from various sources, showing that they diverged into two habitat-associated (free-living and insect-associated) and geographically disparate lineages. More frequent gene flow within than between the lineages confirmed genetic isolation in S. olivaceus. Geographic isolation could not explain the genetic isolation; instead, habitat type was a strong predictor of genetic distance when controlling for geographic distance. The identification of habitat-specific genetic variations, including genes involved in regulation, resource use, and secondary metabolism, suggested a significant role of habitat adaptation in the diversification process. Physiological assays revealed fitness trade-offs under different environmental conditions in the two lineages. Notably, insect-associated isolates could outcompete free-living isolates in a free-iron-deficient environment. Furthermore, substrate (e.g., sialic acid and glycogen) utilization but not thermal traits differentiated the two lineages. Overall, our results argue that adaptive processes drove ecological divergence among closely related streptomycetes, eventually leading to dispersal limitation and gene flow barriers between the lineages. S. olivaceus may best be considered a species complex consisting of two cryptic species. IMPORTANCE Both isolation by distance and isolation by environment occur in bacteria, and different diversification patterns may apply to different species. Streptomyces species, typified by producing useful natural products, are widespread in nature and possess high genetic diversity. However, the ecological processes and evolutionary mechanisms that shape their distribution are not well understood. Here, we show that the population structure of a ubiquitous Streptomyces species complex matches its habitat distribution and can be defined by gene flow discontinuities. Using comparative genomics and physiological assays, we reveal that gains and losses of specific genomic traits play a significant role in the transition between free-living and host-associated lifestyles, driving speciation of the species. These results provide new insights into the evolutionary trajectory of Streptomyces and the notion of species.
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16
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Qiu J, Zhou Q, Ye W, Chen Q, Bao YJ. SweepCluster: A SNP clustering tool for detecting gene-specific sweeps in prokaryotes. BMC Bioinformatics 2022; 23:19. [PMID: 34991447 PMCID: PMC8734265 DOI: 10.1186/s12859-021-04533-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 12/13/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The gene-specific sweep is a selection process where an advantageous mutation along with the nearby neutral sites in a gene region increases the frequency in the population. It has been demonstrated to play important roles in ecological differentiation or phenotypic divergence in microbial populations. Therefore, identifying gene-specific sweeps in microorganisms will not only provide insights into the evolutionary mechanisms, but also unravel potential genetic markers associated with biological phenotypes. However, current methods were mainly developed for detecting selective sweeps in eukaryotic data of sparse genotypes and are not readily applicable to prokaryotic data. Furthermore, some challenges have not been sufficiently addressed by the methods, such as the low spatial resolution of sweep regions and lack of consideration of the spatial distribution of mutations. RESULTS We proposed a novel gene-centric and spatial-aware approach for identifying gene-specific sweeps in prokaryotes and implemented it in a python tool SweepCluster. Our method searches for gene regions with a high level of spatial clustering of pre-selected polymorphisms in genotype datasets assuming a null distribution model of neutral selection. The pre-selection of polymorphisms is based on their genetic signatures, such as elevated population subdivision, excessive linkage disequilibrium, or significant phenotype association. Performance evaluation using simulation data showed that the sensitivity and specificity of the clustering algorithm in SweepCluster is above 90%. The application of SweepCluster in two real datasets from the bacteria Streptococcus pyogenes and Streptococcus suis showed that the impact of pre-selection was dramatic and significantly reduced the uninformative signals. We validated our method using the genotype data from Vibrio cyclitrophicus, the only available dataset of gene-specific sweeps in bacteria, and obtained a concordance rate of 78%. We noted that the concordance rate could be underestimated due to distinct reference genomes and clustering strategies. The application to the human genotype datasets showed that SweepCluster is also applicable to eukaryotic data and is able to recover 80% of a catalog of known sweep regions. CONCLUSION SweepCluster is applicable to a broad category of datasets. It will be valuable for detecting gene-specific sweeps in diverse genotypic data and provide novel insights on adaptive evolution.
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Affiliation(s)
- Junhui Qiu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Qi Zhou
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Weicai Ye
- School of Computer Science and Engineering, Guangdong Province Key Laboratory of Computational Science, and National Engineering Laboratory for Big Data Analysis and Application, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Qianjun Chen
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, 430062, China.
| | - Yun-Juan Bao
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, 430062, China.
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17
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Rodríguez-Gijón A, Nuy JK, Mehrshad M, Buck M, Schulz F, Woyke T, Garcia SL. A Genomic Perspective Across Earth's Microbiomes Reveals That Genome Size in Archaea and Bacteria Is Linked to Ecosystem Type and Trophic Strategy. Front Microbiol 2022; 12:761869. [PMID: 35069467 PMCID: PMC8767057 DOI: 10.3389/fmicb.2021.761869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 12/15/2021] [Indexed: 01/09/2023] Open
Abstract
Our view of genome size in Archaea and Bacteria has remained skewed as the data has been dominated by genomes of microorganisms that have been cultivated under laboratory settings. However, the continuous effort to catalog Earth's microbiomes, specifically propelled by recent extensive work on uncultivated microorganisms, provides an opportunity to revise our perspective on genome size distribution. We present a meta-analysis that includes 26,101 representative genomes from 3 published genomic databases; metagenomic assembled genomes (MAGs) from GEMs and stratfreshDB, and isolates from GTDB. Aquatic and host-associated microbial genomes present on average the smallest estimated genome sizes (3.1 and 3.0 Mbp, respectively). These are followed by terrestrial microbial genomes (average 3.7 Mbp), and genomes from isolated microorganisms (average 4.3 Mbp). On the one hand, aquatic and host-associated ecosystems present smaller genomes sizes in genera of phyla with genome sizes above 3 Mbp. On the other hand, estimated genome size in phyla with genomes under 3 Mbp showed no difference between ecosystems. Moreover, we observed that when using 95% average nucleotide identity (ANI) as an estimator for genetic units, only 3% of MAGs cluster together with genomes from isolated microorganisms. Although there are potential methodological limitations when assembling and binning MAGs, we found that in genome clusters containing both environmental MAGs and isolate genomes, MAGs were estimated only an average 3.7% smaller than isolate genomes. Even when assembly and binning methods introduce biases, estimated genome size of MAGs and isolates are very similar. Finally, to better understand the ecological drivers of genome size, we discuss on the known and the overlooked factors that influence genome size in different ecosystems, phylogenetic groups, and trophic strategies.
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Affiliation(s)
- Alejandro Rodríguez-Gijón
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Julia K. Nuy
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Maliheh Mehrshad
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Moritz Buck
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | - Tanja Woyke
- DOE Joint Genome Institute, Berkeley, CA, United States
| | - Sarahi L. Garcia
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
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18
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Birkholz N, Jackson SA, Fagerlund RD, Fineran P. OUP accepted manuscript. Nucleic Acids Res 2022; 50:3348-3361. [PMID: 35286398 PMCID: PMC8989522 DOI: 10.1093/nar/gkac147] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/14/2022] [Accepted: 02/17/2022] [Indexed: 11/16/2022] Open
Abstract
Epigenetic DNA methylation plays an important role in bacteria by influencing gene expression and allowing discrimination between self-DNA and intruders such as phages and plasmids. Restriction–modification (RM) systems use a methyltransferase (MTase) to modify a specific sequence motif, thus protecting host DNA from cleavage by a cognate restriction endonuclease (REase) while leaving invading DNA vulnerable. Other REases occur solitarily and cleave methylated DNA. REases and RM systems are frequently mobile, influencing horizontal gene transfer by altering the compatibility of the host for foreign DNA uptake. However, whether mobile defence systems affect pre-existing host defences remains obscure. Here, we reveal an epigenetic conflict between an RM system (PcaRCI) and a methylation-dependent REase (PcaRCII) in the plant pathogen Pectobacterium carotovorum RC5297. The PcaRCI RM system provides potent protection against unmethylated plasmids and phages, but its methylation motif is targeted by the methylation-dependent PcaRCII. This potentially lethal co-existence is enabled through epigenetic silencing of the PcaRCII-encoding gene via promoter methylation by the PcaRCI MTase. Comparative genome analyses suggest that the PcaRCII-encoding gene was already present and was silenced upon establishment of the PcaRCI system. These findings provide a striking example for selfishness of RM systems and intracellular competition between different defences.
