From Venezuelan Caves to Rocks on Mars: A New Method for Studying Extreme Environments

Deep inside the Imawarì Yeutà cave, in the heart of Venezuela’s Auyán-tepui, an international group of researchers has, for the first time, conducted a comprehensive in situ study of silica stromatolites – extremely rare structures that are still poorly understood.

The research, published in the journal Biogeosciences, opens up new perspectives for the exploration of extreme environments, on Earth and beyond. Silica structures similar to those found in the Venezuelan cave have in fact also been observed on Mars by the Spirit rover. Whether these formations may have a biological origin remains an open question, but compact and portable instruments such as those used in this study could one day provide an answer directly on the Red Planet.

The structures analysed are silica stromatolites: rock formations composed of opal (amorphous silica), whose growth is generally associated with the activity of photosynthetic microorganisms. Their presence in a completely dark and isolated environment such as the Venezuelan cave represents one of the most fascinating geo-microbiological enigmas of recent years.

The research stems from a 2023 expedition, during which the team of Italian and Venezuelan scholars set up a fully operational research camp inside the cave, bringing in advanced instruments never before used in such a remote context.

Among the technologies used by researchers from the University of Padua were a hyperspectral camera, which made it possible to analyse the composition of the silica structures, and a 3D laser scanner, used to obtain ultra-high-resolution models of the formations.

Researchers from the University of Bologna also employed instruments capable of detecting microbiological activity directly in vivo, identifying active cells on rock surfaces. Completing the picture, the MinION device enabled DNA sequencing to be carried out directly inside the cave, without the need to transport samples outside.

“In this work we developed, applied and validated microbiological procedures directly in the field to study the extraordinary silica stromatolite structures found in the quartzite caves of the Venezuelan tepuis,” says Martina Cappelletti, first author of the article and researcher at the Department of Pharmacy and Biotechnology of the University of Bologna. “Our analyses made it possible to detect microbial activity and to identify the main bacteria that may promote the development of these structures. At the same time, we demonstrated that it is possible to carry out DNA analyses and microbiological studies in real time even in extreme and isolated locations, revealing new aspects of the role of microorganisms in the formation of stromatolites in dark, nutrient-poor environments, such as the remote and ancient caves of the tepuis.”

“For the first time, we have been able to study these extraordinary structures directly in their natural environment, without taking samples,” explains Francesco Sauro, speleologist and researcher at the Department of Geosciences of the University of Padua. “This approach allows us to better understand the interaction between geology and microbiology under extreme conditions, with significant implications for planetary exploration.”

The research group benefited from funding from the Bachelor’s Degree Programme in Genomics at the University of Bologna, which provided the portable sequencer and the reagents required for DNA sequencing, as well as support from Miles Beyond Srl, which purchased and made available the portable Bento Lab laboratory.

Francesco Sauro’s participation in the study forms part of the activities supported by the project The Geosciences for Sustainable Development, funded by the Ministry of University and Research (MUR) under the Departments of Excellence 2023–2027 scheme. Thanks to this funding, the Department of Geosciences of the University of Padua and the Department of Pharmacy and Biotechnology of the University of Bologna have been able to develop innovative technologies, train multidisciplinary teams and carry out scientific missions in extreme environments, consolidating their international leadership in the study of geomicrobiology and geomorphology and opening up new perspectives in research on Martian analogues.