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Ramírez N, Sigurbjörnsdóttir MA, Monteil C, Berge O, Heiðmarsson S, Jackson RW, Morris C, Vilhelmsson O. Pseudomonas syringae isolated in lichens for the first time: Unveiling Peltigera genus as the exclusive host. Environ Microbiol 2023; 25:3502-3511. [PMID: 37658725 DOI: 10.1111/1462-2920.16490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 08/01/2023] [Indexed: 09/03/2023]
Abstract
Pseudomonas syringae is a bacterial complex that is widespread through a range of environments, typically associated with plants where it can be pathogenic, but also found in non-plant environments such as clouds, precipitation, and surface waters. Understanding its distribution within the environment, and the habitats it occupies, is important for examining its evolution and understanding behaviours. After a recent study found P. syringae living among a range of vascular plant species in Iceland, we questioned whether lichens could harbour P. syringae. Sixteen different species of lichens were sampled all over Iceland, but only one lichen genus, Peltigera, was found to consistently harbour P. syringae. Phylogenetic analyses of P. syringae from 10 sampling points where lichen, tracheophyte, and/or moss were simultaneously collected showed significant differences between sampling points, but not between different plants and lichens from the same point. Furthermore, while there were similarities in the P. syringae population in tracheophytes and Peltigera, the densities in Peltigera thalli were lower than in moss and tracheophyte samples. This discovery suggests P. syringae strains can localize and survive in organisms beyond higher plants, and thus reveals opportunities for studying their influence on P. syringae evolution.
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Affiliation(s)
- Natalia Ramírez
- Department of Natural Resource Sciences, University of Akureyri, Akureyri, Iceland
| | | | - Cecile Monteil
- INRA, UR0407 Pathologie Vegétale, Montfavet Cedex, France
| | - Odile Berge
- INRA, UR0407 Pathologie Vegétale, Montfavet Cedex, France
| | | | - Robert W Jackson
- School of Biosciences and Birmingham Institute of Forest Research, University of Birmingham, Birmingham, UK
| | - Cindy Morris
- INRA, UR0407 Pathologie Vegétale, Montfavet Cedex, France
| | - Oddur Vilhelmsson
- Department of Natural Resource Sciences, University of Akureyri, Akureyri, Iceland
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Klarenberg IJ, Keuschnig C, Salazar A, Benning LG, Vilhelmsson O. Moss and underlying soil bacterial community structures are linked to moss functional traits. Ecosphere 2023. [DOI: 10.1002/ecs2.4447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
Affiliation(s)
- Ingeborg J. Klarenberg
- Natural Resource Sciences University of Akureyri Akureyri Iceland
- Faculty of Life and Environmental Sciences University of Iceland Reykjavík Iceland
- Department of Ecological Science Vrije Universiteit Amsterdam Amsterdam Netherlands
| | - Christoph Keuschnig
- Environmental Microbial Genomics Laboratoire Ampère, CNRS, École Centrale de Lyon Écully France
- German Research Centre for Geosciences (GFZ) Interface Geochemistry Potsdam Germany
| | - Alejandro Salazar
- Faculty of Environmental and Forest Sciences Agricultural University of Iceland Reykjavík Iceland
| | - Liane G. Benning
- German Research Centre for Geosciences (GFZ) Interface Geochemistry Potsdam Germany
- Department of Earth Sciences Free University of Berlin Berlin Germany
| | - Oddur Vilhelmsson
- Natural Resource Sciences University of Akureyri Akureyri Iceland
- BioMedical Center University of Iceland Reykjavík Iceland
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3
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Klarenberg IJ, Keuschnig C, Russi Colmenares AJ, Warshan D, Jungblut AD, Jónsdóttir IS, Vilhelmsson O. Long-term warming effects on the microbiome and nifH gene abundance of a common moss species in sub-Arctic tundra. New Phytol 2022; 234:2044-2056. [PMID: 34719786 DOI: 10.1111/nph.17837] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 10/17/2021] [Indexed: 06/13/2023]
Abstract
Bacterial communities form the basis of biogeochemical processes and determine plant growth and health. Mosses harbour diverse bacterial communities that are involved in nitrogen fixation and carbon cycling. Global climate change is causing changes in aboveground plant biomass and shifting species composition in the Arctic, but little is known about the response of moss microbiomes in these environments. Here, we studied the total and potentially active bacterial communities associated with Racomitrium lanuginosum in response to a 20-yr in situ warming in an Icelandic heathland. We evaluated the effect of warming and warming-induced shrub expansion on the moss bacterial community composition and diversity, and nifH gene abundance. Warming changed both the total and the potentially active bacterial community structure, while litter abundance only affected the total bacterial community structure. The abundance of nifH genes was negatively affected by litter abundance. We also found shifts in the potentially nitrogen-fixing community, with Nostoc decreasing and noncyanobacterial diazotrophs increasing in relative abundance. Our data suggest that the moss microbial community and potentially nitrogen fixing taxa will be sensitive to future warming, partly via changes in litter and shrub abundance.
