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Zhang S, Sun C. Ecological divergence of marine bacteria Alteromonas mediterranea. Mol Phylogenet Evol 2025; 208:108359. [PMID: 40262702 DOI: 10.1016/j.ympev.2025.108359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 10/28/2024] [Accepted: 04/19/2025] [Indexed: 04/24/2025]
Abstract
Alteromonas mediterranea, originally designated as A. macleodii, is a deep-sea ecotype that plays an important ecological role in the ocean. However, a comprehensive understanding of their biogeographic distribution and evolutionary histories remains limited. In this study, our analysis indicated that A. mediterranea members could adapt contrasting marine ecosystems and flourish in nutrient-rich habitats such as feces and coral reefs. No significant correlations between the relative abundance of A. mediterranea members and the environmental variables were identified. Phylogenetic analysis and geographic patterns of A. mediterranea strains suggested that they could be clustered into two clades (clade Ⅰ and clade Ⅱ). In contrast, many distinct genomic traits exist between these clades, such as the complete genes encoding cytochrome o ubiquinol oxidase only involved in clade Ⅱ. Genes were more likely to be lost in the evolutionary history of A. mediterranea relatives. Gene loss might be a major force in all phylogenetic groups driving the distinct clades. Adaptation to different biotopes resulted in the functional differentiation of A. mediterranea members, with the loss of genes encoding carbohydrate-active enzymes. Genes acquired horizontally from unclassified bacteria, and Proteobacteria represented by Gammaproteobacteria played key roles in the functional diversification of A. mediterranea in marine habitats. Given these data, these results are useful for information supplementation of A. mediterranea strains, particularly for making significant advances in understanding marine microbial ecology within different clonal frames using genome-wide recruitments.
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Affiliation(s)
- Shuangfei Zhang
- School of Life and Health Sciences, Hainan Province Key Laboratory of One Health, Collaborative Innovation Center of Life and Health, Hainan University, Haikou, Hainan 570228, China; School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, China.
| | - Chongran Sun
- School of Life and Health Sciences, Hainan Province Key Laboratory of One Health, Collaborative Innovation Center of Life and Health, Hainan University, Haikou, Hainan 570228, China; School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, China
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2
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Sher D, George EE, Wietz M, Gifford S, Zoccarato L, Weissberg O, Koedooder C, Valiya Kalladi WB, Barreto Filho MM, Mireles R, Malavin S, Liddor Naim M, Idan T, Shrivastava V, Itelson L, Sade D, Abu Hamoud A, Soussan-Farhat Y, Barak N, Karp P, Moore LR. Collaborative metabolic curation of an emerging model marine bacterium, Alteromonas macleodii ATCC 27126. PLoS One 2025; 20:e0321141. [PMID: 40273159 PMCID: PMC12021255 DOI: 10.1371/journal.pone.0321141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Accepted: 02/28/2025] [Indexed: 04/26/2025] Open
Abstract
Inferring the metabolic capabilities of an organism from its genome is a challenging process, relying on computationally-derived or manually curated metabolic networks. Manual curation can correct mistakes in the draft network and add missing reactions based on the literature, but requires significant expertise and is often the bottleneck for high-quality metabolic reconstructions. Here, we present a synopsis of a community curation workshop for the model marine bacterium Alteromonas macleodii ATCC 27126 and its genome database in BioCyc, focusing on pathways for utilizing organic carbon and nitrogen sources. Due to the scarcity of biochemical information or gene knock-outs, the curation process relied primarily on published growth phenotypes and bioinformatic analyses, including comparisons with related Alteromonas strains. We report full pathways for the utilization of the algal polysaccharides alginate and pectin in contrast to inconclusive evidence for one-carbon metabolism and mixed acid fermentation, in accordance with the lack of growth on methanol and formate. Pathways for amino acid degradation are ubiquitous across Alteromonas macleodii strains, yet enzymes in the pathways for the degradation of threonine, tryptophan and tyrosine were not identified. Nucleotide degradation pathways are also partial in ATCC 27126. We postulate that demonstrated growth on nitrate as sole nitrogen source proceeds via a nitrate reductase pathway that is a hybrid of known pathways. Our evidence highlights the value of joint and interactive curation efforts, but also shows major knowledge gaps regarding Alteromonas metabolism. The manually-curated metabolic reconstruction is available as a "Tier-2" database on BioCyc.
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Affiliation(s)
- Daniel Sher
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Israel
| | - Emma E. George
- Integrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, United States of America
| | - Matthias Wietz
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Scott Gifford
- Department of Earth, Marine and Environmental Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Luca Zoccarato
- Institute of Computational Biology, University of Natural Resources and Life Sciences, Vienna, Austria
- Core Facility Bioinformatics, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Osnat Weissberg
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Israel
| | - Coco Koedooder
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
- Israel Oceanographic and Limnological Research, Haifa, Israel
| | | | | | - Raul Mireles
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel,
| | - Stas Malavin
- Israel Oceanographic and Limnological Research, Haifa, Israel
- Zuckerberg Institute for Water Research, Ben-Gurion University of the Negev, Beer-Sheba, Israel
| | - Michal Liddor Naim
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Tal Idan
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Vibhaw Shrivastava
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Israel
| | - Lynne Itelson
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Dagan Sade
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Alhan Abu Hamoud
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Israel
| | - Yara Soussan-Farhat
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Israel
| | - Noga Barak
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Israel
| | - Peter Karp
- Bioinformatics Research Group, SRI International, Menlo Park, California, United States of America.
| | - Lisa R. Moore
- Bioinformatics Research Group, SRI International, Menlo Park, California, United States of America.
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3
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Rodriguez-Valera F, Bellas C. How Viruses Shape Microbial Plankton Microdiversity. ANNUAL REVIEW OF MARINE SCIENCE 2025; 17:561-576. [PMID: 38950433 DOI: 10.1146/annurev-marine-040623-090847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/03/2024]
Abstract
One major conundrum of modern microbiology is the large pangenome (gene pool) present in microbes, which is much larger than those found in complex organisms such as humans. Here, we argue that this diversity of gene pools carried by different strains is maintained largely due to the control exercised by viral predation. Viruses maintain a high strain diversity through time that we describe as constant-diversity equilibrium, preventing the hoarding of resources by specific clones. Thus, viruses facilitate the release and degradation of dissolved organic matter in the ocean, which may lead to better ecosystem functioning by linking top-down to bottom-up control. By maintaining this equilibrium, viruses act as a key element of the adaptation of marine microbes to their environment and likely behave as a single evolutionary unit.
