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Robertson JM, Garza EA, Stubbusch AKM, Dupont CL, Hwa T, Held NA. Marine bacteria Alteromonas spp. require UDP-glucose-4-epimerase for aggregation and production of sticky exopolymer. mBio 2024:e0003824. [PMID: 38958440 DOI: 10.1128/mbio.00038-24] [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: 01/06/2024] [Accepted: 05/23/2024] [Indexed: 07/04/2024] Open
Abstract
The physiology and ecology of particle-associated marine bacteria are of growing interest, but our knowledge of their aggregation behavior and mechanisms controlling their association with particles remains limited. We have found that a particle-associated isolate, Alteromonas sp. ALT199 strain 4B03, and the related type-strain A. macleodii 27126 both form large (>500 μm) aggregates while growing in rich medium. A non-clumping variant (NCV) of 4B03 spontaneously arose in the lab, and whole-genome sequencing revealed a partial deletion in the gene encoding UDP-glucose-4-epimerase (galEΔ308-324). In 27126, a knock-out of galE (ΔgalE::kmr) resulted in a loss of aggregation, mimicking the NCV. Microscopic analysis shows that both 4B03 and 27126 rapidly form large aggregates, whereas their respective galE mutants remain primarily as single planktonic cells or clusters of a few cells. Strains 4B03 and 27126 also form aggregates with chitin particles, but their galE mutants do not. Alcian Blue staining shows that 4B03 and 27126 produce large transparent exopolymer particles (TEP), but their galE mutants are deficient in this regard. This study demonstrates the capabilities of cell-cell aggregation, aggregation of chitin particles, and production of TEP in strains of Alteromonas, a widespread particle-associated genus of heterotrophic marine bacteria. A genetic requirement for galE is evident for each of the above capabilities, expanding the known breadth of requirement for this gene in biofilm-related processes. IMPORTANCE Heterotrophic marine bacteria have a central role in the global carbon cycle. Well-known for releasing CO2 by decomposition and respiration, they may also contribute to particulate organic matter (POM) aggregation, which can promote CO2 sequestration via the formation of marine snow. We find that two members of the prevalent particle-associated genus Alteromonas can form aggregates comprising cells alone or cells and chitin particles, indicating their ability to drive POM aggregation. In line with their multivalent aggregation capability, both strains produce TEP, an excreted polysaccharide central to POM aggregation in the ocean. We demonstrate a genetic requirement for galE in aggregation and large TEP formation, building our mechanistic understanding of these aggregative capabilities. These findings point toward a role for heterotrophic bacteria in POM aggregation in the ocean and support broader efforts to understand bacterial controls on the global carbon cycle based on microbial activities, community structure, and meta-omic profiling.
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Affiliation(s)
- Jacob M Robertson
- Division of Biological Sciences, UC San Diego, La Jolla, California, USA
| | - Erin A Garza
- Microbial and Environmental Genomics, J Craig Venter Institute, La Jolla, California, USA
| | - Astrid K M Stubbusch
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zürich, Switzerland
- Department of Environmental Microbiology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Department of Earth Sciences, Geological Institute, ETH Zurich, Zurich, Switzerland
| | - Christopher L Dupont
- Microbial and Environmental Genomics, J Craig Venter Institute, La Jolla, California, USA
| | - Terence Hwa
- Division of Biological Sciences, UC San Diego, La Jolla, California, USA
- Department of Physics, UC San Diego, La Jolla, California, USA
| | - Noelle A Held
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zürich, Switzerland
- Department of Environmental Microbiology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Department of Biological Sciences, Marine and Environmental Biology Section, University of Southern California, Los Angeles, California, USA
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2
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Harrison SJ, Malkin SY, Joye SB. Dispersant addition, but not nutrients, stimulated blooms of multiple hydrocarbonoclastic genera in nutrient-replete coastal marine surface waters. MARINE POLLUTION BULLETIN 2024; 204:116490. [PMID: 38843703 DOI: 10.1016/j.marpolbul.2024.116490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 06/17/2024]
Abstract
The range of impacts of chemical dispersants on indigenous marine microbial communities and their activity remains poorly constrained. We tested the response of nearshore surface waters chronically exposed to oil leakage from a downed platform and supplied with nutrients by the Mississippi River to Corexit dispersant and nutrient additions. As assessed using 14C-labeled tracers, hexadecane mineralization potential was orders of magnitude higher in all unamended samples than in previously assessed bathypelagic communities. Nutrient additions stimulated microbial mortality but did not affect community composition and had no generalizable effect on hydrocarbon mineralization potential. By contrast, Corexit amendments caused a rapid shift in community composition and a drawdown of inorganic nitrogen and orthophosphate though no generalizable effect on hydrocarbon mineralization potential. The hydrocarbonoclastic community's response to dispersants is largely driven by the relative availability of organic substrates and nutrients, underscoring the role of environmental conditions and multiple interacting stressors on hydrocarbon degradation potential.
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Affiliation(s)
- Sarah J Harrison
- Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA
| | - Sairah Y Malkin
- Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA
| | - Samantha B Joye
- Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA.
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3
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Layoun P, López-Pérez M, Haro-Moreno JM, Haber M, Thrash JC, Henson MW, Kavagutti VS, Ghai R, Salcher MM. Flexible genomic island conservation across freshwater and marine Methylophilaceae. THE ISME JOURNAL 2024; 18:wrad036. [PMID: 38365254 PMCID: PMC10872708 DOI: 10.1093/ismejo/wrad036] [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: 12/12/2023] [Revised: 12/15/2023] [Accepted: 12/20/2023] [Indexed: 02/18/2024]
Abstract
The evolutionary trajectory of Methylophilaceae includes habitat transitions from freshwater sediments to freshwater and marine pelagial that resulted in genome reduction (genome-streamlining) of the pelagic taxa. However, the extent of genetic similarities in the genomic structure and microdiversity of the two genome-streamlined pelagic lineages (freshwater "Ca. Methylopumilus" and the marine OM43 lineage) has so far never been compared. Here, we analyzed complete genomes of 91 "Ca. Methylopumilus" strains isolated from 14 lakes in Central Europe and 12 coastal marine OM43 strains. The two lineages showed a remarkable niche differentiation with clear species-specific differences in habitat preference and seasonal distribution. On the other hand, we observed a synteny preservation in their genomes by having similar locations and types of flexible genomic islands (fGIs). Three main fGIs were identified: a replacement fGI acting as phage defense, an additive fGI harboring metabolic and resistance-related functions, and a tycheposon containing nitrogen-, thiamine-, and heme-related functions. The fGIs differed in relative abundances in metagenomic datasets suggesting different levels of variability ranging from strain-specific to population-level adaptations. Moreover, variations in one gene seemed to be responsible for different growth at low substrate concentrations and a potential biogeographic separation within one species. Our study provides a first insight into genomic microdiversity of closely related taxa within the family Methylophilaceae and revealed remarkably similar dynamics involving mobile genetic elements and recombination between freshwater and marine family members.
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Affiliation(s)
- Paul Layoun
- Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre CAS, 37005 Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic
| | - Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, 03550 San Juan de Alicante, Spain
| | - Jose M Haro-Moreno
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, 03550 San Juan de Alicante, Spain
| | - Markus Haber
- Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre CAS, 37005 Ceske Budejovice, Czech Republic
| | - J Cameron Thrash
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Michael W Henson
- Department of Geophysical Sciences, University of Chicago, Chicago, IL 60637, USA
| | - Vinicius Silva Kavagutti
- Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre CAS, 37005 Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic
| | - Rohit Ghai
- Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre CAS, 37005 Ceske Budejovice, Czech Republic
| | - Michaela M Salcher
- Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre CAS, 37005 Ceske Budejovice, Czech Republic
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Molina-Pardines C, Haro-Moreno JM, López-Pérez M. Phosphate-related genomic islands as drivers of environmental adaptation in the streamlined marine alphaproteobacterial HIMB59. mSystems 2023; 8:e0089823. [PMID: 38054740 PMCID: PMC10734472 DOI: 10.1128/msystems.00898-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 10/17/2023] [Indexed: 12/07/2023] Open
Abstract
IMPORTANCE These results shed light on the evolutionary strategies of microbes with streamlined genomes to adapt and survive in the oligotrophic conditions that dominate the surface waters of the global ocean. At the individual level, these microbes have been subjected to evolutionary constraints that have led to a more efficient use of nutrients, removing non-essential genes named as "streamlining theory." However, at the population level, they conserve a highly diverse gene pool in flexible genomic islands resulting in polyclonal populations on the same genomic background as an evolutionary response to environmental pressures. Localization of these islands at equivalent positions in the genome facilitates horizontal transfer between clonal lineages. This high level of environmental genomic heterogeneity could explain their cosmopolitan distribution. In the case of the order HIMB59 within the class Alphaproteobacteria, two factors exert evolutionary pressure and determine this intraspecific diversity: phages and the concentration of P in the environment.
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Affiliation(s)
- Carmen Molina-Pardines
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, San Juan, Alicante, Spain
| | - Jose M. Haro-Moreno
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, San Juan, Alicante, Spain
| | - Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, San Juan, Alicante, Spain
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5
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Gonzalez-Serrano R, Rosselli R, Roda-Garcia JJ, Martin-Cuadrado AB, Rodriguez-Valera F, Dunne M. Distantly related Alteromonas bacteriophages share tail fibers exhibiting properties of transient chaperone caps. Nat Commun 2023; 14:6517. [PMID: 37845226 PMCID: PMC10579305 DOI: 10.1038/s41467-023-42114-8] [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: 02/20/2023] [Accepted: 09/27/2023] [Indexed: 10/18/2023] Open
Abstract
The host recognition modules encoding the injection machinery and receptor binding proteins (RBPs) of bacteriophages are predisposed to mutation and recombination to maintain infectivity towards co-evolving bacterial hosts. In this study, we reveal how Alteromonas mediterranea schitovirus A5 shares its host recognition module, including tail fiber and cognate chaperone, with phages from distantly related families including Alteromonas myovirus V22. While the V22 chaperone is essential for producing active tail fibers, here we demonstrate production of functional A5 tail fibers regardless of chaperone co-expression. AlphaFold-generated models of tail fiber and chaperone pairs from phages A5, V22, and other Alteromonas phages reveal how amino acid insertions within both A5-like proteins results in a knob domain duplication in the tail fiber and a chaperone β-hairpin "tentacle" extension. These structural modifications are linked to differences in chaperone dependency between the A5 and V22 tail fibers. Structural similarity between the chaperones and intramolecular chaperone domains of other phage RBPs suggests an additional function of these chaperones as transient fiber "caps". Finally, our identification of homologous host recognition modules from morphologically distinct phages implies that horizontal gene transfer and recombination events between unrelated phages may be a more common process than previously thought among Caudoviricetes phages.
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Affiliation(s)
- Rafael Gonzalez-Serrano
- Evolutionary Genomics Group, Universidad Miguel Hernández, San Juan de Alicante, Spain
- Centro de Biología Molecular Severo Ochoa, CBMSO-CSIC, Madrid, Spain
| | - Riccardo Rosselli
- Research & Development Department, LABAQUA S.A. Las Atalayas, Alicante, Spain
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Juan J Roda-Garcia
- Evolutionary Genomics Group, Universidad Miguel Hernández, San Juan de Alicante, Spain
| | | | | | - Matthew Dunne
- Institute of Food, Nutrition and Health, ETH Zurich, Switzerland.
