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Andreas Brune - One of the best experts on this subject based on the ideXlab platform.
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genome analysis of candidatus ancillula trichonymphae first representative of a deep branching clade of bifidobacteriales strengthens evidence for convergent evolution in Flagellate endosymbionts
Environmental Microbiology Reports, 2016Co-Authors: Jurgen F H Strassert, Aram Mikaelyan, Tanja Woyke, Andreas BruneAbstract:: The Flagellate protists in the hindgut of lower termites play an essential role in the digestion of lignocellulose. Most Flagellate species are associated with host-specific symbionts from various bacterial lineages, which typically lack cultured representatives. In this study, we analyzed the genome of 'Candidatus Ancillula trichonymphae', an endosymbiont of Trichonympha Flagellates from dry-wood termites, which represents a novel, family-level lineage of uncultured Actinobacteria encountered so far only in termite guts. The draft genome of 'Ca. A. trichonymphae' (ca. 1.48 Mbp; 95% complete) revealed a purely fermentative metabolism that is probably fueled by xylose, N-acetyl-glucosamine and glycerol 3-phosphate acquired from the Flagellate host. The absence of fructose bisphosphate aldolase and the presence of a complete gene set encoding the phosphoketolase pathway underscore the sister position of the new lineage to Bifidobacteriaceae. The preservation of the pathways for the assimilation of ammonia and the synthesis of 18 amino acids and several cofactors and vitamins suggests that 'Ca. A. trichonymphae' - like other endosymbionts of termite gut Flagellates - provides essential amino acids and vitamins to its host. Our findings corroborate the emerging concept that numerous lineages of unrelated Flagellate endosymbionts have convergently evolved to fill similar ecological niches.
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Genome analysis of ‘Candidatus Ancillula trichonymphae’, first representative of a deep‐branching clade of Bifidobacteriales, strengthens evidence for convergent evolution in Flagellate endosymbionts
Environmental microbiology reports, 2016Co-Authors: Jurgen F H Strassert, Aram Mikaelyan, Tanja Woyke, Andreas BruneAbstract:The Flagellate protists in the hindgut of lower termites play an essential role in the digestion of lignocellulose. Most Flagellate species are associated with host-specific symbionts from various bacterial lineages, which typically lack cultured representatives. In this study, we analyzed the genome of 'Candidatus Ancillula trichonymphae', an endosymbiont of Trichonympha Flagellates from dry-wood termites, which represents a novel, family-level lineage of uncultured Actinobacteria encountered so far only in termite guts. The draft genome of 'Ca. A. trichonymphae' (ca. 1.48 Mbp; 95% complete) revealed a purely fermentative metabolism that is probably fueled by xylose, N-acetyl-glucosamine and glycerol 3-phosphate acquired from the Flagellate host. The absence of fructose bisphosphate aldolase and the presence of a complete gene set encoding the phosphoketolase pathway underscore the sister position of the new lineage to Bifidobacteriaceae. The preservation of the pathways for the assimilation of ammonia and the synthesis of 18 amino acids and several cofactors and vitamins suggests that 'Ca. A. trichonymphae' - like other endosymbionts of termite gut Flagellates - provides essential amino acids and vitamins to its host. Our findings corroborate the emerging concept that numerous lineages of unrelated Flagellate endosymbionts have convergently evolved to fill similar ecological niches.
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Identification and localization of the multiple bacterial symbionts of the termite gut Flagellate Joenia annectens.