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Affiliation(s)
- Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Spain;
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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; 15:e0003824. [PMID: 38958440 PMCID: PMC11325263 DOI: 10.1128/mbio.00038-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [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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5
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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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Gautam P, Cusick KD. Development of a real-time quantitative PCR assay for detection and quantification of the marine bacterium Alteromonas macleodii from coastal environments. J Microbiol Methods 2023; 204:106629. [PMID: 36460091 DOI: 10.1016/j.mimet.2022.106629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 11/16/2022] [Accepted: 11/23/2022] [Indexed: 11/30/2022]
Abstract
Alteromonas macleodii is a ubiquitous marine bacterial species found in a variety of habitats that displays both planktonic and particle-associated lifestyles. Transcriptomic studies demonstrate that, even when present at low abundance, it can make significant contributions to biogeochemical cycles, and its specific association with key marine phytoplankton species indicates other ecological roles as well. It has also been shown to be one of the early colonizers of copper-treated marine vessels. There currently exist no rapid, reliable molecular assays for the detection and quantification of A. macleodii from its different environments. We developed a real-time PCR assay, specific to A. macleodii. This assay targets the DNA gyrase B subunit (gyrB) gene, which occurs as a single copy in the genome. The assay possesses an amplification efficiency of 94.3%, with a limit of detection of 2.5 gyrB copies per μL. Assay specificity was validated by melt curve analysis, followed by sequencing of the amplified product. The assay was specific to thirteen A. macleodii strains and did not amplify other marine bacteria, including Roseobacter denitrificans, Silicibacter sp. TM1040, Vibrio coralliilyticus, Vibrio harveyi, and Vibrio alginolyticus. It also did not amplify Alteromonas mediterranea, a close relative that can occur in the same environment as A. macleodii. This assay was used to determine the presence and abundance of A. macleodii from a range of coastal habitats. The assay was also used to monitor the A. macleodii growth in biofilm and planktonic cultures over time in the presence of elevated copper. This assay provides a rapid and reliable means to assess the presence and abundance of a ubiquitous marine bacterium that, even at low abundance, has been shown to make significant contributions to key marine processes.
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Affiliation(s)
- Pratima Gautam
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21225, USA
| | - Kathleen D Cusick
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21225, USA.
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Genome and Ecology of a Novel Alteromonas Podovirus, ZP6, Representing a New Viral Genus, Mareflavirus. Microbiol Spectr 2021; 9:e0046321. [PMID: 34643440 PMCID: PMC8515928 DOI: 10.1128/spectrum.00463-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Alteromonas is a ubiquitous, abundant, copiotrophic and phytoplankton-associated marine member of the Gammaproteobacteria with a range extending from tropical waters to polar regions and including hadal zones. Here, we describe a novel Alteromonas phage, ZP6, that was isolated from surface coastal waters of Qingdao, China. ZP6 contains a linear, double-stranded, 38,080-bp DNA molecule with 50.1% G+C content and 47 putative open reading frames (ORFs). Three auxiliary metabolic genes were identified, encoding metal-dependent phosphohydrolase, diaminopurine synthetase, and nucleotide pyrophosphohydrolase. The first two ORFs facilitate the replacement of adenine (A) by diaminopurine (Z) in phage genomes and help phages to evade attack from host restriction enzymes. The nucleotide pyrophosphohydrolase enables the host cells to stop programmed cell death and improves the survival rate of the host in a nutrient-depleted environment. Phylogenetic analysis based on the amino acid sequences of whole genomes and comparative genomic analysis revealed that ZP6 is most closely related to Enhodamvirus but with low similarity (shared genes, <30%, and average nucleotide sequence identity, <65%); it is distinct from other bacteriophages. Together, these results suggest that ZP6 could represent a novel viral genus, here named Mareflavirus. Combining its ability to infect Alteromonas, its harboring of a diaminopurine genome-biosynthetic system, and its representativeness of an understudied viral group, ZP6 could be an important and novel model system for marine virus research. IMPORTANCEAlteromonas is an important symbiotic bacterium of phytoplankton, but research on its bacteriophages is still at an elementary level. Our isolation and genome characterization of a novel Alteromonas podovirus, ZP6, identified a new viral genus of podovirus, namely, Mareflavirus. The ZP6 genome, with a diaminopurine genome-biosynthetic system, is different from those of other isolated Alteromonas phages and will bring new impetus to the development of virus classification and provide important insights into novel viral sequences from metagenomic data sets.
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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: 2.8] [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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Zhang L, Li X, Zhang X, Li Y, Wang L. Bacterial alginate metabolism: an important pathway for bioconversion of brown algae. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:158. [PMID: 34275475 PMCID: PMC8286568 DOI: 10.1186/s13068-021-02007-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/04/2021] [Indexed: 06/13/2023]
Abstract
Brown macroalgae have attracted great attention as an alternative feedstock for biorefining. Although direct conversion of ethanol from alginates (major components of brown macroalgae cell walls) is not amenable for industrial production, significant progress has been made not only on enzymes involved in alginate degradation, but also on metabolic pathways for biorefining at the laboratory level. In this article, we summarise recent advances on four aspects: alginate, alginate lyases, different alginate-degrading systems, and application of alginate lyases and associated pathways. This knowledge will likely inspire sustainable solutions for further application of both alginate lyases and their associated pathways.
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Affiliation(s)
- Lanzeng Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Xue Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Xiyue Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Yingjie Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China.
| | - Lushan Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
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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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11
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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: 16] [Impact Index Per Article: 3.2] [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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12
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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: 28] [Impact Index Per Article: 5.6] [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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13
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Abstract
Microbial populations exchange genetic material through a process called homologous recombination. Although this process has been studied in particular organisms, we lack an understanding of its differential impact over the genome and across microbes with different life-styles. We used a common analytical framework to assess this process in a representative set of microorganisms. Our results uncovered important trends. First, microbes with different lifestyles are differentially impacted, with endosymbionts and obligate pathogens being those less prone to undergo this process. Second, certain genetic elements such as restriction-modification systems seem to be associated with higher rates of recombination. Most importantly, recombined genomes show the footprints of natural selection in which recombined regions preferentially contain genes that can be related to specific ecological adaptations. Taken together, our results clarify the relative contributions of factors modulating homologous recombination and show evidence for a clear a role of this process in shaping microbial genomes and driving ecological adaptations. Homologous recombination (HR) enables the exchange of genetic material between and within species. Recent studies suggest that this process plays a major role in the microevolution of microbial genomes, contributing to core genome homogenization and to the maintenance of cohesive population structures. However, we still have a very poor understanding of the possible adaptive roles of intraspecific HR and of the factors that determine its differential impact across clades and lifestyles. Here we used a unified methodological framework to assess HR in 338 complete genomes from 54 phylogenetically diverse and representative prokaryotic species, encompassing different lifestyles and a broad phylogenetic distribution. Our results indicate that lifestyle and presence of restriction-modification (RM) machineries are among the main factors shaping HR patterns, with symbionts and intracellular pathogens having the lowest HR levels. Similarly, the size of exchanged genomic fragments correlated with the presence of RM and competence machineries. Finally, genes exchanged by HR showed functional enrichments which could be related to adaptations to different environments and ecological strategies. Taken together, our results clarify the factors underlying HR impact and suggest important adaptive roles of genes exchanged through this mechanism. Our results also revealed that the extent of genetic exchange correlated with lifestyle and some genomic features. Moreover, the genes in exchanged regions were enriched for functions that reflected specific adaptations, supporting identification of HR as one of the main evolutionary mechanisms shaping prokaryotic core genomes.
