Inability of Lactobacillus casei strain GG, L. acidophilus, and Bifidobacterium bifidum to degrade intestinal mucus glycoproteins.
Lactic acid bacteria have been suggested for use in the prevention of relapse of ulcerative colitis and of recurrent pouchitis. These strains may not damage the protective intestinal mucus glycoproteins. Lactobacillus casei strain GG and strains isolated from a commercial fermented product (Lactobacillus acidophilus, Bifidobacterium bifidum, and a mesophylic lactic culture) were cultured in vitro on hog gastric mucin and human intestinal glycoproteins. Furthermore, germ-free rats were mono-associated with Lactobacillus GG and poly-associated with the other strains. Glycoproteins were isolated from rat distal ileum, cecum, and colon. Mucus degradation was established by assaying carbohydrates (hexosamines, hexoses, pentoses), proteins, and blood group antigenicity. All strains colonized the intestinal mucus but were not found in the deep crypts. Degradation of mucus glycoproteins was observed neither in vitro nor in vivo. The tested strains do not break down intestinal mucus glycoproteins and thus far are safe to use for therapy.