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Affiliation(s)
- Nils Birkholz
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Bioprotection Aotearoa, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Simon A Jackson
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Bioprotection Aotearoa, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Genetics Otago, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Robert D Fagerlund
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Bioprotection Aotearoa, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Genetics Otago, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Peter C Fineran
- To whom correspondence should be addressed: Tel: +64 3 479 7735;
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19
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Lin X, McNichol J, Chu X, Qian Y, Luo H. Cryptic niche differentiation of novel sediment ecotypes of Rugeria pomeroyi correlates with nitrate respiration. Environ Microbiol 2021; 24:390-403. [PMID: 34964547 DOI: 10.1111/1462-2920.15882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 10/19/2022]
Abstract
Marine intertidal sediments fluctuate in redox conditions and nutrient availability, and they are also known as an important sink of nitrogen mainly through denitrification, yet how denitrifying bacteria adapt to this dynamic habitat remains largely untapped. Here, we investigated novel intertidal benthic ecotypes of the model pelagic marine bacterium Ruegeria pomeroyi DSS-3 with a population genomic approach. While differing by only 1.3% at the 16S rRNA gene level, members of the intertidal benthic ecotypes are complete denitrifiers whereas the pelagic ecotype representative (DSS-3) is a partial denitrifier lacking a nitrate reductase. The intertidal benthic ecotypes are further differentiated by using non-homologous nitrate reductases and a different set of genes that allow alleviating oxidative stress and acquiring organic substrates. In the presence of nitrate, the two ecotypes showed contrasting growth patterns under initial oxygen concentrations at 1 vol% versus 7 vol% and supplemented with different carbon sources abundant in intertidal sediments. Collectively, this combination of evidence indicates that there are cryptic niches in coastal intertidal sediments that support divergent evolution of denitrifying bacteria. This knowledge will in turn help understand how these benthic environments operate to effectively remove nitrogen.
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Affiliation(s)
- Xingqin Lin
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518000, China
| | - Jesse McNichol
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR
| | - Xiao Chu
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR
| | - Yang Qian
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR
| | - Haiwei Luo
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518000, China.,Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR
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20
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Metagenomic outlooks of microbial dynamics influenced by organic manure in tea garden soils of North Bengal, India. Arch Microbiol 2021; 204:33. [PMID: 34923604 DOI: 10.1007/s00203-021-02635-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 10/19/2022]
Abstract
Soil microbial diversity consisted of both culturable and non-culturable microbes. The cultivated microbes can be identified by conventional microbiological processes. However, that is not possible for the non-culturable ones. In those cases, next-generation sequencing (NGS)-based metagenomics become useful. In this study, we targeted two very popular tea gardens of Darjeeling hills-Makaibari (Mak) and Castleton (Cas). The main difference between these two study areas is the type of manure they use. Mak is solely an organic tea garden using all organic manure and fertilizers whereas Cas uses inorganic pesticides and fertilizers. The main aim was to compare the effect of organic manure over chemical fertilizers on the soil microbiomes. We have performed the 16 s metagenomics analysis based on the V3-V4 region. Downstream bioinformatics analysis including reverse ecology was performed. We found that the overall microbial diversity is higher in Mak compared to Cas. Moreover, the use of organic manure has reduced the population of pathogenic bacteria in Mak soil when compared to Cas soil. From the observations made through the metagenomics analysis of Mak and Cas soil samples, we may conclude that the application of organic manure supports the population of good bacteria in the soil which may eventually impact the tea garden workers' health.
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21
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Ibrahim S, Li K, Ahmad N, Kuang L, Sadau SB, Tian Z, Huang L, Wang X, Dun X, Wang H. Genetic Dissection of Mature Root Characteristics by Genome-Wide Association Studies in Rapeseed ( Brassica napus L.). PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10122569. [PMID: 34961040 PMCID: PMC8705616 DOI: 10.3390/plants10122569] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/16/2021] [Accepted: 11/19/2021] [Indexed: 06/14/2023]
Abstract
Roots are complicated quantitative characteristics that play an essential role in absorbing water and nutrients. To uncover the genetic variations for root-related traits in rapeseed, twelve mature root traits of a Brassica napus association panel were investigated in the field within three environments. All traits showed significant phenotypic variation among genotypes, with heritabilities ranging from 55.18% to 79.68%. Genome-wide association studies (GWAS) using 20,131 SNPs discovered 172 marker-trait associations, including 103 significant SNPs (-log10 (p) > 4.30) that explained 5.24-20.31% of the phenotypic variance. With the linkage disequilibrium r2 > 0.2, these significant associations were binned into 40 quantitative trait loci (QTL) clusters. Among them, 14 important QTL clusters were discovered in two environments and/or with phenotypic contributions greater than 10%. By analyzing the genomic regions within 100 kb upstream and downstream of the peak SNPs within the 14 loci, 334 annotated genes were found. Among these, 32 genes were potentially associated with root development according to their expression analysis. Furthermore, the protein interaction network using the 334 annotated genes gave nine genes involved in a substantial number of interactions, including a key gene associated with root development, BnaC09g36350D. This research provides the groundwork for deciphering B. napus' genetic variations and improving its root system architecture.
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Affiliation(s)
- Sani Ibrahim
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Wuhan 430062, China; (S.I.); (K.L.); (N.A.); (L.K.); (Z.T.); (L.H.); (X.W.); (H.W.)
- Department of Plant Biology, Faculty of Life Sciences, College of Physical and Pharmaceutical Sciences, Bayero University, Kano, P.M.B. 3011, Kano 700006, Nigeria
| | - Keqi Li
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Wuhan 430062, China; (S.I.); (K.L.); (N.A.); (L.K.); (Z.T.); (L.H.); (X.W.); (H.W.)
| | - Nazir Ahmad
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Wuhan 430062, China; (S.I.); (K.L.); (N.A.); (L.K.); (Z.T.); (L.H.); (X.W.); (H.W.)
| | - Lieqiong Kuang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Wuhan 430062, China; (S.I.); (K.L.); (N.A.); (L.K.); (Z.T.); (L.H.); (X.W.); (H.W.)
| | - Salisu Bello Sadau
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China;
| | - Ze Tian
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Wuhan 430062, China; (S.I.); (K.L.); (N.A.); (L.K.); (Z.T.); (L.H.); (X.W.); (H.W.)
| | - Lintao Huang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Wuhan 430062, China; (S.I.); (K.L.); (N.A.); (L.K.); (Z.T.); (L.H.); (X.W.); (H.W.)
| | - Xinfa Wang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Wuhan 430062, China; (S.I.); (K.L.); (N.A.); (L.K.); (Z.T.); (L.H.); (X.W.); (H.W.)
| | - Xiaoling Dun
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Wuhan 430062, China; (S.I.); (K.L.); (N.A.); (L.K.); (Z.T.); (L.H.); (X.W.); (H.W.)
| | - Hanzhong Wang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Wuhan 430062, China; (S.I.); (K.L.); (N.A.); (L.K.); (Z.T.); (L.H.); (X.W.); (H.W.)