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14
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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: 1.3] [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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15
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Haro-Moreno JM, López-Pérez M, de la Torre JR, Picazo A, Camacho A, Rodriguez-Valera F. Fine metagenomic profile of the Mediterranean stratified and mixed water columns revealed by assembly and recruitment. MICROBIOME 2018; 6:128. [PMID: 29991350 PMCID: PMC6040077 DOI: 10.1186/s40168-018-0513-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/02/2018] [Indexed: 05/07/2023]
Abstract
BACKGROUND The photic zone of aquatic habitats is subjected to strong physicochemical gradients. To analyze the fine-scale variations in the marine microbiome, we collected seven samples from a single offshore location in the Mediterranean at 15 m depth intervals during a period of strong stratification, as well as two more samples during the winter when the photic water column was mixed. We were able to recover 94 new metagenome-assembled genomes (MAGs) from these metagenomes and examine the distribution of key marine microbes within the photic zone using metagenomic recruitment. RESULTS Our results showed significant differences in the microbial composition of different layers within the stratified photic water column. The majority of microorganisms were confined to discreet horizontal layers of no more than 30 m (stenobathic). Only a few such as members of the SAR11 clade appeared at all depths (eurybathic). During the winter mixing period, only some groups of bloomers such as Pseudomonas were favored. Although most microbes appeared in both seasons, some groups like the SAR116 clade and some Bacteroidetes and Verrucomicrobia seemed to disappear during the mixing period. Furthermore, we found that some microbes previously considered seasonal (e.g., Archaea or Actinobacteria) were living in deeper layers within the photic zone during the stratification period. A strong depth-related specialization was detected, not only at the taxonomic level but also at the functional level, even within the different clades, for the manipulation and uptake of specific polysaccharides. Rhodopsin sequences (green or blue) also showed narrow depth distributions that correlated with the taxonomy of the microbe in which they were found but not with depth. CONCLUSIONS Although limited to a single location in the Mediterranean, this study has profound implications for our understanding of how marine microbial communities vary with depth within the photic zone when stratified. Our results highlight the importance of collecting samples at different depths in the water column when comparing seasonal variations and have important ramifications for global marine studies that most often take samples from only one single depth. Furthermore, our perspective and approaches (metagenomic assembly and recruitment) are broadly applicable to other metagenomic studies.
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Affiliation(s)
- Jose M Haro-Moreno
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, 03550, Alicante, Spain
| | - Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, 03550, Alicante, Spain
| | - José R de la Torre
- Department of Biology, San Francisco State University, San Francisco, CA, 94132, USA
| | - Antonio Picazo
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Burjassot, E-46100, Valencia, Spain
| | - Antonio Camacho
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Burjassot, E-46100, Valencia, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, 03550, Alicante, Spain.
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16
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Grand Challenges in Marine Biotechnology: Overview of Recent EU-Funded Projects. GRAND CHALLENGES IN MARINE BIOTECHNOLOGY 2018. [DOI: 10.1007/978-3-319-69075-9_11] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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17
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Draft Genome Sequence of Deep-Sea Alteromonas sp. Strain V450 Isolated from the Marine Sponge Leiodermatium sp. GENOME ANNOUNCEMENTS 2017; 5:5/5/e01508-16. [PMID: 28153886 PMCID: PMC5289672 DOI: 10.1128/genomea.01508-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The proteobacterium Alteromonas sp. strain V450 was isolated from the Atlantic deep-sea sponge Leiodermatium sp. Here, we report the draft genome sequence of this strain, with a genome size of approx. 4.39 Mb and a G+C content of 44.01%. The results will aid deep-sea microbial ecology, evolution, and sponge-microbe association studies.
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18
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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: 5.6] [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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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: 14] [Impact Index Per Article: 1.8] [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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20
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Vannier T, Leconte J, Seeleuthner Y, Mondy S, Pelletier E, Aury JM, de Vargas C, Sieracki M, Iudicone D, Vaulot D, Wincker P, Jaillon O. Survey of the green picoalga Bathycoccus genomes in the global ocean. Sci Rep 2016; 6:37900. [PMID: 27901108 PMCID: PMC5128809 DOI: 10.1038/srep37900] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 11/03/2016] [Indexed: 01/23/2023] Open
Abstract
Bathycoccus is a cosmopolitan green micro-alga belonging to the Mamiellophyceae, a class of picophytoplankton that contains important contributors to oceanic primary production. A single species of Bathycoccus has been described while the existence of two ecotypes has been proposed based on metagenomic data. A genome is available for one strain corresponding to the described phenotype. We report a second genome assembly obtained by a single cell genomics approach corresponding to the second ecotype. The two Bathycoccus genomes are divergent enough to be unambiguously distinguishable in whole DNA metagenomic data although they possess identical sequence of the 18S rRNA gene including in the V9 region. Analysis of 122 global ocean whole DNA metagenome samples from the Tara-Oceans expedition reveals that populations of Bathycoccus that were previously identified by 18S rRNA V9 metabarcodes are only composed of these two genomes. Bathycoccus is relatively abundant and widely distributed in nutrient rich waters. The two genomes rarely co-occur and occupy distinct oceanic niches in particular with respect to depth. Metatranscriptomic data provide evidence for gain or loss of highly expressed genes in some samples, suggesting that the gene repertoire is modulated by environmental conditions.
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Affiliation(s)
- Thomas Vannier
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.,CNRS, UMR 8030, CP5706 Evry, France.,Université d'Evry, UMR 8030, CP5706 Evry, France
| | - Jade Leconte
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.,CNRS, UMR 8030, CP5706 Evry, France.,Université d'Evry, UMR 8030, CP5706 Evry, France
| | - Yoann Seeleuthner
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.,CNRS, UMR 8030, CP5706 Evry, France.,Université d'Evry, UMR 8030, CP5706 Evry, France
| | - Samuel Mondy
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.,CNRS, UMR 8030, CP5706 Evry, France.,Université d'Evry, UMR 8030, CP5706 Evry, France
| | - Eric Pelletier
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.,CNRS, UMR 8030, CP5706 Evry, France.,Université d'Evry, UMR 8030, CP5706 Evry, France
| | - Jean-Marc Aury
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France
| | - Colomban de Vargas
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR7144, Station Biologique de Roscoff, 29680 Roscoff, France
| | - Michael Sieracki
- National Science Foundation, 4201 Wilson Blvd., Arlington, VA 22230, USA
| | - Daniele Iudicone
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
| | - Daniel Vaulot
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR7144, Station Biologique de Roscoff, 29680 Roscoff, France
| | - Patrick Wincker
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.,CNRS, UMR 8030, CP5706 Evry, France.,Université d'Evry, UMR 8030, CP5706 Evry, France
| | - Olivier Jaillon
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.,CNRS, UMR 8030, CP5706 Evry, France.,Université d'Evry, UMR 8030, CP5706 Evry, France
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21
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De Maayer P, Cowan DA. Comparative genomic analysis of the flagellin glycosylation island of the Gram-positive thermophile Geobacillus. BMC Genomics 2016; 17:913. [PMID: 27842516 PMCID: PMC5109656 DOI: 10.1186/s12864-016-3273-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/05/2016] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Protein glycosylation involves the post-translational attachment of sugar chains to target proteins and has been observed in all three domains of life. Post-translational glycosylation of flagellin, the main structural protein of the flagellum, is a common characteristic among many Gram-negative bacteria and Archaea. Several distinct functions have been ascribed to flagellin glycosylation, including stabilisation and maintenance of the flagellar filament, motility, surface recognition, adhesion, and virulence. However, little is known about this trait among Gram-positive bacteria. RESULTS Using comparative genomic approaches the flagellin glycosylation loci of multiple strains of the Gram-positive thermophilic genus Geobacillus were identified and characterized. Eighteen of thirty-six compared strains of the genus carry these loci, which show evidence of horizontal acquisition. The Geobacillus flagellin glycosylation islands (FGIs) can be clustered into five distinct types, which are predicted to encode highly variable glycans decorated with distinct and heavily modified sugars. CONCLUSIONS Our comparative genomic analyses showed that, while not universal, flagellin glycosylation islands are relatively common among members of the genus Geobacillus and that the encoded flagellin glycans are highly variable. This suggests that flagellin glycosylation plays an important role in the lifestyles of members of this thermophilic genus.