Microbiology (Reading England), 2010Co-Authors: Jurgen F H Strassert, Mahesh S Desai, Renate Radek, Andreas BruneAbstract:The hindgut of wood-feeding lower termites is densely colonized by a multitude of symbiotic micro-organisms. While it is well established that the eukaryotic Flagellates play a major role in the degradation of lignocellulose, much less is known about the identity and function of the prokaryotic symbionts associated with the Flagellates. Our ultrastructural investigations of the gut Flagellate Joenia annectens (from the termite Kalotermes flavicollis) revealed a dense colonization of this Flagellate by diverse ecto- and endosymbiotic bacteria. Phylogenetic analysis of the small-subunit rRNA gene sequences combined with fluorescence in situ hybridization allowed us to identify and localize the different morphotypes. Furthermore, we could show that K. flavicollis harbours two phylotypes of J. annectens that could be distinguished not only by their small-subunit rRNA gene sequences, but also by differences in their assemblages of bacterial symbionts. Each of the Flagellate populations hosted phylogenetically distinct ectosymbionts from the phylum Bacteroidetes, one of them closely related to the ectosymbionts of other termite gut Flagellates. A single phylotype of 'Endomicrobia' was consistently associated with only one of the host phylotypes, although not all individuals were colonized, corroborating that 'Endomicrobia' symbionts do not always cospeciate with their host lineages. Flagellates from both populations were loosely associated with a single phylotype of Spirochaetales attached to their cell surface in varying abundance. Current evidence for the involvement of Bacteroidales and 'Endomicrobia' symbionts in the nitrogen metabolism of the host Flagellate is discussed.
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Strict cospeciation of devescovinid Flagellates and Bacteroidales ectosymbionts in the gut of dry‐wood termites (Kalotermitidae)
Environmental microbiology, 2009Co-Authors: Mahesh Desai, Jurgen F H Strassert, Renate Radek, Wakako Ikeda-ohtsubo, Katja Meuser, Horst Hertel, Andreas BruneAbstract:The surface of many termite gut Flagellates is colonized with a dense layer of bacteria, yet little is known about the evolutionary relationships of such ectosymbionts and their hosts. Here we investigated the molecular phylogenies of devescovinid Flagellates (Devescovina spp.) and their symbionts from a wide range of dry-wood termites (Kalotermitidae). From species-pure Flagellate suspensions isolated with micropipettes, we obtained SSU rRNA gene sequences of symbionts and host. Phylogenetic analysis showed that the Devescovina spp. present in many species of Kalotermitidae form a monophyletic group, which includes also the unique devescovinid Flagellate Caduceia versatilis. All members of this group were consistently associated with a distinct lineage of Bacteroidales, whose location on the cell surface was confirmed by fluorescence in situ hybridization. The well-supported congruence of the phylogenies of devescovinids and their ectosymbionts documents a strict cospeciation. In contrast, the endosymbionts of the same Flagellates ('Endomicrobia') were clearly polyphyletic and must have been acquired independently by horizontal transfer from other Flagellate lineages. Also the Bacteroidales ectosymbionts of Oxymonas Flagellates present in several Kalotermitidae belonged to several distantly related lines of descent, underscoring the general perception that the evolutionary history of Flagellate-bacteria symbioses in the termite gut is complex.
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strict cospeciation of devescovinid Flagellates and bacteroidales ectosymbionts in the gut of dry wood termites kalotermitidae
Environmental Microbiology, 2009Co-Authors: Mahesh Desai, Jurgen F H Strassert, Renate Radek, Katja Meuser, Horst Hertel, Wakako Ikedaohtsubo, Andreas BruneAbstract:The surface of many termite gut Flagellates is colonized with a dense layer of bacteria, yet little is known about the evolutionary relationships of such ectosymbionts and their hosts. Here we investigated the molecular phylogenies of devescovinid Flagellates (Devescovina spp.) and their symbionts from a wide range of dry-wood termites (Kalotermitidae). From species-pure Flagellate suspensions isolated with micropipettes, we obtained SSU rRNA gene sequences of symbionts and host. Phylogenetic analysis showed that the Devescovina spp. present in many species of Kalotermitidae form a monophyletic group, which includes also the unique devescovinid Flagellate Caduceia versatilis. All members of this group were consistently associated with a distinct lineage of Bacteroidales, whose location on the cell surface was confirmed by fluorescence in situ hybridization. The well-supported congruence of the phylogenies of devescovinids and their ectosymbionts documents a strict cospeciation. In contrast, the endosymbionts of the same Flagellates ('Endomicrobia') were clearly polyphyletic and must have been acquired independently by horizontal transfer from other Flagellate lineages. Also the Bacteroidales ectosymbionts of Oxymonas Flagellates present in several Kalotermitidae belonged to several distantly related lines of descent, underscoring the general perception that the evolutionary history of Flagellate-bacteria symbioses in the termite gut is complex.
