Most of the molecules that organisms synthesize are polymeric, and so most of the bioavailable organic matter in the environment consists of high-molecular weight molecules. In order to access these molecules, heterotrophic microbes must first break them down into smaller units. Thus, the ability of microbial communities to express extracellular enzymes, and the dynamics of those enzymes once produced, serve as a proximate control on the remineralization of organic matter, and thus Earth’s carbon cycle.
We study the nature, dynamics, and controls on microbial extracellular enzymes in aquatic environments, including marine sediments, estuaries, and freshwater systems. Our work investigates:
- Kinetics of peptidases and polysaccharide hydrolases across diverse environments
- Substrate specificity of aquatic extracellular peptidases
- Stability of extracellular enzymes in deep subsurface sediments
- Community-level controls on enzyme activity and diversity
This work helps us understand a fundamental bottleneck in the global carbon cycle: how organic polymers are transformed into bioavailable monomers that microbes can consume.