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Affiliation(s)
- Pieter De Maayer
- School of Molecular and Cell Biology, University of the Witwatersrand, Private Bag 3, Wits, 2050, Johannesburg, South Africa.
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Genomics Research Institute, University of Pretoria, Pretoria, 0002, South Africa
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22
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Ellegaard KM, Engel P. Beyond 16S rRNA Community Profiling: Intra-Species Diversity in the Gut Microbiota. Front Microbiol 2016; 7:1475. [PMID: 27708630 PMCID: PMC5030217 DOI: 10.3389/fmicb.2016.01475] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 09/05/2016] [Indexed: 12/31/2022] Open
Abstract
Interactions with microbes affect many aspects of animal biology, including immune system development, nutrition and health. In vertebrates, the gut microbiota is dominated by a small subset of phyla, but the species composition within these phyla is typically not conserved. Moreover, several recent studies have shown that bacterial species in the gut are composed of a multitude of strains, which frequently co-exist in their host, and may be host-specific. However, since the study of intra-species diversity is challenging, particularly in the setting of complex, host-associated microbial communities, our current understanding of the distribution, evolution and functional relevance of intra-species diversity in the gut is scarce. In order to unravel how genomic diversity translates into phenotypic diversity, community analyses going beyond 16S rRNA profiling, in combination with experimental approaches, are needed. Recently, the honeybee has emerged as a promising model for studying gut bacterial communities, particularly in terms of strain-level diversity. Unlike most other invertebrates, the honeybee gut is colonized by a remarkably consistent and specific core microbiota, which is dominated by only eight bacterial species. As for the vertebrate gut microbiota, these species are composed of highly diverse strains suggesting that similar evolutionary forces shape gut community structures in vertebrates and social insects. In this review, we outline current knowledge on the evolution and functional relevance of strain diversity within the gut microbiota, including recent insights gained from mammals and other animals such as the honeybee. We discuss methodological approaches and propose possible future avenues for studying strain diversity in complex bacterial communities.
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Affiliation(s)
- Kirsten M Ellegaard
- Department of Fundamental Microbiology, University of Lausanne Lausanne, Switzerland
| | - Philipp Engel
- Department of Fundamental Microbiology, University of Lausanne Lausanne, Switzerland
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23
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Abstract
We have examined a collection of the free-living marine bacterium Alteromonas genomes with cores diverging in average nucleotide identities ranging from 99.98% to 73.35%, i.e., from microbes that can be considered members of a natural clone (like in a clinical epidemiological outbreak) to borderline genus level. The genomes were largely syntenic allowing a precise delimitation of the core and flexible regions in each. The core was 1.4 Mb (ca. 30% of the typical strain genome size). Recombination rates along the core were high among strains belonging to the same species (37.7-83.7% of all nucleotide polymorphisms) but they decreased sharply between species (18.9-5.1%). Regarding the flexible genome, its main expansion occurred within the boundaries of the species, i.e., strains of the same species already have a large and diverse flexible genome. Flexible regions occupy mostly fixed genomic locations. Four large genomic islands are involved in the synthesis of strain-specific glycosydic receptors that we have called glycotypes. These genomic regions are exchanged by homologous recombination within and between species and there is evidence for their import from distant taxonomic units (other genera within the family). In addition, several hotspots for integration of gene cassettes by illegitimate recombination are distributed throughout the genome. They code for features that give each clone specific properties to interact with their ecological niche and must flow fast throughout the whole genus as they are found, with nearly identical sequences, in different species. Models for the generation of this genomic diversity involving phage predation are discussed.
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Affiliation(s)
- Mario López-Pérez
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, Alicante, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, Alicante, Spain
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24
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Flexible genomic islands as drivers of genome evolution. Curr Opin Microbiol 2016; 31:154-160. [DOI: 10.1016/j.mib.2016.03.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/29/2016] [Accepted: 03/30/2016] [Indexed: 12/26/2022]
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Fadeev E, De Pascale F, Vezzi A, Hübner S, Aharonovich D, Sher D. Why Close a Bacterial Genome? The Plasmid of Alteromonas Macleodii HOT1A3 is a Vector for Inter-Specific Transfer of a Flexible Genomic Island. Front Microbiol 2016; 7:248. [PMID: 27014193 PMCID: PMC4781885 DOI: 10.3389/fmicb.2016.00248] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 02/15/2016] [Indexed: 12/20/2022] Open
Abstract
Genome sequencing is rapidly becoming a staple technique in environmental and clinical microbiology, yet computational challenges still remain, leading to many draft genomes which are typically fragmented into many contigs. We sequenced and completely assembled the genome of a marine heterotrophic bacterium, Alteromonas macleodii HOT1A3, and compared its full genome to several draft genomes obtained using different reference-based and de novo methods. In general, the de novo assemblies clearly outperformed the reference-based or hybrid ones, covering >99% of the genes and representing essentially all of the gene functions. However, only the fully closed genome (∼4.5 Mbp) allowed us to identify the presence of a large, 148 kbp plasmid, pAM1A3. While HOT1A3 belongs to A. macleodii, typically found in surface waters (“surface ecotype”), this plasmid consists of an almost complete flexible genomic island (fGI), containing many genes involved in metal resistance previously identified in the genomes of Alteromonas mediterranea (“deep ecotype”). Indeed, similar to A. mediterranea, A. macleodii HOT1A3 grows at concentrations of zinc, mercury, and copper that are inhibitory for other A. macleodii strains. The presence of a plasmid encoding almost an entire fGI suggests that wholesale genomic exchange between heterotrophic marine bacteria belonging to related but ecologically different populations is not uncommon.
