Adaptation to extreme conditions thermal water biofilm studies could help understand ancient ecosystems

Adaptation to extreme conditions thermal water biofilm studies could help understand ancient ecosystems
by Erica Marchand
Paris, France (SPX) Mar 11, 2025

Hungarian scientists have uncovered distinctive bacterial communities in thermal waters, offering key insights into the processes behind stromatolite development, some of Earth's most ancient rock formations. Their findings not only provide a deeper understanding of the planet's geological past but also shed light on modern extreme environments where similar processes still occur.

A research team from Eotvos Lorand University, the University of Sopron, and the HUN-REN Research Centre for Astronomy and Earth Sciences, Geological and Geochemical Institute has identified critical factors influencing microbial carbonate formation. Their study, published in Scientific Reports, reveals new connections between bacterial activity and the formation of stromatolites.

Stromatolites are layered carbonate structures formed by photosynthetic cyanobacteria, dating back over 3.5 billion years. These microorganisms thrived in vast, shallow-water colonies, contributing significantly to the rise of atmospheric oxygen approximately 2.2 billion years ago during the Archaean era. However, actively forming stromatolites are now rare, making them difficult to study in contemporary environments.

During an investigation at the Korom thermal spring in Hungary's Borsod-Abauj-Zemplen County, researchers identified biological structures resembling ancient stromatolites. The thermal spring harbors red and green layered biofilms, 3-5 cm thick, which are carbonate-rich microbial mats. These biofilms persist under extreme conditions, including low organic matter, high salinity, elevated arsenic levels, and temperatures reaching 79.2 C.

The study established a correlation between bacterial community composition, environmental factors, and limestone precipitation processes. Researchers were the first to highlight the striking similarities between present-day red biofilms and fossilized stromatolites, offering a rare opportunity to observe modern analogs of ancient formations.

By analyzing these actively forming microbial mats, the study significantly advances the understanding of biogenic carbonate formation, helping interpret fossilized microbial structures and reconstruct past ecosystems. These insights also contribute to broader geobiological research, revealing how microbial life adapts to extreme conditions, both in Earth's history and in contemporary extreme environments.

The research was carried out by Judit Makk, Nora Tunde Lange-Enyedi, Erika Toth, and Andrea Borsodi from the Microbiology Department of Eotvos Lorand University, in collaboration with the University of Sopron and the HUN-REN Research Centre for Astronomy and Earth Sciences, Geological and Geochemical Institute.

Research Report:Actively forming microbial mats provide insight into the development of microdigitate stromatolites