The goal of this clinical trial is to explore the pathophysiological effects of the persistently colonized microbiome in irritable bowel syndrome (IBS) patients. The main questions it aims to answer are: Question 1: the microbiome difference of the biofilm between IBS and healthy patients. Question 2: the metabolic product patterns between IBS and healthy patients. Participants will need to take a colonoscopy examination, two gut mucosal biopsy samples will be collected during the examination. Researchers will compare the IBS and healthy control groups to see if there was the disease-specific pattern in the microbiome and metabolic product of the biofilm.