Prof. Dr. Dr. h. c. Michael Wagner
We love to study the hidden world of microbes and are particularly excited to investigate microbes directly in their natural environment. My team has two major research foci. We are interested in all aspects of the biology of ammonia-oxidizing archaea and bacteria and we continuously develop innovative single cell tools for investigating the identity and function of individual microbial cells within their natural habitats.
Ammonia-oxidizing archaea and bacteria
Ammonia oxidation is a key step in the biogeochemical nitrogen cycle and is producing nitrite for nitrite-oxidizing or nitrite-reducing microbes. This process is of major importance for nitrogen cycling in the environment and a central step in efficient wastewater treatment, but also strongly contributes to fertilizer loss in agriculture. Microbial ammonia oxidation has been intensively investigated since the pioneering work of Sergeij Winogradsky more than a century ago, but until recently only two bacterial groups within the Proteobacteria were known to aerobically thrive on ammonia as substrate for growth. During the last decade it became apparent that members of the archaeal phylum Thaumarchaeota are also capable of ammonia-oxidation for energy generation. My lab investigates the evolution, physiology and ecology of ammonia-oxidizing microbes in the framework of the ERC Advanced Grant project Nitricare. Our efforts in this field range from pure culture physiological studies to advanced single cell genomics approaches.
- We have obtained an enrichment of the ammonia-oxidizing thaumarchaeote Nitrososphaera gargensis and have analyzed this moderately thermophilic strain genomically (Spang et al., 2012). Interestingly it produces F420 and has a more flexible central carbon metabolism than expected. In the meantime we succeeded in obtaining a pure culture of this strain.
Previously working on this theme: Roland Hatzenpichler, Alexander Galushko, Márton Palatinszky
- We recently demonstrated that N. gargensis is the first known organisms that can grow on cyanate as sole source of energy and reductant. While other known ammonia-oxidizers lack this capability, all genome-sequenced nitrite-oxidizers possess a cyanase for conversion of cyanate to ammonium and CO2. We postulate that cyanate-positive nitrite-oxidizers can team up with cyanase negative ammonia oxidizers to enable growth of both partners on cyanate. Together with the group of Holger Daims, co-culture studies are currently performed to experimentally demonstrate this new type of interaction between nitrifiers via reciprocal feeding. Furthermore, we recently launched a new project in order to determine the importance of cyanate conversion in terrestrial and aquatic environments.
Now working on this theme: Ping Han, Katharina Kitzinger, Mario Pogoda, Maria Mooshammer (previously Alexander Galushko, Márton Palatinszky)
Collaboration partners: Nico Jehmlich, Martin van Bergen (UFZ, Leipzig, Germany)
- In collaboration with Yujie Men and Kathrin Fenner from the EAWAG in Switzerland we investigate micropollutant degradation by ammonia-oxidizing bacteria and archaea.
Now working on this theme: Ping Han
- We have shown that close relatives of N. gargensis in an industrial wastewater treatment plant encode and express amoA, but obtain their energy from substrates other than ammonia (Mussman et al. 2010). Using single-cell, cultivation and meta-omic techniques we are characterizing thauamarchaeotes in various municipal and industrial wastewater treatment plants to better understand (i) their contribution to nitrification in these systems and (ii) their physiological versatility.
- We investigate the diversity of ammonia-oxidizing microbes in wastewater treatment plants by single microcolony isotope labeling, subsequent Raman sorting and single microcolony genomics. As closely attached interaction partners of the ammonia-oxidizers are also sorted, this approach does not only reveal genomic information of the active members of this guild, but also enables genomic characterization of nitrifier interaction partners in the wilderness. This project is supported by an ETOP- and a CSP-project of the JGI and is performed in collaboration with Tanja Woyke.
In order to establish an encompassing framework for comparative genomics of sorted ammonia oxidizers, we are currently sequencing the genomes of many cultures strains of this guild. This project is performed in collaboration with Andreas Pommerening-Röser (University of Hanburg, Germany) and Tanja Woyke from the JGI (Walnut Creek, USA).
