Bacterial taxonomic and functional changes following oral lyophilized donor fecal microbiota transplantation in patients with ulcerative colitis

Oral lyophilized fecal microbiota transplantation (FMT) can induce remission in patients with active ulcerative colitis (UC); however, our understanding of how this form of FMT alters the patient microbiome remains limited. Here, we analyzed data from a recent randomized, double-blind, placebo-controlled clinical trial of FMT in UC to assess donor species colonization and factors responsible for efficacy using this form of therapy. The gut microbiome of donors and patients was profiled longitudinally using deep shotgun metagenomic sequencing, and microbiome diversity, species-genome bin presence, functional profiles, and the resistome were studied. The gut microbiome of patients treated with oral lyophilized FMT significantly increased in species-genome bin richness and shifted in composition toward the donor profiles; this was not observed in patients receiving placebo. While species-genome bin richness was not associated with clinical response in this trial, we identified donor- and patient-specific features associated with the induction of remission and maintenance of response. However, the presence of a Clostridium species-genome bin, as well as L-citrulline biosynthesis contributed by Alistipes spp., was seen in responders treated by either donor. Several of the above outcomes were found to be consistent when data were analyzed at the level of metagenome-assembled genomes. FMT was also found to deplete the resistome within patients treated with antibiotics to levels lower than the UC baseline. Single donor oral lyophilized FMT substantially modifies taxonomic diversity and composition as well as microbiome function and the resistome in patients with UC, with several features identified as strongly linked to response regardless of the donor used.IMPORTANCEThere is a limited amount of work examining the effects of oral lyophilized fecal microbiota transplantation (FMT) on the microbiome of patients with ulcerative colitis (UC), and less so studies examining species-level dynamics and functional changes using this form of FMT. We performed deep shotgun metagenomic sequencing to provide an in-depth species-genome bin-level analysis of the microbiome of patients with UC receiving oral lyophilized FMT from a single donor. We identified key taxonomic and functional features that transferred into patients and were associated with clinical response. We also determined how FMT impacts the resistome of patients with UC. We believe these findings will be important in ongoing efforts to not only improve the efficacy of FMT in UC but also allow for the transition to defined microbial therapeutics, foregoing the need for FMT donors.