The University of Sopron and Its Scientific Partners Researched Ancient Processes in Thermal Waters

The stromatolites are layered carbonate formations created by photosynthesizing cyanobacteria. With a history dating back to more than 3.5 billion years, they are among the oldest fossils on Earth. These organisms formed vast colonies in the shallow waters of ancient oceans and seas, playing a crucial role in increasing the oxygen content of the Earth’s atmosphere round 2.2 billion years ago during the Archean Eon. It is of great scientific interest, from both ecological and evolutionary perspectives, to understand the formation of these unique carbonate structures. However, their study is challenging, as the number of actively developing stromatolites has significantly declined in modern times.

Two members of the Functional Genomics and Bioinformatics Group operating at the University of Sopron, Dr. Nóra Tünde Lange-Enyedi and Prof. Dr. György Sipos collaborated with researchers from the Eötvös Loránd University and the Institute of Geology and Geochemistry of the HUN-REN Research Centre for Astronomy and Earth Sciences. During the study of the Köröm thermal well in Borsod-Abaúj Zemplén County, they observed biogenic structures, whose composition resembles that of the ancient stromatolites. In the thermal well’s environment, they examined 3-5 cm thick, red and green, layered, carbonate-rich biofilms (Figure 1), and they found that the mats made by bacteria can grow even under unfavourable conditions, such as low organic matter content, temperature of 79.2°C, high salinity, and significant arsenic concentration. They found a correlation between the composition of bacterial communities, physicochemical properties, and the process of limestone precipitation. For the first time, they describe the similarity between the structure of the currently living and developing red biofilm and the fossilized stromatolites (Figure 2).