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Affiliation(s)
- Ingeborg J Klarenberg
- Natural Resource Sciences, University of Akureyri, Borgir i Nordurslod, Akureyri, 600, Iceland
- Faculty of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 102, Reykjavík, Iceland
| | - Christoph Keuschnig
- Environmental Microbial Genomics, Laboratoire Ampère, École Centrale de Lyon, Université de Lyon, Avenue Guy de Collongue 36, Écully, 69134, France
| | - Ana J Russi Colmenares
- Faculty of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 102, Reykjavík, Iceland
| | - Denis Warshan
- Faculty of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 102, Reykjavík, Iceland
| | - Anne D Jungblut
- Life Sciences Department, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | - Ingibjörg S Jónsdóttir
- Faculty of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 102, Reykjavík, Iceland
| | - Oddur Vilhelmsson
- Natural Resource Sciences, University of Akureyri, Borgir i Nordurslod, Akureyri, 600, Iceland
- BioMedical Center, University of Iceland, Vatnsmýrarvegur 16, 101, Reykjavík, Iceland
- School of Biological Sciences, University of Reading, Whiteknights, Reading, RG6 6AJ, UK
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4
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Klarenberg IJ, Keuschnig C, Warshan D, Jónsdóttir IS, Vilhelmsson O. The Total and Active Bacterial Community of the Chlorolichen Cetraria islandica and Its Response to Long-Term Warming in Sub-Arctic Tundra. Front Microbiol 2020; 11:540404. [PMID: 33391192 PMCID: PMC7775390 DOI: 10.3389/fmicb.2020.540404] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 11/30/2020] [Indexed: 01/04/2023] Open
Abstract
Lichens are traditionally defined as a symbiosis between a fungus and a green alga and or a cyanobacterium. This idea has been challenged by the discovery of bacterial communities inhabiting the lichen thalli. These bacteria are thought to contribute to the survival of lichens under extreme and changing environmental conditions. How these changing environmental conditions affect the lichen-associated bacterial community composition remains unclear. We describe the total (rDNA-based) and potentially metabolically active (rRNA-based) bacterial community of the lichen Cetaria islandica and its response to long-term warming using a 20-year warming experiment in an Icelandic sub-Arctic tundra. 16S rRNA and rDNA amplicon sequencing showed that the orders Acetobacterales (of the class Alphaproteobacteria) and Acidobacteriales (of the phylum Acidobacteria) dominated the bacterial community. Numerous amplicon sequence variants (ASVs) could only be detected in the potentially active community but not in the total community. Long-term warming led to increases in relative abundance of bacterial taxa on class, order and ASV level. Warming altered the relative abundance of ASVs of the most common bacterial genera, such as Granulicella and Endobacter. The potentially metabolically active bacterial community was also more responsive to warming than the total community. Our results suggest that the bacterial community of the lichen C. islandica is dominated by acidophilic taxa and harbors disproportionally active rare taxa. We also show for the first time that climate warming can lead to shifts in lichen-associated bacterial community composition.
