Matthias Horn - Department of Microbial Ecology

	Prof. Dr. Matthias Horn Department für Mikrobielle Ökologie Wiener Ökologiezentrum Universität Wien Althanstr. 14 A-1090 Wien Austria phone: +43 1 4277 54393 fax: +43 1 4277 54389 email:

Bacterial endosymbionts of free-living amoebae The occurrence of bacterial endosymbionts in free-living amoebae has been known for decades, but their obligate intracellular lifestyle hampered their identification. Only recently, application of the full cycle rRNA approach including 16S rRNA gene sequencing and fluorescence in situ hybridization with 16S rRNA-targeted oligonucleotide probes assigned the symbionts of Acanthamoeba spp. and Hartmannella sp. to five different evolutionary lineages within the Proteobacteria, the Bacteroidetes, and the Chlamydiae, respectively. Several of these bacterial symbiont groups are most closely related to bacterial pathogens of humans, and it has been suggested that some of them should be considered potential emerging pathogens. Complete genome sequence analysis of a chlamydia-related symbiont of Acanthamoeba sp. showed that this endosymbiont uses similar mechanisms for interaction with its eukaryotic host cell as well known bacterial pathogens of humans. Furthermore, phylogenetic analysis suggested that these mechanisms have been invented by the ancestor of the amoeba symbionts in interplay with ancient unicellular eukaryotes. more ... Topics Environmental chlamydiae Nucleotide transport proteins in environmental chlamydiae Environmental chlamydia genomics and post-genomics Whole genome analysis of 'Candidatus Amoebophilus asiaticus'

Publications in peer reviewed journals Berry D, Horn M, Xi C, Raskin L. 2010. Mycobacterium avium infections of Acanthamoeba strains: host strain variability, grazing-acquired infections, and altered dynamics of inactivation with monochloramine Appl. Environ. Microbiol. , in press. Heinz E, Rockey DD, Montanaro J, Aistleitner K, Wagner M, Horn M. 2010. Inclusion membrane proteins of Protochlamydia amoebophila UWE25 reveal a conserved mechanism for host cell interaction among the Chlamydiae. J. Bacteriol. , in press. Haider S, Wagner M, Schmid MC, Sixt BS, Christian JG, Häcker G, Pichler P, Mechtler K, Müller A, Baranyi C, Toenshoff ER, Montanaro J, Horn M. 2010. Raman microspectroscopy reveals long-term extracellular activity of chlamydiae. Mol. Microbiol. 77: 687-700. PDF PUBMED Supporting information [PDF] Highlighted in Nature [PDF] Highlighted by Faculty of 1000 Schmitz-Esser S, Tischler P, Arnold R, Montanaro J, Wagner M, Rattei T, Horn M. 2010. The genome of the amoeba symbiont 'Candidatus Amoebophilus asiaticus' reveals common mechanisms for host cell interaction among amoeba-associated bacteria. J. Bacteriol. 192: 1045-1057. PDF PUBMED Supplementary material [PDF] Webster NS, Taylor MW, Behnam F, Lücker S, Rattei T, Whalan S, Horn M, Wagner M. 2010. Deep sequencing reveals exceptional diversity and modes of transmission for bacterial sponge symbionts. Environ. Microbiol. 12: 2070-2082. PDF PUBMED Supplementary material [PDF] Heinz E, Tischler P, Rattei T, Myers G, Wagner M, Horn M. 2009. Comprehensive in silico prediction and analysis of chlamydial outer membrane proteins reflects evolution and life style of the Chlamydiae. BMC Genomics 10: 634. PDF PUBMED Supporting information PDF] Arnold R, Brandmaier S, Kleine F, Tischler P, Heinz E, Behrens S, Niinikoski A, Mewes HW, Horn M, Rattei T. 2009. Sequence-based prediction of type III secreted proteins. PLoS Pathogens 5: e1000376. PDF PUBMED Ast M, Gruber A, Schmitz-Esser S, Neuhaus HE, Kroth PG, Horn M, Haferkamp I. 2009. Diatom plastids depend on nucleotide import from the cytosol. Proc. Natl. Acad. Sci. USA 106: 3621-3626. PDF PUBMED Supplementary online material [PDF] Rinke C, Schmitz-Esser S, Loy A, Horn M, Wagner M, Bright M. 2009. High genetic similarity between two geographically distinct strains of the sulfur-oxidizing symbiont 'Candidatus Thiobios zoothamnicoli' FEMS Microbiol. Ecol. 67: 229-41. PDF PUBMED Schmitz-Esser S, Toenshoff ER, Haider S, Heinz E, Hoenninger VM, Wagner M, Horn M. 2008. Diversity of bacterial endosymbionts of environmental Acanthamoeba isolates. Appl. Environ. Microbiol. 