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6
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Puente-Sánchez F, Hoetzinger M, Buck M, Bertilsson S. Exploring environmental intra-species diversity through non-redundant pangenome assemblies. Mol Ecol Resour 2023; 23:1724-1736. [PMID: 37382302 DOI: 10.1111/1755-0998.13826] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 05/24/2023] [Accepted: 06/15/2023] [Indexed: 06/30/2023]
Abstract
At the genome level, microorganisms are highly adaptable both in terms of allele and gene composition. Such heritable traits emerge in response to different environmental niches and can have a profound influence on microbial community dynamics. As a consequence, any individual genome or population will contain merely a fraction of the total genetic diversity of any operationally defined "species", whose ecological potential can thus be only fully understood by studying all of their genomes and the genes therein. This concept, known as the pangenome, is valuable for studying microbial ecology and evolution, as it partitions genomes into core (present in all the genomes from a species, and responsible for housekeeping and species-level niche adaptation among others) and accessory regions (present only in some, and responsible for intra-species differentiation). Here we present SuperPang, an algorithm producing pangenome assemblies from a set of input genomes of varying quality, including metagenome-assembled genomes (MAGs). SuperPang runs in linear time and its results are complete, non-redundant, preserve gene ordering and contain both coding and non-coding regions. Our approach provides a modular view of the pangenome, identifying operons and genomic islands, and allowing to track their prevalence in different populations. We illustrate this by analysing intra-species diversity in Polynucleobacter, a bacterial genus ubiquitous in freshwater ecosystems, characterized by their streamlined genomes and their ecological versatility. We show how SuperPang facilitates the simultaneous analysis of allelic and gene content variation under different environmental pressures, allowing us to study the drivers of microbial diversification at unprecedented resolution.
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Affiliation(s)
- Fernando Puente-Sánchez
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Matthias Hoetzinger
- 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
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
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7
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Idola D, Mori H, Nagata Y, Nonaka L, Yano H. Host range of strand-biased circularizing integrative elements: a new class of mobile DNA elements nesting in Gammaproteobacteria. Mob DNA 2023; 14:7. [PMID: 37237359 DOI: 10.1186/s13100-023-00295-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023] Open
Abstract
BACKGROUND The strand-biased circularizing integrative elements (SEs) are putatively non-mobilizable integrative elements for transmitting antimicrobial resistance genes. The transposition mode and the prevalence of SEs in prokaryotes remain vague. RESULTS To corroborate the transposition mode and the prevalence of SEs, hypothetical transposition intermediates of an SE were searched for in genomic DNA fractions of an SE host. Then, the SE core genes were defined based on gene knockout experiments, and the synteny blocks of their distant homologs were searched for in the RefSeq complete genome sequence database using PSI-BLAST. A genomic DNA fractionation experiment revealed that SE copies are present in a double-stranded nicked circular form in vivo. Operonic structure of three conserved coding sequences (intA, tfp, intB) and srap located at the left end of SEs were identified as essential for attL × attR recombination. The synteny blocks of tfp and srap homologs were detected in 3.6% of the replicons of Gammaproteobacteria but not in other taxa, implying that SE movement is host-dependent. SEs have been discovered most frequently in the orders Vibrionales (19% of replicons), Pseudomonadales (18%), Alteromonadales (17%), and Aeromonadales (12%). Genomic comparisons revealed 35 new SE members with identifiable termini. SEs are present at 1 to 2 copies per replicon and have a median length of 15.7 kb. Three newly identified SE members carry antimicrobial resistance genes, like tmexCD-toprJ, mcr-9, and blaGMA-1. Further experiments validated that three new SE members possess the strand-biased attL × attR recombination activity. CONCLUSIONS This study suggested that transposition intermediates of SEs are double-stranded circular DNA. The main hosts of SEs are a subset of free-living Gammaproteobacteria; this represents a rather narrow host range compared to those of mobile DNA element groups discovered to date. As the host range, genetic organization, and movements are unique among the mobile DNA elements, SEs provide a new model system for host-mobile DNA element coevolution studies.
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Affiliation(s)
- Desmila Idola
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aobaku, Sendai, 980-8577, Japan
| | - Hiroshi Mori
- Department of Informatics, National Institute of Genetics, 1111 Yata, Mishima, 411-8540, Japan
| | - Yuji Nagata
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aobaku, Sendai, 980-8577, Japan
| | - Lisa Nonaka
- Faculty of Human Life Sciences, Shokei University, 2-6-78 Kuhonji, Kumamoto, 862-8678, Japan
| | - Hirokazu Yano
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aobaku, Sendai, 980-8577, Japan.
- Antimicrobial Resistance Research Center, National Institute of Infectious Diseases, 4-2-1 Aobacho, Higashimurayama, Tokyo, 189-0002, Japan.
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8
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Roda-Garcia JJ, Haro-Moreno JM, Rodriguez-Valera F, Almagro-Moreno S, López-Pérez M. Single-amplified genomes reveal most streamlined free-living marine bacteria. Environ Microbiol 2023. [PMID: 36755376 DOI: 10.1111/1462-2920.16348] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 02/04/2023] [Indexed: 02/10/2023]
Abstract
Evolutionary adaptations of prokaryotes to the environment sometimes result in genome reduction. Our knowledge of this phenomenon among free-living bacteria remains scarce. We address the dynamics and limits of genome reduction by examining one of the most abundant bacteria in the ocean, the SAR86 clade. Despite its abundance, comparative genomics has been limited by the absence of pure cultures and the poor representation in metagenome-assembled genomes. We co-assembled multiple previously available single-amplified genomes to obtain the first complete genomes from members of the four families. All families showed a convergent evolutionary trajectory with characteristic features of streamlined genomes, most pronounced in the TMED112 family. This family has a genome size of ca. 1 Mb and only 1 bp as median intergenic distance, exceeding values found in other abundant microbes such as SAR11, OM43 and Prochlorococcus. This genomic simplification led to a reduction in the biosynthesis of essential molecules, DNA repair-related genes, and the ability to sense and respond to environmental factors, which could suggest an evolutionary dependence on other co-occurring microbes for survival (Black Queen hypothesis). Therefore, these reconstructed genomes within the SAR86 clade provide new insights into the limits of genome reduction in free-living marine bacteria.
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Affiliation(s)
- Juan J Roda-Garcia
- Evolutionary Genomics Group, Departamento Producción Vegetal y Microbiología, Universidad Miguel Hernández, Alicante, Spain
| | - Jose M Haro-Moreno
- Evolutionary Genomics Group, Departamento Producción Vegetal y Microbiología, Universidad Miguel Hernández, Alicante, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento Producción Vegetal y Microbiología, Universidad Miguel Hernández, Alicante, Spain
| | - Salvador Almagro-Moreno
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, USA.,National Center for Integrated Coastal Research, University of Central Florida, Orlando, Florida, USA
| | - Mario López-Pérez
- Evolutionary Genomics Group, Departamento Producción Vegetal y Microbiología, Universidad Miguel Hernández, Alicante, Spain
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9
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Phototroph-heterotroph interactions during growth and long-term starvation across Prochlorococcus and Alteromonas diversity. THE ISME JOURNAL 2023; 17:227-237. [PMID: 36335212 PMCID: PMC9860064 DOI: 10.1038/s41396-022-01330-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/02/2022] [Accepted: 10/05/2022] [Indexed: 11/08/2022]
Abstract
Due to their potential impact on ecosystems and biogeochemistry, microbial interactions, such as those between phytoplankton and bacteria, have been studied intensively using specific model organisms. Yet, to what extent interactions differ between closely related organisms, or how these interactions change over time, or culture conditions, remains unclear. Here, we characterize the interactions between five strains each of two globally abundant marine microorganisms, Prochlorococcus (phototroph) and Alteromonas (heterotroph), from the first encounter between individual strains and over more than a year of repeated cycles of exponential growth and long-term nitrogen starvation. Prochlorococcus-Alteromonas interactions had little effect on traditional growth parameters such as Prochlorococcus growth rate, maximal fluorescence, or lag phase, affecting primarily the dynamics of culture decline, which we interpret as representing cell mortality and lysis. The shape of the Prochlorococcus decline curve and the carrying capacity of the co-cultures were determined by the phototroph and not the heterotroph strains involved. Comparing various mathematical models of culture mortality suggests that Prochlorococcus death rate increases over time in mono-cultures but decreases in co-cultures, with cells potentially becoming more resistant to stress. Our results demonstrate intra-species differences in ecologically relevant co-culture outcomes. These include the recycling efficiency of N and whether the interactions are mutually synergistic or competitive. They also highlight the information-rich growth and death curves as a useful readout of the interaction phenotype.
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10
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Wietz M, López-Pérez M, Sher D, Biller SJ, Rodriguez-Valera F. Microbe Profile: Alteromonas macleodii - a widespread, fast-responding, 'interactive' marine bacterium. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36748580 DOI: 10.1099/mic.0.001236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Alteromonas macleodii is a marine heterotrophic bacterium with widespread distribution - from temperate to tropical oceans, and from surface to deep waters. Strains of A. macleodii exhibit considerable genomic and metabolic variability, and can grow rapidly on diverse organic compounds. A. macleodii is a model organism for the study of population genomics, physiological adaptations and microbial interactions, with individual genomes encoding diverse phenotypic traits influenced by recombination and horizontal gene transfer.
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Affiliation(s)
- Matthias Wietz
- Deep-Sea Ecology and Technology, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.,Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Alicante, Spain
| | - Daniel Sher
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Steven J Biller
- Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts, USA
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11
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Buck M, Mehrshad M, Bertilsson S. mOTUpan: a robust Bayesian approach to leverage metagenome-assembled genomes for core-genome estimation. NAR Genom Bioinform 2022; 4:lqac060. [PMID: 35979445 PMCID: PMC9376867 DOI: 10.1093/nargab/lqac060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 05/25/2022] [Accepted: 07/28/2022] [Indexed: 12/02/2022] Open
Abstract
Recent advances in sequencing and bioinformatics have expanded the tree of life by providing genomes for uncultured environmentally relevant clades, either through metagenome-assembled genomes or through single-cell genomes. While this expanded diversity can provide novel insights into microbial population structure, most tools available for core-genome estimation are sensitive to genome completeness. Consequently, a major portion of the huge phylogenetic diversity uncovered by environmental genomic approaches remains excluded from such analyses. We present mOTUpan, a novel iterative Bayesian method for computing the core genome for sets of genomes of highly diverse completeness range. The likelihood for each gene cluster to belong to core or accessory genome is estimated by computing the probability of its presence/absence pattern in the target genome set. The core-genome prediction is computationally efficient and can be scaled up to thousands of genomes. It has shown comparable estimates to state-of-the-art tools Roary and PPanGGOLiN for high-quality genomes and is capable of using genomes at lower completeness thresholds. mOTUpan wraps a bootstrapping procedure to estimate the quality of a specific core-genome prediction, as the accuracy of each run will depend on the specific completeness distribution and the number of genomes in the dataset under scrutiny. mOTUpan is implemented in the mOTUlizer software package, and available at github.com/moritzbuck/mOTUlizer, under GPL 3.0 license.