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22
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Varahan S, Laxman S. Bend or break: how biochemically versatile molecules enable metabolic division of labor in clonal microbial communities. Genetics 2021; 219:iyab109. [PMID: 34849891 PMCID: PMC8633146 DOI: 10.1093/genetics/iyab109] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 06/29/2021] [Indexed: 02/05/2023] Open
Abstract
In fluctuating nutrient environments, isogenic microbial cells transition into "multicellular" communities composed of phenotypically heterogeneous cells, showing functional specialization. In fungi (such as budding yeast), phenotypic heterogeneity is often described in the context of cells switching between different morphotypes (e.g., yeast to hyphae/pseudohyphae or white/opaque transitions in Candida albicans). However, more fundamental forms of metabolic heterogeneity are seen in clonal Saccharomyces cerevisiae communities growing in nutrient-limited conditions. Cells within such communities exhibit contrasting, specialized metabolic states, and are arranged in distinct, spatially organized groups. In this study, we explain how such an organization can stem from self-organizing biochemical reactions that depend on special metabolites. These metabolites exhibit plasticity in function, wherein the same metabolites are metabolized and utilized for distinct purposes by different cells. This in turn allows cell groups to function as specialized, interdependent cross-feeding systems which support distinct metabolic processes. Exemplifying a system where cells exhibit either gluconeogenic or glycolytic states, we highlight how available metabolites can drive favored biochemical pathways to produce new, limiting resources. These new resources can themselves be consumed or utilized distinctly by cells in different metabolic states. This thereby enables cell groups to sustain contrasting, even apparently impossible metabolic states with stable transcriptional and metabolic signatures for a given environment, and divide labor in order to increase community fitness or survival. We speculate on possible evolutionary implications of such metabolic specialization and division of labor in isogenic microbial communities.
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Affiliation(s)
- Sriram Varahan
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bengaluru 560065, India
| | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bengaluru 560065, India
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23
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Novick A, Doolittle WF. 'Species' without species. STUDIES IN HISTORY AND PHILOSOPHY OF SCIENCE 2021; 87:72-80. [PMID: 34111824 DOI: 10.1016/j.shpsa.2021.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 12/23/2020] [Accepted: 03/18/2021] [Indexed: 06/12/2023]
Abstract
Biological science uses multiple species concepts. Order can be brought to this diversity if we recognize two key features. First, any given species concept is likely to have a patchwork structure, generated by repeated application of the concept to new domains. We illustrate this by showing how two species concepts (biological and ecological) have been modified from their initial eukaryotic applications to apply to prokaryotes. Second, both within and between patches, distinct species concepts may interact and hybridize. We thus defend a semantic picture of the species concept as a collection of interacting patchwork structures. Thus, although not all uses of the term pick out the same kind of unit in nature, the diversity of uses reflects something more than mere polysemy. We suggest that the emphasis on the use of species to pick out natural units is itself problematic, because that is not the term's sole function. In particular, species concepts are used to manage inquiry into processes of speciation, even when these processes do not produce clearly delimited species.
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Affiliation(s)
- Aaron Novick
- Department of Philosophy, University of Washington, Seattle, WA, USA.
| | - W Ford Doolittle
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
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Pan-Resistome Insights into the Multidrug Resistance of Acinetobacter baumannii. Antibiotics (Basel) 2021; 10:antibiotics10050596. [PMID: 34069870 PMCID: PMC8157372 DOI: 10.3390/antibiotics10050596] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/18/2021] [Accepted: 04/22/2021] [Indexed: 02/02/2023] Open
Abstract
Acinetobacter baumannii is an important Gram-negative opportunistic pathogen that is responsible for many nosocomial infections. This etiologic agent has acquired, over the years, multiple mechanisms of resistance to a wide range of antimicrobials and the ability to survive in different environments. In this context, our study aims to elucidate the resistome from the A. baumannii strains based on phylogenetic, phylogenomic, and comparative genomics analyses. In silico analysis of the complete genomes of A. baumannii strains was carried out to identify genes involved in the resistance mechanisms and the phylogenetic relationships and grouping of the strains based on the sequence type. The presence of genomic islands containing most of the resistance gene repertoire indicated high genomic plasticity, which probably enabled the acquisition of resistance genes and the formation of a robust resistome. A. baumannii displayed an open pan-genome and revealed a still constant genetic permutation among their strains. Furthermore, the resistance genes suggest a specific profile within the species throughout its evolutionary history. Moreover, the current study performed screening and characterization of the main genes present in the resistome, which can be used in applied research to develop new therapeutic methods to control this important bacterial pathogen.
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25
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Li Y, Sun ZZ, Rong JC, Xie BB. Comparative genomics reveals broad genetic diversity, extensive recombination and nascent ecological adaptation in Micrococcus luteus. BMC Genomics 2021; 22:124. [PMID: 33602135 PMCID: PMC7890812 DOI: 10.1186/s12864-021-07432-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 02/08/2021] [Indexed: 01/21/2023] Open
Abstract
Background Micrococcus luteus is a group of actinobacteria that is widely used in biotechnology and is being thought as an emerging nosocomial pathogen. With one of the smallest genomes of free-living actinobacteria, it is found in a wide range of environments, but intraspecies genetic diversity and adaptation strategies to various environments remain unclear. Here, comparative genomics, phylogenomics, and genome-wide association studies were used to investigate the genomic diversity, evolutionary history, and the potential ecological differentiation of the species. Results High-quality genomes of 66 M. luteus strains were downloaded from the NCBI GenBank database and core and pan-genome analysis revealed a considerable intraspecies heterogeneity. Phylogenomic analysis, gene content comparison, and average nucleotide identity calculation consistently indicated that the species has diverged into three well-differentiated clades. Population structure analysis further suggested the existence of an unknown ancestor or the fourth, yet unsampled, clade. Reconstruction of gene gain/loss events along the evolutionary history revealed both early events that contributed to the inter-clade divergence and recent events leading to the intra-clade diversity. We also found convincing evidence that recombination has played a key role in the evolutionary process of the species, with upto two-thirds of the core genes having been affected by recombination. Furthermore, distribution of mammal-associated strains (including pathogens) on the phylogenetic tree suggested that the last common ancestor had a free-living lifestyle, and a few recently diverged lineages have developed a mammal-associated lifestyle separately. Consistently, genome-wide association analysis revealed that mammal-associated strains from different lineages shared genes functionally relevant to the host-associated lifestyle, indicating a recent ecological adaption to the new host-associated habitats. Conclusions These results revealed high intraspecies genomic diversity of M. luteus and highlighted that gene gain/loss events and extensive recombination events played key roles in the genome evolution. Our study also indicated that, as a free-living species, some lineages have recently developed or are developing a mammal-associated lifestyle. This study provides insights into the mechanisms that drive the genome evolution and adaption to various environments of a bacterial species. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07432-5.
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Affiliation(s)
- Yisong Li
- Microbial Technology Institute and State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Zhong-Zhi Sun
- Microbial Technology Institute and State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Jin-Cheng Rong
- Microbial Technology Institute and State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Bin-Bin Xie
- Microbial Technology Institute and State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China.
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26
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Jia TZ, Caudan M, Mamajanov I. Origin of Species before Origin of Life: The Role of Speciation in Chemical Evolution. Life (Basel) 2021; 11:154. [PMID: 33671365 PMCID: PMC7922636 DOI: 10.3390/life11020154] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/11/2021] [Accepted: 02/15/2021] [Indexed: 11/17/2022] Open
Abstract
Speciation, an evolutionary process by which new species form, is ultimately responsible for the incredible biodiversity that we observe on Earth every day. Such biodiversity is one of the critical features which contributes to the survivability of biospheres and modern life. While speciation and biodiversity have been amply studied in organismic evolution and modern life, it has not yet been applied to a great extent to understanding the evolutionary dynamics of primitive life. In particular, one unanswered question is at what point in the history of life did speciation as a phenomenon emerge in the first place. Here, we discuss the mechanisms by which speciation could have occurred before the origins of life in the context of chemical evolution. Specifically, we discuss that primitive compartments formed before the emergence of the last universal common ancestor (LUCA) could have provided a mechanism by which primitive chemical systems underwent speciation. In particular, we introduce a variety of primitive compartment structures, and associated functions, that may have plausibly been present on early Earth, followed by examples of both discriminate and indiscriminate speciation affected by primitive modes of compartmentalization. Finally, we discuss modern technologies, in particular, droplet microfluidics, that can be applied to studying speciation phenomena in the laboratory over short timescales. We hope that this discussion highlights the current areas of need in further studies on primitive speciation phenomena while simultaneously proposing directions as important areas of study to the origins of life.
