FRIPRO-Fri prosjektstøtte

Life on our planet has ever since its origin some 3.5 billion years ago, had a profound impact on the Earths evolution. We know this to be true also today where an active biosphere is crucial for maintaining balance in all the major geochemical cycles, vital for our existence. Hence, our understanding of how these cycles are regulated is tightly linked to our knowledge concerning the functioning of the biosphere. For a long time we thought that our knowledge related to the different compartments of the Earths biosphere and its fundamental functioning was relatively complete. However, the presence of a vast and previously unknown component of the global biosphere was recently discovered deep within the ocean crust. This habitat, covering more than 60% of the Earths surface, is now estimated to be home to more than a mind baffling 10^29 organisms, most of them belonging to the microbial domain of life. Our current knowledge about this deep biosphere is basically limited to its presence, and fundamental questions related to its mechanisms of survival and potential influence on our surface world is unknown. The project EnterDeep is designed to explore the deep crustal biosphere and investigate the inhabitants and their environmental impact and significance. This will be done through controlled experiments in the laboratory but also by installing a in situ observatory deep into the iconic volcanic island Surtsey. During the project period we have visited Surtsey twice and have successfully retrieved geochemical and microbial data from the borehole observatory. This precious sample material has been analyzed using a combination of molecular analyses and advanced scanning electron microscopy. Results suggest that the incubators were indeed colonized and both molecular and textural biosignatures were found. We are currently in the final stages of writing a scientific paper which describes the microbiome responsible for the initial colonization of fresh basalt glass and olivine based on 16S rRNA gene data. Our results are consistent with data from the original drill core material recently published by our Icelandic colleagues. However, the total diversity was lower, indicating a less developed community, compared to the native Surtsey environment. Additionally, we describe alteration structures formed at 140 degree celsius which are similar to features that have previously been interpreted as biological within the literature, raising questions about their biogenicity. Currently we and our collaborators in Sweden and Germany are in the process of analyzing sample material with atomic force and time-of-flight microscopy to estimate alteration rates and validate textural biosignatures. Alongside this, a significant effort has been invested into developing a new and innovative fluid flow-through design and all components are now assembled and the first laboratory tests are running. The design is tailored to clarify the influence of microbial activity in the crustal biosphere from a quantitative point of view and we hope by this to overcome many of the previous shortcomings in this research field.

Every day ~100 billion cubic meters of bottom seawater enters the permeable upper oceanic crust, where it reacts with the basaltic rocks. The seawater ultimately returns to the oceans, with a significantly altered chemical composition, having profound consequences for the Earth system. There is strong evidence that microbial cells are common and widespread in the crustal aquifer. However, given the inherent technical and economical challenges involved in studying the oceanic crust, investigation of this biosphere have until now largely been descriptive. Hence, we lack fundamental knowledge of the rates of metabolic processes, the extent to which these influence rock alteration and mineral dissolution, and how these processes are preserved as textural and molecular biosignatures. This project will advance the state of the art through (1) unprecedented access to newly formed subsurface oceanic basalt spanning the temperature limits of life; (2) continuous in situ monitoring using borehole observatories; (3) an interdisciplinary approach combining comprehensive genomics with atomic-scale mineral dissolution measurements, biogeochemical rate modelling, and integrated geobiological data analysis, to quantitatively test long-standing hypotheses. The proposed research will uncover an unexplored part of one of the most ancient and most extensive ecosystems on Earth. Quantification of processes and rates will help settle a number of long-debated, first-order questions regarding the geochemical significance of microbe-rock interactions. The results will thus have wide implications for our understanding of global element cycles, and ultimately shed new light on the ways in which our planet has co-evolved with the life it hosts.