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Affiliation(s)
- Eduard Fadeev
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa Haifa, Israel
| | - Fabio De Pascale
- Department of Biology and CRIBI Biotechnology Centre, University of Padua Padova, Italy
| | - Alessandro Vezzi
- Department of Biology and CRIBI Biotechnology Centre, University of Padua Padova, Italy
| | - Sariel Hübner
- Department of Botany and Biodiversity Research Centre, University of British ColumbiaVancouver, Canada; The Department of Evolutionary and Environmental Biology, University of HaifaHaifa, Israel
| | - Dikla Aharonovich
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa Haifa, Israel
| | - Daniel Sher
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa Haifa, Israel
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Lassalle F, Muller D, Nesme X. Ecological speciation in bacteria: reverse ecology approaches reveal the adaptive part of bacterial cladogenesis. Res Microbiol 2015; 166:729-41. [DOI: 10.1016/j.resmic.2015.06.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 06/28/2015] [Accepted: 06/30/2015] [Indexed: 11/30/2022]
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Ikuta T, Takaki Y, Nagai Y, Shimamura S, Tsuda M, Kawagucci S, Aoki Y, Inoue K, Teruya M, Satou K, Teruya K, Shimoji M, Tamotsu H, Hirano T, Maruyama T, Yoshida T. Heterogeneous composition of key metabolic gene clusters in a vent mussel symbiont population. ISME JOURNAL 2015; 10:990-1001. [PMID: 26418631 PMCID: PMC4796938 DOI: 10.1038/ismej.2015.176] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 08/10/2015] [Accepted: 08/13/2015] [Indexed: 11/09/2022]
Abstract
Chemosynthetic symbiosis is one of the successful systems for adapting to a wide range of habitats including extreme environments, and the metabolic capabilities of symbionts enable host organisms to expand their habitat ranges. However, our understanding of the adaptive strategies that enable symbiotic organisms to expand their habitats is still fragmentary. Here, we report that a single-ribotype endosymbiont population in an individual of the host vent mussel, Bathymodiolus septemdierum has heterogeneous genomes with regard to the composition of key metabolic gene clusters for hydrogen oxidation and nitrate reduction. The host individual harbours heterogeneous symbiont subpopulations that either possess or lack the gene clusters encoding hydrogenase or nitrate reductase. The proportions of the different symbiont subpopulations in a host appeared to vary with the environment or with the host's development. Furthermore, the symbiont subpopulations were distributed in patches to form a mosaic pattern in the gill. Genomic heterogeneity in an endosymbiont population may enable differential utilization of diverse substrates and confer metabolic flexibility. Our findings open a new chapter in our understanding of how symbiotic organisms alter their metabolic capabilities and expand their range of habitats.
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Affiliation(s)
- Tetsuro Ikuta
- Department of Marine Biodiversity Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, Japan
| | - Yoshihiro Takaki
- Department of Subsurface Geobiological Analysis and Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, Japan
| | - Yukiko Nagai
- Department of Marine Biodiversity Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, Japan
| | - Shigeru Shimamura
- Department of Subsurface Geobiological Analysis and Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, Japan
| | - Miwako Tsuda
- Department of Subsurface Geobiological Analysis and Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, Japan
| | - Shinsuke Kawagucci
- Department of Subsurface Geobiological Analysis and Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, Japan
| | - Yui Aoki
- Department of Marine Biodiversity Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, Japan
| | - Koji Inoue
- Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Morimi Teruya
- Okinawa Industrial Technology Center, 12-2 Suzaki, Uruma, Okinawa, Japan
| | - Kazuhito Satou
- Okinawa Institute of Advanced Sciences (OIAS), 5-1 Suzaki, Uruma, Okinawa, Japan
| | - Kuniko Teruya
- Okinawa Institute of Advanced Sciences (OIAS), 5-1 Suzaki, Uruma, Okinawa, Japan
| | - Makiko Shimoji
- Okinawa Institute of Advanced Sciences (OIAS), 5-1 Suzaki, Uruma, Okinawa, Japan
| | - Hinako Tamotsu
- Okinawa Institute of Advanced Sciences (OIAS), 5-1 Suzaki, Uruma, Okinawa, Japan
| | - Takashi Hirano
- Okinawa Institute of Advanced Sciences (OIAS), 5-1 Suzaki, Uruma, Okinawa, Japan.,Okinawa Science and Technology Promotion Center (OSTC), 112-18 Asahimachi, Naha, Okinawa, Japan
| | - Tadashi Maruyama
- Research and Development Center for Marine Biosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, Japan
| | - Takao Yoshida
- Department of Marine Biodiversity Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, Japan
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Martin-Cuadrado AB, Pašić L, Rodriguez-Valera F. Diversity of the cell-wall associated genomic island of the archaeon Haloquadratum walsbyi. BMC Genomics 2015; 16:603. [PMID: 26268990 PMCID: PMC4535781 DOI: 10.1186/s12864-015-1794-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 07/22/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Haloquadratum walsbyi represents up to 80% of cells in NaCl-saturated brines worldwide, but is notoriously difficult to maintain under laboratory conditions. In order to establish the extent of genetic diversity in a natural population of this microbe, we screened a H. walsbyi enriched metagenomic fosmid library and recovered seven novel version of its cell-wall associated genomic island. The fosmid inserts were sequenced and analysed. RESULTS The novel cell-wall associated islands delineated two major clades within H. walsbyi. The islands predominantly contained genes putatively involved in biosynthesis of surface layer, genes encoding cell surface glycoproteins and genes involved in envelope formation. We further found that these genes are maintained in the population and that the diversity of this region arises through homologous recombination but also through the action of mobile genetic elements, including viruses. CONCLUSIONS The population of H. walsbyi in the studied saltern brine is composed of numerous clonal lineages that differ in surface structures including the cell wall. This type of variation probably reflects a number of mechanisms that minimize the infection rate of predating viruses.
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Affiliation(s)
- Ana-Belen Martin-Cuadrado
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, Alicante, Spain.
| | - Lejla Pašić
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, Alicante, Spain. .,Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000, Ljubljana, Slovenia.
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, Alicante, Spain.
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Neumann AM, Balmonte JP, Berger M, Giebel HA, Arnosti C, Voget S, Simon M, Brinkhoff T, Wietz M. Different utilization of alginate and other algal polysaccharides by marine Alteromonas macleodii ecotypes. Environ Microbiol 2015; 17:3857-68. [PMID: 25847866 DOI: 10.1111/1462-2920.12862] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/29/2015] [Indexed: 10/23/2022]
Abstract
The marine bacterium Alteromonas macleodii is a copiotrophic r-strategist, but little is known about its potential to degrade polysaccharides. Here, we studied the degradation of alginate and other algal polysaccharides by A. macleodii strain 83-1 in comparison to other A. macleodii strains. Cell densities of strain 83-1 with alginate as sole carbon source were comparable to those with glucose, but the exponential phase was delayed. The genome of 83-1 was found to harbour an alginolytic system comprising five alginate lyases, whose expression was induced by alginate. The alginolytic system contains additional CAZymes, including two TonB-dependent receptors, and is part of a 24 kb genomic island unique to the A. macleodii 'surface clade' ecotype. In contrast, strains of the 'deep clade' ecotype contain only a single alginate lyase in a separate 7 kb island. This difference was reflected in an eightfold greater efficiency of surface clade strains to grow on alginate. Strain 83-1 furthermore hydrolysed laminarin, pullulan and xylan, and corresponding polysaccharide utilization loci were detected in the genome. Alteromonas macleodii alginate lyases were predominantly detected in Atlantic Ocean metagenomes. The demonstrated hydrolytic capacities are likely of ecological relevance and represent another level of adaptation among A. macleodii ecotypes.