- My group has a long-standing interest in the interaction of marine sponges with their microbial symbionts (Hentschel et al. 2002, Taylor et al. 2007, Webster et al. 2010). Using Ianthella basta from the Great Barrier Reef in Australia as model sponge we investigate by metagenomics, metaproteomics, and isotope labeling techniques the physiological interaction between this sponge and its symbionts. In contrast to many other sponges, I. basta harbors only three abundant symbionts and one of them is an ammonia-oxidizing member of the Thaumarchaeotes. This project has been supported by the Marie Curie International Training Networks Symbiomics.
Now working on this theme: Florian Moeller
Collaboration partners: Nicole Webster (AIMS, Australia), Thomas Schweder, Stephanie Markert (University of Greifswald, Germany), Mads Albertsen, Per Nielsen (Aalborg University, Denmark), Thomas Rattei, and Andreas Richter (University of Vienna, Austria)
Selected publications on this theme:
Hatzenpichler R, Lebedeva EV, Spieck E, Stoecker K, Richter A, Daims H, Wagner M. 2008. A moderately thermophilic ammonia-oxidizing crenarchaeote from a hot spring. Proc. Natl. Acad. Sci. USA 105: 2134-2139.
Mußmann M, Brito I, Pitcher A, Damsté JSS, Hatzenpichler R, Richter A, Nielsen JL, Nielsen PH, Müller A, Daims H, Wagner M, Head IM. 2011. Thaumarchaeotes abundant in refinery nitrifying sludges express amoA but are not obligate autotrophic ammonia oxidizers. Proc. Natl. Acad. Sci. USA 108: 16771-16776.
Pester M, Schleper C, Wagner M. 2011. The Thaumarchaeota: An Emerging View of their Phylogeny and Ecophysiology. Curr. Opin. Microbiol. 14: 300-306.
Pester M, Rattei T, Flechl S, Gröngröft A, Richter A, Overmann J, Reinhold-Hurek B, Loy A, Wagner M. 2012. amoA-based consensus phylogeny of ammonia-oxidizing archaea and deep sequencing of amoA genes from soils of four different geographic regions. Environ. Microbiol. 14: 525-539.
Spang A, Poehlein A, Offre P, Zumbrägel S, Haider S, Rychlik N, Nowka B, Schmeisser C, Lebedeva EV, Rattei T, Böhm C, Schmid M, Galushko A, Hatzenpichler R, Weinmaier T, Daniel R, Schleper C, Spieck E, Streit W, Wagner M. 2012. The genome of the ammonia-oxidizing Candidatus Nitrososphaera gargensis: Insights into metabolic versatility and environmental adaptations. Environ. Microbiol. 14: 3122-45.
What are they doing there? New single cell tools for functional analyses of microbes in their ecosystems
My team has a long-standing interest in the development of methods for functional analyses of microbes within complex microbial communities (Wagner et al. 1998; Adamczyk et al. 2003). For example, we pioneered the combination of FISH and microautoradiography (Lee et al., 1999) that enabled microbial ecologists for the first time to observe substrate utilization of uncultured individual microbial cells in their natural habitat. Currently, second generation methods for single cell isotope probing mainly using 13C-, 15N and 2H-labeled compounds are developed and combined with single cell genomics approaches. For the detection of isotopes within microbial cells we use nanometer-scale secondary ion mass spectrometry (NanoSIMS) and Raman microspectroscopy.
NanoSIMS. NanoSIMS imaging is perfectly suited to measure and visualize the distribution of virtually any elements and their stable isotopes of interest in microbial cells. We run in our team since 2010 a CAMECA NanoSIMS 50L (the only NanoSIMS instrument in Austria) that offers a spatial resolution for element/ isotope mapping down to 50 nm and thus even allows highly sensitive analyses at the sub-cellular level. The NanoSIMS 50L is equipped with Cs+ and O- primary ion sources, an electron gun for analysis of insulating samples, a secondary electron detector, and a magnetic sector mass analyser with a large version of the magnet and a multi-collection system of 7 detectors all equipped with Faraday cups and electron multiplier detectors. In microbial ecology we combine NanoSIMS with stable isotope probing and cell identification techniques such as fluorescence in situ hybridization to obtain previously inaccessible information about the functional role of microorganisms in their environment. Using this approach, previously unrecognized physiological properties of bacteria and archaea thriving in soils, microbial mats, deep groundwater samples and within corals as well as mice guts could be deciphered.