Jurgen F H Strassert - One of the best experts on this subject based on the ideXlab platform.
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genome analysis of candidatus ancillula trichonymphae first representative of a deep branching clade of bifidobacteriales strengthens evidence for convergent evolution in Flagellate endosymbionts
Environmental Microbiology Reports, 2016Co-Authors: Jurgen F H Strassert, Aram Mikaelyan, Tanja Woyke, Andreas BruneAbstract:: The Flagellate protists in the hindgut of lower termites play an essential role in the digestion of lignocellulose. Most Flagellate species are associated with host-specific symbionts from various bacterial lineages, which typically lack cultured representatives. In this study, we analyzed the genome of 'Candidatus Ancillula trichonymphae', an endosymbiont of Trichonympha Flagellates from dry-wood termites, which represents a novel, family-level lineage of uncultured Actinobacteria encountered so far only in termite guts. The draft genome of 'Ca. A. trichonymphae' (ca. 1.48 Mbp; 95% complete) revealed a purely fermentative metabolism that is probably fueled by xylose, N-acetyl-glucosamine and glycerol 3-phosphate acquired from the Flagellate host. The absence of fructose bisphosphate aldolase and the presence of a complete gene set encoding the phosphoketolase pathway underscore the sister position of the new lineage to Bifidobacteriaceae. The preservation of the pathways for the assimilation of ammonia and the synthesis of 18 amino acids and several cofactors and vitamins suggests that 'Ca. A. trichonymphae' - like other endosymbionts of termite gut Flagellates - provides essential amino acids and vitamins to its host. Our findings corroborate the emerging concept that numerous lineages of unrelated Flagellate endosymbionts have convergently evolved to fill similar ecological niches.
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Genome analysis of ‘Candidatus Ancillula trichonymphae’, first representative of a deep‐branching clade of Bifidobacteriales, strengthens evidence for convergent evolution in Flagellate endosymbionts
Environmental microbiology reports, 2016Co-Authors: Jurgen F H Strassert, Aram Mikaelyan, Tanja Woyke, Andreas BruneAbstract:The Flagellate protists in the hindgut of lower termites play an essential role in the digestion of lignocellulose. Most Flagellate species are associated with host-specific symbionts from various bacterial lineages, which typically lack cultured representatives. In this study, we analyzed the genome of 'Candidatus Ancillula trichonymphae', an endosymbiont of Trichonympha Flagellates from dry-wood termites, which represents a novel, family-level lineage of uncultured Actinobacteria encountered so far only in termite guts. The draft genome of 'Ca. A. trichonymphae' (ca. 1.48 Mbp; 95% complete) revealed a purely fermentative metabolism that is probably fueled by xylose, N-acetyl-glucosamine and glycerol 3-phosphate acquired from the Flagellate host. The absence of fructose bisphosphate aldolase and the presence of a complete gene set encoding the phosphoketolase pathway underscore the sister position of the new lineage to Bifidobacteriaceae. The preservation of the pathways for the assimilation of ammonia and the synthesis of 18 amino acids and several cofactors and vitamins suggests that 'Ca. A. trichonymphae' - like other endosymbionts of termite gut Flagellates - provides essential amino acids and vitamins to its host. Our findings corroborate the emerging concept that numerous lineages of unrelated Flagellate endosymbionts have convergently evolved to fill similar ecological niches.
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Identification and localization of the multiple bacterial symbionts of the termite gut Flagellate Joenia annectens.