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Affiliation(s)
- Anna M Neumann
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, 26129, Germany
| | - John P Balmonte
- Department of Marine Sciences, University of North Carolina, 3117 Venable Hall, Chapel Hill, NC, USA
| | - Martine Berger
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, 26129, Germany
| | - Helge-Ansgar Giebel
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, 26129, Germany
| | - Carol Arnosti
- Department of Marine Sciences, University of North Carolina, 3117 Venable Hall, Chapel Hill, NC, USA
| | - Sonja Voget
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, University of Göttingen, Göttingen, 37077, Germany
| | - Meinhard Simon
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, 26129, Germany
| | - Thorsten Brinkhoff
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, 26129, Germany
| | - Matthias Wietz
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, 26129, Germany
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Martin-Cuadrado AB, Garcia-Heredia I, Moltó AG, López-Úbeda R, Kimes N, López-García P, Moreira D, Rodriguez-Valera F. A new class of marine Euryarchaeota group II from the Mediterranean deep chlorophyll maximum. ISME JOURNAL 2014; 9:1619-34. [PMID: 25535935 DOI: 10.1038/ismej.2014.249] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 11/14/2014] [Accepted: 11/19/2014] [Indexed: 11/09/2022]
Abstract
We have analyzed metagenomic fosmid clones from the deep chlorophyll maximum (DCM), which, by genomic parameters, correspond to the 16S ribosomal RNA (rRNA)-defined marine Euryarchaeota group IIB (MGIIB). The fosmid collections associated with this group add up to 4 Mb and correspond to at least two species within this group. From the proposed essential genes contained in the collections, we infer that large sections of the conserved regions of the genomes of these microbes have been recovered. The genomes indicate a photoheterotrophic lifestyle, similar to that of the available genome of MGIIA (assembled from an estuarine metagenome in Puget Sound, Washington Pacific coast), with a proton-pumping rhodopsin of the same kind. Several genomic features support an aerobic metabolism with diversified substrate degradation capabilities that include xenobiotics and agar. On the other hand, these MGIIB representatives are non-motile and possess similar genome size to the MGIIA-assembled genome, but with a lower GC content. The large phylogenomic gap with other known archaea indicates that this is a new class of marine Euryarchaeota for which we suggest the name Thalassoarchaea. The analysis of recruitment from available metagenomes indicates that the representatives of group IIB described here are largely found at the DCM (ca. 50 m deep), in which they are abundant (up to 0.5% of the reads), and at the surface mostly during the winter mixing, which explains formerly described 16S rRNA distribution patterns. Their uneven representation in environmental samples that are close in space and time might indicate sporadic blooms.
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Affiliation(s)
- Ana-Belen Martin-Cuadrado
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Inmaculada Garcia-Heredia
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Aitor Gonzaga Moltó
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Rebeca López-Úbeda
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Nikole Kimes
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Purificación López-García
- Unité d'Ecologie, Systématique et Evolution, UMR CNRS 8079, Université Paris-Sud, Orsay Cedex, France
| | - David Moreira
- Unité d'Ecologie, Systématique et Evolution, UMR CNRS 8079, Université Paris-Sud, Orsay Cedex, France
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
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31
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RNA sequencing provides evidence for functional variability between naturally co-existing Alteromonas macleodii lineages. BMC Genomics 2014; 15:938. [PMID: 25344729 PMCID: PMC4223743 DOI: 10.1186/1471-2164-15-938] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 10/16/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Alteromonas macleodii is a ubiquitous gammaproteobacterium shown to play a biogeochemical role in marine environments. Two A. macleodii strains (AltDE and AltDE1) isolated from the same sample (i.e., the same place at the same time) show considerable genomic differences. In this study, we investigate the transcriptional response of these two strains to varying growth conditions in order to investigate differences in their ability to adapt to varying environmental parameters. RESULTS RNA sequencing revealed transcriptional changes between all growth conditions examined (e.g., temperature and medium) as well as differences between the two A. macleodii strains within a given condition. The main inter-strain differences were more marked in the adaptation to grow on minimal medium with glucose and, even more so, under starvation. These differences suggested that AltDE1 may have an advantage over AltDE when glucose is the major carbon source, and co-culture experiments confirmed this advantage. Additional differences were observed between the two strains in the expression of ncRNAs and phage-related genes, as well as motility. CONCLUSIONS This study shows that the genomic diversity observed in closely related strains of A. macleodii from a single environment result in different transcriptional responses to changing environmental parameters. This data provides additional support for the idea that greater diversity at the strain level of a microbial community could enhance the community's ability to adapt to environmental shifts.
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Garcia-Heredia I, Rodriguez-Valera F, Martin-Cuadrado AB. Novel group of podovirus infecting the marine bacterium Alteromonas macleodii.. BACTERIOPHAGE 2014; 3:e24766. [PMID: 24228219 PMCID: PMC3821669 DOI: 10.4161/bact.24766] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 04/22/2013] [Accepted: 04/22/2013] [Indexed: 12/29/2022]
Abstract
Four novel, closely related podoviruses, which displayed lytic activity against the gamma-proteobacterium Alteromonas macleodii, have been isolated and sequenced. Alterophages AltAD45-P1 to P4 were obtained from water recovered near a fish farm in the Mediterranean Sea. Their morphology indicates that they belong to the Podoviridae. Their linear and dsDNA genomes are 100–104 kb in size, remarkably larger than any other described podovirus. The four AltAD45-phages share 99% nucleotide sequence identity over 97% of their ORFs, although an insertion was found in AltAD45-P1 and P2 and some regions were slightly more divergent. Despite the high overall sequence similarity among these four phages, the group with the insertion and the group without it, have different host ranges against the A. macleodii strains tested. The AltAD45-P1 to P4 phages have genes for DNA replication and transcription as well as structural genes, which are similar to the N4-like Podoviridae genus that is widespread in proteobacteria. However, in terms of their genomic structure, AltAD45-P1 to P4 differ from that of the N4-like phages. Some distinguishing features include the lack of a large virion encapsidated RNA polymerase gene, very well conserved among all the previously described N4-like phages, a single-stranded DNA binding protein and different tail protein genes. We conclude that the AltAD45 phages characterized in this study constitute a new genus within the Podoviridae.
