Microbial Life Deep Underfoot

Soil is one of the most diverse microbial habitats on Earth. While the distribution and abundance of microbial taxa in surface soils have been well described, the phylogenetic and functional diversity of bacteria and archaea in deep-soil strata remains unexplored. Brewer et al. (mBio 10:e01318-19, 2019, https://doi.org/10.1128/mBio.01318-19) documented consistent shifts in the composition and genomic attributes of microbial communities as a function of depth in 20 soil pits that spanned a range of ecosystems across North America. The unique microorganisms found in deep soils appear to be adapted to conditions of low energy based on the recovery of genes that code for traits such as internal resource storage, mixotrophy, and dormancy.