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Affiliation(s)
- Moritz Buck
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences , Lennart Hjelms väg 9, 75651 Uppsala, Sweden
| | - Maliheh Mehrshad
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences , Lennart Hjelms väg 9, 75651 Uppsala, Sweden
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences , Lennart Hjelms väg 9, 75651 Uppsala, Sweden
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12
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Arcadi E, Rastelli E, Tangherlini M, Rizzo C, Mancuso M, Sanfilippo M, Esposito V, Andaloro F, Romeo T. Shallow-Water Hydrothermal Vents as Natural Accelerators of Bacterial Antibiotic Resistance in Marine Coastal Areas. Microorganisms 2022; 10:microorganisms10020479. [PMID: 35208933 PMCID: PMC8877554 DOI: 10.3390/microorganisms10020479] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 02/01/2023] Open
Abstract
Environmental contamination by heavy metals (HMs) poses several indirect risks to human health, including the co-spreading of genetic traits conferring resistance to both HMs and antibiotics among micro-organisms. Microbial antibiotic resistance (AR) acquisition is enhanced at sites anthropogenically polluted by HMs, as well as in remote systems naturally enriched in HMs, such as hydrothermal vents in the deep sea. However, to date, the possible role of hydrothermal vents at shallower water depths as hot spots of microbial AR gain and spreading has not been tested, despite the higher potential risks associated with the closer vicinity of such ecosystems to coasts and human activities. In this work, we collected waters and sediments at the Panarea shallow-water hydrothermal vents, testing the presence of culturable marine bacteria and their sensitivity to antibiotics and HMs. All of the bacterial isolates showed resistance to at least one antibiotic and one HM and, most notably, 80% of them displayed multi-AR on average to 12 (min 8, max 15) different antibiotics, as well as multi-HM tolerance. We show that our isolates displayed high similarity (≥99%) to common marine bacteria, affiliating with Actinobacteria, Gammaproteobacteria, Alphaproteobacteria and Firmicutes, and all displayed wide growth ranges for temperature and salinity during in vitro physiological tests. Notably, the analysis of the genomes available in public databases for their closest relatives highlighted the lack of genes for AR, posing new questions on the origin of multi-AR acquisition in this peculiar HM-rich environment. Overall, our results point out that shallow-water hydrothermal vents may contribute to enhance AR acquisition and spreading among common marine bacteria in coastal areas, highlighting this as a focus for future research.
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Affiliation(s)
- Erika Arcadi
- Department of Integrative Marine Ecology, Stazione Zoologica “Anton Dohrn”, Sicily Marine Centre, Contrada Porticatello, 29, 98167 Messina, Italy;
- Correspondence: (E.A.); (E.R.)
| | - Eugenio Rastelli
- Department of Marine Biotechnology, Stazione Zoologica “Anton Dohrn”, Fano Marine Centre, Viale Adriatico 1-N, 61032 Fano, Italy
- Correspondence: (E.A.); (E.R.)
| | - Michael Tangherlini
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica “Anton Dohrn”, Villa Comunale, 80121 Napoli, Italy;
| | - Carmen Rizzo
- Stazione Zoologica Anton Dohrn–Marine Biotechnology Department, Sicily Marine Centre, Villa Pace, Contrada Porticatello 29, 98167 Messina, Italy;
- Institute of Polar Sciences, National Research Council (CNR-ISP), Spianata S. Raineri 86, 98122 Messina, Italy
| | - Monique Mancuso
- Department of Integrative Marine Ecology, Stazione Zoologica “Anton Dohrn”, Sicily Marine Centre, Contrada Porticatello, 29, 98167 Messina, Italy;
- Institute for Marine Biological Resources and Biotechnology (IRBIM), National Research Country (CNR), Messina, Spianata S. Raineri 86, 98122 Messina, Italy
| | - Marilena Sanfilippo
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica “Anton Dohrn”, Sicily Marine Centre, Contrada Porticatello, 29, 98167 Messina, Italy;
| | - Valentina Esposito
- Istituto Nazionale di Oceanografia e di Geofisica Sperimentale—OGS Borgo Grotta Gigante 42/C, 34010 Sgonico, Italy;
| | - Franco Andaloro
- Department of Integrative Marine Ecology, Stazione Zoologica “Anton Dohrn”, Sicily Marine Centre, Lungomare Cristoforo Colombo (Complesso Roosevelt), 90149 Palermo, Italy;
| | - Teresa Romeo
- Department of Integrative Marine Ecology, Stazione Zoologica “Anton Dohrn”, Sicily Marine Centre, Via dei Mille 46, 98057 Milazzo, Italy;
- National Institute for Environmental Protection and Research, Via dei Mille 46, 98057 Milazzo, Italy
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13
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Enhanced copper-resistance gene repertoire in Alteromonas macleodii strains isolated from copper-treated marine coatings. PLoS One 2021; 16:e0257800. [PMID: 34582496 PMCID: PMC8478169 DOI: 10.1371/journal.pone.0257800] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 09/12/2021] [Indexed: 11/19/2022] Open
Abstract
Copper is prevalent in coastal ecosystems due to its use as an algaecide and as an anti-fouling agent on ship hulls. Alteromonas spp. have previously been shown to be some of the early colonizers of copper-based anti-fouling paint but little is known about the mechanisms they use to overcome this initial copper challenge. The main models of copper resistance include the Escherichia coli chromosome-based Cue and Cus systems; the plasmid-based E. coli Pco system; and the plasmid-based Pseudomonas syringae Cop system. These were all elucidated from strains isolated from copper-rich environments of agricultural and/or enteric origin. In this work, copper resistance assays demonstrated the ability of Alteromonas macleodii strains CUKW and KCC02 to grow at levels lethal to other marine bacterial species. A custom database of Hidden Markov Models was designed based on proteins from the Cue, Cus, and Cop/Pco systems and used to identify potential copper resistance genes in CUKW and KCC02. Comparative genomic analyses with marine bacterial species and bacterial species isolated from copper-rich environments demonstrated that CUKW and KCC02 possess genetic elements of all systems, oftentimes with multiple copies, distributed throughout the chromosome and mega-plasmids. In particular, two copies of copA (the key player in cytoplasmic detoxification), each with its own apparent MerR-like transcriptional regulator, occur on a mega-plasmid, along with multiple copies of Pco homologs. Genes from both systems were induced upon exposure to elevated copper levels (100 μM- 3 mM). Genomic analysis identified one of the merR-copA clusters occurs on a genomic island (GI) within the plasmid, and comparative genomic analysis found that either of the merR-copA clusters, which also includes genes coding for a cupredoxin domain-containing protein and an isoprenylcysteine methyltransferase, occurs on a GI across diverse bacterial species. These genomic findings combined with the ability of CUKW and KCC02 to grow in copper-challenged conditions are couched within the context of the genome flexibility of the Alteromonas genus.
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Haro-Moreno JM, López-Pérez M, Rodriguez-Valera F. Enhanced Recovery of Microbial Genes and Genomes From a Marine Water Column Using Long-Read Metagenomics. Front Microbiol 2021; 12:708782. [PMID: 34512586 PMCID: PMC8430335 DOI: 10.3389/fmicb.2021.708782] [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: 05/14/2021] [Accepted: 07/30/2021] [Indexed: 12/12/2022] Open
Abstract
Third-generation sequencing has penetrated little in metagenomics due to the high error rate and dependence for assembly on short-read designed bioinformatics. However, second-generation sequencing metagenomics (mostly Illumina) suffers from limitations, particularly in the assembly of microbes with high microdiversity and retrieval of the flexible (adaptive) fraction of prokaryotic genomes. Here, we have used a third-generation technique to study the metagenome of a well-known marine sample from the mixed epipelagic water column of the winter Mediterranean. We have compared PacBio Sequel II with the classical approach using Illumina Nextseq short reads followed by assembly to study the metagenome. Long reads allow for efficient direct retrieval of complete genes avoiding the bias of the assembly step. Besides, the application of long reads on metagenomic assembly allows for the reconstruction of much more complete metagenome-assembled genomes (MAGs), particularly from microbes with high microdiversity such as Pelagibacterales. The flexible genome of reconstructed MAGs was much more complete containing many adaptive genes (some with biotechnological potential). PacBio Sequel II CCS appears particularly suitable for cellular metagenomics due to its low error rate. For most applications of metagenomics, from community structure analysis to ecosystem functioning, long reads should be applied whenever possible. Specifically, for in silico screening of biotechnologically useful genes, or population genomics, long-read metagenomics appears presently as a very fruitful approach and can be analyzed from raw reads before a computationally demanding (and potentially artifactual) assembly step.
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Affiliation(s)
- Jose M. Haro-Moreno
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Alicante, Spain
| | - Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Alicante, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Alicante, Spain
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
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15
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Feng X, Yan W, Wang A, Ma R, Chen X, Lin TH, Chen YL, Wei S, Jin T, Jiao N, Zhang R. A Novel Broad Host Range Phage Infecting Alteromonas. Viruses 2021; 13:v13060987. [PMID: 34073246 PMCID: PMC8228385 DOI: 10.3390/v13060987] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/19/2021] [Accepted: 05/20/2021] [Indexed: 12/24/2022] Open
Abstract
Bacteriophages substantially contribute to bacterial mortality in the ocean and play critical roles in global biogeochemical processes. Alteromonas is a ubiquitous bacterial genus in global tropical and temperate waters, which can cross-protect marine cyanobacteria and thus has important ecological benefits. However, little is known about the biological and ecological features of Alteromonas phages (alterophages). Here, we describe a novel alterophage vB_AmeP-R8W (R8W), which belongs to the Autographiviridae family and infects the deep-clade Alteromonas mediterranea. R8W has an equidistant and icosahedral head (65 ± 1 nm in diameter) and a short tail (12 ± 2 nm in length). The genome size of R8W is 48,825 bp, with a G + C content of 40.55%. R8W possesses three putative auxiliary metabolic genes encoding proteins involved in nucleotide metabolism and DNA binding: thymidylate synthase, nucleoside triphosphate pyrophosphohydrolase, and PhoB. R8W has a rapid lytic cycle with a burst size of 88 plaque-forming units/cell. Notably, R8W has a wide host range, such that it can infect 35 Alteromonas strains; it exhibits a strong specificity for strains isolated from deep waters. R8W has two specific receptor binding proteins and a compatible holin-endolysin system, which contribute to its wide host range. The isolation of R8W will contribute to the understanding of alterophage evolution, as well as the phage-host interactions and ecological importance of alterophages.
