Bile acid fitness determinants of a <i>Bacteroides fragilis</i> isolate from a human pouchitis patient

Abstract

The Gram-negative bacterium <i>Bacteroides fragilis</i> 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 <i>B. fragilis</i> 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 <i>B. fragilis</i> strain isolated from a UC pouchitis patient. Bile acids limit microbial growth and are altered in abundance in UC pouches, where <i>B. fragilis</i> often blooms. Using this resource, we uncovered pathways and processes that impact <i>B. fragilis</i> fitness in bile and that may contribute to population expansions during bouts of gut inflammation.