Exploration of the deep ocean has expanded our understanding of oceanic ecosystems and yet still little is known about these deep sites on Earth. Some of the most poorly understood ecosystems are subsurface sedimentary environments and ultra-deep trenches, particularly as it pertains to the distribution of novel microbial lineages and their associated metabolic abilities. In this presentation, I will share an two examples of work that has advance our understanding of the distribution and metabolic potential of novel microbial lineages, such as those that are part of the Candidate Phyla Radiation, and archaeal lineages such as Bathyarchaea and Asgard archaea Superphylum. Overall, this research seeks to reveal the metabolic potential of novel microbial lineages, which significantly contributes to our overall understanding of the ecosystem function of subsurface sedimentary environments.