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Affiliation(s)
- Xuejin Feng
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
| | - Wei Yan
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
- College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China
| | - Anan Wang
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
| | - Ruijie Ma
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
| | - Xiaowei Chen
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
| | - Ta-Hui Lin
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
| | - Yi-Lung Chen
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
| | - Shuzhen Wei
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
| | - Tao Jin
- Guangzhou Magigene Biotechnology Co., Ltd., Guangzhou 510000, China;
| | - Nianzhi Jiao
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
- Correspondence: (N.J.); (R.Z.)
| | - Rui Zhang
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (X.F.); (W.Y.); (A.W.); (R.M.); (X.C.); (T.-H.L.); (Y.-L.C.); (S.W.)
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519080, China
- Correspondence: (N.J.); (R.Z.)
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16
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Zhang DF, Cui XW, Li WJ, Zhang XM, Xue HP, Huang JK, Zhang AH. Description of Salinimonas profundi sp. nov., a deep-sea bacterium harboring a transposon Tn6333. Antonie van Leeuwenhoek 2021; 114:69-81. [DOI: 10.1007/s10482-020-01501-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 11/17/2020] [Indexed: 11/28/2022]
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Genomes of the " Candidatus Actinomarinales" Order: Highly Streamlined Marine Epipelagic Actinobacteria. mSystems 2020; 5:5/6/e01041-20. [PMID: 33323418 PMCID: PMC7771536 DOI: 10.1128/msystems.01041-20] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Microbiology is in a new age in which sequence databases are primary sources of information about many microbes. However, in-depth analysis of environmental genomes thus retrieved is essential to substantiate the new knowledge. “Candidatus Actinomarinales” was defined as a subclass of exclusively marine Actinobacteria with small cells and genomes. We have collected all the available genomes in databases to assess the diversity included in this group and analyzed it by comparative genomics. We have found the equivalent of five genera and 18 genomospecies. They have genome reduction parameters equal to those of freshwater actinobacterial “Candidatus Nanopelagicales” or marine alphaproteobacterial Pelagibacterales. Genome recruitment shows that they are found only in the photic zone and mainly in surface waters, with only one genus that is found preferentially at or below the deep chlorophyll maximum. “Ca. Actinomarinales” show a highly conserved core genome (80% of the gene families conserved for the whole order) with a saturation of genomic diversity of the flexible genome at the genomospecies level. We found only a flexible genomic island preserved throughout the order; it is related to the sugar decoration of the envelope and uses several tRNAs as hot spots to increase its genomic diversity. Populations had a discrete level of sequence diversity similar to other marine microbes but drastically different from the much higher levels found for Pelagibacterales. Genomic analysis suggests that they are all aerobic photoheterotrophs with one type 1 rhodopsin and a heliorhodopsin. Like other actinobacteria, they possess the F420 coenzyme biosynthesis pathway, and its lower reduction potential could provide access to an increased range of redox chemical transformations. Last, sequence analysis revealed the first “Ca. Actinomarinales” phages, including a prophage, with metaviromic islands related to sialic acid cleavage. IMPORTANCE Microbiology is in a new age in which sequence databases are primary sources of information about many microbes. However, in-depth analysis of environmental genomes thus retrieved is essential to substantiate the new knowledge. Here, we study 182 genomes belonging to the only known exclusively marine pelagic group of the phylum Actinobacteria. The aquatic branch of this phylum is largely known from environmental sequencing studies (single-amplified genomes [SAGs] and metagenome-assembled genomes [MAGs]), and we have collected and analyzed the available information present in databases about the “Ca. Actinomarinales.” They are among the most streamlined microbes to live in the epipelagic zone of the ocean, and their study is critical to obtain a proper view of the diversity of Actinobacteria and their role in aquatic ecosystems.
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18
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Abstract
As the most abundant bacteria in oceans, the Pelagibacterales order (here SAR11) plays an important role in the global carbon cycle, but the study of the evolutionary forces driving its evolution has lagged considerably due to the inherent difficulty of obtaining pure cultures. Multiple evolutionary models have been proposed to explain the diversification of distinct lineages within a population; however, the identification of many of these patterns in natural populations remains mostly enigmatic. We have used a metagenomic approach to explore microdiversity patterns in their natural habitats. Comparison with a collection of bacterial and archaeal groups from the same environments shows that SAR11 populations have a different evolutionary regime, where multiple genotypes coexist within the same population and remain stable over time. Widespread homologous recombination could be one of the main driving factors of this homogenization. The SAR11 clade of Alphaproteobacteria is the most abundant group of planktonic cells in the near-surface epipelagic waters of the ocean, but the mechanisms underlying its exceptional success have not been fully elucidated. Here, we applied a metagenomic approach to explore microdiversity patterns by measuring the accumulation of synonymous and nonsynonymous mutations as well as homologous recombination in populations of SAR11 from different aquatic habitats (marine epipelagic, bathypelagic, and surface freshwater). The patterns of mutation accumulation and recombination were compared to those of other groups of representative marine microbes with multiple ecological strategies that share the same marine habitat, namely, Cyanobacteria (Prochlorococcus and Synechococcus), Archaea (“Candidatus Nitrosopelagicus” and Marine Group II Thalassoarchaea), and some heterotrophic marine bacteria (Alteromonas and Erythrobacter). SAR11 populations showed widespread recombination among distantly related members, preventing divergence leading to a genetically stable population. Moreover, their high intrapopulation sequence diversity with an enrichment in synonymous replacements supports the idea of a very ancient divergence and the coexistence of multiple different clones. However, other microbes analyzed seem to follow different evolutionary dynamics where processes of diversification driven by geographic and ecological instability produce a higher number of nonsynonymous replacements and lower intrapopulation sequence diversity. Together, these data shed light on some of the evolutionary and ecological processes that lead to the large genomic diversity in SAR11. Furthermore, this approach can be applied to other similar microbes that are difficult to culture in the laboratory, but abundant in nature, to investigate the underlying dynamics of their genomic evolution. IMPORTANCE As the most abundant bacteria in oceans, the Pelagibacterales order (here SAR11) plays an important role in the global carbon cycle, but the study of the evolutionary forces driving its evolution has lagged considerably due to the inherent difficulty of obtaining pure cultures. Multiple evolutionary models have been proposed to explain the diversification of distinct lineages within a population; however, the identification of many of these patterns in natural populations remains mostly enigmatic. We have used a metagenomic approach to explore microdiversity patterns in their natural habitats. Comparison with a collection of bacterial and archaeal groups from the same environments shows that SAR11 populations have a different evolutionary regime, where multiple genotypes coexist within the same population and remain stable over time. Widespread homologous recombination could be one of the main driving factors of this homogenization.
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19
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Bellas CM, Schroeder DC, Edwards A, Barker G, Anesio AM. Flexible genes establish widespread bacteriophage pan-genomes in cryoconite hole ecosystems. Nat Commun 2020; 11:4403. [PMID: 32879312 PMCID: PMC7468147 DOI: 10.1038/s41467-020-18236-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 08/10/2020] [Indexed: 12/20/2022] Open
Abstract
Bacteriophage genomes rapidly evolve via mutation and horizontal gene transfer to counter evolving bacterial host defenses; such arms race dynamics should lead to divergence between phages from similar, geographically isolated ecosystems. However, near-identical phage genomes can reoccur over large geographical distances and several years apart, conversely suggesting many are stably maintained. Here, we show that phages with near-identical core genomes in distant, discrete aquatic ecosystems maintain diversity by possession of numerous flexible gene modules, where homologous genes present in the pan-genome interchange to create new phage variants. By repeatedly reconstructing the core and flexible regions of phage genomes from different metagenomes, we show a pool of homologous gene variants co-exist for each module in each location, however, the dominant variant shuffles independently in each module. These results suggest that in a natural community, recombination is the largest contributor to phage diversity, allowing a variety of host recognition receptors and genes to counter bacterial defenses to co-exist for each phage. Bacteriophages and their hosts are involved in a constant evolutionary arms race that should lead to divergence between phage genes over time. Here, the authors recruit metagenomic reads to virus reference genomes and genome fragments in samples from cryoconite holes and show that phages with near-identical core genomes maintain diversity by possession of numerous flexible gene modules, where homologous genes present in the pan-genome interchange to create new phage variants.
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Affiliation(s)
- Christopher M Bellas
- Department of Ecology, Lake and Glacier Ecology, University of Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria.
| | - Declan C Schroeder
- Department of Veterinary Population Medicine, University of Minnesota, 1333 Gortner Avenue, St. Paul, MN, 55108, USA.,School of Biological Sciences, University of Reading, Reading, UK
| | - Arwyn Edwards
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3EE, UK
| | - Gary Barker
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Alexandre M Anesio
- Department of Environmental Science, Aarhus University, Frederiksborgvej 399, 4000, Roskilde, Denmark
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Zarandona I, Estupiñán M, Pérez C, Alonso-Sáez L, Guerrero P, de la Caba K. Chitosan Films Incorporated with Exopolysaccharides from Deep Seawater Alteromonas Sp. Mar Drugs 2020; 18:md18090447. [PMID: 32867255 PMCID: PMC7551391 DOI: 10.3390/md18090447] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 08/20/2020] [Accepted: 08/25/2020] [Indexed: 12/26/2022] Open
Abstract
Two Alteromonas sp. strains isolated from deep seawater were grown to promote the production of exopolysaccharides (EPS, E611 and E805), which were incorporated into chitosan solutions to develop films. The combination of the major marine polysaccharides (chitosan and the isolated bacterial EPS) resulted in the formation of homogenous, transparent, colorless films, suggesting good compatibility between the two components of the film-forming formulation. With regards to optical properties, the films showed low values of gloss, in the range of 5-10 GU, indicating the formation of non-glossy and rough surfaces. In addition to the film surface, both showed hydrophobic character, with water contact angles higher than 100 º, regardless of EPS addition. Among the two EPS under analysis, chitosan films with E805 showed better mechanical performance, leading to resistant, flexible, easy to handle films.
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Affiliation(s)
- Iratxe Zarandona
- BIOMAT research group, University of the Basque Country (UPV/EHU), Escuela de Ingeniería de Gipuzkoa, Plaza de Europa 1, 20018 Donostia-San Sebastián, Spain;
| | - Mónica Estupiñán
- AZTI Marine Research, Basque Research and Technology Alliance (BRTA), Txatxarramendi ugartea z/g, 48395 Sukarrieta, Spain; (M.E.); (C.P.); (L.A.-S.)
| | - Carla Pérez
- AZTI Marine Research, Basque Research and Technology Alliance (BRTA), Txatxarramendi ugartea z/g, 48395 Sukarrieta, Spain; (M.E.); (C.P.); (L.A.-S.)
| | - Laura Alonso-Sáez
- AZTI Marine Research, Basque Research and Technology Alliance (BRTA), Txatxarramendi ugartea z/g, 48395 Sukarrieta, Spain; (M.E.); (C.P.); (L.A.-S.)
| | - Pedro Guerrero
- BIOMAT research group, University of the Basque Country (UPV/EHU), Escuela de Ingeniería de Gipuzkoa, Plaza de Europa 1, 20018 Donostia-San Sebastián, Spain;
- Correspondence: (P.G.); (K.d.l.C.)
| | - Koro de la Caba
- BIOMAT research group, University of the Basque Country (UPV/EHU), Escuela de Ingeniería de Gipuzkoa, Plaza de Europa 1, 20018 Donostia-San Sebastián, Spain;
- Correspondence: (P.G.); (K.d.l.C.)