74: 5822-5831. PDF PUBMED Supplementary material (Table S1) Schmitz-Esser S, Haferkamp I, Knab S, Penz T, Ast M, Kohl C, Wagner M, Horn M. 2008. Lawsonia intracellularis encodes a functional rickettsia-like ATP/ADP translocase for host exploitation. J. Bacteriol. 190: 5746-5752. PDF PUBMED Loy A, Arnold R, Tischler P, Rattei T, Wagner M, Horn M. 2008. probeCheck - a central resource for evaluating oligonucleotide probe coverage and specificity. Environ. Microbiol. 10: 2894-2896. PDF PUBMED Horn M. 2008. Chlamydiae as symbionts in eukaryotes. Ann. Rev. Microbiol. 62: 113-131. PDF PUBMED Haider S, Collingro A, Walochnik J, Wagner M, Horn M. 2008. Chlamydia-like bacteria in respiratory samples of community-acquired pneumonia patients. FEMS Microbiol. Lett. 281: 198-202. PDF PUBMED Trentmann O, Horn M, van Scheltinga AC, Neuhaus HE, Haferkamp I. 2007. Enlightening energy parasitism by analysis of an ATP/ADP transporter from chlamydiae. PLoS Biol. 9: e231. PDF PUBMED Supporting information (Figs S1, S2) Heinz E, Kolarov I, Kästner C, Toenshoff ER, Wagner M, Horn M. 2007. An Acanthamoeba sp. containing two phylogenetically different bacterial endosymbionts Environ. Microbiol. 9: 1604-1609. PDF PUBMED Loy A, Maixner F, Wagner M, Horn M. 2007. probeBase - an online resource for rRNA-targeted oligonucleotide probes: new features 2007. Nucleic Acids Res. 35: D800-D804. PDF PUBMED Wagner M, Horn M. 2006. The Planctomycetes, Verrucomicrobia, Chlamydiae and sister phyla comprise a superphylum with biotechnological and medical relevance. Curr. Opin. Biotechnol. 17: 241-249. PDF PUBMED Strous M, Pelletier E, Mangenot S, Rattei T, Lehner A, Taylor MW, Horn M, Daims H, Bartol-Mave D, Wincker P, Barbe V, Fonknechten N, Vallenet D, Segurens B, Schenowitz-Truong C, Médigue C, Collingro A, Snel B, Dutilh BE, Op den Camp HJM, van der Drift C, Cirpus I, van de Pas-Schoonen KT, Harhangi HR, van Niftrik L, Schmid MC, Keltjens J, van de Vossenberg J, Kartal B, Meier H, Frishman D, Huynen MA, Mewes HW, Weissenbach J, Jetten MSM, Wagner M, Le Paslier D. 2006. Deciphering the evolution and metabolism of an anammox bacterium from a community genome. Nature 440: 790-794. PDF PUBMED Supplementary material [PDF] Haferkamp I, Schmitz-Esser S, Wagner M, Neigel N, Horn M, Neuhaus HE. 2006. Tapping the nucleotide pool of the host: novel nucleotide carrier proteins of Protochlamydia amoebophila. Mol. Microbiol. 60: 1534-1545. PDF PUBMED Supplemental Material Rinke C, Schmitz-Esser S, Stoecker K, Nussbaumer AD , Molnár DA, Vanura K, Wagner M, Horn M, Ott J, Bright M. 2006. Candidatus Thiobios zoothamnicoli, an ectosymbiotic bacterium covering the giant marine ciliate Zoothamnium niveum. Appl. Environ. Microbiol. 72: 2014-2021. PDF PUBMED Collingro A, Toenshoff ER, Taylor MW, Fritsche TR, Wagner M, Horn M. 2005. 'Candidatus Protochlamydia amoebophila', an endosymbiont of Acanthamoeba spp. Int. J. Syst. Evol. Microbiol. 55: 1863-1866. PDF PUBMED Everett KDE, Thao M, Horn M, Dyszynski GLE, Baumann P. 2005. Novel chlamydiae in whiteflies and scale insects: endosymbionts "Candidatus Fritschea bemisiae" strain Falk and "Candidatus Fritschea eriococci" strain Elm. Int. J. Syst. Evol. Microbiol. 55: 1581-1587. PDF PUBMED Collingro A, Poppert S, Heinz E, Schmitz-Esser S, Essig A, Schweikert M, Wagner M, Horn M. 2005. Recovery of an environmental chlamydia strain from activated sludge by co-cultivation with Acanthamoeba sp. Microbiology 151: 301-309. PDF PUBMED Molmeret M, Horn M, Wagner M, Santic M, Abu Kwaik Y. 2005. Amoeba as training grounds intracellular bacterial pathogens. Appl. Environ. Microbiol. 