Microbial Seed Banks: Patterns and Mechanisms of Bacterial Dormancy in Soils

Soils are the largest reservoir of microbial diversity on earth.  This diversity is important for a variety of ecosystem services, including pathogen resistance, contaminant degradation, and carbon sequestration.  However, soil ecologists still lack a deep understanding of how the interactions between microbial taxa and their environment influence the maintenance of soil biodiversity.  Here, we explore the role that dormancy plays in the coexistence of soil bacterial species.  Dormancy is a bet-hedging strategy that allows microorganisms to enter a reversible state of reduced metabolic activity.  Theory suggests that dormancy allows for the long-term persistence of individuals, but that it also has important implications for the structure and function of complex communities.  Our research will integrate genome sequences from reference strains with an existing functional trait database to discern the dormancy strategies that soil bacterial use to contend with desiccation stress.  Second, we will use a combination of stable isotope probing (SIP) and metagenomics to test hypotheses about the expression of dormancy genes under altered precipitation regimes.  Lastly, we will explore how dormancy dynamics influence the turnover and maintenance of bacterial taxa in a manipulative field experiment.  Results from the proposed research will advance our understanding of soil microbial diversity, but will also greatly expand the existing knowledge about dormancy dynamics of microorganisms in non-clinical settings, which may have implications for pest management and disease dynamics in a variety of natural and managed ecosystems.