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Affiliation(s)
- Ingeborg J. Klarenberg
- Natural Resource Sciences, University of Akureyri, Akureyri, Iceland
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
| | - Christoph Keuschnig
- Environmental Microbial Genomics, Laboratoire Ampère, CNRS, École Centrale de Lyon, Écully, France
| | - Denis Warshan
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
| | | | - Oddur Vilhelmsson
- Natural Resource Sciences, University of Akureyri, Akureyri, Iceland
- BioMedical Center, University of Iceland, Reykjavík, Iceland
- School of Biological Sciences, University of Reading, Reading, United Kingdom
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Þorsteinsdóttir GV, Blischke A, Sigurbjörnsdóttir MA, Òskarsson F, Arnarson ÞS, Magnússon KP, Vilhelmsson O. Gas seepage pockmark microbiomes suggest the presence of sedimentary coal seams in the Öxarfjörður graben of northeastern Iceland. Can J Microbiol 2019; 66:25-38. [PMID: 31557445 DOI: 10.1139/cjm-2019-0081] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Natural gas seepage pockmarks are found off- and onshore in the Öxarfjörður graben, Iceland. The bacterial communities of two onshore seepage sites were analysed by 16S rRNA gene amplicon sequencing; the geochemical characteristics, hydrocarbon content, and the carbon isotope composition of the sites were also determined. While one site was found to be characterised by biogenic origin of methane gas, with a carbon isotope ratio (δ13C (‰)) of -63.2, high contents of organic matter and complex hydrocarbons, the other site showed a mixed origin of the methane gas (δ13C (‰) = -26.6) with geothermal characteristics and lower organic matter content. While both sites harboured Proteobacteria as the most abundant bacterial phyla, the Deltaproteobacteria were more abundant at the geothermal site and the Alphaproteobacteria at the biogenic site. The Dehalococcoidia class of phylum Chloroflexi was abundant at the geothermal site while the Anaerolineae class was more abundant at the biogenic site. Bacterial strains from the seepage pockmarks were isolated on a variety of selective media targeting bacteria with bioremediation potential. A total of 106 strains were isolated and characterised, including representatives from the phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. This article describes the first microbial study on gas seepage pockmarks in Iceland.
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Affiliation(s)
- Guðný Vala Þorsteinsdóttir
- Faculty of Natural Resource Sciences, University of Akureyri, Borgir v. Norðurslóð, 600 Akureyri, Iceland.,Icelandic Institute of Natural History, Borgir v. Norðurslóð, 600 Akureyri, Iceland
| | - Anett Blischke
- Iceland GeoSurvey, Branch at Akureyri, Rangarvollum, 603 Akureyri, Iceland
| | - M Auður Sigurbjörnsdóttir
- Faculty of Natural Resource Sciences, University of Akureyri, Borgir v. Norðurslóð, 600 Akureyri, Iceland
| | - Finnbogi Òskarsson
- Iceland GeoSurvey, Department of Geothermal Engineering, Grensásvegi 9, 108 Reykjavík, Iceland
| | | | - Kristinn P Magnússon
- Faculty of Natural Resource Sciences, University of Akureyri, Borgir v. Norðurslóð, 600 Akureyri, Iceland.,Icelandic Institute of Natural History, Borgir v. Norðurslóð, 600 Akureyri, Iceland.,Biomedical Center, University of Iceland, Vatnsmýrarvegur 16, 101 Reykjavík, Iceland
| | - Oddur Vilhelmsson
- Faculty of Natural Resource Sciences, University of Akureyri, Borgir v. Norðurslóð, 600 Akureyri, Iceland.,Biomedical Center, University of Iceland, Vatnsmýrarvegur 16, 101 Reykjavík, Iceland.,School of Biological Sciences, University of Reading, Earley, Reading RG6 6AS, UK
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6
