S551 Profiling Gut Microbiota of Colorectal Cancer in Indonesia: A Focus on Beneficial Taxa Depletion

Introduction: Regional differences in the gut microbiota and CRC incidence and mortality rates are well-documented. However, studies on the microbiota associated with CRC in Indonesia remain scarce. This study aimed to characterize the gut microbiota profile of CRC in Indonesia. Methods: We collected stool samples from 14 patients with CRC (CRC), 19 patients with non-CRC bowel diseases (non-CRC), and 16 healthy controls (HC). The gut microbiota profiles across the 3 groups were analyzed using 16S rRNA gene amplicon sequencing. Data analysis was performed using several software packages: QIIME2, ANCOM-BC2, and PICRUSt2. Results: In comparison to the non-CRC and HC groups, patients with CRC demonstrated significant differences in both alpha and beta diversity. The CRC group had lower evenness and richness than the HC group. Firmicutes and Bacteroidota were identified as the predominant phyla across all groups. The differential abundance analysis identified 5 beneficial genera that were substantially reduced in Indonesian CRC patients: Roseburia, Dialister, Agathobacter, and Muribaculaceae. No genera were found to be significantly enriched in CRC. Functional prediction analysis revealed multiple pathways such as mTOR, mRNA surveillance, basal transcription factors, phagosome, and proteasome, were reduced in CRC. Conversely, CRC demonstrated a significant upregulation of pathways related to lipid metabolism and the biosynthesis of flavonoids, stilbenoids, diarylheptanoids, and gingerols. Conclusion: It is important to highlight those 4 depleted genera in the CRC group—Roseburia, Dialister, Agathobacter, and Muribaculaceae—have been shown to have anti-inflammatory and anti-tumorigenic properties. In our study, depletion of these 4 genera in CRC aligns with existing evidence suggesting their crucial role in maintaining gut health. The reduction in pathways identified by functional analysis may indicate disrupted cellular processes and impaired immune responses mediated by altered microbial community in CRC. Alterations in metabolic pathways may suggest changes in gut microbial metabolism and its effect on host metabolism. While numerous studies report increased abundance of harmful taxa in colorectal cancer, the loss of beneficial.