Biology subjects

Pribasnig, T.

Publications and source records attributed to Pribasnig, T..

4 recordsLinked to original sources

bioRxiv2026

Biofilm Lifestyle Drives Ecophysiological Niche Expansion in an Archaeal Soil Nitrifier

As key drivers of nitrification, ammonia-oxidizing archaea (AOA) play a central role in the global nitrogen cycle and contribute significantly to the emissions of the potent greenhouse gas nitrous oxide (N2O). However, the ecological implications of AOA growth as biofilms, remain poorly understood. Since nitrite production can be used to follow cellular activities directly we were able to compare biofilms with planktonic cells of the terrestrial model AOA Nitrososphaera viennensis at ecologically and agriculturally relevant conditions. Biofilms were more resistant across nearly all tested conditions and remained active at lower temperatures, acidic pH, and high ammonium concentrations. Collectively, activities in biofilm help reconcile discrepancies between earlier laboratory and environmental observations of soil AOA. Additionally, biofilms showed a high general resilience and lowered sensitivities to nitrification inhibitors. Although in situ biofilms grown in microrespiratory chambers exhibited activity and ammonia affinity similar to planktonic cells, biofilm cultures produced only half as much N2O. The enhanced fitness of biofilms across all tested conditions vastly expands the potential ecophysiological niche of AOA and supports the hypothesis that biofilm growth represents the in situ phenotype of AOA in soil environments.

microbiology↗

bioRxiv2025

Oxygen production as an electron overflow pathway in ammonia-oxidizing archaea

Ammonia-oxidizing archaea (AOA) are widespread in nature and contribute to global carbon and nitrogen cycling. Although their energy production is an aerobic process, AOA occur in environments of low oxygen and in fully anoxic zones. Recently, oxygen production under anoxic conditions was demonstrated, raising the hypothesis that this activity can sustain oxygen dependent ammonia oxidation. In the work presented here, Nitrososphaera viennensis produces high amounts of oxygen in anoxia in dependence of nitrite but not ammonia. Rather than conferring a physiological benefit, oxygen production impaired recovery from anoxia. Produced oxygen is mostly not consumed and therefore cannot sustain ammonia oxidation in the absence of external oxygen. Instead, it is tightly linked to the amount of available redox equivalents. These observations indicate that oxygen production represents a general physiological strategy for alleviating the potential accumulation of reactive intermediates in the ammonia oxidation pathway, analogous to nitrifier denitrification in ammonia-oxidizing bacteria. TeaserOxygen production in ammonia-oxidizing archaea is not an adaptation to anoxia, but rather an electron overflow pathway that is detectable in anoxic conditions.

microbiology↗

bioRxiv2024

Biofilm lifestyle as a common trait of ammonia-oxidizing archaea

Although widespread in nature, growth in biofilms has been relatively little explored in the globally distributed ammonia oxidizing archaea (AOA). Here we investigated six representatives of three different terrestrial and marine clades of AOA in a longitudinal and quantitative study for their ability to form biofilm and studied gene expression patterns of three representatives. While all strains grew on a solid surface, soil strains exhibited the highest capacity for biofilm formation. Based on microscopic and gene expression data, two different colonization strategies could be distinguished. S-layer containing AOA (from both soil and marine habitats) initialized attachment as single cells and subsequently formed denser layers and three-dimensional structures, while the S-layer free species of the Nitrosocosmicus clade attached as suspended aggregates to the surface and henceforth showed fastest establishment of biofilm. Transcription profiles were significantly different between planktonic and biofilm growth in all strains and revealed individual reactions, often fulfilling shared functions. In particular the strong expression of different types of multicopper oxidases was observed in all strains indicating modifications of their cell coats. S-layer carrying AOA each additionally expressed a set of adhesion proteins supporting attachment. Detoxification of nitrous compounds, copper acquisition as well as the expression of transcription factor B were also shared reactions among biofilm producing strains. However, the majority of differentially expressed protein families was distinct among the three strains illustrating that individual solutions have evolved for the shared growth mode of biofilm formation in AOA, probably driven by the different ecological niches.

microbiology↗

bioRxiv2021

Comparative proteogenomics deciphers the origin and evolution of eukaryotic chromatin

Histones and associated chromatin proteins have essential functions in eukaryotic genome organization and regulation. Despite this fundamental role in eukaryotic cell biology, we lack a phylogenetically-comprehensive understanding of chromatin evolution. Here, we combine comparative proteomics and genomics analysis of chromatin in eukaryotes and archaea. Proteomics uncovers the existence of histone post-translational modifications in Archaea. However, archaeal histone modifications are scarce, in contrast with the highly conserved and abundant marks we identify across eukaryotes. Phylogenetic analysis reveals that chromatin-associated catalytic functions (e.g., methyltransferases) have pre-eukaryotic origins, whereas histone mark readers and chaperones are eukaryotic innovations. We show that further chromatin evolution is characterized by expansion of readers, including capture by transposable elements and viruses. Overall, our study infers detailed evolutionary history of eukaryotic chromatin: from its archaeal roots, through the emergence of nucleosome-based regulation in the eukaryotic ancestor, to the diversification of chromatin regulators and their hijacking by genomic parasites.

evolutionary biology↗