71: 20-28. PDF PUBMED Haferkamp I, Schmitz-Esser S, Linka N, Urbany C, Collingro A, Wagner M, Horn M, Neuhaus HE. 2004. A candidate NAD+ transporter in an intracellular bacterial symbiont related to chlamydiae. Nature 432: 622-625. PDF PUBMED Supplementary material [PDF] Fokin SI, Przybos E, Chivilev SM, Beier CL, Horn M, Skotarczak B, Wodecka B, Fujishima M. 2004. Morphological and molecular investigations of Paramecium schewiakoffi sp. nov. (Ciliophora, Oligohymenophorea) and current status of distribution and taxonomy of Paramecium spp. Europ. J. Protist. 40: 225-243. PDF Horn M, Wagner M. 2004. Bacterial endosymbionts of free-living amoebae. J. Euk. Microbiol. 51: 509-514. PDF PUBMED Horn M, Collingro A, Schmitz-Esser S, Beier CL, Purkhold U, Fartmann B, Brandt P, Nyakatura GJ, Droege M, Frishman D, Rattei T, Mewes HW, Wagner M. 2004. Illuminating the evolutionary history of chlamydiae. Science 304: 728-730. PDF PUBMED Supplementary material [PDF] Press release [PDF] Press release (German) [PDF] Movie showing environmental chlamydia UWE25 within its amoeba host cells. © AAAS/Science. [Windows Media Player] Movie showing environmental chlamydia UWE25 within its amoeba host cells. © AAAS/Science.[Quicktime] Environmental chlamydia genome database Fieseler L, Horn M, Wagner M, Hentschel U. 2004. Discovery of the novel candidate phylum "Poribacteria" in marine sponges. Appl. Environ. Microbiol. 70: 3724-3732. PDF PUBMED Collingro A, Walochnik J, Baranyi C, Michel R, Wagner M, Horn M, Aspöck H. 2004. Chlamydial endocytobionts of free-living amoebae differentially affect the growth rate of their hosts. Europ. J. Protist. 40: 57-60. PDF Schmitz-Esser S, Linka N, Collingro A, Beier CL, Neuhaus HE, Wagner M, Horn M. 2004. ATP/ADP translocases: A common feature of obligate intracellular amoebal symbionts related to chlamydiae and rickettsiae. J. Bacteriol. 186: 683-691. PDF PUBMED ARB/FastA database Hutter G, Schlagenhauf U, Valenza G, Horn M, Burgemeister S, Claus H, Vogel U. 2003. Molecular analysis of bacteria in periodontitis: evaluation of clone libraries, novel phylotypes and putative pathogens. Microbiology 149: 67-75. PDF PUBMED Adamczyk J, Hesselsoe M, Iversen N, Horn M, Lehner A, Nielsen PH, Schloter M, Roslev P, Wagner M. 2003. The isotope array, a new tool that employs substrate-mediated labeling of rRNA for determination of microbial community structure and function. Appl. Environ. Microbiol. 69: 6875-6887. PDF PUBMED Wagner M, Horn M, Daims H . 2003. Fluorescence in situ hybridisation for the identification and charcterisation of prokaryotes. Curr. Opin. Microbiol. 6: 302-309. PDF PUBMED Thoms C, Horn M, Wagner M, Hentschel U, Proksch P. 2003. Monitoring microbial diversity and natural products profiles of the sponge Aplysina cavernicola following transplantation. Marine Biology 142: 685-692. PDF Loy A, Horn M, Wagner M.. 2003. probeBase - an online resource for rRNA-targeted oligonucleotide probes. Nucleic Acids Res. 31: 514-516. PDF PUBMED Beier CL, Horn M, Michel R, Schweikert M, Gortz HD, Wagner M. 2002. The genus Caedibacter comprises endosymbionts of Paramecium spp. related to the Rickettsiales (Alphaproteobacteria) and to Francisella tularensis (Gammaproteobacteria). Appl. Environ. Microbiol. 68: 6043-6050. PDF PUBMED Hentschel U, Hopke J, Horn M, Friedrich AB, Wagner M, Hacker J, Moore BS. 2002. Molecular evidence for a uniform microbial community in sponges from different oceans. Appl. Environ. Microbiol. 68: 4431-4440. PDF PUBMED Poppert S, Essig A, Marre R, Wagner M, Horn M. 2002. Detection and differentiation of chlamydiae by fluorescence in situ hybridization (FISH). Appl. Environ. Microbiol. 