Microbiology (Reading England), 2010Co-Authors: Jurgen F H Strassert, Mahesh S Desai, Renate Radek, Andreas BruneAbstract:The hindgut of wood-feeding lower termites is densely colonized by a multitude of symbiotic micro-organisms. While it is well established that the eukaryotic Flagellates play a major role in the degradation of lignocellulose, much less is known about the identity and function of the prokaryotic symbionts associated with the Flagellates. Our ultrastructural investigations of the gut Flagellate Joenia annectens (from the termite Kalotermes flavicollis) revealed a dense colonization of this Flagellate by diverse ecto- and endosymbiotic bacteria. Phylogenetic analysis of the small-subunit rRNA gene sequences combined with fluorescence in situ hybridization allowed us to identify and localize the different morphotypes. Furthermore, we could show that K. flavicollis harbours two phylotypes of J. annectens that could be distinguished not only by their small-subunit rRNA gene sequences, but also by differences in their assemblages of bacterial symbionts. Each of the Flagellate populations hosted phylogenetically distinct ectosymbionts from the phylum Bacteroidetes, one of them closely related to the ectosymbionts of other termite gut Flagellates. A single phylotype of 'Endomicrobia' was consistently associated with only one of the host phylotypes, although not all individuals were colonized, corroborating that 'Endomicrobia' symbionts do not always cospeciate with their host lineages. Flagellates from both populations were loosely associated with a single phylotype of Spirochaetales attached to their cell surface in varying abundance. Current evidence for the involvement of Bacteroidales and 'Endomicrobia' symbionts in the nitrogen metabolism of the host Flagellate is discussed.
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Strict cospeciation of devescovinid Flagellates and Bacteroidales ectosymbionts in the gut of dry‐wood termites (Kalotermitidae)
Environmental microbiology, 2009Co-Authors: Mahesh Desai, Jurgen F H Strassert, Renate Radek, Wakako Ikeda-ohtsubo, Katja Meuser, Horst Hertel, Andreas BruneAbstract:The surface of many termite gut Flagellates is colonized with a dense layer of bacteria, yet little is known about the evolutionary relationships of such ectosymbionts and their hosts. Here we investigated the molecular phylogenies of devescovinid Flagellates (Devescovina spp.) and their symbionts from a wide range of dry-wood termites (Kalotermitidae). From species-pure Flagellate suspensions isolated with micropipettes, we obtained SSU rRNA gene sequences of symbionts and host. Phylogenetic analysis showed that the Devescovina spp. present in many species of Kalotermitidae form a monophyletic group, which includes also the unique devescovinid Flagellate Caduceia versatilis. All members of this group were consistently associated with a distinct lineage of Bacteroidales, whose location on the cell surface was confirmed by fluorescence in situ hybridization. The well-supported congruence of the phylogenies of devescovinids and their ectosymbionts documents a strict cospeciation. In contrast, the endosymbionts of the same Flagellates ('Endomicrobia') were clearly polyphyletic and must have been acquired independently by horizontal transfer from other Flagellate lineages. Also the Bacteroidales ectosymbionts of Oxymonas Flagellates present in several Kalotermitidae belonged to several distantly related lines of descent, underscoring the general perception that the evolutionary history of Flagellate-bacteria symbioses in the termite gut is complex.
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strict cospeciation of devescovinid Flagellates and bacteroidales ectosymbionts in the gut of dry wood termites kalotermitidae
Environmental Microbiology, 2009Co-Authors: Mahesh Desai, Jurgen F H Strassert, Renate Radek, Katja Meuser, Horst Hertel, Wakako Ikedaohtsubo, Andreas BruneAbstract:The surface of many termite gut Flagellates is colonized with a dense layer of bacteria, yet little is known about the evolutionary relationships of such ectosymbionts and their hosts. Here we investigated the molecular phylogenies of devescovinid Flagellates (Devescovina spp.) and their symbionts from a wide range of dry-wood termites (Kalotermitidae). From species-pure Flagellate suspensions isolated with micropipettes, we obtained SSU rRNA gene sequences of symbionts and host. Phylogenetic analysis showed that the Devescovina spp. present in many species of Kalotermitidae form a monophyletic group, which includes also the unique devescovinid Flagellate Caduceia versatilis. All members of this group were consistently associated with a distinct lineage of Bacteroidales, whose location on the cell surface was confirmed by fluorescence in situ hybridization. The well-supported congruence of the phylogenies of devescovinids and their ectosymbionts documents a strict cospeciation. In contrast, the endosymbionts of the same Flagellates ('Endomicrobia') were clearly polyphyletic and must have been acquired independently by horizontal transfer from other Flagellate lineages. Also the Bacteroidales ectosymbionts of Oxymonas Flagellates present in several Kalotermitidae belonged to several distantly related lines of descent, underscoring the general perception that the evolutionary history of Flagellate-bacteria symbioses in the termite gut is complex.
