CNR ExploRA

Abstract in atti di convegno, 2023, ENG

Exploring biominerals' formation in extreme environments: from terrestrial hot springs to sulfuric acid systems

Federica Barilaro (1), Laura Sanna (2), Crisogono Vasconcelos (3), Judith A. McKenzie (4), Gabriele Carugati (5), Andrea Di Capua (1),(5)

(1) National Research Council, Institute of Environmental Geology and Geoengineering, Milan, Italy; (2) National Research Council, Institute of Environmental Geology and Geoengineering, Cagliari, Italy; (3) Geological Survey of Brazil, Center of Applied Geosciences, Rio de Janeiro, Brazil; (4) ETH Zurich, Department of Earth Sciences, Geological Institute, Zurich, Switzerland; (5) University of Insubria, Como, Italy

During the first two billion years the prokaryotes were the major form of life on Earth. These microorganisms dominated the Earth surface and played important roles in biogeochemical cycling and Earth and life evolu¬tion. Microbes have the potential to dissolve and precipitate minerals and also act on lithification processes. Therefore, understanding the mechanisms of biomineral formation and diagenesis will provide important insight concerning the role of microbes in mineral nucleation and growth. The approach which utilize modern environments, where biomineralization takes place, open the possibility to: 1) improve our understanding of the impact of life on the Earth's systems and its permanent imprint in the geological records and, 2) provide knowledge to be used in medical, environmental and materials sciences. An interdisciplinary investigation on modern carbonate hot spring systems (Tuscany, Italy) and sulphuric acid environment of an abandoned mine (Sardinia, Italy) have been performed. The unique occurrence of authigenic minerals in association with microbial communities in the study areas, acted as classical natural laboratories providing the opportunity to evaluate bio-geochemical and physicochemical factors that have direct influence in mineral precipitation. Using traditional and new tools from a sedimentary, petrographic, geochemical, mineralogical and geomicrobiological perspective integrated with high resolution techniques, it was possible to: 1) unequivocally identify different types of biominerals; 2) define their morphological features and composition linked to biotic compounds, 3) document nucleation processes, growth and diagenesis, and 4) provide 3D microscale visualization of the organomineral complex. This investigation confirms the existence of a direct link between biological activities, degradation of organ¬ic matter and biomineral formations. Filamentous bacteria, virus-like particles and extracellular polymeric substances are the main sites where minerals nucleate and grow. The very early stage of mineralization con¬sists into inorganic nanoparticles that gradually coalesce to form well-developed crystals. At larger scale, the microbial community interfaces with the environmental abiotic factors to form peculiar sedimentary bodies.

36th International Meeting of Sedimentology, pp. 340–340, Dubrovnik, Croatia, 12-16/06/2023