• We seek to understand

    the role of microorganisms in Earth's nutrient cycles

    and as symbionts of other organisms

  • Cycling of carbon, nitrogen and sulfur

    affect the health of our planet

  • Ancient invaders -

    Bacterial symbionts of amoebae

    and the evolution of the intracellular lifestyle

  • The human microbiome -

    Our own social network of microbial friends

  • Marine symbioses:

    Listening in on conversations

    between animals and the microbes they can't live without

  • Single cell techniques offer new insights

    into the ecology of microbes

  • Apply for the DOME International PhD/PostDoc program

Dome News

Latest publications

Convergent patterns in the evolution of mealybug symbioses involving different intrabacterial symbionts

Mealybugs (Insecta: Hemiptera: Pseudococcidae) maintain obligatory relationships with bacterial symbionts, which provide essential nutrients to their insect hosts. Most pseudococcinae mealybugs harbor a unique symbiosis setup with enlarged betaproteobacterial symbionts (‘Candidatus Tremblaya princeps’) which themselves contain gammaproteobacterial symbionts. Here we investigated the symbiosis of the manna mealybug, Trabutina mannipara, using a metagenomic approach. Phylogenetic analyses revealed that the intrabacterial symbiont of T. mannipara represents a novel lineage within the Gammaproteobacteria, for which we propose the tentative name ‘Candidatus Trabutinella endobia’. Combining our results with previous data available for the nested symbiosis of the citrus mealybug, Planococcus citri, we show that synthesis of essential amino acids and vitamins, and translation related functions partition between the symbiotic partners in a highly similar manner in the two systems, despite the distinct evolutionary origin of the intrabacterial symbionts. Bacterial genes found in both mealybug genomes and complementing missing functions in both symbioses were likely integrated in ancestral mealybugs before T. mannipara and P. citri diversified. The high level of correspondence between two mealybug systems and their highly intertwined metabolic pathways are unprecedented. Our work contributes to a better understanding of the only known intracellular symbiosis between two bacteria and suggests that the evolution of this unique symbiosis included the replacement of intrabacterial symbionts in ancestral mealybugs.

Szabó G, Schulz F, Toenshoff ER, Volland JM, Finkel OM, Belkin S, Horn M
2016 - ISME J, in press

IMNGS: A comprehensive open resource of processed 16S rRNA microbial profiles for ecology and diversity studies.

The SRA (Sequence Read Archive) serves as primary depository for massive amounts of Next Generation Sequencing data, and currently host over 100,000 16S rRNA gene amplicon-based microbial profiles from various host habitats and environments. This number is increasing rapidly and there is a dire need for approaches to utilize this pool of knowledge. Here we created IMNGS (Integrated Microbial Next Generation Sequencing), an innovative platform that uniformly and systematically screens for and processes all prokaryotic 16S rRNA gene amplicon datasets available in SRA and uses them to build sample-specific sequence databases and OTU-based profiles. Via a web interface, this integrative sequence resource can easily be queried by users. We show examples of how the approach allows testing the ecological importance of specific microorganisms in different hosts or ecosystems, and performing targeted diversity studies for selected taxonomic groups. The platform also offers a complete workflow for de novo analysis of users' own raw 16S rRNA gene amplicon datasets for the sake of comparison with existing data. IMNGS can be accessed at www.imngs.org.

Lagkouvardos I, Joseph D, Kapfhammer M, Giritli S, Horn M, Haller D, Clavel T
2016 - Sci Rep, 33721

Free-living amoebae and their associated bacteria in Austrian cooling towers: a 1-year routine screening

Free-living amoebae (FLA) are widely spread in the environment and known to cause rare but often serious infections. Besides this, FLA may serve as vehicles for bacterial pathogens. In particular, Legionella pneumophila is known to replicate within FLA thereby also gaining enhanced infectivity. Cooling towers have been the source of outbreaks of Legionnaires' disease in the past and are thus usually screened for legionellae on a routine basis, not considering, however, FLA and their vehicle function. The aim of this study was to incorporate a screening system for host amoebae into a Legionella routine screening. A new real-time PCR-based screening system for various groups of FLA was established. Three cooling towers were screened every 2 weeks over the period of 1 year for FLA and Legionella spp., by culture and molecular methods in parallel. Altogether, 83.3 % of the cooling tower samples were positive for FLA, Acanthamoeba being the dominating genus. Interestingly, 69.7 % of the cooling tower samples were not suitable for the standard Legionella screening due to their high organic burden. In the remaining samples, positivity for Legionella spp. was 25 % by culture, but overall positivity was 50 % by molecular methods. Several amoebal isolates revealed intracellular bacteria.

Scheikl U, Tsao HF, Horn M, Indra A, Walochnik J
2016 - Parasitol Res, 115: 3365-74

Lecture series

The tale of the rumen microbiome – from interaction with the host to plasmid mediated gene mobility

Itzhak Mizrahi
Ben-Gurion University of the Negev, Israel
12:00 h
Hörsaal 2. (UZA I)

Importance of chemosymbiotic lucinid bivalves in seagrass community functioning

Matthijs van der Geest
Université de Montpellier
11:00 h
Seminar room DoME (2.309), UZA 1

The contribution of phage-mediated gene transfer to microbial genome evolution

Tal Dagan
Christian-Albrechts-Universität zu Kiel
13:30 h
Seminar room DoME (2.309)