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Affiliation(s)
- Inmaculada Garcia-Heredia
- Evolutionary Genomics Group; División de Microbiología; Universidad Miguel Hernández; San Juan, Alicante Spain
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López-Pérez M, Gonzaga A, Ivanova EP, Rodriguez-Valera F. Genomes of Alteromonas australica, a world apart. BMC Genomics 2014; 15:483. [PMID: 24942065 PMCID: PMC4119200 DOI: 10.1186/1471-2164-15-483] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 06/13/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Alteromonas is a genus of marine bacteria that is very easy to isolate and grow in the laboratory. There are genomes available of the species Alteromonas macleodii from different locations around the world and an Alteromonas sp. isolated from a sediment in Korea. We have analyzed the genomes of two strains classified by 16S rRNA (>99% similarity) as the recently described species Alteromonas australica, and isolated from opposite ends of the world; A. australica DE170 was isolated in the South Adriatic (Mediterranean) at 1000 m depth while A. australica H17T was isolated from a sea water sample collected in St Kilda Beach, Tasman Sea. RESULTS Although these two strains belong to a clearly different species from A. macleodii, the overall synteny is well preserved and the flexible genomic islands seem to code for equivalent functions and be located at similar positions. Actually the genomes of all the Alteromonas species known to date seem to preserve synteny quite well with the only exception of the sediment isolate SN2. Among the specific metabolic features found for the A. australica isolates there is the degradation of xylan and production of cellulose as extracellular polymeric substance by DE170 or the potential ethanol/methanol degradation by H17T. CONCLUSIONS The genomes of the two A. australica isolates are not more different than those of strains of A. macleodii isolated from the same sample. Actually the recruitment from metagenomes indicates that all the available genomes are found in most tropical-temperate marine samples analyzed and that they live in consortia of several species and multiple clones within each. Overall the hydrolytic activities of the Alteromonas genus as a whole are impressive and fit with its known capabilities to exploit sudden inputs of organic matter in their environment.
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Affiliation(s)
| | | | | | - Francisco Rodriguez-Valera
- División de Microbiología, Evolutionary Genomics Group, Universidad Miguel Hernández, Apartado 18, San Juan, 03550 Alicante, Spain.
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López-Pérez M, Martin-Cuadrado AB, Rodriguez-Valera F. Homologous recombination is involved in the diversity of replacement flexible genomic islands in aquatic prokaryotes. Front Genet 2014; 5:147. [PMID: 24904647 PMCID: PMC4033161 DOI: 10.3389/fgene.2014.00147] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/06/2014] [Indexed: 01/22/2023] Open
Abstract
Different strains of the same prokaryotic species, even very similar ones, vary in large regions of their genomes. This flexible genome represents a huge reservoir of diversity that allows prokaryotes to exploit their environment efficiently. Most of the flexible genome is concentrated in genomic islands, some of which are present in all the strains and coding for similar functions but containing different genes. These replacement genomic islands are typically involved in exposed cellular structures, and their diversity has been connected to their recognition as targets by prokaryotic viruses (phages). We have compared genomes of closely related aquatic microbes from different origins and found examples of recent replacement of some of these flexible genomic islands. In all cases, that include Gram positive and negative bacteria and one archaeon, the replaced regions boundaries contain tell-tale peaks of increased, mostly synonymous, nucleotide substitutions. They tended to be sharper at the boundary closest to the origin of replication of the island. We will present the hypothesis that replacement flexible genomic islands are often exchanged by homologous recombination between different clonal frames. These recombination events are possibly selected due to the immediate reward provided by a change in the phage sensitivity spectrum.
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Affiliation(s)
- Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández Alicante, Spain
| | - Ana-Belen Martin-Cuadrado
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández Alicante, Spain
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Kashtan N, Roggensack SE, Rodrigue S, Thompson JW, Biller SJ, Coe A, Ding H, Marttinen P, Malmstrom RR, Stocker R, Follows MJ, Stepanauskas R, Chisholm SW. Single-cell genomics reveals hundreds of coexisting subpopulations in wild Prochlorococcus. Science 2014; 344:416-20. [PMID: 24763590 DOI: 10.1126/science.1248575] [Citation(s) in RCA: 320] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Extensive genomic diversity within coexisting members of a microbial species has been revealed through selected cultured isolates and metagenomic assemblies. Yet, the cell-by-cell genomic composition of wild uncultured populations of co-occurring cells is largely unknown. In this work, we applied large-scale single-cell genomics to study populations of the globally abundant marine cyanobacterium Prochlorococcus. We show that they are composed of hundreds of subpopulations with distinct "genomic backbones," each backbone consisting of a different set of core gene alleles linked to a small distinctive set of flexible genes. These subpopulations are estimated to have diverged at least a few million years ago, suggesting ancient, stable niche partitioning. Such a large set of coexisting subpopulations may be a general feature of free-living bacterial species with huge populations in highly mixed habitats.
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Affiliation(s)
- Nadav Kashtan
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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Mizuno CM, Ghai R, Rodriguez-Valera F. Evidence for metaviromic islands in marine phages. Front Microbiol 2014; 5:27. [PMID: 24550898 PMCID: PMC3909814 DOI: 10.3389/fmicb.2014.00027] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/16/2014] [Indexed: 11/13/2022] Open
Abstract
Metagenomic islands (MGIs) have been defined as genomic regions in prokaryotic genomes that under-recruit from metagenomes where most of the same genome recruits at close to 100% identity over most of its length. The presence of MGIs in prokaryotes has been associated to the diversity of concurrent lineages that vary at this level to disperse the predatory pressure of phages that, reciprocally, maintain high clonal diversity in the population and improve ecosystem performance. This was proposed as a Constant-Diversity (C-D) model. Here we have investigated the regions of phage genomes under-recruiting in a metavirome constructed with a sample from the same habitat where they were retrieved. Some of the genes found to under-recruit are involved in host recognition as would be expected from the C-D model. Furthermore, the recruitment of intragenic regions known to be involved in molecular recognition also had a significant under-recruitment compared to the rest of the gene. However, other genes apparently disconnected from the recognition process under-recruited often, specifically the terminases involved in packaging of the phage genome in the capsid and a few others. In addition, some highly related phage genomes (at nucleotide sequence level) had no metaviromic islands (MVIs). We speculate that the latter might be generalist phages with broad infection range that do not require clone specific lineages.