Regin Ronn - One of the best experts on this subject based on the ideXlab platform.
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Functional GacS in Pseudomonas DSS73 prevents digestion by Caenorhabditis elegans and protects the nematode from killer Flagellates
The ISME Journal, 2009Co-Authors: Lisa Bjornlund, Regin Ronn, Maria Péchy-tarr, Monika Maurhofer, Christoph Keel, Ole NybroeAbstract:The success of biocontrol bacteria in soil depends in part on their ability to escape predation. We explored the interactions between Pseudomonas strain DSS73 and two predators, the nematode Caenorhabditis elegans and the Flagellate Cercomonas sp. Growth of the nematode in liquid culture was arrested when it was feeding on DSS73 or a DSS73 mutant (DSS73-15C2) unable to produce the biosurfactant amphisin, whereas a regulatory gacS mutant (DSS73-12H8) that produces no exoproducts supported fast growth of the nematode. The Flagellate Cercomonas sp. was able to grow on all three strains. The biosurfactant-deficient DSS73 mutant caused severe dilation of the nematode gut. In three-species systems (DSS73, Cercomonas and C. elegans ), the nematodes fed on the Flagellates, which in turn grazed the bacteria and the number of C. elegans increased. The Flagellates Cercomonas sp. usually kill C. elegans. However, DSS73 protected the nematodes from Flagellate killing. Soil microcosms inoculated with six rhizobacteria and grazed by nematodes were colonized more efficiently by DSS73 than similar systems grazed by Flagellates or without grazers. In conclusion, our results suggest that C. elegans and DSS73 mutually increase the survival of one another in complex multispecies systems and that this interaction depends on the GacS regulator.
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david and goliath of the soil food web Flagellates that kill nematodes
Soil Biology & Biochemistry, 2008Co-Authors: Lisa Bjornlund, Regin RonnAbstract:Nematodes and Flagellates are important bacterial predators in soil and sediments. Generally, these organisms are considered to be competitors for bacterial food. We studied the interaction among Flagellates and nematodes using axenic liquid cultures amended with heat-killed bacteria as food and showed for the first time that a small and common soil Flagellate (Cercomonas sp.) is able to attack and kill the much larger nematode Caenorhabditis elegans. The killing process is not caused by soluble metabolites but requires direct contact between the Flagellate cells and the nematode surface and occurs rapidly (within a few hours) at high Flagellate density. At lower Flagellate density, adult nematodes sometimes avoid attachment of Flagellates, feed on them and become the dominant bacterial predator. Considering that bacterial feeders affect bacterial communities differently, and that one bacterial feeder can control the abundance of another, suggests a new perspective on how bacterial diversity and trophic interactions are linked in the soil food web.
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‘David and Goliath’ of the soil food web – Flagellates that kill nematodes
Soil Biology & Biochemistry, 2008Co-Authors: Lisa Bjornlund, Regin RonnAbstract:Nematodes and Flagellates are important bacterial predators in soil and sediments. Generally, these organisms are considered to be competitors for bacterial food. We studied the interaction among Flagellates and nematodes using axenic liquid cultures amended with heat-killed bacteria as food and showed for the first time that a small and common soil Flagellate (Cercomonas sp.) is able to attack and kill the much larger nematode Caenorhabditis elegans. The killing process is not caused by soluble metabolites but requires direct contact between the Flagellate cells and the nematode surface and occurs rapidly (within a few hours) at high Flagellate density. At lower Flagellate density, adult nematodes sometimes avoid attachment of Flagellates, feed on them and become the dominant bacterial predator. Considering that bacterial feeders affect bacterial communities differently, and that one bacterial feeder can control the abundance of another, suggests a new perspective on how bacterial diversity and trophic interactions are linked in the soil food web.