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Affiliation(s)
- Tony Z. Jia
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan;
- Blue Marble Space Institute of Science, 1001 4th Ave., Suite 3201, Seattle, WA 98154, USA
| | - Melina Caudan
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan;
| | - Irena Mamajanov
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan;
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27
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Hoetzinger M, Pitt A, Huemer A, Hahn MW. Continental-Scale Gene Flow Prevents Allopatric Divergence of Pelagic Freshwater Bacteria. Genome Biol Evol 2021; 13:6126423. [PMID: 33674852 PMCID: PMC7936036 DOI: 10.1093/gbe/evab019] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/25/2021] [Indexed: 12/24/2022] Open
Abstract
Allopatric divergence is one of the principal mechanisms for speciation of macro-organisms. Microbes by comparison are assumed to disperse more freely and to be less limited by dispersal barriers. However, thermophilic prokaryotes restricted to geothermal springs have shown clear signals of geographic isolation, but robust studies on this topic for microbes with less strict habitat requirements are scarce. Furthermore, it has only recently been recognized that homologous recombination among conspecific individuals provides species coherence in a wide range of prokaryotes. Recombination barriers thus may define prokaryotic species boundaries, yet, the extent to which geographic distance between populations gives rise to such barriers is an open question. Here, we investigated gene flow and population structure in a widespread species of pelagic freshwater bacteria, Polynucleobacter paneuropaeus. Through comparative genomics of 113 conspecific strains isolated from freshwater lakes and ponds located across a North–South range of more than 3,000 km, we were able to reconstruct past gene flow events. The species turned out to be highly recombinogenic as indicated by significant signs of gene transfer and extensive genome mosaicism. Although genomic differences increased with spatial distance on a regional scale (<170 km), such correlations were mostly absent on larger scales up to 3,400 km. We conclude that allopatric divergence in European P. paneuropaeus is minor, and that effective gene flow across the sampled geographic range in combination with a high recombination efficacy maintains species coherence.
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Affiliation(s)
- Matthias Hoetzinger
- Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria.,Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala SE-75651, Sweden
| | - Alexandra Pitt
- Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria
| | - Andrea Huemer
- Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria
| | - Martin W Hahn
- Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria
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28
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Young JPW, Moeskjær S, Afonin A, Rahi P, Maluk M, James EK, Cavassim MIA, Rashid MHO, Aserse AA, Perry BJ, Wang ET, Velázquez E, Andronov EE, Tampakaki A, Flores Félix JD, Rivas González R, Youseif SH, Lepetit M, Boivin S, Jorrin B, Kenicer GJ, Peix Á, Hynes MF, Ramírez-Bahena MH, Gulati A, Tian CF. Defining the Rhizobium leguminosarum Species Complex. Genes (Basel) 2021; 12:111. [PMID: 33477547 PMCID: PMC7831135 DOI: 10.3390/genes12010111] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/08/2021] [Accepted: 01/13/2021] [Indexed: 01/21/2023] Open
Abstract
Bacteria currently included in Rhizobium leguminosarum are too diverse to be considered a single species, so we can refer to this as a species complex (the Rlc). We have found 429 publicly available genome sequences that fall within the Rlc and these show that the Rlc is a distinct entity, well separated from other species in the genus. Its sister taxon is R. anhuiense. We constructed a phylogeny based on concatenated sequences of 120 universal (core) genes, and calculated pairwise average nucleotide identity (ANI) between all genomes. From these analyses, we concluded that the Rlc includes 18 distinct genospecies, plus 7 unique strains that are not placed in these genospecies. Each genospecies is separated by a distinct gap in ANI values, usually at approximately 96% ANI, implying that it is a 'natural' unit. Five of the genospecies include the type strains of named species: R. laguerreae, R. sophorae, R. ruizarguesonis, "R. indicum" and R. leguminosarum itself. The 16S ribosomal RNA sequence is remarkably diverse within the Rlc, but does not distinguish the genospecies. Partial sequences of housekeeping genes, which have frequently been used to characterize isolate collections, can mostly be assigned unambiguously to a genospecies, but alleles within a genospecies do not always form a clade, so single genes are not a reliable guide to the true phylogeny of the strains. We conclude that access to a large number of genome sequences is a powerful tool for characterizing the diversity of bacteria, and that taxonomic conclusions should be based on all available genome sequences, not just those of type strains.
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Affiliation(s)
| | - Sara Moeskjær
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark;
| | - Alexey Afonin
- Laboratory for Genetics of Plant-Microbe Interactions, ARRIAM, Pushkin, 196608 Saint-Petersburg, Russia;
| | - Praveen Rahi
- National Centre for Microbial Resource, National Centre for Cell Science, Pune 411007, India;
| | - Marta Maluk
- Ecological Sciences, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK; (M.M.); (E.K.J.)
| | - Euan K. James
- Ecological Sciences, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK; (M.M.); (E.K.J.)
| | - Maria Izabel A. Cavassim
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA;
| | - M. Harun-or Rashid
- Biotechnology Division, Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh 2202, Bangladesh;
| | - Aregu Amsalu Aserse
- Ecosystems and Environment Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, FI-00014 Helsinki, Finland;
| | - Benjamin J. Perry
- Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand;
| | - En Tao Wang
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad De México 11340, Mexico;
| | - Encarna Velázquez
- Departamento de Microbiología y Genética, Universidad de Salamanca, Instituto Hispanoluso de Investigaciones Agrarias (CIALE), Unidad Asociada Grupo de Interacción planta-microorganismo (Universidad de Salamanca-IRNASA-CSIC), 37007 Salamanca, Spain; (E.V.); (R.R.G.)
| | - Evgeny E. Andronov
- Department of Microbial Monitoring, ARRIAM, Pushkin, 196608 Saint-Petersburg, Russia;
| | - Anastasia Tampakaki
- Department of Crop Science, Agricultural University of Athens, Iera Odos 75, Votanikos, 11855 Athens, Greece;
| | - José David Flores Félix
- CICS-UBI—Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal;
| | - Raúl Rivas González
- Departamento de Microbiología y Genética, Universidad de Salamanca, Instituto Hispanoluso de Investigaciones Agrarias (CIALE), Unidad Asociada Grupo de Interacción planta-microorganismo (Universidad de Salamanca-IRNASA-CSIC), 37007 Salamanca, Spain; (E.V.); (R.R.G.)
| | - Sameh H. Youseif
- Department of Microbial Genetic Resources, National Gene Bank (NGB), Agricultural Research Center (ARC), Giza 12619, Egypt;
| | - Marc Lepetit
- Institut Sophia Agrobiotech, UMR INRAE 1355, Université Côte d’Azur, CNRS, 06903 Sophia Antipolis, France;
| | - Stéphane Boivin
- Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR INRAE-IRD-CIRAD-UM2-SupAgro, Campus International de Baillarguet, TA-A82/J, CEDEX 05, 34398 Montpellier, France;
| | - Beatriz Jorrin
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK;
| | - Gregory J. Kenicer
- Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, UK;
| | - Álvaro Peix
- Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Unidad Asociada Grupo de Interacción Planta-Microorganismo (Universidad de Salamanca-IRNASA-CSIC), 37008 Salamanca, Spain;
| | - Michael F. Hynes
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada;
| | - Martha Helena Ramírez-Bahena
- Departamento de Didáctica de las Matemáticas y de las Ciencias Experimentales. Universidad de Salamanca, 37008 Salamanca, Spain;
| | - Arvind Gulati
- Microbial Prospection, CSIR-Institute of Himalayan Bioresource Technology, Palampur (H.P.) 176 061, India;
| | - Chang-Fu Tian
- State Key Laboratory of Agrobiotechnology, Rhizobium Research Center, and College of Biological Sciences, China Agricultural University, Beijing 100193, China;
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Abstract
Metagenomic sequencing of the gut microbial communities of two closely related bee species, the Western honey bee (Apis mellifera) and the Eastern honey bee (Apis cerana), show that organisms with similar characteristics can harbor unexpected differences in their microbiomes.