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Affiliation(s)
- Carolina Megumi Mizuno
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández Alicante, Spain
| | - Rohit Ghai
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández Alicante, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández Alicante, Spain
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López-Pérez M, Gonzaga A, Rodriguez-Valera F. Genomic diversity of "deep ecotype" Alteromonas macleodii isolates: evidence for Pan-Mediterranean clonal frames. Genome Biol Evol 2013; 5:1220-32. [PMID: 23729633 PMCID: PMC3698932 DOI: 10.1093/gbe/evt089] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We have compared genomes of Alteromonas macleodii “deep ecotype” isolates from two deep Mediterranean sites and two surface samples from the Aegean and the English Channel. A total of nine different genomes were analyzed. They belong to five clonal frames (CFs) that differ among them by approximately 30,000 single-nucleotide polymorphisms (SNPs) over their core genomes. Two of the CFs contain three strains each with nearly identical genomes (∼100 SNPs over the core genome). One of the CFs had representatives that were isolated from samples taken more than 1,000 km away, 2,500 m deeper, and 5 years apart. These data mark the longest proven persistence of a CF in nature (outside of clinical settings). We have found evidence for frequent recombination events between or within CFs and even with the distantly related A. macleodii surface ecotype. The different CFs had different flexible genomic islands. They can be classified into two groups; one type is additive, that is, containing different numbers of gene cassettes, and is very variable in short time periods (they often varied even within a single CF). The other type was more stable and produced the complete replacement of a genomic fragment by another with different genes. Although this type was more conserved within each CF, we found examples of recombination among distantly related CFs including English Channel and Mediterranean isolates.
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Affiliation(s)
- Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Alicante, Spain
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Mizuno CM, Rodriguez-Valera F, Kimes NE, Ghai R. Expanding the marine virosphere using metagenomics. PLoS Genet 2013; 9:e1003987. [PMID: 24348267 PMCID: PMC3861242 DOI: 10.1371/journal.pgen.1003987] [Citation(s) in RCA: 188] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 10/15/2013] [Indexed: 11/19/2022] Open
Abstract
Viruses infecting prokaryotic cells (phages) are the most abundant entities of the biosphere and contain a largely uncharted wealth of genomic diversity. They play a critical role in the biology of their hosts and in ecosystem functioning at large. The classical approaches studying phages require isolation from a pure culture of the host. Direct sequencing approaches have been hampered by the small amounts of phage DNA present in most natural habitats and the difficulty in applying meta-omic approaches, such as annotation of small reads and assembly. Serendipitously, it has been discovered that cellular metagenomes of highly productive ocean waters (the deep chlorophyll maximum) contain significant amounts of viral DNA derived from cells undergoing the lytic cycle. We have taken advantage of this phenomenon to retrieve metagenomic fosmids containing viral DNA from a Mediterranean deep chlorophyll maximum sample. This method allowed description of complete genomes of 208 new marine phages. The diversity of these genomes was remarkable, contributing 21 genomic groups of tailed bacteriophages of which 10 are completely new. Sequence based methods have allowed host assignment to many of them. These predicted hosts represent a wide variety of important marine prokaryotic microbes like members of SAR11 and SAR116 clades, Cyanobacteria and also the newly described low GC Actinobacteria. A metavirome constructed from the same habitat showed that many of the new phage genomes were abundantly represented. Furthermore, other available metaviromes also indicated that some of the new phages are globally distributed in low to medium latitude ocean waters. The availability of many genomes from the same sample allows a direct approach to viral population genomics confirming the remarkable mosaicism of phage genomes.
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Affiliation(s)
- Carolina Megumi Mizuno
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
- * E-mail:
| | - Nikole E. Kimes
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Rohit Ghai
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
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Lineage specific gene family enrichment at the microscale in marine systems. Curr Opin Microbiol 2013; 16:605-17. [DOI: 10.1016/j.mib.2013.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Mizuno CM, Kimes NE, López-Pérez M, Ausó E, Rodriguez-Valera F, Ghai R. A hybrid NRPS-PKS gene cluster related to the bleomycin family of antitumor antibiotics in Alteromonas macleodii strains. PLoS One 2013; 8:e76021. [PMID: 24069455 PMCID: PMC3777966 DOI: 10.1371/journal.pone.0076021] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 08/19/2013] [Indexed: 11/24/2022] Open
Abstract
Although numerous marine bacteria are known to produce antibiotics via hybrid NRPS-PKS gene clusters, none have been previously described in an Alteromonas species. In this study, we describe in detail a novel hybrid NRPS-PKS cluster identified in the plasmid of the Alteromonasmacleodii strain AltDE1 and analyze its relatedness to other similar gene clusters in a sequence-based characterization. This is a mobile cluster, flanked by transposase-like genes, that has even been found inserted into the chromosome of some Alteromonasmacleodii strains. The cluster contains separate genes for NRPS and PKS activity. The sole PKS gene appears to carry a novel acyltransferase domain, quite divergent from those currently characterized. The predicted specificities of the adenylation domains of the NRPS genes suggest that the final compound has a backbone very similar to bleomycin related compounds. However, the lack of genes involved in sugar biosynthesis indicates that the final product is not a glycopeptide. Even in the absence of these genes, the presence of the cluster appears to confer complete or partial resistance to phleomycin, which may be attributed to a bleomycin-resistance-like protein identified within the cluster. This also suggests that the compound still shares significant structural similarity to bleomycin. Moreover, transcriptomic evidence indicates that the NRPS-PKS cluster is expressed. Such sequence-based approaches will be crucial to fully explore and analyze the diversity and potential of secondary metabolite production, especially from increasingly important sources like marine microbes.
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Affiliation(s)
- Carolina Megumi Mizuno
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiologia, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Nikole E. Kimes
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiologia, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Mario López-Pérez
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiologia, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Eva Ausó
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiologia, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiologia, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
- * E-mail:
| | - Rohit Ghai
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiologia, Universidad Miguel Hernández, San Juan de Alicante, Alicante, Spain
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López-Pérez M, Gonzaga A, Martin-Cuadrado AB, López-García P, Rodriguez-Valera F, Kimes NE. Intra- and intergenomic variation of ribosomal RNA operons in concurrent Alteromonas macleodii strains. MICROBIAL ECOLOGY 2013; 65:720-730. [PMID: 23269455 DOI: 10.1007/s00248-012-0153-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 12/06/2012] [Indexed: 06/01/2023]
Abstract
Biodiversity estimates based on ribosomal operon sequence diversity rely on the premise that a sequence is characteristic of a single specific taxon or operational taxonomic unit (OTU). Here, we have studied the sequence diversity of 14 ribosomal RNA operons (rrn) contained in the genomes of two isolates (five operons in each genome) and four metagenomic fosmids, all from the same seawater sample. Complete sequencing of the isolate genomes and the fosmids establish that they represent strains of the same species, Alteromonas macleodii, with average nucleotide identity (ANI) values >97 %. Nonetheless, we observed high levels of intragenomic heterogeneity (i.e., variability between operons of a single genome) affecting multiple regions of the 16S and 23S rRNA genes as well as the internally transcribed spacer 1 (ITS-1) region. Furthermore, the ribosomal operons exhibited intergenomic heterogeneity (i.e., variability between operons located in separate genomes) in each of these regions, compounding the variability. Our data reveal the extensive heterogeneity observed in natural populations of A. macleodii at a single point in time and support the idea that distinct lineages of A. macleodii exist in the deep Mediterranean. These findings highlight the potential of rRNA fingerprinting methods to misrepresent species diversity while simultaneously failing to recognize the ecological significance of individual strains.
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Affiliation(s)
- Mario López-Pérez
- División de Microbiología, Universidad Miguel Hernández, San Juan, Alicante, Spain
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