The bowel contains many microorganisms but the most prevalent bacterium is 未知类型：{'options': ['[tex=0.643x0.786]UUCIIc0kAs+A7XMSj7he2Q==[/tex]-hemolytic streptococci', 'Lactobacillus', 'S. epidemidis', 'E.coli', 'B. fragilis'], 'type': 102}