Christiane Lancelot - One of the best experts on this subject based on the ideXlab platform.
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characterization of phaeocystis globosa prymnesiophyceae the blooming species in the southern north sea
Journal of Sea Research, 2013Co-Authors: Véronique Rousseau, François Lantoine, Francisco Rodriguez, Florence Legall, Mariejosephe Chretiennotdinet, Christiane LancelotAbstract:Abstract Despite significant research dedicated to the marine genus Phaeocystis , which forms large blooms in the coastal waters of the Southern North Sea, some aspects of the taxonomy and biology of this species still suffer from a sketchy knowledge. It is currently admitted that P. globosa is the species that blooms in the Southern North Sea. This has however, never been confirmed by SSU rDNA sequencing which constitutes nowadays, together with the morphology of the haploid Flagellate, a reliable taxonomic criterion to distinguish between Phaeocystis species. Also, although the fine morphology of the haploid scaly Flagellate is well known, there is a lack of comparable and harmonized description of the other cell types, i.e. colonial cells and diploid Flagellates, previously identified within the Phaeocystis life cycle. In this study, we used SSU rDNA sequencing, light and electron scanning microscopy and flow cytometry to identify and characterize three cell types produced in controlled and reproducible manner from two strains of Phaeocystis isolated from the Belgian coastal zone. Our morphometry and sequencing data confirm unambiguously that P. globosa is the species that blooms in the Southern North Sea, but suggest in addition that both strains are representative of the original P. globosa Scherffel. Our study compares, for the first time since the species description, the fine morphometry and ploidy features of diploid colonial cells, diploid and haploid Flagellates originating from same strains, providing therefore unambiguous identification criteria for distinguishing them from each other. The diploid stage, colonial or Flagellated cell, is thus characterized by a naked surface, has a size range nearly twice that of the haploid Flagellate and do not produce the chitinous filaments specific of the haploid stage. Colonial cells lack flagella and haptonema but possess on their apical side two appendages, which elongate to form the flagella of the diploid Flagellate.
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Characterization of Phaeocystis globosa (Prymnesiophyceae), the blooming species in the Southern North Sea
Journal of Sea Research, 2013Co-Authors: Véronique Rousseau, François Lantoine, Francisco Rodriguez, Florence Legall, Marie-josèphe Chrétiennot-dinet, Christiane LancelotAbstract:Despite significant research dedicated to the marine genus Phaeocystis, which forms large blooms in the coastal waters of the Southern North Sea, some aspects of the taxonomy and biology of this species still suffer from a sketchy knowledge. It is currently admitted that P. globosa is the species that blooms in the Southern North Sea. This has however, never been confirmed by SSU rDNA sequencing which constitutes nowadays, together with the morphology of the haploid Flagellate, a reliable taxonomic criterion to distinguish between Phaeocystis species. Also, although the fine morphology of the haploid scaly Flagellate is Well known, there is a lack of comparable and harmonized description of the other cell types, i.e. colonial cells and diploid Flagellates, previously identified within the Phaeocystis life cycle. In this study, we used SSU rDNA sequencing, light and electron scanning microscopy and flow cytometry to identify and characterize three cell types produced in controlled and reproducible manner from two strains of Phaeocystis isolated from the Belgian coastal zone. Our morphometry and sequencing data confirm unambiguously that P. globosa is the species that blooms in the Southern North Sea, but suggest in addition that both strains are representative of the original P. globosa Scherffel. Our study compares, for the first time since the species description, the fine morphometry and ploidy features of diploid colonial cells, diploid and haploid Flagellates originating from same strains, providing therefore unambiguous identification criteria for distinguishing them from each other. The diploid stage, colonial or Flagellated cell, is thus characterized by a naked surface, has a size range nearly twice that of the haploid Flagellate and do not produce the chitinous filaments specific of the haploid stage. Colonial cells lack flagella and haptonema but possess on their apical side two appendages, which elongate to form the flagella of the diploid Flagellate. (C) 2012 Elsevier B.V. All rights reserved.