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Sigurbjörnsdóttir MA, Vilhelmsson O. Selective isolation of potentially phosphate-mobilizing, biosurfactant-producing and biodegradative bacteria associated with a sub-Arctic, terricolous lichen, Peltigera membranacea. FEMS Microbiol Ecol 2016; 92:fiw090. [PMID: 27127196 DOI: 10.1093/femsec/fiw090] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2016] [Indexed: 12/19/2022] Open
Abstract
Lichens are the symbiotic association of fungi and a photosynthetic partner. However, non-phototrophic bacteria are also present and thought to comprise an essential part of the lichen symbiosis, although their roles in the symbiosis are still poorly understood. In this study, we isolated and characterized 110 non-phototrophic bacterial lichen associates from thalli of the terricolous lichen Peltigera membranacea The biodegradative and other nutrient-scavenging properties studied among selected isolates were phosphate mobilization, biosurfactant production and degradation of napthalene and several biopolymers, suggesting organic and inorganic nutrient scavenging as roles for bacteria in the lichen symbiotic association. Identification by partial 16S rRNA gene sequencing revealed that the isolates comprised 18 genera within the Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes, many with high similarities with bacteria typically associated with the plant and rhizosphere environments, could suggest that plants may be important sources of terricolous lichen-associated bacteria, or vice versa.
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Affiliation(s)
- Margrét Auður Sigurbjörnsdóttir
- Department of Natural Resource Sciences, University of Akureyri, Borgir vid Nordurslod, 600 Akureyri, Iceland Faculty of Life and Environmental Sciences, University of Iceland, 101 Reykjavik, Iceland
| | - Oddur Vilhelmsson
- Department of Natural Resource Sciences, University of Akureyri, Borgir vid Nordurslod, 600 Akureyri, Iceland Biomedical Center, University of Iceland, Vatnsmýrarvegur 16, 101 Reykjavik, Iceland
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7
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Sigurbjörnsdóttir MA, Andrésson ÓS, Vilhelmsson O. Nutrient scavenging activity and antagonistic factors of non-photobiont lichen-associated bacteria: a review. World J Microbiol Biotechnol 2016; 32:68. [PMID: 26931608 DOI: 10.1007/s11274-016-2019-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 01/28/2016] [Indexed: 02/05/2023]
Abstract
Lichens are defined as the specific symbiotic structure comprising a fungus and a green alga and/or cyanobacterium. Up until recently, non-photobiont endothallic bacteria, while known to be present in large numbers, have generally been dismissed as functionally irrelevant cohabitants of the lichen thallus, or even environmental contaminants. Recent analyses of lichen metagenomes and innovative co-culture experiments have uncovered a functionally complex community that appears to contribute to a healthy lichen thallus in several ways. Lichen-associated bacteriomes are typically dominated by several lineages of Proteobacteria, some of which may be specific for lichen species. Recent work has implicated members of these lineages in several important ecophysiological roles. These include nutrient scavenging, including mobilization of iron and phosphate, nitrogen fixation, cellulase, xylanase and amylase activities, and oxidation of recalcitrant compounds, e.g. aromatics and aliphatics. Production of volatile organic compounds, conferring antibacterial and antifungal activity, has also been demonstrated for several lichen-associated isolates. In the present paper we review the nature of non-phototrophic endolichenic bacteria associated with lichens, and give insight into the current state of knowledge on their importance the lichen symbiotic association.
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Affiliation(s)
- M Auður Sigurbjörnsdóttir
- Department of Natural Resource Sciences, University of Akureyri, Borgir vid Nordurslod, 600, Akureyri, Iceland.
