Abstract: Taxonomic and functional changes to the composition of the gut microbiome have been implicated in multiple human diseases. The presentation will focus on how the microbiota drives intestinal disease through alterations in microbial community architecture, disruption of the mucosal barrier, modulation of innate and adaptive immunity, and dysfunction of the enteric nervous system. Fecal microbiota transplantation (FMT) is a treatment for microbiome-associated diseases in which gut microbiota are transferred from a healthy donor to a patient. Clinical case studies will be used discuss  the forces governing bacterial engraftment in humans and design principles of bacterial therapeutics that target diseases ranging from ulcerative colitis to cancer