    ‘Sentence E What serves aso biological barrier by campeting for space and food  inthe Gitmce    Sentence 2 There is good evidence that reintroduction of probiotic flo such  {pure cultures of the lactoboclti normally found in unpasteurized yogurt.  helps restore a healthy bolonce of microbial popuitions in intestinal  infections in children and encouraging pretiminary dat in sties on bocteral  ‘gastroenteritis, inflammatory towel diseases, urinary trac infection and post    surgical infections