Bile acid fitness determinants of a isolate from a human pouchitis patient.

The Gram-negative bacterium is a common member of the human gut microbiota that colonizes multiple host niches and can influence human physiology through a variety of mechanisms. Identification of genes that enable to grow across a range of host environments has been impeded in part by the relatively limited genetic tractability of this species. We have developed a high-throughput genetic resource for a strain isolated from a UC pouchitis patient. Bile acids limit microbial growth and are altered in abundance in UC pouches, where often blooms. Using this resource, we uncovered pathways and processes that impact fitness in bile and that may contribute to population expansions during bouts of gut inflammation.