Ulcerative colitis (UC), a type of inflammatory bowel disease, is characterized by recurring remission and recurrence. The gut microbiome is crucial for the development of UC. The changes in the microbiome profile during illness remission have received little attention. For a study, UC pathogenesis was most likely to begin in the mucosal barrier. As a result, the researchers looked into the ability of mucosal tissue microbiomes to distinguish patients with subclinical UC from healthy people. Researchers studied the microbiomes of cecal and rectal biopsies and feces from 13 healthy people and 45 people with subclinical UC. From the samples, total genomic DNA was extracted and their microbial communities were identified using next-generation sequencing. In the microbiome generated from rectal tissues, the researchers discovered that changes in the relative abundance of subclinical UC were indicated by a drop in Proteobacteria and an increase in Bacteroidetes phyla, but not in cecal tissue or feces. Subclinical UC patients demonstrated much higher community richness and evenness in the microbiome of rectal tissue than controls. In the subclinical UC cohort, twenty-seven operational taxonomic units were enriched, with the bulk of the taxa belonging to the Firmicutes phylum. According to inferences of putative microbial functional pathways, the rectal sample microbiome revealed a distinct increase in interleukin-17 signaling and T-helper cell differentiation pathways. For microbiome assays to identify people with subclinical UC from healthy adults, rectal biopsy tissue was suggested to be more suitable than fecal samples. The assessment of the rectal biopsy microbiome may provide clinical insight into the course of UC disease and predict relapse.