68: 4081-4089. PDF PUBMED Skriwan C, Fajardo M, Hagele S, Horn M, Wagner M, Michel R, Krohne G, Schleicher M, Hacker J, Steinert M. 2002. Various bacterial pathogens and symbionts infect the amoeba Dictyostelium discoideum. Int. J. Med. Microbiol. 291: 615-624. PDF PUBMED Horn M, Fritsche TR, Linner T, Gautom RK, Harzenetter MD, Wagner M. 2002. Obligate bacterial endosymbionts of Acanthamoeba spp. related to the ß-subclass of Proteobacteria: proposal of 'Candidatus Procabacter acanthamoebae' gen. nov., sp. nov. Int. J. Syst. Evol. Microbiol. 52: 599–605. PDF PUBMED Horn M, Wagner M. 2001. Evidence for additional genus-level diversity of Chlamydiales in the environment. FEMS Microbiol. Lett. 204: 71-74. PDF PUBMED Horn M, Harzenetter MD, Linner T, Schmid EN, Muller KD, Michel R, Wagner M. 2001. Members of the Cytophaga-Flavobacterium-Bacteroides phylum as intracellular bacteria of acanthamoebae: proposal of 'Candidatus Amoebophilus asiaticus'. Environ. Microbiol. 3: 440-449. PDF PUBMED Kanagawa T, Kamagata Y, Aruga S, Kohno T, Horn M, Wagner M. 2000. Phylogenetic relationships of filamentous bacteria of the Eikelboom Type 021N isolated from bulking activated sludge and development of an encompassing set of 021N-specific oligonucleotide probes. Appl. Environ. Microbiol. 66: 5043-5052. PDF PUBMED Fritsche TR, Horn M, Wagner M, Herwig RP, Schleifer KH, Gautom RK. 2000. Phylogenetic diversity among geographically dispersed Chlamydiales endosymbionts recovered from clinical and environmental isolates of Acanthamoeba spp. Appl. Environ. Microbiol. 66: 2613-2619. PDF PUBMED Horn M, Wagner M, Muller KD, Schmid EN, Fritsche TR, Schleifer KH, Michel R. 2000. Neochlamydia hartmannellae gen. nov. sp. nov. (Parachlamydiaceae), an endoparasite of the amoeba Hartmannella vermiformis. Microbiology 146: 1231-1239. PDF PUBMED Horn M, Fritsche TR, Gautom RK, Schleifer KH, Wagner M. 1999. Novel Bacterial Endosymbionts of Acanthamoeba isolates related to the Paramecium Symbiont Caedibacter caryophilus. Environ. Microbiol. 1: 357-367. PDF PUBMED Fritsche TR, Horn M, Seyedirashti S, Gautom RK, Schleifer KH, Wagner M. 1999. In situ detection of novel bacterial endosymbionts of Acanthamoeba spp. phylogenetically related to members of the Rickettsiales. Appl. Environ. Microbiol. 65: 206-212. PDF PUBMED Book chapters and other publications Horn M, Collingro A, Schmitz-Esser S, Wagner M. 2006. Environmental chlamydia genomics. In Chlamydia: genomics and pathogenesis, pp. 25-44. (Bavoil PM, Wyrick PB, ed.). Horizon Scientific Press, Norfolk. PDF Order information Horn M, Wagner M. 2005. Die Evolution der Chlamydien - Einblicke in die Entwicklungsgeschichte bedeutender bakterieller Krankheitserreger. GenomXpress Sonderausgabe 3: 50. Collingro A, Horn M. 2005. Chlamydien als Symbionten frei lebender Amöben. BioSpektrum 4: 393-394. Collingro A, Horn, M, Wagner M. 2004. Die Evolution der Chlamydien - Einblicke in die Entwicklungsgeschichte bedeutender bakterieller Krankheitserreger aus einer genomischen Perspektive. GenomXPress 2: 13-14. Hentschel U, Fieseler L, Wehrl M, Gernert C, Steinert M, Hacker J, Horn M. 2003. Microbial diversity of sponges. In Marine Molecular Biotechnology., pp. 59-88. (Müller WEG, ed.). Springer-Verlag, Berlin Heidelberg. PDF Hu J, Limaye AP, Fritsche TR, Horn M, Juretschko S, Gautom R. 2001. Direct detection of Legionellae in respiratory tract specimens using fluorescence in situ hybridization. In Legionella., pp. 221-224. (Marre R, ed.). Amer. Soc. Microbiol. Press, Washington, D.C.. Horn M, Wagner M. 2001. Dasein im Verborgenem. Bakterien, die in Acanthamöben leben. Biologie in unserer Zeit 31: 160-168. Schleifer KH, Horn M. 2000. Mikrobielle Vielfalt. Biologen heute 452: 1-5.

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