Can marine and terrestrial subsurfaces in Brazil harbor archaea that may illuminate the origin of complex life and the habitability of ocean worlds?

Abstract

We will use environmental DNA, metagenomics, and geochemistry on Brazilian terrestrial and marine subsurface samples to test whether uncultivated extremophilic archaea are underrepresented and can help to shed light on the origin of complex life on Earth, on the adaptability of life under extremes, and if they can be proposed as models for the search for life in subsurface ocean worlds of our Solar System. In addition, we will compare Archaea between terrestrial and marine subsurfaces to answer whether they share taxa and functionalities that have practical implications for understanding life's habitability on Earth and beyond. Studying life in extreme environments offers insights into fundamental biological processes providing a unique window into the evolutionary history of life itself. Marine and terrestrial subsurfaces are the largest habitats on Earth and still the least explored. Despite extreme conditions, subsurface life, particularly Archaea, is surprisingly widespread and diverse, with recent studies suggesting a significant underestimation of their diversity on Earth. Investigating subsurface archaeal communities is challenging, but crucial for understanding their evolutionary and astrobiological significance. By recovering genomes from metagenomic data, we aim to uncover novel archaeal taxa in caves and subseafloor in Brazil, potentially contributing to improve our understanding of microbial evolution on Earth. Moreover, we aim to enlighten the mystery surrounding whether the microbiomes of marine and terrestrial subsurface environments harbor exclusive or overlapping taxa, novel lineages, and shared adaptation mechanisms to subsurface conditions. By bridging gaps in our understanding of the subsurface biosphere, this research might offer insights into the evolutionary history and adaptability of microbial life in extreme environments, having broader implications for our quest to uncover the origins and limits of life in a planetary context. (AU)