Purification and characterization of a component produced by Lactobacillus fermentum that inhibits the adhesion of K88 expressing Escherichia coli to porcine ileal mucus

It has previously been shown that Lactobacillus fermentum strain 104r releases compounds into its culture fluid that inhibit the adhesion of enterotoxigenic Escherichia coli K88. The aim of the present study was to purify and identify this compound. Judged by gel filtration, the compound was found to be approximately 1700 kDa. The amount of active compound increased upon prolonged incubation, while the number of viable cells reduced, suggesting that the activity was coming from dead cells. As the activity can be destroyed by lysozyme treatment and contains glucose, N -acetylglucosamine and galactose, it was concluded that cell wall fragments are the active agent, although cell wall preparations did not have the same effect. Adhesion to some mucus fractions could be inhibited by spent culture fluid, indicating specific interaction between mucus and the active compound. The compound was not able to interfere with the adhesion of E. coli 1107 to neutral lipids from mucus which contain a glycolipid receptor for K88 fimbriae.