Approximately 150 Pg of organic carbon resides in subsurface sediments (Ciais et al. 2013). Understanding the preservation, transformation, and remineralization of this carbon is a prerequisite to understanding the global carbon cycle. Extracellular enzymes are required by subsurface heterotrophic microbes to access complex molecules from this reservoir (Arnosti 2011) and thus, influence carbon turnover. Identifying which microbes produce which extracellular enzymes and under what conditions has remained a challenge. Here, it is proposed to apply bottom-up metaproteomics, metatranscriptomics, and shotgun-metagenomics on subsurface microbe communities from the White Oak River estuary to help close this knowledge gap.