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Affiliation(s)
- Waldan K Kwong
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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30
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Groussin M, Mazel F, Alm EJ. Co-evolution and Co-speciation of Host-Gut Bacteria Systems. Cell Host Microbe 2020; 28:12-22. [DOI: 10.1016/j.chom.2020.06.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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31
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Abstract
There is controversy about whether bacterial diversity is clustered into distinct species groups or exists as a continuum. To address this issue, we analyzed bacterial genome databases and reports from several previous large-scale environment studies and identified clear discrete groups of species-level bacterial diversity in all cases. Genetic analysis further revealed that quasi-sexual reproduction via horizontal gene transfer is likely a key evolutionary force that maintains bacterial species integrity. We next benchmarked over 100 metrics to distinguish these bacterial species from each other and identified several genes encoding ribosomal proteins with high species discrimination power. Overall, the results from this study provide best practices for bacterial species delineation based on genome content and insight into the nature of bacterial species population genetics. Longstanding questions relate to the existence of naturally distinct bacterial species and genetic approaches to distinguish them. Bacterial genomes in public databases form distinct groups, but these databases are subject to isolation and deposition biases. To avoid these biases, we compared 5,203 bacterial genomes from 1,457 environmental metagenomic samples to test for distinct clouds of diversity and evaluated metrics that could be used to define the species boundary. Bacterial genomes from the human gut, soil, and the ocean all exhibited gaps in whole-genome average nucleotide identities (ANI) near the previously suggested species threshold of 95% ANI. While genome-wide ratios of nonsynonymous and synonymous nucleotide differences (dN/dS) decrease until ANI values approach ∼98%, two methods for estimating homologous recombination approached zero at ∼95% ANI, supporting breakdown of recombination due to sequence divergence as a species-forming force. We evaluated 107 genome-based metrics for their ability to distinguish species when full genomes are not recovered. Full-length 16S rRNA genes were least useful, in part because they were underrecovered from metagenomes. However, many ribosomal proteins displayed both high metagenomic recoverability and species discrimination power. Taken together, our results verify the existence of sequence-discrete microbial species in metagenome-derived genomes and highlight the usefulness of ribosomal genes for gene-level species discrimination. IMPORTANCE There is controversy about whether bacterial diversity is clustered into distinct species groups or exists as a continuum. To address this issue, we analyzed bacterial genome databases and reports from several previous large-scale environment studies and identified clear discrete groups of species-level bacterial diversity in all cases. Genetic analysis further revealed that quasi-sexual reproduction via horizontal gene transfer is likely a key evolutionary force that maintains bacterial species integrity. We next benchmarked over 100 metrics to distinguish these bacterial species from each other and identified several genes encoding ribosomal proteins with high species discrimination power. Overall, the results from this study provide best practices for bacterial species delineation based on genome content and insight into the nature of bacterial species population genetics.
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32
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Bobay LM, Ellis BSH, Ochman H. ConSpeciFix: classifying prokaryotic species based on gene flow. Bioinformatics 2019; 34:3738-3740. [PMID: 29771275 DOI: 10.1093/bioinformatics/bty400] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/09/2018] [Indexed: 11/12/2022] Open
Abstract
Summary Classification of prokaryotic species is usually based on sequence similarity thresholds, which are easy to apply but lack a biologically-relevant foundation. Here, we present ConSpeciFix, a program that classifies prokaryotes into species using criteria set forth by the Biological Species Concept, thereby unifying species definition in all domains of life. Availability and implementation ConSpeciFix's webserver is freely available at www.conspecifix.com. The local version of the program can be freely downloaded from https://github.com/Bobay-Ochman/ConSpeciFix. ConSpeciFix is written in Python 2.7 and requires the following dependencies: Usearch, MCL, MAFFT and RAxML.
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Affiliation(s)
- Louis-Marie Bobay
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC, USA
| | - Brian Shin-Hua Ellis
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Howard Ochman
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
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33
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Delmont TO, Kiefl E, Kilinc O, Esen OC, Uysal I, Rappé MS, Giovannoni S, Eren AM. Single-amino acid variants reveal evolutionary processes that shape the biogeography of a global SAR11 subclade. eLife 2019; 8:46497. [PMID: 31478833 PMCID: PMC6721796 DOI: 10.7554/elife.46497] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 08/13/2019] [Indexed: 12/14/2022] Open
Abstract
Members of the SAR11 order Pelagibacterales dominate the surface oceans. Their extensive diversity challenges emerging operational boundaries defined for microbial 'species' and complicates efforts of population genetics to study their evolution. Here, we employed single-amino acid variants (SAAVs) to investigate ecological and evolutionary forces that maintain the genomic heterogeneity within ubiquitous SAR11 populations we accessed through metagenomic read recruitment using a single isolate genome. Integrating amino acid and protein biochemistry with metagenomics revealed that systematic purifying selection against deleterious variants governs non-synonymous variation among very closely related populations of SAR11. SAAVs partitioned metagenomes into two main groups matching large-scale oceanic current temperatures, and six finer proteotypes that connect distant oceanic regions. These findings suggest that environmentally-mediated selection plays a critical role in the journey of cosmopolitan surface ocean microbial populations, and the idea 'everything is everywhere but the environment selects' has credence even at the finest resolutions.
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Affiliation(s)
- Tom O Delmont
- Department of Medicine, The University of Chicago, Chicago, United States
| | - Evan Kiefl
- Department of Medicine, The University of Chicago, Chicago, United States.,Graduate Program in Biophysical Sciences, University of Chicago, Chicago, United States
| | - Ozsel Kilinc
- Department of Electrical Engineering, University of South Florida, Tampa, United States
| | - Ozcan C Esen
- Department of Medicine, The University of Chicago, Chicago, United States
| | - Ismail Uysal
- Department of Electrical Engineering, University of South Florida, Tampa, United States
| | - Michael S Rappé
- Hawaii Institute of Marine Biology, University of Hawaii at Manoa, Kaneohe, United States
| | - Steven Giovannoni
- Department of Microbiology, Oregon State University, Corvallis, United States
| | - A Murat Eren
- Department of Medicine, The University of Chicago, Chicago, United States.,Marine Biological Laboratory, Woods Hole, United States
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34
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A Reverse Ecology Approach Based on a Biological Definition of Microbial Populations. Cell 2019; 178:820-834.e14. [DOI: 10.1016/j.cell.2019.06.033] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/28/2019] [Accepted: 06/24/2019] [Indexed: 01/30/2023]
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35
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Global-level population genomics reveals differential effects of geography and phylogeny on horizontal gene transfer in soil bacteria. Proc Natl Acad Sci U S A 2019; 116:15200-15209. [PMID: 31285337 DOI: 10.1073/pnas.1900056116] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Although microorganisms are known to dominate Earth's biospheres and drive biogeochemical cycling, little is known about the geographic distributions of microbial populations or the environmental factors that pattern those distributions. We used a global-level hierarchical sampling scheme to comprehensively characterize the evolutionary relationships and distributional limitations of the nitrogen-fixing bacterial symbionts of the crop chickpea, generating 1,027 draft whole-genome sequences at the level of bacterial populations, including 14 high-quality PacBio genomes from a phylogenetically representative subset. We find that diverse Mesorhizobium taxa perform symbiosis with chickpea and have largely overlapping global distributions. However, sampled locations cluster based on the phylogenetic diversity of Mesorhizobium populations, and diversity clusters correspond to edaphic and environmental factors, primarily soil type and latitude. Despite long-standing evolutionary divergence and geographic isolation, the diverse taxa observed to nodulate chickpea share a set of integrative conjugative elements (ICEs) that encode the major functions of the symbiosis. This symbiosis ICE takes 2 forms in the bacterial chromosome-tripartite and monopartite-with tripartite ICEs confined to a broadly distributed superspecies clade. The pairwise evolutionary relatedness of these elements is controlled as much by geographic distance as by the evolutionary relatedness of the background genome. In contrast, diversity in the broader gene content of Mesorhizobium genomes follows a tight linear relationship with core genome phylogenetic distance, with little detectable effect of geography. These results illustrate how geography and demography can operate differentially on the evolution of bacterial genomes and offer useful insights for the development of improved technologies for sustainable agriculture.