Now working on this theme: Arno Schintlmeister
Selected publications on this theme:
Berry D, Stecher B, Schintlmeister A, Reichert J, Brugiroux S, Wildd B, Wanek W, Richter A, Rauch I, Decker T, Loy A, Wagner M. 2013. Host-compound foraging by intestinal microbiota revealed by single-cell stable isotope probing. Proc. Natl. Acad. Sci. USA 110: 4720-4725.
Koch H, Galushko A, Albertsen M, Schintlmeister A, Gruber-Dorninger C, Lücker S, Pelletier E, Le Paslier D, Spieck E, Richter A, Nielsen PH, Wagner M, Daims H. 2014. Growth of nitrite-oxidizing bacteria by aerobic hydrogen oxidation. Science 345: 1052-1054.
Woebken D, Burow L, Behnam F, Mayali X, Schintlmeister A, Fleming E, Prufert-Bebout L, Singer S, López Cortés A, Hoehler T, Pett-Ridge J, Spormann A, Wagner M, Weber P, Bebout B. 2015. Revisiting N2 fixation in Guerrero Negro intertidal microbial mats with a functional single-cell approach. ISME J. 9: 485-496.
Raman microspectroscopy. In my lab we develop new confocal Raman microspectrocopy-based methods for functional analyses of microbes in complex ecosystems. Raman microspectroscopy has single cell resolution and is nondestructive. It enables us to record within seconds a chemical fingerprint of a microbial cell that reveals the presence of defined storage compounds (Milucka et al., 2012), cytochromes and pigments. Raman microspectroscopy can be directly combined with FISH (Huang et al. 2007) for simultaneous identification of the analyzed microbes. Furthermore, Raman microspectroscopy can be applied to detect and quantify the incorporation of stable isotopes in individual microbial cells and is the most straightforward technique to perform single cell stable isotope probing experiments with complex microbial communities. In addition to detection of 13C-labeled cells (Huang et al. 2007), we recently applied Raman microspectroscopy for tracking the incorporation of deuterium from heavy water in microbial cells in order to measure their activity (Berry et al. 2015). Excitingly, Raman spectra of microbial cells can also be recorded while holding them with an optical tweezer. Subsequently, cells can then be sorted according to their Raman spectrum for single cell genomics or cultivation (Berry et al. 2015). We are currently developing in collaboration with Roman Stocker (MIT, USA) a microfluidics chamber for high-throughput sorting of microbial cells according to their Raman spectra for directly combining single cell stable isotope probing and single cell genomics.
At DOME two cutting edge confocal Raman microspectrometer are available. A LabRAM HR800 and an HR Evolution (both from Horiba Jobin-Yvon). Availabe lasers are a 532-nm neodymium-yttrium aluminium garnet laser, a pulsed 532-nm laser, a 785 nm laser, and a 1,064-nm laser for optical trapping.
Selected publications on this theme:
Berry D, Mader E, Lee TK, Woebken D, Wang Y, Zhu D, Palatinszky M, Schintlmeister A, Schmid MC, Hanson BT, Shterzer , Mizrahi I, Rauch I, Decker T, Bocklitz T, Popp J, Gibson CM, Fowler PW, Huang WE, Wagner M. 2015. Tracking heavy water (D2O) incorporation for identifying and sorting active microbial cells. Proc. Natl. Acad. Sci. USA Jan 13;112(2):E194-203.
Huang WE, Stoecker K, Griffiths R, Newbold L, Daims H, Whiteley AS, Wagner M. 2007. Raman-FISH: Combining stable-isotope Raman spectroscopy and fluorescence in situ hybridization for the single cell analysis of identity and function. Environ. Microbiol. 9: 1878-1889.
Milucka J, Ferdelman TG, Polerecky L, Franzke D, Wegener G, Schmid M, Lieberwirth I, Wagner M, Widdel F, Kuypers MMM. 2012. Zero-valent sulphur is a key intermediate in marine methane oxidation. Nature 491: 541-546.
Joining the team
Information on open research positions can be found here. If you are interested in joining our team with your own fellowship, please check out our PhD & postdoc program and get in touch with Michael for details.