- Faculty of Life and Environmental Sciences, University of Iceland, 101, Reykjavík, Iceland.
| | - Ólafur S Andrésson
- Faculty of Life and Environmental Sciences, University of Iceland, 101, Reykjavík, Iceland
- Biomedical Center, University of Iceland, Vatnsmýrarvegur 16, 101, Reykjavík, Iceland
| | - Oddur Vilhelmsson
- Department of Natural Resource Sciences, University of Akureyri, Borgir vid Nordurslod, 600, Akureyri, Iceland
- Biomedical Center, University of Iceland, Vatnsmýrarvegur 16, 101, Reykjavík, Iceland
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8
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Vilhelmsson O, Sigurbjörnsdóttir A, Grube M, Höfte M. Are lichens potential natural reservoirs for plant pathogens? Mol Plant Pathol 2016; 17:143-145. [PMID: 26806074 PMCID: PMC6638420 DOI: 10.1111/mpp.12344] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Revised: 11/11/2015] [Accepted: 11/11/2015] [Indexed: 06/05/2023]
Affiliation(s)
- Oddur Vilhelmsson
- Faculty of Natural Resource Sciences, University of Akureyri, Akureyri, Iceland
- Biomedical Center, University of Iceland, Reykjavik, Iceland
| | | | - Martin Grube
- Institut für Pflanzenwissenschaften Karl-Franzens-Universität Graz, Graz, Austria
| | - Monica Höfte
- Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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Sigurbjörnsdóttir MA, Andrésson ÓS, Vilhelmsson O. Analysis of the Peltigera membranacea metagenome indicates that lichen-associated bacteria are involved in phosphate solubilization. Microbiology (Reading) 2015; 161:989-996. [PMID: 25737483 DOI: 10.1099/mic.0.000069] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 02/28/2015] [Indexed: 11/18/2022]
Abstract
Although lichens are generally described as mutualistic symbioses of fungi and photosynthetic partners, they also harbour a diverse non-phototrophic microbiota, which is now regarded as a significant part of the symbiosis. However, the role of the non-phototrophic microbiota within the lichen is still poorly known, although possible functions have been suggested, including phosphate solubilization and various lytic activities. In the present study we focus on the bacterial biota associated with the foliose lichen Peltigera membranacea. To address our hypotheses on possible roles of the non-phototrophic microbiota, we used a metagenomic approach. A DNA library of bacterial sequence contigs was constructed from the lichen thallus material and the bacterial microbiota DNA sequence was analysed in terms of phylogenetic diversity and functional gene composition. Analysis of about 30,000 such bacterial contigs from the P. membranacea metagenome revealed significant representation of several genes involved in phosphate solubilization and biopolymer degradation.
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Affiliation(s)
- Margrét Auður Sigurbjörnsdóttir
- Faculty of Life and Environmental Sciences, University of Iceland, 101 Reykjavik, Iceland.,Department of Natural Resource Sciences, University of Akureyri, Borgir vid Nordurslod, 600 Akureyri, Iceland
| | - Ólafur S Andrésson
- Biomedical Center, University of Iceland, Vatnsmýrarvegur 16, 101 Reykjavik, Iceland.,Faculty of Life and Environmental Sciences, University of Iceland, 101 Reykjavik, Iceland
| | - Oddur Vilhelmsson
- Department of Natural Resource Sciences, University of Akureyri, Borgir vid Nordurslod, 600 Akureyri, Iceland.,Biomedical Center, University of Iceland, Vatnsmýrarvegur 16, 101 Reykjavik, Iceland
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Sigurbjörnsdóttir MA, Heiðmarsson S, Jónsdóttir AR, Vilhelmsson O. Novel bacteria associated with Arctic seashore lichens have potential roles in nutrient scavenging. Can J Microbiol 2014; 60:307-17. [PMID: 24802938 DOI: 10.1139/cjm-2013-0888] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
While generally described as a bipartite mutualistic association between fungi and algae or cyanobacteria, lichens also host diverse and heretofore little explored communities of nonphototrophic endolichenic bacteria. The composition and possible roles of these bacterial communities in the lichen symbiotic association constitute an emerging field of research. Saxicolous (rock-dwelling) seashore lichens present an unusual environment, characterized by rapid fluctuations in temperature, salinity, exposure to solar radiation, etc. The present study focuses on the bacterial biota associated with 4 species of crustose, halophilic, saxicolous seashore lichens found in northern Iceland. A denaturing gradient gel electrophoresis based characterization of the composition of the lichen-associated microbiotas indicated that they are markedly lichen-species-specific and clearly distinguishable from the environmental microbiota represented by control sampling. A collection of bacterial strains was investigated and partially identified by 16S rDNA sequencing. The strains were found to belong to 7 classes: Alphaproteobacteria, Bacilli, Actinobacteria, Flavobacteria, Cytophagia, Sphingobacteria, and Gammaproteobacteria. Several isolates display only a modest level of similarity to their nearest relatives found in GenBank, suggesting that they comprise previously undescribed taxa. Selected strains were tested for inorganic phosphate solubilization and biodegradation of several biopolymers, such as barley β-glucan, xylan, chitosan, and lignin. The results support a nutrient-scavenging role of the associate microbiota in the seashore lichen symbiotic association.