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36
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Chiner-Oms Á, Sánchez-Busó L, Corander J, Gagneux S, Harris SR, Young D, González-Candelas F, Comas I. Genomic determinants of speciation and spread of the Mycobacterium tuberculosis complex. SCIENCE ADVANCES 2019; 5:eaaw3307. [PMID: 31448322 PMCID: PMC6691555 DOI: 10.1126/sciadv.aaw3307] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 05/10/2019] [Indexed: 06/10/2023]
Abstract
Models on how bacterial lineages differentiate increase our understanding of early bacterial speciation events and the genetic loci involved. Here, we analyze the population genomics events leading to the emergence of the tuberculosis pathogen. The emergence is characterized by a combination of recombination events involving core pathogenesis functions and purifying selection on early diverging loci. We identify the phoR gene, the sensor kinase of a two-component system involved in virulence, as a key functional player subject to pervasive positive selection after the divergence of the Mycobacterium tuberculosis complex from its ancestor. Previous evidence showed that phoR mutations played a central role in the adaptation of the pathogen to different host species. Now, we show that phoR mutations have been under selection during the early spread of human tuberculosis, during later expansions, and in ongoing transmission events. Our results show that linking pathogen evolution across evolutionary and epidemiological time scales points to past and present virulence determinants.
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Affiliation(s)
- Á. Chiner-Oms
- Unidad Mixta “Infección y Salud Pública” FISABIO-CSISP/Universidad de Valencia, Instituto de Biología Integrativa de Sistemas (ISysBio), Valencia, Spain
| | - L. Sánchez-Busó
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - J. Corander
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
- Department of Biostatistics, University of Oslo, 0317 Oslo, Norway
- Helsinki Institute of Information Technology (HIIT), Department of Mathematics and Statistics, University of Helsinki, 00014 Helsinki, Finland
| | - S. Gagneux
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - S. R. Harris
- Microbiotica, BioData Innovation Centre, Wellcome Genome Campus, Cambridge CB10 1DR, UK
| | - D. Young
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - F. González-Candelas
- Unidad Mixta “Infección y Salud Pública” FISABIO-CSISP/Universidad de Valencia, Instituto de Biología Integrativa de Sistemas (ISysBio), Valencia, Spain
- CIBER en Epidemiología y Salud Pública, Valencia, Spain
| | - I. Comas
- CIBER en Epidemiología y Salud Pública, Valencia, Spain
- Instituto de Biomedicina de Valencia (IBV-CSIC), Valencia, Spain
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37
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Affiliation(s)
- Aaron Novick
- Department of Philosophy, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail: (AN); (WFD)
| | - W. Ford Doolittle
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail: (AN); (WFD)
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Tracing Genomic Divergence of Vibrio Bacteria in the Harveyi Clade. J Bacteriol 2018; 200:JB.00001-18. [PMID: 29555692 DOI: 10.1128/jb.00001-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 03/10/2018] [Indexed: 11/20/2022] Open
Abstract
The mechanism of bacterial speciation remains a topic of tremendous interest. To understand the ecological and evolutionary mechanisms of speciation in Vibrio bacteria, we analyzed the genomic dissimilarities between three closely related species in the so-called Harveyi clade of the genus Vibrio, V. campbellii, V. jasicida, and V. hyugaensis The analysis focused on strains isolated from diverse geographic locations over a long period of time. The results of phylogenetic analyses and calculations of average nucleotide identity (ANI) supported the classification of V. jasicida and V. hyugaensis into two species. These analyses also identified two well-supported clades in V. campbellii; however, strains from both clades were classified as members of the same species. Comparative analyses of the complete genome sequences of representative strains from the three species identified higher syntenic coverage between genomes of V. jasicida and V. hyugaensis than that between the genomes from the two V. campbellii clades. The results from comparative analyses of gene content between bacteria from the three species did not support the hypothesis that gene gain and/or loss contributed to their speciation. We also did not find support for the hypothesis that ecological diversification toward associations with marine animals contributed to the speciation of V. jasicida and V. hyugaensis Overall, based on the results obtained in this study, we propose that speciation in Harveyi clade species is a result of stochastic diversification of local populations, which was influenced by multiple evolutionary processes, followed by extinction events.IMPORTANCE To investigate the mechanisms underlying speciation in the genus Vibrio, we provided a well-assembled reference of genomes and performed systematic genomic comparisons among three evolutionarily closely related species. We resolved taxonomic ambiguities and identified genomic features separating the three species. Based on the study results, we propose a hypothesis explaining how species in the Harveyi clade of Vibrio bacteria diversified.
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Abstract
Due to their dependence on cellular organisms for metabolism and replication, viruses are typically named and assigned to species according to their genome structure and the original host that they infect. But because viruses often infect multiple hosts and the numbers of distinct lineages within a host can be vast, their delineation into species is often dictated by arbitrary sequence thresholds, which are highly inconsistent across lineages. Here we apply an approach to determine the boundaries of viral species based on the detection of gene flow within populations, thereby defining viral species according to the biological species concept (BSC). Despite the potential for gene transfer between highly divergent genomes, viruses, like the cellular organisms they infect, assort into reproductively isolated groups and can be organized into biological species. This approach revealed that BSC-defined viral species are often congruent with the taxonomic partitioning based on shared gene contents and host tropism, and that bacteriophages can similarly be classified in biological species. These results open the possibility to use a single, universal definition of species that is applicable across cellular and acellular lifeforms.
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Vinuesa P, Ochoa-Sánchez LE, Contreras-Moreira B. GET_PHYLOMARKERS, a Software Package to Select Optimal Orthologous Clusters for Phylogenomics and Inferring Pan-Genome Phylogenies, Used for a Critical Geno-Taxonomic Revision of the Genus Stenotrophomonas. Front Microbiol 2018; 9:771. [PMID: 29765358 PMCID: PMC5938378 DOI: 10.3389/fmicb.2018.00771] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/05/2018] [Indexed: 12/17/2022] Open
Abstract
The massive accumulation of genome-sequences in public databases promoted the proliferation of genome-level phylogenetic analyses in many areas of biological research. However, due to diverse evolutionary and genetic processes, many loci have undesirable properties for phylogenetic reconstruction. These, if undetected, can result in erroneous or biased estimates, particularly when estimating species trees from concatenated datasets. To deal with these problems, we developed GET_PHYLOMARKERS, a pipeline designed to identify high-quality markers to estimate robust genome phylogenies from the orthologous clusters, or the pan-genome matrix (PGM), computed by GET_HOMOLOGUES. In the first context, a set of sequential filters are applied to exclude recombinant alignments and those producing anomalous or poorly resolved trees. Multiple sequence alignments and maximum likelihood (ML) phylogenies are computed in parallel on multi-core computers. A ML species tree is estimated from the concatenated set of top-ranking alignments at the DNA or protein levels, using either FastTree or IQ-TREE (IQT). The latter is used by default due to its superior performance revealed in an extensive benchmark analysis. In addition, parsimony and ML phylogenies can be estimated from the PGM. We demonstrate the practical utility of the software by analyzing 170 Stenotrophomonas genome sequences available in RefSeq and 10 new complete genomes of Mexican environmental S. maltophilia complex (Smc) isolates reported herein. A combination of core-genome and PGM analyses was used to revise the molecular systematics of the genus. An unsupervised learning approach that uses a goodness of clustering statistic identified 20 groups within the Smc at a core-genome average nucleotide identity (cgANIb) of 95.9% that are perfectly consistent with strongly supported clades on the core- and pan-genome trees. In addition, we identified 16 misclassified RefSeq genome sequences, 14 of them labeled as S. maltophilia, demonstrating the broad utility of the software for phylogenomics and geno-taxonomic studies. The code, a detailed manual and tutorials are freely available for Linux/UNIX servers under the GNU GPLv3 license at https://github.com/vinuesa/get_phylomarkers. A docker image bundling GET_PHYLOMARKERS with GET_HOMOLOGUES is available at https://hub.docker.com/r/csicunam/get_homologues/, which can be easily run on any platform.