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21
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Chen M, Song Y, Feng X, Tang K, Jiao N, Tian J, Zhang Y. Genomic Characteristics and Potential Metabolic Adaptations of Hadal Trench Roseobacter and Alteromonas Bacteria Based on Single-Cell Genomics Analyses. Front Microbiol 2020; 11:1739. [PMID: 32793171 PMCID: PMC7393951 DOI: 10.3389/fmicb.2020.01739] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 07/03/2020] [Indexed: 11/30/2022] Open
Abstract
Heterotrophic bacteria such as those from the Roseobacter group and genus Alteromonas dominate the hadal zones of oceans; however, we know little about the genomic characteristics and potential metabolic adaptations of hadal trench-dwelling bacteria. Here, we report multiple single amplified genomes (SAGs) belonging to Roseobacter and Alteromonas, recovered from the hadal zone of the Mariana Trench. While phylogenetic analyses show that these hadal SAGs cluster with their surface relatives, an analysis of genomic recruitment indicates that they have higher relative abundances in the hadal zone of the Mariana Trench. Comparative genomic analyses between the hadal SAGs and reference genomes of closely related shallow-water relatives indicate that genes involved in the mobilome (prophages and transposons) are overrepresented among the unique genes of the hadal Roseobacter and Alteromonas SAGs; the functional proteins encoded by this category of genes also shows higher amino acid sequence variation than those encoded by other gene sets within the Roseobacter SAGs. We also found that genes involved in cell wall/membrane/envelope biogenesis, transcriptional regulation, and metal transport may be important for the adaptation of hadal Roseobacter and Alteromonas lineages. These results imply that the modification of cell surface-related proteins and transporters is the major direction of genomic evolution in Roseobacter and Alteromonas bacteria adapting to the hadal environment, and that prophages and transposons may be the key factors driving this process.
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Affiliation(s)
- Mingming Chen
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen, China
| | - Yu Song
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen, China
| | - Xiaoyuan Feng
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Kai Tang
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen, China
| | - Nianzhi Jiao
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen, China
| | - Jiwei Tian
- Physical Oceanography Laboratory, Ocean University of China, Qingdao, China
| | - Yao Zhang
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Science, Xiamen University, Xiamen, China
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Takebe H, Tominaga K, Fujiwara K, Yamamoto K, Yoshida T. Differential Responses of a Coastal Prokaryotic Community to Phytoplanktonic Organic Matter Derived from Cellular Components and Exudates. Microbes Environ 2020; 35. [PMID: 32554942 PMCID: PMC7511794 DOI: 10.1264/jsme2.me20033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The phytoplanktonic production and prokaryotic consumption of organic matter significantly contribute to marine carbon cycling. Organic matter released from phytoplankton via three processes (exudation of living cells, cell disruption through grazing, and viral lysis) shows distinct chemical properties. We herein investigated the effects of phytoplanktonic whole-cell fractions (WF) (representing cell disruption by grazing) and extracellular fractions (EF) (representing exudates) prepared from Heterosigma akashiwo, a bloom-forming Raphidophyceae, on prokaryotic communities using culture-based experiments. We analyzed prokaryotic community changes for two weeks. The shift in cell abundance by both treatments showed similar dynamics, reaching the first peak (~4.1×106 cells mL–1) on day 3 and second peak (~1.1×106 cells mL–1) on day 13. We classified the sequences obtained into operational taxonomic units (OTUs). A Bray-Curtis dissimilarity analysis revealed that the OTU-level community structure changed distinctively with the two treatments. Ten and 13 OTUs were specifically abundant in the WF and EF treatments, respectively. These OTUs were assigned as heterotrophic bacteria mainly belonging to the Alteromonadales (Gammaproteobacteria) and Bacteroidetes clades and showed successive dynamics following the addition of organic matter. We also analyzed the dynamics of these OTUs in the ocean using publicly available metagenomic data from a natural coastal bloom in Monterey Bay, USA. At least two WF treatment OTUs showed co-occurrence with H. akashiwo, indicating that the blooms of H. akashiwo also affect these OTUs in the ocean. The present results strongly suggest that the thriving and dead cells of uninfected phytoplankton differentially influence the marine prokaryotic community.
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Affiliation(s)
| | | | | | - Keigo Yamamoto
- Research Institute of Environment, Agriculture and Fisheries, Osaka Prefecture
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Gonzalez-Serrano R, Dunne M, Rosselli R, Martin-Cuadrado AB, Grosboillot V, Zinsli LV, Roda-Garcia JJ, Loessner MJ, Rodriguez-Valera F. Alteromonas Myovirus V22 Represents a New Genus of Marine Bacteriophages Requiring a Tail Fiber Chaperone for Host Recognition. mSystems 2020; 5:e00217-20. [PMID: 32518192 PMCID: PMC7289586 DOI: 10.1128/msystems.00217-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 05/20/2020] [Indexed: 12/24/2022] Open
Abstract
Marine phages play a variety of critical roles in regulating the microbial composition of our oceans. Despite constituting the majority of genetic diversity within these environments, there are relatively few isolates with complete genome sequences or in-depth analyses of their host interaction mechanisms, such as characterization of their receptor binding proteins (RBPs). Here, we present the 92,760-bp genome of the Alteromonas-targeting phage V22. Genomic and morphological analyses identify V22 as a myovirus; however, due to a lack of sequence similarity to any other known myoviruses, we propose that V22 be classified as the type phage of a new Myoalterovirus genus within the Myoviridae family. V22 shows gene homology and synteny with two different subfamilies of phages infecting enterobacteria, specifically within the structural region of its genome. To improve our understanding of the V22 adsorption process, we identified putative RBPs (gp23, gp24, and gp26) and tested their ability to decorate the V22 propagation strain, Alteromonas mediterranea PT11, as recombinant green fluorescent protein (GFP)-tagged constructs. Only GFP-gp26 was capable of bacterial recognition and identified as the V22 RBP. Interestingly, production of functional GFP-gp26 required coexpression with the downstream protein gp27. GFP-gp26 could be expressed alone but was incapable of host recognition. By combining size-exclusion chromatography with fluorescence microscopy, we reveal how gp27 is not a component of the final RBP complex but instead is identified as a new type of phage-encoded intermolecular chaperone that is essential for maturation of the gp26 RBP.IMPORTANCE Host recognition by phage-encoded receptor binding proteins (RBPs) constitutes the first step in all phage infections and the most critical determinant of host specificity. By characterizing new types of RBPs and identifying their essential chaperones, we hope to expand the repertoire of known phage-host recognition machineries. Due to their genetic plasticity, studying RBPs and their associated chaperones can shed new light onto viral evolution affecting phage-host interactions, which is essential for fields such as phage therapy or biotechnology. In addition, since marine phages constitute one of the most important reservoirs of noncharacterized genetic diversity on the planet, their genomic and functional characterization may be of paramount importance for the discovery of novel genes with potential applications.
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Affiliation(s)
| | - Matthew Dunne
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Riccardo Rosselli
- NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Utrecht University, Den Burg, The Netherlands
- Laboratory for Theoretical and Computer Studies of Biological Macromolecules and Genomes, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | | | | | - Léa V Zinsli
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Juan J Roda-Garcia
- Evolutionary Genomics Group, Universidad Miguel Hernández, San Juan de Alicante, Spain
| | - Martin J Loessner
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Universidad Miguel Hernández, San Juan de Alicante, Spain
- Laboratory for Theoretical and Computer Studies of Biological Macromolecules and Genomes, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
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Transcriptomic Study of Substrate-Specific Transport Mechanisms for Iron and Carbon in the Marine Copiotroph Alteromonas macleodii. mSystems 2020; 5:5/2/e00070-20. [PMID: 32345736 PMCID: PMC7190382 DOI: 10.1128/msystems.00070-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
As the major facilitators of the turnover of organic matter in the marine environment, the ability of heterotrophic bacteria to acquire specific compounds within the diverse range of dissolved organic matter will affect the regeneration of essential nutrients such as iron and carbon. TonB-dependent transporters are a prevalent cellular tool in Gram-negative bacteria that allow a relatively high-molecular-weight fraction of organic matter to be directly accessed. However, these transporters are not well characterized in marine bacteria, limiting our understanding of the flow of specific substrates through the marine microbial loop. Here, we characterize the TonB-dependent transporters responsible for iron and carbon acquisition in a representative marine copiotroph and examine their distribution across the genus Alteromonas. We provide evidence that substrate-specific bioavailability is niche specific, particularly for iron complexes, indicating that transport capacity may serve as a significant control on microbial community dynamics and the resultant cycling of organic matter. Iron is an essential micronutrient for all microbial growth in the marine environment, and in heterotrophic bacteria, iron is tightly linked to carbon metabolism due to its central role as a cofactor in enzymes of the respiratory chain. Here, we present the iron- and carbon-regulated transcriptomes of a representative marine copiotroph, Alteromonas macleodii ATCC 27126, and characterize its cellular transport mechanisms. ATCC 27126 has distinct metabolic responses to iron and carbon limitation and, accordingly, uses distinct sets of TonB-dependent transporters for the acquisition of iron and carbon. These distinct sets of TonB-dependent transporters were of a similar number, indicating that the diversity of carbon and iron substrates available to ATCC 27126 is of a similar scale. For the first time in a marine bacterium, we have also identified six characteristic inner membrane permeases for the transport of siderophores via an ATPase-independent mechanism. An examination of the distribution of specific TonB-dependent transporters in 31 genomes across the genus Alteromonas points to niche specialization in transport capacity, particularly for iron. We conclude that the substrate-specific bioavailability of both iron and carbon in the marine environment will likely be a key control on the processing of organic matter through the microbial loop. IMPORTANCE As the major facilitators of the turnover of organic matter in the marine environment, the ability of heterotrophic bacteria to acquire specific compounds within the diverse range of dissolved organic matter will affect the regeneration of essential nutrients such as iron and carbon. TonB-dependent transporters are a prevalent cellular tool in Gram-negative bacteria that allow a relatively high-molecular-weight fraction of organic matter to be directly accessed. However, these transporters are not well characterized in marine bacteria, limiting our understanding of the flow of specific substrates through the marine microbial loop. Here, we characterize the TonB-dependent transporters responsible for iron and carbon acquisition in a representative marine copiotroph and examine their distribution across the genus Alteromonas. We provide evidence that substrate-specific bioavailability is niche specific, particularly for iron complexes, indicating that transport capacity may serve as a significant control on microbial community dynamics and the resultant cycling of organic matter.