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Vilhelmsson O. J.N. Stokland, J. Siitonen and B.G. Jonsson, Biodiversity in Dead Wood (Cambridge, UK: Cambridge University Press, 2012). ACTA ACUST UNITED AC 2013. [DOI: 10.33112/nm.8.1.27] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Decaying wood is a fascinating habitat where a variety of organisms make their home, from bacteria to beetles and bryophytes.
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Sveinsdóttir H, Vilhelmsson O, Gudmundsdóttir Á. Proteome analysis of abundant proteins in two age groups of early Atlantic cod (Gadus morhua) larvae. Comparative Biochemistry and Physiology Part D: Genomics and Proteomics 2008; 3:243-50. [DOI: 10.1016/j.cbd.2008.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 06/04/2008] [Accepted: 06/07/2008] [Indexed: 12/15/2022]
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13
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Vilhelmsson O, Hafsteinsson H, Kristjánsson J. Isolation and characterization of moderately halophilic bacteria from fully cured salted cod (bachalao). ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1996.tb03287.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Martin SAM, Vilhelmsson O, Médale F, Watt P, Kaushik S, Houlihan DF. Proteomic sensitivity to dietary manipulations in rainbow trout. Biochim Biophys Acta 2003; 1651:17-29. [PMID: 14499585 DOI: 10.1016/s1570-9639(03)00231-0] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Changes in dietary protein sources due to substitution of fish meal by other protein sources can have metabolic consequences in farmed fish. A proteomics approach was used to study the protein profiles of livers of rainbow trout that have been fed two diets containing different proportions of plant ingredients. Both diets control (C) and soy (S) contained fish meal and plant ingredients and synthetic amino acids, but diet S had a greater proportion of soybean meal. A feeding trial was performed for 12 weeks at the end of which, growth and protein metabolism parameters were measured. Protein growth rates were not different in fish fed different diets; however, protein consumption and protein synthesis rates were higher in the fish fed the diet S. Fish fed diet S had lower efficiency of retention of synthesised protein. Ammonia excretion was increased as well as the activities of hepatic glutamate dehydrogenase and aspartate amino transferase (ASAT). No differences were found in free amino acid pools in either liver or muscle between diets. Protein extraction followed by high-resolution two-dimensional electrophoresis, coupled with gel image analysis, allowed identification and expression of hundreds of protein. Individual proteins of interest were then subjected to further analysis leading to protein identification by trypsin digest fingerprinting. During this study, approximately 800 liver proteins were analysed for expression pattern, of which 33 were found to be differentially expressed between diets C and S. Seventeen proteins were positively identified after database searching. Proteins were identified from diverse metabolic pathways, demonstrating the complex nature of gene expression responses to dietary manipulation revealed by proteomic characterisation.
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Affiliation(s)
- S A M Martin
- School for Biological Sciences, University of Aberdeen, Scotland AB24 2TZ, Aberdeen, UK.