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Affiliation(s)
- Pablo Vinuesa
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Luz E Ochoa-Sánchez
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Bruno Contreras-Moreira
- Estación Experimental de Aula Dei - Consejo Superior de Investigaciones Científicas, Zaragoza, Spain.,Fundación Agencia Aragonesa para la Investigacion y el Desarrollo (ARAID), Zaragoza, Spain
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Martin-Platero AM, Cleary B, Kauffman K, Preheim SP, McGillicuddy DJ, Alm EJ, Polz MF. High resolution time series reveals cohesive but short-lived communities in coastal plankton. Nat Commun 2018; 9:266. [PMID: 29348571 PMCID: PMC5773528 DOI: 10.1038/s41467-017-02571-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 12/11/2017] [Indexed: 11/09/2022] Open
Abstract
Because microbial plankton in the ocean comprise diverse bacteria, algae, and protists that are subject to environmental forcing on multiple spatial and temporal scales, a fundamental open question is to what extent these organisms form ecologically cohesive communities. Here we show that although all taxa undergo large, near daily fluctuations in abundance, microbial plankton are organized into clearly defined communities whose turnover is rapid and sharp. We analyze a time series of 93 consecutive days of coastal plankton using a technique that allows inference of communities as modular units of interacting taxa by determining positive and negative correlations at different temporal frequencies. This approach shows both coordinated population expansions that demarcate community boundaries and high frequency of positive and negative associations among populations within communities. Our analysis thus highlights that the environmental variability of the coastal ocean is mirrored in sharp transitions of defined but ephemeral communities of organisms.
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Affiliation(s)
- Antonio M Martin-Platero
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Department of Microbiology, University of Granada, Granada, 18071, Spain
| | - Brian Cleary
- Broad Institute, Cambridge, MA, 02139, USA.,Computational and Systems Biology Program, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Kathryn Kauffman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Sarah P Preheim
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Department of Geography and Environmental Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Dennis J McGillicuddy
- Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA
| | - Eric J Alm
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA. .,Broad Institute, Cambridge, MA, 02139, USA. .,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Martin F Polz
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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Bobay LM, Ochman H. The Evolution of Bacterial Genome Architecture. Front Genet 2017; 8:72. [PMID: 28611826 PMCID: PMC5447742 DOI: 10.3389/fgene.2017.00072] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 05/12/2017] [Indexed: 11/15/2022] Open
Abstract
The genome architecture of bacteria and eukaryotes evolves in opposite directions when subject to genetic drift, a difference that can be ascribed to the fact that bacteria exhibit a mutational bias that deletes superfluous sequences, whereas eukaryotes are biased toward large insertions. Expansion of eukaryotic genomes occurs through the addition of non-functional sequences, such as repetitive sequences and transposable elements, whereas variation in bacterial genome size is largely due to the acquisition and loss of functional accessory genes. These properties create the situation in which eukaryotes with very similar numbers of genes can have vastly different genome sizes, while in bacteria, gene number scales linearly with genome size. Some bacterial genomes, however, particularly those of species that undergo bottlenecks due to recent association with hosts, accumulate pseudogenes and mobile elements, conferring them a low gene content relative to their genome size. These non-functional sequences are gradually eroded and eliminated after long-term association with hosts, with the result that obligate symbionts have the smallest genomes of any cellular organism. The architecture of bacterial genomes is shaped by complex and diverse processes, but for most bacterial species, genome size is governed by a non-adaptive process, i.e., genetic drift coupled with a mutational bias toward deletions. Thus, bacteria with small effective population sizes typically have the smallest genomes. Some marine bacteria counter this near-universal trend: despite having immense population sizes, selection, not drift, acts to reduce genome size in response to metabolic constraints in their nutrient-limited environment.
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Affiliation(s)
- Louis-Marie Bobay
- Department of Integrative Biology, University of Texas, AustinTX, United States
| | - Howard Ochman
- Department of Integrative Biology, University of Texas, AustinTX, United States
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43
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The underlying process of early ecological and genetic differentiation in a facultative mutualistic Sinorhizobium meliloti population. Sci Rep 2017; 7:675. [PMID: 28386109 PMCID: PMC5429615 DOI: 10.1038/s41598-017-00730-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 03/10/2017] [Indexed: 11/21/2022] Open
Abstract
The question of how genotypic and ecological units arise and spread in natural microbial populations remains controversial in the field of evolutionary biology. Here, we investigated the early stages of ecological and genetic differentiation in a highly clonal sympatric Sinorhizobium meliloti population. Whole-genome sequencing revealed that a large DNA region of the symbiotic plasmid pSymB was replaced in some isolates with a similar synteny block carrying densely clustered SNPs and displaying gene acquisition and loss. Two different versions of this genomic island of differentiation (GID) generated by multiple genetic exchanges over time appear to have arisen recently, through recombination in a particular clade within this population. In addition, these isolates display resistance to phages from the same geographic region, probably due to the modification of surface components by the acquired genes. Our results suggest that an underlying process of early ecological and genetic differentiation in S. meliloti is primarily triggered by acquisition of genes that confer resistance to soil phages within particular large genomic DNA regions prone to recombination.
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Booth A, Mariscal C, Doolittle WF. The Modern Synthesis in the Light of Microbial Genomics. Annu Rev Microbiol 2016; 70:279-97. [DOI: 10.1146/annurev-micro-102215-095456] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Austin Booth
- Department of Philosophy, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada;
| | - Carlos Mariscal
- Department of Philosophy, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada;
- Department of Philosophy, University of Nevada, Reno, Nevada 89557
| | - W. Ford Doolittle
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada;
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A Small Number of Phylogenetically Distinct Clonal Complexes Dominate a Coastal Vibrio cholerae Population. Appl Environ Microbiol 2016; 82:5576-86. [PMID: 27371587 DOI: 10.1128/aem.01177-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 06/29/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Vibrio cholerae is a ubiquitous aquatic microbe in temperate and tropical coastal areas. It is a diverse species, with many isolates that are harmless to humans, while others are highly pathogenic. Most notable among them are strains belonging to the pandemic O1/O139 serogroup lineage, which contains the causative agents of cholera. The environmental selective regimes that led to this diversity are key to understanding how pathogens evolve in environmental reservoirs. A local population of V. cholerae and its close relative Vibrio metoecus from a coastal pond and lagoon system was extensively sampled during two consecutive months across four size fractions (480 isolates). In stark contrast to previous studies, the observed population was highly clonal, with 60% of V. cholerae isolates falling into one of five clonal complexes, which varied in abundance in the short temporal scale sampled. V. cholerae clonal complexes had significantly different distributions across size fractions and the two environments sampled, the pond and the lagoon. Sequencing the genomes of 20 isolates representing these five V. cholerae clonal complexes revealed different evolutionary trajectories, with considerable variations in gene content with potential ecological significance. Showing genotypic differentiation and differential spatial distribution, the dominant clonal complexes are likely ecologically divergent. Temporal variation in the relative abundance of these complexes suggests that transient blooms of specific clones could dominate local diversity. IMPORTANCE Vibrio cholerae is commonly found in coastal areas worldwide, with only a single group of this bacterium capable of causing severe cholera outbreaks. However, the potential to evolve the ability to cause disease exists in many strains of this species in its aquatic reservoir. Understanding how pathogenic bacteria evolve requires the study of their natural environments. By extensive sampling in a geographically restricted location in the United States, we found that most cells of a V. cholerae population belong to only a small number of strains. Analysis of their genome composition and spatial distribution indicates differential environmental adaptations between these strains. Other strains exist in smaller numbers, and the population was found to be temporally varied. This suggests frequent bloom and collapse cycles on a time scale of weeks. These population dynamics make it possible that more virulent strains could stochastically rise to large numbers, allowing for infection to occur.
