The community of microorganisms within the human gastrointestinal tract is one of the most diverse ecosystems known, yet we currently have limited tools to unravel its intrinsic complexity. Next-generation sequencing approaches have been invaluable for the characterisation of gut microbial distribution, abundance, and evolution, but elucidating the mechanistic basis for these dynamics requires an ability to perturb the system through manipulation and testing. However, most species of the human gut microbiota are genetically untractable. We are developing novel genetic systems for non-model organisms living within the human gut.