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25
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Abstract
SAR11 clade members are among the most abundant bacteria on Earth. Their study is complicated by their great diversity and difficulties in being grown and manipulated in the laboratory. On the other hand, and due to their extraordinary abundance, metagenomic data sets provide enormous richness of information about these microbes. Given the major role played by phages in the lifestyle and evolution of prokaryotic cells, the contribution of several new bacteriophage genomes preying on this clade opens windows into the infection strategies and life cycle of its viruses. Such strategies could provide models of attack of large-genome phages preying on streamlined aquatic microbes. The SAR11 clade is one of the most abundant bacterioplankton groups in surface waters of most of the oceans and lakes. However, only 15 SAR11 phages have been isolated thus far, and only one of them belongs to the Myoviridae family (pelagimyophages). Here, we have analyzed 26 sequences of myophages that putatively infect the SAR11 clade. They have been retrieved by mining ca. 45 Gbp aquatic assembled cellular metagenomes and viromes. Most of the myophages were obtained from the cellular fraction (0.2 μm), indicating a bias against this type of virus in viromes. We have found the first myophages that putatively infect Candidatus Fonsibacter (freshwater SAR11) and another group putatively infecting bathypelagic SAR11 phylogroup Ic. The genomes have similar sizes and maintain overall synteny in spite of low average nucleotide identity values, revealing high similarity to marine cyanomyophages. Pelagimyophages recruited metagenomic reads widely from several locations but always much more from cellular metagenomes than from viromes, opposite to what happens with pelagipodophages. Comparing the genomes resulted in the identification of a hypervariable island that is related to host recognition. Interestingly, some genes in these islands could be related to host cell wall synthesis and coinfection avoidance. A cluster of curli-related proteins was widespread among the genomes, although its function is unclear. IMPORTANCE SAR11 clade members are among the most abundant bacteria on Earth. Their study is complicated by their great diversity and difficulties in being grown and manipulated in the laboratory. On the other hand, and due to their extraordinary abundance, metagenomic data sets provide enormous richness of information about these microbes. Given the major role played by phages in the lifestyle and evolution of prokaryotic cells, the contribution of several new bacteriophage genomes preying on this clade opens windows into the infection strategies and life cycle of its viruses. Such strategies could provide models of attack of large-genome phages preying on streamlined aquatic microbes.
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26
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Koch H, Germscheid N, Freese HM, Noriega-Ortega B, Lücking D, Berger M, Qiu G, Marzinelli EM, Campbell AH, Steinberg PD, Overmann J, Dittmar T, Simon M, Wietz M. Genomic, metabolic and phenotypic variability shapes ecological differentiation and intraspecies interactions of Alteromonas macleodii. Sci Rep 2020; 10:809. [PMID: 31964928 PMCID: PMC6972757 DOI: 10.1038/s41598-020-57526-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 12/23/2019] [Indexed: 01/28/2023] Open
Abstract
Ecological differentiation between strains of bacterial species is shaped by genomic and metabolic variability. However, connecting genotypes to ecological niches remains a major challenge. Here, we linked bacterial geno- and phenotypes by contextualizing pangenomic, exometabolomic and physiological evidence in twelve strains of the marine bacterium Alteromonas macleodii, illuminating adaptive strategies of carbon metabolism, microbial interactions, cellular communication and iron acquisition. In A. macleodii strain MIT1002, secretion of amino acids and the unique capacity for phenol degradation may promote associations with Prochlorococcus cyanobacteria. Strain 83-1 and three novel Pacific isolates, featuring clonal genomes despite originating from distant locations, have profound abilities for algal polysaccharide utilization but without detrimental implications for Ecklonia macroalgae. Degradation of toluene and xylene, mediated via a plasmid syntenic to terrestrial Pseudomonas, was unique to strain EZ55. Benzoate degradation by strain EC673 related to a chromosomal gene cluster shared with the plasmid of A. mediterranea EC615, underlining that mobile genetic elements drive adaptations. Furthermore, we revealed strain-specific production of siderophores and homoserine lactones, with implications for nutrient acquisition and cellular communication. Phenotypic variability corresponded to different competitiveness in co-culture and geographic distribution, indicating linkages between intraspecific diversity, microbial interactions and biogeography. The finding of "ecological microdiversity" helps understanding the widespread occurrence of A. macleodii and contributes to the interpretation of bacterial niche specialization, population ecology and biogeochemical roles.
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Affiliation(s)
- Hanna Koch
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
- Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Nora Germscheid
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Heike M Freese
- Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Beatriz Noriega-Ortega
- ICBM-MPI Bridging Group for Marine Geochemistry, University of Oldenburg, Oldenburg, Germany
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Dominik Lücking
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Martine Berger
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Galaxy Qiu
- Centre for Marine Science and Innovation, University of New South Wales, Kensington, Australia
- Western Sydney University, Hawkesbury, Australia
| | - Ezequiel M Marzinelli
- Centre for Marine Science and Innovation, University of New South Wales, Kensington, Australia
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- Sydney Institute of Marine Science, Mosman, Australia
- University of Sydney, Camperdown, Australia
| | - Alexandra H Campbell
- Centre for Marine Science and Innovation, University of New South Wales, Kensington, Australia
- University of Sunshine Coast, Sunshine Coast, Australia
| | - Peter D Steinberg
- Centre for Marine Science and Innovation, University of New South Wales, Kensington, Australia
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- Sydney Institute of Marine Science, Mosman, Australia
| | - Jörg Overmann
- Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
- Braunschweig University of Technology, Braunschweig, Germany
| | - Thorsten Dittmar
- ICBM-MPI Bridging Group for Marine Geochemistry, University of Oldenburg, Oldenburg, Germany
| | - Meinhard Simon
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Matthias Wietz
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany.
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
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Royo-Llonch M, Sánchez P, González JM, Pedrós-Alió C, Acinas SG. Ecological and functional capabilities of an uncultured Kordia sp. Syst Appl Microbiol 2019; 43:126045. [PMID: 31831198 DOI: 10.1016/j.syapm.2019.126045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 10/28/2019] [Accepted: 11/12/2019] [Indexed: 01/07/2023]
Abstract
Cultivable bacteria represent only a fraction of the diversity in microbial communities. However, the official procedures for classification and characterization of a novel prokaryotic species still rely on isolates. Nevertheless, due to single cell genomics, it is possible to retrieve genomes from environmental samples by sequencing them individually, and to assign specific genes to a specific taxon, regardless of their ability to grow in culture. In this study, a complete description was performed for uncultured Kordia sp. TARA_039_SRF, a proposed novel species within the genus Kordia, using culture-independent techniques. The type material was a high-quality draft genome (94.97% complete, 4.65% gene redundancy) co-assembled using ten nearly identical single amplified genomes (SAGs) from surface seawater in the North Indian Ocean during the Tara Oceans Expedition. The assembly process was optimized to obtain the best possible assembly metrics and a less fragmented genome. The closest relative of the species was Kordia periserrulae, which shared 97.56% similarity of the 16S rRNA gene, 75% orthologs and 89.13% average nucleotide identity. The functional potential of the proposed novel species included proteorhodopsin, the ability to incorporate nitrate, cytochrome oxidases with high affinity for oxygen, and CAZymes that were unique features within the genus. Its abundance at different depths and size fractions was also evaluated together with its functional annotation, revealing that its putative ecological niche could be particles of phytoplanktonic origin. It could putatively attach to these particles and consume them while sinking to the deeper and oxygen depleted layers of the North Indian Ocean.
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Affiliation(s)
- M Royo-Llonch
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM), CSIC, Barcelona, Spain
| | - P Sánchez
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM), CSIC, Barcelona, Spain
| | - J M González
- Department of Microbiology, University of La Laguna, La Laguna, Spain
| | - C Pedrós-Alió
- Systems Biology Program, Centro Nacional de Biotecnología (CNB), CSIC, Madrid, Spain
| | - S G Acinas
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM), CSIC, Barcelona, Spain.
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28
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Zoledowska S, Motyka-Pomagruk A, Sledz W, Mengoni A, Lojkowska E. High genomic variability in the plant pathogenic bacterium Pectobacterium parmentieri deciphered from de novo assembled complete genomes. BMC Genomics 2018; 19:751. [PMID: 30326842 PMCID: PMC6192338 DOI: 10.1186/s12864-018-5140-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 10/03/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pectobacterium parmentieri is a newly established species within the plant pathogenic family Pectobacteriaceae. Bacteria belonging to this species are causative agents of diseases in economically important crops (e.g. potato) in a wide range of different environmental conditions, encountered in Europe, North America, Africa, and New Zealand. Severe disease symptoms result from the activity of P. parmentieri virulence factors, such as plant cell wall degrading enzymes. Interestingly, we observe significant phenotypic differences among P. parmentieri isolates regarding virulence factors production and the abilities to macerate plants. To establish the possible genomic basis of these differences, we sequenced 12 genomes of P. parmentieri strains (10 isolated in Poland, 2 in Belgium) with the combined use of Illumina and PacBio approaches. De novo genome assembly was performed with the use of SPAdes software, while annotation was conducted by NCBI Prokaryotic Genome Annotation Pipeline. RESULTS The pan-genome study was performed on 15 genomes (12 de novo assembled and three reference strains: P. parmentieri CFBP 8475T, P. parmentieri SCC3193, P. parmentieri WPP163). The pan-genome includes 3706 core genes, a high number of accessory (1468) genes, and numerous unique (1847) genes. We identified the presence of well-known genes encoding virulence factors in the core genome fraction, but some of them were located in the dispensable genome. A significant fraction of horizontally transferred genes, virulence-related gene duplications, as well as different CRISPR arrays were found, which can explain the observed phenotypic differences. Finally, we found also, for the first time, the presence of a plasmid in one of the tested P. parmentieri strains isolated in Poland. CONCLUSIONS We can hypothesize that a large number of the genes in the dispensable genome and significant genomic variation among P. parmentieri strains could be the basis of the potential wide host range and widespread diffusion of P. parmentieri. The obtained data on the structure and gene content of P. parmentieri strains enabled us to speculate on the importance of high genomic plasticity for P. parmentieri adaptation to different environments.
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Affiliation(s)
- S Zoledowska
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - A Motyka-Pomagruk
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - W Sledz
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - A Mengoni
- Department of Biology, University of Florence, Sesto Fiorentino, Florence, Italy
| | - E Lojkowska
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland.
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Docherty KM, Pearce DS, Lemmer KM, Hale RL. Distributing regionally, distinguishing locally: examining the underlying effects of local land use on airborne bacterial biodiversity. Environ Microbiol 2018; 20:3529-3542. [DOI: 10.1111/1462-2920.14307] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 06/05/2018] [Accepted: 06/06/2018] [Indexed: 01/08/2023]
Affiliation(s)
- Kathryn M. Docherty
- Department of Biological Sciences Western Michigan University Kalamazoo Michigan USA
| | - Douglas S. Pearce
- Department of Biological Sciences Western Michigan University Kalamazoo Michigan USA
| | - Kristina M. Lemmer
- Department of Mechanical and Aerospace Engineering Western Michigan University Kalamazoo Michigan USA
| | - Rebecca L. Hale
- Department of Biological Sciences Idaho State University Pocatello Idaho USA
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30
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González-Torres P, Gabaldón T. Genome Variation in the Model Halophilic Bacterium Salinibacter ruber. Front Microbiol 2018; 9:1499. [PMID: 30072959 PMCID: PMC6060240 DOI: 10.3389/fmicb.2018.01499] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/18/2018] [Indexed: 01/08/2023] Open
Abstract
The halophilic bacterium Salinibacter ruber is an abundant and ecologically important member of halophilic communities worldwide. Given its broad distribution and high intraspecific genetic diversity, S. ruber is considered one of the main models for ecological and evolutionary studies of bacterial adaptation to hypersaline environments. However, current insights on the genomic diversity of this species is limited to the comparison of the genomes of two co-isolated strains. Here, we present a comparative genomic analysis of eight S. ruber strains isolated at two different time points in each of two different Mediterranean solar salterns. Our results show an open pangenome with contrasting evolutionary patterns in the core and accessory genomes. We found that the core genome is shaped by extensive homologous recombination (HR), which results in limited sequence variation within population clusters. In contrast, the accessory genome is modulated by horizontal gene transfer (HGT), with genomic islands and plasmids acting as gateways to the rest of the genome. In addition, both types of genetic exchange are modulated by restriction and modification (RM) or CRISPR-Cas systems. Finally, genes differentially impacted by such processes reveal functional processes potentially relevant for environmental interactions and adaptation to extremophilic conditions. Altogether, our results support scenarios that conciliate “Neutral” and “Constant Diversity” models of bacterial evolution.
