Beyond the limits of our senses exists an incredibly diverse microbial world. This microcosmos [pdf] extends into virtually every imaginable habitat, thrives under powerful extremes, and helps create and sustain the ecological and biogeochemical conditions for life on Earth. Just as cellular complexity arises through networks of genes, proteins, and metabolites interacting across multiple hierarchical levels, so ecological and biogeochemical phenotypes arise from interactions between microbial community members. In the Hallam Lab, we work at the interface of microbial ecology, biological engineering, and bioinformatics to explore the microcosmos, determining microbial community structure and function across a wide range of natural and engineered environments with an eye toward converting basic science insights into biotechnology innovations.