• Hunting for microbes since 2003

  • 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

  • The human microbiome -

    Our own social network of microbial friends

  • Ancient invaders -

    Bacterial symbionts of amoebae

    and the evolution of the intracellular lifestyle

  • 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

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Dome News

Latest publications

Ecology and biotechnological potential of bacteria belonging to the Pseudovibrio genus.

Bacteria belonging to the genushave been isolated worldwide from a great variety of marines sources as both free living and host associated. So far, the available data depict a group of Alphaproteobacteria characterized by a versatile metabolism, which allows them to use a variety of substrates to meet their carbon, nitrogen, sulfur, and phosphorous requirements. Additionally,-related bacteria have been shown to proliferate under extreme oligotrophic conditions, tolerate high heavy metal concentrations, and metabolize potentially toxic compounds. Considering this versatility, it is not surprising that they have been detected from temperate to tropical regions, and are often the most abundant isolates obtained from marine invertebrates. Such association is particularly recurrent with marine sponges and corals, animals that play a key role in benthic marine systems. The data so far available indicate that these bacteria are mainly beneficial to the host, and besides being involved in major nutrient cycles, they could provide the host with both vitamins/cofactors and protection from potential pathogens via the synthesis of antimicrobial secondary metabolites. In fact, the biosynthetic abilities ofhave been emerging in recent years, and both genomic and analytic studies underlined how these organisms promise novel natural products of biotechnological value.

Romano S
2018 - Appl. Environ. Microbiol., in press

Coexistence of novel gammaproteobacterial and Arsenophonus symbionts in the scale insect Greenisca brachypodii (Hemiptera, Coccomorpha: Eriococcidae).

Scale insects are commonly associated with obligate, intracellular microorganisms which play important roles in complementing their hosts with essential nutrients. Here we characterized the symbiotic system of Greenisca brachypodii, a member of the family Eriococcidae. Histological and ultrastructural analyses have indicated that G. brachypodii is stably associated with coccoid and rod-shaped bacteria. Phylogenetic analyses have revealed that the coccoid bacteria represent a sister group to the secondary symbiont of the mealybug Melanococcus albizziae, whereas the rod-shaped symbionts are close relatives of Arsenophonus symbionts in insects - to our knowledge, this is the first report of the presence of Arsenophonus bacterium in scale insects. As a comparison of 16S and 23S rRNA genes sequences of the G. brachypodii coccoid symbiont with other gammaprotebacterial sequences showed only low similarity (∼90%), we propose the name 'Candidatus Kotejella greeniscae' for its tentative classification. Both symbionts are transovarially transmitted from one generation to the next. The infection takes place in the neck region of the ovariole. The bacteria migrate between follicular cells, as well as through the cytoplasm of those cells to the perivitelline space, where they form a characteristic 'symbiont ball'. Our findings provide evidence for a polyphyletic origin of symbionts of Eriococcidae. This article is protected by copyright. All rights reserved.

Michalik A, Schulz F, Michalik K, Wascher F, Horn M, Szklarzewicz T
2018 - Environ. Microbiol., in press

Cultivation and genomic analysis of “Candidatus Nitrosocaldus islandicus”, an obligately thermophilic, ammonia-oxidizing thaumarchaeon from a hot spring biofilm in Graendalur valley, Iceland

Ammonia-oxidizing archaea (AOA) within the phylum Thaumarchaeota are the only known aerobic ammonia oxidizers in geothermal environments. Although molecular data indicate the presence of phylogenetically diverse AOA from the Nitrosocaldus clade, group 1.1b and group 1.1a Thaumarchaeota in terrestrial high-temperature habitats, only one enrichment culture of an AOA thriving above 50 °C has been reported and functionally analyzed. In this study, we physiologically and genomically characterized a newly discovered thaumarchaeon from the deep-branching Nitrosocaldaceae family of which we have obtained a high (~85 %) enrichment from biofilm of an Icelandic hot spring (73 °C). This AOA, which we provisionally refer to as “Candidatus Nitrosocaldus islandicus”, is an obligately thermophilic, aerobic chemolithoautotrophic ammonia oxidizer, which stoichiometricall converts ammonia to nitrite at temperatures between 50 °C and 70 °C. “Ca. N. islandicus” encodes the expected repertoire of enzymes proposed to be required for archaeal ammonia oxidation, but unexpectedly lacks a nirK gene and also possesses no identifiable other enzyme for nitric oxide (NO) generation*. Nevertheless, ammonia oxidation by this AOA appears to be NO-dependent as “Ca. N. islandicus” is, like all other tested AOA, inhibited by the addition of an NO scavenger. Furthermore, comparative genomics revealed that “Ca. N. islandicus” has the potential for aromatic amino acid fermentation as its genome encodes an indolepyruvate oxidoreductase (iorAB) as well as a type 3b hydrogenase, which are not present in any other sequenced AOA. A further surprising genomic feature of this thermophilic ammonia oxidizer is the absence of DNA polymerase D genes – one of the predominant replicative DNA polymerases in all other ammonia-oxidizing Thaumarchaeota. Collectively, our findings suggest that metabolic versatility and DNA replication might differ substantially between obligately thermophilic and other AOA.

Daebeler A, Herbold C, Vierheilig J, Sedlacek CJ, Pjevac P, Albertsen M, Kirkegaard RH, De La Torre JR, Daims H, Wagner M
2018 - Front Microbiol, 9: 193

Lecture series

Microbiomics of the human gut and the ocean

Peer Bork
Structural and Computational Biology Unit, EMBL Heidelberg
24.11.2017
09:30 h
Hörsaal 2, UZA 1, Althanstr. 14, 1090 Wien

The rapidly expanding universe of giant viruses

Chantal Abergel
Centre National de la Recherche Scientifique & Aix-Marseille University
29.06.2017
16:30 h
Hörsaal 2, UZA 1, Althanstr. 14, 1090 Wien

The importance of growing slowly: roles for redox-active "antibiotics" in microbial survival and development

Dianne Newman
California Institute of Technology
24.05.2017
14:00 h
Hörsaal 2, UZA1, Althanstr. 14, 1090 Wien