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Affiliation(s)
- Pedro González-Torres
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain.,Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Toni Gabaldón
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain.,Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
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31
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Bakermans C. Adaptations to marine versus terrestrial low temperature environments as revealed by comparative genomic analyses of the genus Psychrobacter. FEMS Microbiol Ecol 2018; 94:5032373. [DOI: 10.1093/femsec/fiy102] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 05/27/2018] [Indexed: 12/13/2022] Open
Affiliation(s)
- Corien Bakermans
- Division of Mathematics and Natural Sciences, Penn State Altoona, United States
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32
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Homologous Recombination in Core Genomes Facilitates Marine Bacterial Adaptation. Appl Environ Microbiol 2018; 84:AEM.02545-17. [PMID: 29572211 DOI: 10.1128/aem.02545-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 03/20/2018] [Indexed: 01/01/2023] Open
Abstract
Acquisition of ecologically relevant genes is common among ocean bacteria, but whether it has a major impact on genome evolution in marine environments remains unknown. Here, we analyzed the core genomes of 16 phylogenetically diverse and ecologically relevant bacterioplankton lineages, each consisting of up to five genomes varying at the strain level. Statistical approaches identified from each lineage up to ∼50 loci showing anomalously high divergence at synonymous sites, which is best explained by recombination with distantly related organisms. The enriched gene categories in these outlier loci match well with the characteristics previously identified as the key phenotypes of these lineages. Examples are antibiotic synthesis and detoxification in Phaeobacter inhibens, exopolysaccharide production in Alteromonas macleodii, hydrocarbon degradation in Marinobacter hydrocarbonoclasticus, and cold adaptation in Pseudoalteromonas haloplanktis Intriguingly, the outlier loci feature polysaccharide catabolism in Cellulophaga baltica but not in Cellulophaga lytica, consistent with their primary habitat preferences in macroalgae and beach sands, respectively. Likewise, analysis of Prochlorococcus showed that photosynthesis-related genes listed in the outlier loci are found only in the high-light-adapted ecotype and not in the low-light adapted ecotype. These observations strongly suggest that recombination with distant relatives is a key mechanism driving the ecological diversification among marine bacterial lineages.IMPORTANCE Acquisition of new metabolic genes has been known as an important mechanism driving bacterial evolution and adaptation in the ocean, but acquisition of novel alleles of existing genes and its potential ecological role have not been examined. Guided by population genetic theories, our genomic analysis showed that divergent allele acquisition is prevalent in phylogenetically diverse marine bacterial lineages and that the affected loci often encode metabolic functions that underlie the known ecological roles of the lineages under study.
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33
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Schuelke T, Pereira TJ, Hardy SM, Bik HM. Nematode-associated microbial taxa do not correlate with host phylogeny, geographic region or feeding morphology in marine sediment habitats. Mol Ecol 2018; 27:1930-1951. [DOI: 10.1111/mec.14539] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Revised: 12/18/2017] [Accepted: 01/02/2018] [Indexed: 01/18/2023]
Affiliation(s)
- Taruna Schuelke
- Department of Nematology; University of California, Riverside; Riverside CA USA
| | - Tiago José Pereira
- Department of Nematology; University of California, Riverside; Riverside CA USA
| | - Sarah M. Hardy
- School of Fisheries and Ocean Sciences; University of Alaska; Fairbanks AK USA
| | - Holly M. Bik
- Department of Nematology; University of California, Riverside; Riverside CA USA
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34
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Nóbrega MS, Silva BS, Leomil L, Tschoeke DA, Campeão ME, Garcia GD, Dias GA, Vieira VV, Thompson CC, Thompson FL. Description of Alteromonas abrolhosensis sp. nov., isolated from sea water of Abrolhos Bank, Brazil. Antonie van Leeuwenhoek 2018; 111:1131-1138. [PMID: 29349565 DOI: 10.1007/s10482-018-1016-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 01/10/2018] [Indexed: 11/29/2022]
Abstract
Two Gram-negative, motile, aerobic bacteria isolated from waters of the Abrolhos Bank were classified through a whole genome-based taxonomy. Strains PEL67ET and PEL68C shared 99% 16S rRNA and dnaK sequence identity with Alteromonas marina SW-47T and Alteromonas macleodii ATCC 27126T. In silico DNA-DNA Hybridization, i.e. genome-to-genome distance (GGD), average amino acid identity (AAI) and average nucleotide identity (ANI) showed that PEL67ET and PEL68C had identity values between 33-36, 86-88 and 83-84%, and 85-86 and 83%, respectively, towards their close neighbors A. macleodii ATCC 27126T and A. marina SW-47T. The DNA G + C contents of PEL67ET and PEL68C were 44.5%. The phenotypic features that differentiate PEL67ET and PEL68C strains from their close neighbors were assimilation of galactose and activity of phosphatase, and lack of mannitol, maltose, acetate, xylose and glycerol assimilation and lack of lipase, α and β-glucosidase activity. The new species Alteromonas abrolhosensis is proposed. The type strain is PEL67ET (= CBAS 610T = CAIM 1925T).
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Affiliation(s)
- Maria S Nóbrega
- Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil
| | - Bruno S Silva
- Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil
| | - Luciana Leomil
- Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil
| | - Diogo Antonio Tschoeke
- Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil.,Núcleo em Ecologia e Desenvolvimento Sócio-Ambiental de Macaé (NUPEM), Universidade Federal do Rio de Janeiro, Macaé, RJ, Brazil.,SAGE-COPPE, Federal University of Rio de Janeiro, Rio De Janeiro, RJ, Brazil
| | - Mariana E Campeão
- Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil
| | - Gizele D Garcia
- Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil.,Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Macaé, RJ, Brazil
| | - Graciela A Dias
- Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil
| | | | - Cristiane C Thompson
- Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil. .,CCS/IB/BIOMAR, Lab. de Microbiologia, Cidade Universitária, Av. Carlos Chagas Filho 373. Sala 102, Bloco A, Rio de Janeiro, RJ, CEP 21941-599, Brazil.
| | - Fabiano L Thompson
- Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil. .,SAGE-COPPE, Federal University of Rio de Janeiro, Rio De Janeiro, RJ, Brazil. .,CCS/IB/BIOMAR, Lab. de Microbiologia, Cidade Universitária, Av. Carlos Chagas Filho 373. Sala 102, Bloco A, Rio de Janeiro, RJ, CEP 21941-599, Brazil.
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Hou S, López-Pérez M, Pfreundt U, Belkin N, Stüber K, Huettel B, Reinhardt R, Berman-Frank I, Rodriguez-Valera F, Hess WR. Benefit from decline: the primary transcriptome of Alteromonas macleodii str. Te101 during Trichodesmium demise. ISME JOURNAL 2018; 12:981-996. [PMID: 29335641 PMCID: PMC5864184 DOI: 10.1038/s41396-017-0034-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 11/20/2017] [Accepted: 11/26/2017] [Indexed: 12/21/2022]
Abstract
Interactions between co-existing microorganisms deeply affect the physiology of the involved organisms and, ultimately, the function of the ecosystem as a whole. Copiotrophic Alteromonas are marine gammaproteobacteria that thrive during the late stages of phytoplankton blooms in the marine environment and in laboratory co-cultures with cyanobacteria such as Trichodesmium. The response of this heterotroph to the sometimes rapid and transient changes in nutrient supply when the phototroph crashes is not well understood. Here, we isolated and sequenced the strain Alteromonas macleodii str. Te101 from a laboratory culture of Trichodesmium erythraeum IMS101, yielding a chromosome of 4.63 Mb and a single plasmid of 237 kb. Increasing salinities to ≥43 ppt inhibited the growth of Trichodesmium but stimulated growth of the associated Alteromonas. We characterized the transcriptomic responses of both microorganisms and identified the complement of active transcriptional start sites in Alteromonas at single-nucleotide resolution. In replicate cultures, a similar set of genes became activated in Alteromonas when growth rates of Trichodesmium declined and mortality was high. The parallel activation of fliA, rpoS and of flagellar assembly and growth-related genes indicated that Alteromonas might have increased cell motility, growth, and multiple biosynthetic activities. Genes with the highest expression in the data set were three small RNAs (Aln1a-c) that were identified as analogs of the small RNAs CsrB-C in E. coli or RsmX-Z in pathogenic bacteria. Together with the carbon storage protein A (CsrA) homolog Te101_05290, these RNAs likely control the expression of numerous genes in responding to changes in the environment.
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Affiliation(s)
- Shengwei Hou
- Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany
| | - Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan, 03550, Alicante, Spain
| | - Ulrike Pfreundt
- Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany.,ETH Zürich, Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, Stefano-Franscini-Platz 5, CH-8093, Zürich, Switzerland
| | - Natalia Belkin
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 52900, Israel
| | - Kurt Stüber
- Max Planck-Genome-Centre Cologne, Carl-von-Linné-Weg 10, D-50829, Köln, Germany
| | - Bruno Huettel
- Max Planck-Genome-Centre Cologne, Carl-von-Linné-Weg 10, D-50829, Köln, Germany
| | - Richard Reinhardt
- Max Planck-Genome-Centre Cologne, Carl-von-Linné-Weg 10, D-50829, Köln, Germany
| | - Ilana Berman-Frank
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 52900, Israel
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan, 03550, Alicante, Spain
| | - Wolfgang R Hess
- Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany. .,Freiburg Institute for Advanced Studies, University of Freiburg, Albertstr. 19, D-79104, Freiburg, Germany.
