A Bait-and-Switch strategy links phenotypes to genes coding for Polymer-Degrading Enzymes in Intact Microbiomes

Advances in next generation sequencing have made it possible to explore microbial community dynamics and regulation of functionally important genes through metagenomics and metatranscriptomics. However, the use of meta-omics to link enzyme function directly with complex, community-level phenotypes remain largely unexplored. To overcome this gap, we developed a novel framework that integrates ecological concepts by microbial community perturbation with association analysis to a targeted phenotype. Specifically, we introduce a hypothesis-free “bait and switch” strategy demonstrated through salt marsh soil microcosm pulse experiments to detect and characterize novel enzymes responsible for chitin degradation. Soil microbial communities were “baited” with shell compost, a chitin-rich substrate, to trigger community succession toward chitin degraders and gene upregulation of chitinases. A “switch” was then employed, by addition of glucose, inducing rapid downregulation of genes putatively responsible for chitin degradation. Results demonstrate the feasibility of this approach to identify functionally important enzymes, in this example, 48 hours after chitin addition. The bait and switch community perturbation provides a framework for discovery of polymer degrading enzymes present in complex microbial communities and serves as a proof of concept applicable for linking enzyme function with emergent community level phenotypes.