Christopher J Sedlacek

Christopher J Sedlacek
University of Vienna | UniWien · Department of Microbiology and Ecosystem Science, Division of Microbial Ecology

PhD

About

27
Publications
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Introduction
I'm currently a Postdoctoral Researcher within the Division of Microbial Ecology (DOME) at the University of Vienna in the research group of Dr. Michael Wagner. My research focuses on the ecophysiological characterization of environmentally relevant microorganisms involved in the global nitrogen cycle. Currently, I utilize a wide range of culture dependent and molecular methods to investigate the cellular kinetics, growth adaptations, and stress response of nitrifying microorganisms. Other ongoing research interests include microbe-microbe interactions and genomic comparisons. My most recent publication is: 'Kinetic analysis of a complete nitrifier reveals an oligotrophic lifestyle.' Thank you for your interest and please feel free to contact me at sedlacek@microbial-ecology.net

Publications

Publications (27)
Article
Full-text available
Importance: Aerobic ammonia oxidizing microorganisms play an important role in the global nitrogen cycle, converting ammonia to nitrite. In their natural environment they coexist and interact with nitrite oxidizers, which convert nitrite to nitrate, and with heterotrophic microorganisms. The presence of nitrite oxidizers and heterotrophic bacteria...
Article
Full-text available
Nitrosomonas sp. Is79 is a chemolithoautotrophic ammonia-oxidizing bacterium that belongs to the family Nitrosomonadaceae within the phylum Proteobacteria. Ammonia oxidation is the first step of nitrification, an important process in the global nitrogen cycle ultimately resulting in the production of nitrate. Nitrosomonas sp. Is79 is an ammonia oxi...
Article
Full-text available
The resistance and resilience provided by functional redundancy, a common feature of microbial communities, is not always advantageous. An example is nitrite oxidation in partial nitritation-anammox (PNA) reactors designed for nitrogen removal in wastewater treatment, where suppression of nitrite oxidizers like Nitrospira is sought. In these ecosys...
Preprint
Full-text available
The resistance and resilience provided by functional redundancy, a common feature of microbial communities, is not always advantageous. An example is nitrite oxidation in partial nitritation-anammox (PNA) reactors during wastewater treatment, where suppression of nitrite oxidizers like Nitrospira is sought. In these ecosystems, biofilms provide mic...
Article
The discovery of anaerobic ammonia-oxidizing bacteria (Anammox) and, more recently, aerobic bacteria common in many natural and engineered systems that oxidize ammonia completely to nitrate (Comammox) have significantly altered our understanding of the global nitrogen cycle. A high affinity for ammonia (Km(app),NH3 ≈ 63nM) and oxygen place Comammox...
Article
Full-text available
Nitrification, the oxidation of ammonia to nitrate, is an essential process in the biogeochemical nitrogen cycle. The first step of nitrification, ammonia oxidation, is performed by three, often co-occurring guilds of chemolithoautotrophs: ammonia-oxidizing bacteria (AOB), archaea (AOA), and complete ammonia oxidizers (comammox). Substrate kinetics...
Preprint
Full-text available
Nitrification, the oxidation of ammonia to nitrate, is an essential process in the biogeochemical nitrogen cycle. The first step of nitrification, ammonia oxidation, is performed by three, often co-occurring guilds of chemolithoautotrophs: ammonia-oxidizing bacteria (AOB), archaea (AOA), and complete ammonia oxidizers (comammox). Substrate kinetics...
Preprint
Full-text available
The discovery of complete aerobic and anaerobic ammonia-oxidizing bacteria (Comammox and Anammox) significantly altered our understanding of the global nitrogen cycle. A high affinity for ammonia ( K m(app),NH3 ≈ 63nM) and oxygen place the first described isolate, Comammox Nitrospira inopinata in the same trophic category as organisms such as some...
Article
Full-text available
It has been almost 150 years since Jean-Jacques Schloesing and Achille Müntz discovered that the process of nitrification, the oxidation of ammonium to nitrate, is a biological process carried out by microorganisms. In the following 15 years, numerous researchers independently contributed paradigm shifting discoveries that formed the foundation of...
Article
Full-text available
Fertilizers are added to crops in order to produce enough food to feed the human population. Fertilizers provide crops with nutrients like potassium, phosphorus, and nitrogen, which allow crops to grow bigger, faster, and to produce more food. Nitrogen in particular is an essential nutrient for the growth of every organism on Earth. Nitrogen is all...
Article
Full-text available
Nitrification is a ubiquitous microbially mediated process in the environment and an essential process in engineered systems such as wastewater and drinking water treatment plants. However, nitrification also contributes to fertilizer loss from agricultural environments, increasing the eutrophication of downstream aquatic ecosystems, and produces t...
Article
Full-text available
Ammonia-oxidizing bacteria (AOB) within the genus Nitrosomonas perform the first step in nitrification, ammonia oxidation, and are found in diverse aquatic and terrestrial environments. Nitrosomonas AOB were grouped into six defined clusters, which correlate with physiological characteristics that contribute to adaptations to a variety of abiotic e...
Preprint
Full-text available
Classifying taxa, including those that have not previously been identified, is a key task in characterizing the microbial communities of under-described habitats, including permanently ice-covered lakes in the dry valleys of the Antarctic. Current supervised phylogeny-based methods fall short on recognizing species assembled from metagenomic datase...
Preprint
Full-text available
Ammonia-oxidizing microorganisms perform the first step of nitrification, the oxidation of ammonia to nitrite. The bacterium Nitrosomonas europaea is the best characterized ammonia oxidizer to date. Exposure to hypoxic conditions has a profound effect on the physiology of N. europaea , e.g. by inducing nitrifier denitrification, resulting in increa...
Article
Full-text available
Nitrous oxide (N2O) and nitric oxide (NO) are atmospheric trace gases that contribute to climate change and affect stratospheric and ground-level ozone concentrations. Ammonia oxidizing bacteria (AOB) and archaea (AOA) are key players in the nitrogen cycle and major producers of N2O and NO globally. However, nothing is known about N2O and NO produc...
Article
Full-text available
Nitrification is a key process of the biogeochemical nitrogen cycle and of biological wastewater treatment. The second step, nitrite oxidation to nitrate, is catalyzed by phylogenetically diverse, chemolithoautotrophic nitrite-oxidizing bacteria (NOB). Uncultured NOB from the genus "Candidatus Nitrotoga" are widespread in natural and engineered eco...
Article
Full-text available
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...
Preprint
Ammonia-oxidizing archaea (AOA) within the phylum Thaumarchaea 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 Thaumarchaea in terrestrial high-temperature habitats, only one enrichment cultu...
Article
paragraph Nitrification, the oxidation of ammonia (NH3) via nitrite (NO2⁻) to nitrate (NO3⁻), is a key process of the biogeochemical nitrogen cycle. For decades, ammonia and nitrite oxidation were thought to be separately catalyzed by ammonia-oxidizing bacteria (AOB) and archaea (AOA), and by nitrite-oxidizing bacteria (NOB). The recent discovery o...

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