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Pérez Carrascal OM, VanInsberghe D, Juárez S, Polz MF, Vinuesa P, González V. Population genomics of the symbiotic plasmids of sympatric nitrogen-fixing Rhizobium species associated with Phaseolus vulgaris. Environ Microbiol 2016; 18:2660-76. [PMID: 27312778 DOI: 10.1111/1462-2920.13415] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 06/13/2016] [Indexed: 11/28/2022]
Abstract
Cultivated common beans are the primary protein source for millions of people around the world who subsist on low-input agriculture, enabled by the symbiotic N2 -fixation these legumes perform in association with rhizobia. Within a single agricultural plot, multiple Rhizobium species can nodulate bean roots, but it is unclear how genetically isolated these species remain in sympatry. To better understand this issue, we sequenced and compared the genomes of 33 strains isolated from the rhizosphere and root nodules of a particular bean variety grown in the same agricultural plot. We found that the Rhizobium species we observed coexist with low genetic recombination across their core genomes. Accessory plasmids thought to be necessary for the saprophytic lifestyle in soil show similar levels of genetic isolation, but with higher rates of recombination than the chromosomes. However, the symbiotic plasmids are extremely similar, with high rates of recombination and do not appear to have co-evolved with the chromosome or accessory plasmids. Therefore, while Rhizobium species are genetically isolated units within the microbial community, a common symbiotic plasmid allows all Rhizobium species to engage in symbiosis with the same host in a single agricultural plot.
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Affiliation(s)
- Olga M Pérez Carrascal
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, México
| | - David VanInsberghe
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Soledad Juárez
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, México
| | - Martin F Polz
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Pablo Vinuesa
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, México
| | - Víctor González
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, México
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Paul S, Minnick MF, Chattopadhyay S. Mutation-Driven Divergence and Convergence Indicate Adaptive Evolution of the Intracellular Human-Restricted Pathogen, Bartonella bacilliformis. PLoS Negl Trop Dis 2016; 10:e0004712. [PMID: 27167125 PMCID: PMC4864206 DOI: 10.1371/journal.pntd.0004712] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/24/2016] [Indexed: 02/06/2023] Open
Abstract
Among all species of Bartonella, human-restricted Bartonella bacilliformis is the most virulent but harbors one of the most reduced genomes. Carrión’s disease, the infection caused by B. bacilliformis, has been afflicting poor rural populations for centuries in the high-altitude valleys of the South American Andes, where the pathogen’s distribution is probably restricted by its sand fly vector’s range. Importantly, Carrión’s disease satisfies the criteria set by the World Health Organization for a disease amenable to elimination. However, to date, there are no genome-level studies to identify potential footprints of B. bacilliformis (patho)adaptation. Our comparative genomic approach demonstrates that the evolution of this intracellular pathogen is shaped predominantly via mutation. Analysis of strains having publicly-available genomes shows high mutational divergence of core genes leading to multiple sub-species. We infer that the sub-speciation event might have happened recently where a possible adaptive divergence was accelerated by intermediate emergence of a mutator phenotype. Also, within a sub-species the pathogen shows inter-clonal adaptive evolution evidenced by non-neutral accumulation of convergent amino acid mutations. A total of 67 non-recombinant core genes (over-representing functional categories like DNA repair, glucose metabolic process, ATP-binding and ligase) were identified as candidates evolving via adaptive mutational convergence. Such convergence, both at the level of genes and their encoded functions, indicates evolution of B. bacilliformis clones along common adaptive routes, while there was little diversity within a single clone. How host-restriction, intracellularity and genome reduction interplay to exert or maintain virulence is poorly characterized. The fact that B. bacilliformis is the most pathogenic Bartonella and has a highly reduced genome makes it an attractive model to gain insights into (patho)adaptive evolution of intracellular pathogens. Also, B. bacilliformis is known to lack many virulence genes present in other Bartonella, indicating unique strategies of (patho)adaptation. Our study reveals a prevalent nature of mutational force in B. bacilliformis evolution with two distinct outcomes: (a) mutational divergence leading to sub-speciation, possibly recently, via accelerated accumulation and fixation of favorable mutations mediated by a mutator phenotype; and (b) mutational convergence between clones of a sub-species exhibiting shared functional trajectories of adaptive evolution. Our findings highlight positions accumulating adaptive mutations in candidate genes, offering future functional studies to elucidate B. bacilliformis virulence evolution, and of broad application to intracellular pathogens with a reduced gene repertoire.
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Affiliation(s)
- Sandip Paul
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Michael F. Minnick
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Sujay Chattopadhyay
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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48
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Le Roux F, Wegner KM, Polz MF. Oysters and Vibrios as a Model for Disease Dynamics in Wild Animals. Trends Microbiol 2016; 24:568-580. [PMID: 27038736 DOI: 10.1016/j.tim.2016.03.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/02/2016] [Accepted: 03/11/2016] [Indexed: 12/18/2022]
Abstract
Disease dynamics in the wild are influenced by a number of ecological and evolutionary factors not addressed by traditional laboratory-based characterization of pathogens. Here we propose the oyster, Crassostrea gigas, as a model for studying the interaction of the environment, bacterial pathogens, and the host in disease dynamics. We show that an important first step is to ask whether the functional unit of pathogenesis is a bacterial clone, a population, or a consortium in order to assess triggers of disease outbreaks and devise appropriate monitoring tools. Moreover, the development of specific-pathogen-free (SPF) oysters has enabled assessment of the infection process under natural conditions. Finally, recent results show the importance of microbial interactions and host genetics in determining oyster health and disease.
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Affiliation(s)
- Frédérique Le Roux
- Ifremer, Unité Physiologie Fonctionnelle des Organismes Marins, ZI de la Pointe du Diable, CS 10070, F-29280 Plouzané, France; Sorbonne Universités, UPMC Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France.
| | - K Mathias Wegner
- AWI - Alfred Wegener Institut - Helmholtz-Zentrum für Polar- und Meeresforschung, Coastal Ecology, Waddensea Station Sylt, Hafenstrasse 43, 25992 List, Germany
| | - Martin F Polz
- Parsons Lab for Environmental Science and Engineering, MIT, Cambridge, MA 02139, USA
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49
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Baltrus DA. Divorcing Strain Classification from Species Names. Trends Microbiol 2016; 24:431-439. [PMID: 26947794 DOI: 10.1016/j.tim.2016.02.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 01/29/2016] [Accepted: 02/04/2016] [Indexed: 02/01/2023]
Abstract
Confusion about strain classification and nomenclature permeates modern microbiology. Although taxonomists have traditionally acted as gatekeepers of order, the numbers of, and speed at which, new strains are identified has outpaced the opportunity for professional classification for many lineages. Furthermore, the growth of bioinformatics and database-fueled investigations have placed metadata curation in the hands of researchers with little taxonomic experience. Here I describe practical challenges facing modern microbial taxonomy, provide an overview of complexities of classification for environmentally ubiquitous taxa like Pseudomonas syringae, and emphasize that classification can be independent of nomenclature. A move toward implementation of relational classification schemes based on inherent properties of whole genomes could provide sorely needed continuity in how strains are referenced across manuscripts and data sets.
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Affiliation(s)
- David A Baltrus
- School of Plant Sciences, University of Arizona, Tucson, AZ, USA.
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