Univ.-Prof. Dr. Holger Daims






Deputy Head of the Division of Microbial Ecology

☎ +43 1 4277 91204


Our research focuses on microorganisms driving the biogeochemical nitrogen cycle, with particular emphasis on key players in the nitrification process: nitrite-oxidizing bacteria (NOB) and complete ammonia oxidizers (comammox). Employing various molecular, 'omics', and microbial physiology techniques, we identify new nitrifying microbes and investigate the metabolism, ecophysiology, and evolution of these elusive organisms. Our objective is to gain a fundamental biological understanding of nitrification in natural and engineered ecosystems, which could also improve management practices in agriculture and wastewater treatment, and mitigate greenhouse gas (nitrous oxide) emissions.

Another area of interest are microbe-microbe interactions within complex microbiomes, such as biofilms in engineered and natural environments. Integrating 'omics', fluorescence and chemical imaging, and computational approaches, we pinpoint microbial partners and uncover their in situ interactions. Our aim is to reveal core principles of microbial interactions that govern the composition, spatial structuring, and functional adaptability of microbial communities.

Research Topics

Join the Team

If you are interested in joining our team, explore our open positions and learn more about available PhD and postdoc stipends here.


To view Holger Daims' teaching activities at the University of Vienna, visit u:find.

Group Members


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Glasl, B., Luter, H. M., Damjanovic, K., Kitzinger, K., Mueller, A. J., Mahler, L., Engelberts, J. P., Rix, L., Osvatic, J. T., Hausmann, B., Séneca, J., Daims, H., Pjevac, P., & Wagner, M. (2024). Co-occurring nitrifying symbiont lineages are vertically inherited and widespread in marine sponges. The ISME Journal, [wrae069]. https://doi.org/10.1093/ismejo/wrae069

Ni, G., Leung, P. M., Daebeler, A., Guo, J., Hu, S., Cook, P., Nicol, G. W., Daims, H., & Greening, C. (2023). Nitrification in acidic and alkaline environments. Essays in biochemistry, 67(4), 753-768. https://doi.org/10.1042/EBC20220194

Zhang, Y., Liu, T., Li, M-M., Hua, Z-S., Evans, P., Qu, Y., Tan, S., Zheng, M., Lu, H., Jiao, J-Y., Lücker, S., Daims, H., Li, W-J., & Guo, J. (2023). Hot spring distribution and survival mechanisms of thermophilic comammox Nitrospira. The ISME Journal, 17(7), 993-1003. https://doi.org/10.1038/s41396-023-01409-w