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What Microbial Population Genomics Has Taught Us About Speciation. POPULATION GENOMICS: MICROORGANISMS 2018. [DOI: 10.1007/13836_2018_10] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Nourdin-Galindo G, Sánchez P, Molina CF, Espinoza-Rojas DA, Oliver C, Ruiz P, Vargas-Chacoff L, Cárcamo JG, Figueroa JE, Mancilla M, Maracaja-Coutinho V, Yañez AJ. Comparative Pan-Genome Analysis of Piscirickettsia salmonis Reveals Genomic Divergences within Genogroups. Front Cell Infect Microbiol 2017; 7:459. [PMID: 29164068 PMCID: PMC5671498 DOI: 10.3389/fcimb.2017.00459] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 10/16/2017] [Indexed: 11/13/2022] Open
Abstract
Piscirickettsia salmonis is the etiological agent of salmonid rickettsial septicemia, a disease that seriously affects the salmonid industry. Despite efforts to genomically characterize P. salmonis, functional information on the life cycle, pathogenesis mechanisms, diagnosis, treatment, and control of this fish pathogen remain lacking. To address this knowledge gap, the present study conducted an in silico pan-genome analysis of 19 P. salmonis strains from distinct geographic locations and genogroups. Results revealed an expected open pan-genome of 3,463 genes and a core-genome of 1,732 genes. Two marked genogroups were identified, as confirmed by phylogenetic and phylogenomic relationships to the LF-89 and EM-90 reference strains, as well as by assessments of genomic structures. Different structural configurations were found for the six identified copies of the ribosomal operon in the P. salmonis genome, indicating translocation throughout the genetic material. Chromosomal divergences in genomic localization and quantity of genetic cassettes were also found for the Dot/Icm type IVB secretion system. To determine divergences between core-genomes, additional pan-genome descriptions were compiled for the so-termed LF and EM genogroups. Open pan-genomes composed of 2,924 and 2,778 genes and core-genomes composed of 2,170 and 2,228 genes were respectively found for the LF and EM genogroups. The core-genomes were functionally annotated using the Gene Ontology, KEGG, and Virulence Factor databases, revealing the presence of several shared groups of genes related to basic function of intracellular survival and bacterial pathogenesis. Additionally, the specific pan-genomes for the LF and EM genogroups were defined, resulting in the identification of 148 and 273 exclusive proteins, respectively. Notably, specific virulence factors linked to adherence, colonization, invasion factors, and endotoxins were established. The obtained data suggest that these genes could be directly associated with inter-genogroup differences in pathogenesis and host-pathogen interactions, information that could be useful in designing novel strategies for diagnosing and controlling P. salmonis infection.
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Affiliation(s)
- Guillermo Nourdin-Galindo
- Facultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile.,Laboratory of Integrative Bioinformatics, Facultad de Ciencias, Centro de Genómica y Bioinformática, Universidad Mayor, Santiago, Chile
| | - Patricio Sánchez
- Facultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile.,Centro FONDAP, Interdisciplinary Center for Aquaculture Research, Concepción, Chile
| | - Cristian F Molina
- Facultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile.,AUSTRAL-omics, Universidad Austral de Chile, Valdivia, Chile
| | - Daniela A Espinoza-Rojas
- Facultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile.,Laboratory of Integrative Bioinformatics, Facultad de Ciencias, Centro de Genómica y Bioinformática, Universidad Mayor, Santiago, Chile
| | - Cristian Oliver
- Facultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile.,Centro FONDAP, Interdisciplinary Center for Aquaculture Research, Concepción, Chile.,Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Viña del Mar, Chile
| | - Pamela Ruiz
- Facultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile.,Centro FONDAP, Interdisciplinary Center for Aquaculture Research, Concepción, Chile
| | - Luis Vargas-Chacoff
- Facultad de Ciencias, Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile
| | - Juan G Cárcamo
- Facultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile.,Centro FONDAP, Interdisciplinary Center for Aquaculture Research, Concepción, Chile
| | - Jaime E Figueroa
- Facultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile.,Centro FONDAP, Interdisciplinary Center for Aquaculture Research, Concepción, Chile
| | - Marcos Mancilla
- Laboratorio de Diagnóstico y Biotecnología, ADL Diagnostic Chile SpA., Puerto Montt, Chile
| | - Vinicius Maracaja-Coutinho
- Laboratory of Integrative Bioinformatics, Facultad de Ciencias, Centro de Genómica y Bioinformática, Universidad Mayor, Santiago, Chile.,Laboratory of Integrative Bioinformatics, Instituto Vandique, João Pessoa, Brazil.,Beagle Bioinformatics, Santiago, Chile
| | - Alejandro J Yañez
- Facultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile.,Centro FONDAP, Interdisciplinary Center for Aquaculture Research, Concepción, Chile.,AUSTRAL-omics, Universidad Austral de Chile, Valdivia, Chile
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Hoetzinger M, Hahn MW. Genomic divergence and cohesion in a species of pelagic freshwater bacteria. BMC Genomics 2017; 18:794. [PMID: 29037158 PMCID: PMC5644125 DOI: 10.1186/s12864-017-4199-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 10/08/2017] [Indexed: 11/15/2022] Open
Abstract
Background In many prokaryotic genera a clustered phylogeny is observed, akin to the occurrence of species in sexually reproducing organisms. For some taxa, homologous recombination has been invoked as the underlying mechanism providing genomic cohesion among conspecific individuals. Whether this mechanism is applicable to prokaryotes in freshwaters with low habitat connectivity – i.e. elevated geographic barriers to gene flow – is unclear. To investigate further we studied genomic trends within the globally abundant PnecC cluster (genus Polynucleobacter, Betaproteobacteria) and analyzed homologous recombination within the affiliated species P. asymbioticus. Results Comparisons among 20 PnecC genomes revealed a clearly discontinuous distribution of nucleotide sequence similarities. Among the nine conspecific individuals (P. asymbioticus) all average nucleotide identity (ANI) values were greater than 97%, whereas all other comparisons exhibited ANI values lower than 85%. The reconstruction of recombination and mutation events for the P. asymbioticus core genomes yielded an r/m ratio of 7.4, which is clearly above estimated thresholds for recombination to act as a cohesive force. Hotspots of recombination were found to be located in the flanking regions of genomic islands. Even between geographically separated habitats a high flux of recombination was evident. While a biogeographic population structure was suggested from MLST data targeting rather conserved loci, such a structure was barely visible when whole genome data was considered. However, both MLST and whole genome data showed evidence of differentiation between two lineages of P. asymbioticus. The ratios of non-synonymous to synonymous substitution rates as well as growth rates in transplantation experiments suggested that this divergence was not selectively neutral. Conclusions The high extent of homologous recombination among P. asymbioticus bacteria can act as a cohesive force that effectively counteracts genetic divergence. At least on a regional scale, homologous recombination can act across geographically separated ecosystems and therefore plays an important role in the evolution and consistency of bacterial freshwater species. A species model akin to the biological species concept may be applicable for P. asymbioticus. Nonetheless, two genetically distinct lineages have emerged and further research may clarify if their divergence has been initiated by reinforced geographical barriers or has been evolving in sympatry. Electronic supplementary material The online version of this article (10.1186/s12864-017-4199-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Matthias Hoetzinger
- Research Institute for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310, Mondsee, Austria.
| | - Martin W Hahn
- Research Institute for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310, Mondsee, Austria
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Microdiversification of a Pelagic Polynucleobacter Species Is Mainly Driven by Acquisition of Genomic Islands from a Partially Interspecific Gene Pool. Appl Environ Microbiol 2017; 83:AEM.02266-16. [PMID: 27836842 DOI: 10.1128/aem.02266-16] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/07/2016] [Indexed: 12/13/2022] Open
Abstract
Microdiversification of a planktonic freshwater bacterium was studied by comparing 37 Polynucleobacter asymbioticus strains obtained from three geographically separated sites in the Austrian Alps. Genome comparison of nine strains revealed a core genome of 1.8 Mb, representing 81% of the average genome size. Seventy-five percent of the remaining flexible genome is clustered in genomic islands (GIs). Twenty-four genomic positions could be identified where GIs are potentially located. These positions are occupied strain specifically from a set of 28 GI variants, classified according to similarities in their gene content. One variant, present in 62% of the isolates, encodes a pathway for the degradation of aromatic compounds, and another, found in 78% of the strains, contains an operon for nitrate assimilation. Both variants were shown in ecophysiological tests to be functional, thus providing the potential for microniche partitioning. In addition, detected interspecific horizontal exchange of GIs indicates a large gene pool accessible to Polynucleobacter species. In contrast to core genes, GIs are spread more successfully across spatially separated freshwater habitats. The mobility and functional diversity of GIs allow for rapid evolution, which may be a key aspect for the ubiquitous occurrence of Polynucleobacter bacteria. IMPORTANCE Assessing the ecological relevance of bacterial diversity is a key challenge for current microbial ecology. The polyphasic approach which was applied in this study, including targeted isolation of strains, genome analysis, and ecophysiological tests, is crucial for the linkage of genetic and ecological knowledge. Particularly great importance is attached to the high number of closely related strains which were investigated, represented by genome-wide average nucleotide identities (ANI) larger than 97%. The extent of functional diversification found on this narrow phylogenetic scale is compelling. Moreover, the transfer of metabolically relevant genomic islands between more distant members of the Polynucleobacter community provides important insights toward a better understanding of the evolution of these globally abundant freshwater bacteria.
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40
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López-Pérez M, Ramon-Marco N, Rodriguez-Valera F. Networking in microbes: conjugative elements and plasmids in the genus Alteromonas. BMC Genomics 2017; 18:36. [PMID: 28056800 PMCID: PMC5217437 DOI: 10.1186/s12864-016-3461-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 12/22/2016] [Indexed: 12/15/2022] Open
Abstract
Background To develop evolutionary models for the free living bacterium Alteromonas the genome sequences of isolates of the genus have been extensively analyzed. However, the main genetic exchange drivers in these microbes, conjugative elements (CEs), have not been considered in detail thus far. In this work, CEs have been searched in several complete Alteromonas genomes and their sequence studied to understand their role in the evolution of this genus. Six genomes are reported here for the first time. Results We have found nine different plasmids of sizes ranging from 85 to 600 Kb, most of them were found in a single strain. Networks of gene similarity could be established among six of the plasmids that were also connected with another cluster of plasmids found in Shewanella strains. The cargo genes found in these plasmids included cassettes found before in chromosome flexible genomic islands of Alteromonas strains. We describe also the plasmids pAMCP48-600 and pAMCP49-600, the largest found in Alteromonas thus far (ca. 600 Kb) and containing all the hallmarks to be classified as chromids. We found in them some housekeeping genes and a cluster that code for an exocellular polysaccharide. They could represent the transport vectors for the previously described replacement flexible genomic islands. Integrative and conjugative elements (ICEs) were more common than plasmids and showed similar patterns of variation with cargo genes coding for components of additive flexible genomic islands. A nearly identical ICE was found in A. mediterranea MED64 and Vibrio cholera AHV1003 isolated from a human pathogen, indicating the potential exchange of these genes across phylogenetic distances exceeding the family threshold. Conclusion We have seen evidence of how CEs can be vectors to transfer gene cassettes acquired in the chromosomal flexible genomic islands, both of the additive and replacement kind. These CEs showed evidence of how genetic material is exchanged among members of the same species but also (albeit less frequently) across genus and family barriers. These gradients of exchange frequency are probably one of the main drivers of species origin and maintenance in prokaryotes and also provide these taxa with large genetic diversity. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3461-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mario López-Pérez
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Apartado 18, San Juan, 03550, Alicante, Spain
| | - Nieves Ramon-Marco
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Apartado 18, San Juan, 03550, Alicante, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Apartado 18, San Juan, 03550, Alicante, Spain.
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