Lisa Bjornlund - One of the best experts on this subject based on the ideXlab platform.
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Functional GacS in Pseudomonas DSS73 prevents digestion by Caenorhabditis elegans and protects the nematode from killer Flagellates
The ISME Journal, 2009Co-Authors: Lisa Bjornlund, Regin Ronn, Maria Péchy-tarr, Monika Maurhofer, Christoph Keel, Ole NybroeAbstract:The success of biocontrol bacteria in soil depends in part on their ability to escape predation. We explored the interactions between Pseudomonas strain DSS73 and two predators, the nematode Caenorhabditis elegans and the Flagellate Cercomonas sp. Growth of the nematode in liquid culture was arrested when it was feeding on DSS73 or a DSS73 mutant (DSS73-15C2) unable to produce the biosurfactant amphisin, whereas a regulatory gacS mutant (DSS73-12H8) that produces no exoproducts supported fast growth of the nematode. The Flagellate Cercomonas sp. was able to grow on all three strains. The biosurfactant-deficient DSS73 mutant caused severe dilation of the nematode gut. In three-species systems (DSS73, Cercomonas and C. elegans ), the nematodes fed on the Flagellates, which in turn grazed the bacteria and the number of C. elegans increased. The Flagellates Cercomonas sp. usually kill C. elegans. However, DSS73 protected the nematodes from Flagellate killing. Soil microcosms inoculated with six rhizobacteria and grazed by nematodes were colonized more efficiently by DSS73 than similar systems grazed by Flagellates or without grazers. In conclusion, our results suggest that C. elegans and DSS73 mutually increase the survival of one another in complex multispecies systems and that this interaction depends on the GacS regulator.
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david and goliath of the soil food web Flagellates that kill nematodes
Soil Biology & Biochemistry, 2008Co-Authors: Lisa Bjornlund, Regin RonnAbstract:Nematodes and Flagellates are important bacterial predators in soil and sediments. Generally, these organisms are considered to be competitors for bacterial food. We studied the interaction among Flagellates and nematodes using axenic liquid cultures amended with heat-killed bacteria as food and showed for the first time that a small and common soil Flagellate (Cercomonas sp.) is able to attack and kill the much larger nematode Caenorhabditis elegans. The killing process is not caused by soluble metabolites but requires direct contact between the Flagellate cells and the nematode surface and occurs rapidly (within a few hours) at high Flagellate density. At lower Flagellate density, adult nematodes sometimes avoid attachment of Flagellates, feed on them and become the dominant bacterial predator. Considering that bacterial feeders affect bacterial communities differently, and that one bacterial feeder can control the abundance of another, suggests a new perspective on how bacterial diversity and trophic interactions are linked in the soil food web.
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‘David and Goliath’ of the soil food web – Flagellates that kill nematodes
Soil Biology & Biochemistry, 2008Co-Authors: Lisa Bjornlund, Regin RonnAbstract:Nematodes and Flagellates are important bacterial predators in soil and sediments. Generally, these organisms are considered to be competitors for bacterial food. We studied the interaction among Flagellates and nematodes using axenic liquid cultures amended with heat-killed bacteria as food and showed for the first time that a small and common soil Flagellate (Cercomonas sp.) is able to attack and kill the much larger nematode Caenorhabditis elegans. The killing process is not caused by soluble metabolites but requires direct contact between the Flagellate cells and the nematode surface and occurs rapidly (within a few hours) at high Flagellate density. At lower Flagellate density, adult nematodes sometimes avoid attachment of Flagellates, feed on them and become the dominant bacterial predator. Considering that bacterial feeders affect bacterial communities differently, and that one bacterial feeder can control the abundance of another, suggests a new perspective on how bacterial diversity and trophic interactions are linked in the soil food web.