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15
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Abstract
The effects of different humectants (sodium chloride, sucrose, and glycerol) on the growth of and compatible solute (glycine betaine, proline, and carnitine) uptake by the osmotolerant foodborne pathogen Staphylococcus aureus were investigated. While growth in the presence of the impermeant humectants sodium chloride and sucrose induced the accumulation of proline and glycine betaine by cells, growth in the presence of the permeant humectant glycerol did not. When compatible solutes were omitted from low-water-activity media, growth was very poor in the presence of impermeant humectants. In contrast, the addition of compatible solutes had essentially no effect on growth when cells were grown in low-water-activity media containing glycerol as the humectant. Carnitine was found to accumulate to high intracellular levels in osmotically stressed cells when proline and glycine betaine were absent, making it a potentially important compatible solute for this organism.
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Affiliation(s)
- Oddur Vilhelmsson
- Department of Food Science, The Pennsylvania State University, University Park 16802, USA
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16
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Vilhelmsson O, Miller KJ. Synthesis of pyruvate dehydrogenase in Staphylococcus aureus is stimulated by osmotic stress. Appl Environ Microbiol 2002; 68:2353-8. [PMID: 11976108 PMCID: PMC127531 DOI: 10.1128/aem.68.5.2353-2358.2002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2001] [Accepted: 02/14/2002] [Indexed: 11/20/2022] Open
Abstract
The pyruvate dehydrogenase multienzyme complex (PDHC) was found to be upregulated by osmotic stress in the osmotolerant pathogen Staphylococcus aureus. Upregulation was detectable in the levels of both activity and protein and was judged to be about fourfold when sodium chloride was used to adjust the water activity (a(w)) of the growth medium to 0.94. The upregulation of the PDHC was also found to be humectant dependent and was greatest when impermeant, nonmetabolizable humectants were used to adjust a(w). Further experiments provided evidence that in addition to osmotic upregulation, the PDHC complex is also subject to catabolite repression, thus providing a possible explanation for the observation that high concentrations of carbohydrates are generally more inhibitory to the growth of this bacterial pathogen than are high concentrations of salts.
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Affiliation(s)
- Oddur Vilhelmsson
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
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Abstract
Staphylococcus aureus is the most osmotolerant foodborne pathogen, and outbreaks of staphylococcal food poisoning are often linked to foods of reduced water activity (a(w)) values. While it is generally known that the thermal tolerance of microorganisms increases as the a(w) of the heating menstruum is decreased, surprisingly little research has examined the influence of growth medium a(w) on microbial thermal tolerance. In the present study, we show that growth of S. aureus at an a(w) value of 0.94 leads to the development of dramatically enhanced thermal tolerance (i.e., less than 1 log reduction after heating for 20 min at 60 degrees C). We further show that the identity of the accumulated compatible solute within cells grown at low a(w) can also influence the overall level of thermal tolerance of S. aureus. Finally, we provide evidence that the synthesis of general stress and/or osmotic stress proteins is required for the development of enhanced thermal tolerance of S. aureus at low a(w).
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Affiliation(s)
- J R Shebuski
- Department of Food Science, The Pennsylvania State University, University Park 16802, USA
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19
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Abstract
Gram-positive cocci were isolated in high numbers from salted codfish during processing. They were found to be the main bacterial type in fully cured and dried salted cod. Phenotypic characterization of 37 strains showed them to belong to the novobiocin resistant staphylococci, most likely Staphylococcus arlettae or xylosus. Based on sequencing of 16S rDNA and comparison of 700 bases it was concluded that they should be assigned to the species Staphylococcus arlettae. They were found to be extremely halotolerant, growing well at salt concentrations from 0.06 M NaCl, and even displaying clear growth at 4.5 M NaCl. Likewise, the strains grew over a wide temperature range, from 8 to 45 degrees C. Optimal growth conditions were found to be at 0.4-0.6 M NaCl and 30-32 degrees C. This is all in accordance with findings for related staphylococci that have been isolated from other heavily salted meat or fish products.
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Affiliation(s)
- O Vilhelmsson
- Technological Institute of Iceland, Keldnaholt, Reykjavik, Iceland
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