Bacterial and Fungal Dysbiosis in the Guts of Patients with Irritable Bowel Syndrome (IBS) and Crohn's Disease (CD)

There has been rising interest in the interaction between the gut microbiome and gastrointestinal diseases, and studies suggest an association between the two. Irritable Bowel Syndrome is associated with abdominal pain and abnormal bowel movements while Crohn's disease is a result of abnormal immune response to gut microbiota. This study will characterize and analyze the gut bacteriome and mycobiome in adult South Korean patients diagnosed with IBS and CD. Participants were selected from healthy South Korean individuals (HC; n = 52) and individuals diagnosed with either IBS (n = 92) or CD (n = 35). Participants provided a fecal sample, and fecal DNA was retrieved. Gut bacteriome and mycobiome composition and diversity were analyzed with Illumina Sequencing of the 16S rRNA gene for bacteria and ITS1 for fungi. The sequence reads were processed by Quantitative Insights into Microbial Ecology (QIIME, QIIME2) and PIPITS to filter samples, pick for operational taxonomic units (OTUs), and provide alpha diversity values. Patients with IBS and CD display altered bacterial and fungal taxa abundance compared to HC, and both have significantly lower alpha diversities when compared to HC. Beta diversity showed distinct grouping from HC, except for bacterial IBS. Negative correlations in Candida tropicalis with Akkermansia muciniphila and Lactobacillus ruminis were found in IBS while Candida albicans was found to be negatively correlated with Bifidobacteria adolescentis in CD. L. ruminis also inhibited Candida growth in vitro when co-cultured. Based on this data, gut bacteriome and mycobiome dysbiosis is involved in the onset of IBS and CD.