Adhesion mechanisms of Bifidobacterium animalis subsp. lactis JCM 10602 to dietary fiber

Abstract

Adherence of probiotics to dietary fibers present in the intestinal tract may affect adhesion to intestinal epithelial cells. The properties of the adhesion of bifidobacteria to mucin or epithelial cells have been well studied; however, adhesion of bifidobacteria to dietary fiber has not been investigated. The adhesion ratio of six Bifidobacterium strains to cellulose and chitin was examined; among the strains, Bifidobacterium animalis subsp. lactis JCM 10602 showed high adherence to both cellulose and chitin, and two strains showed high adherence to only chitin. The ratios of adhesion of B. animalis to cellulose and chitin were positively and negatively correlated with ionic strength, respectively. These data suggest that hydrophobic and electrostatic interactions are involved in the adhesion to cellulose and chitin, respectively. The adhesion ratios of the cells in the late logarithmic phase to cellulose and chitin decreased by approximately 40% and 70% of the cells in the early logarithmic phase, respectively. Furthermore, the adhesion ratio to cellulose decreased with increasing bile concentration regardless of the culture phase of the cells. On the other hand, the adhesion ratio to chitin of cells in the early logarithmic phase decreased with increasing bile concentration; however, that of cells in the late logarithmic phase increased slightly, suggesting that adhesins differ depending on the culture phase. Our results indicated the importance of considering adhesion to both dietary fibers and the intestinal mucosa when using bifidobacteria as probiotics.

Keywords: Bifidobacterium; adhesion; bile; cellulose; chitin; growth phase.

Fig. 1.

Adhesion ratios of Bifidobacterium strains to dietary fiber. Filled columns, cellulose; open columns, chitin. Adhesion ratios (%) are presented as means ± standard error of triplicate samples. Bars with the same letters are not significantly different from each other (p<0.05) by Tukey’s test.

Fig. 2.

Effect of pH on adhesion of B. animalis to dietary fiber. **p<0.01 by Student’s t-test. Filled columns, pH 7.0; open columns, pH 5.0.

Fig. 3.

Effect of ionic strength on adhesion of B. animalis to dietary fiber (pH 7.0). Closed circles, cellulose; open circles, chitin.

Fig. 4.

Time course of the growth of B. animalis. Circles, triangles, and squares indicate the values of OD₆₆₀ of the culture broth in different runs.

Fig. 5.

Effect of culture time on adhesion of B. animalis to dietary fiber (pH 7.0). Closed circles, cellulose; open circles, chitin.

Fig. 6.

Effect of growth phase and bile on adhesion of B. animalis to cellulose (pH 7.0). Closed circles, early logarithmic phase cells; open circles, late logarithmic phase cells.

Fig. 7.

Effect of growth phase and bile on adhesion of B. animalis to chitin (pH 7.0). Closed circles, early logarithmic phase cells; open circles, late logarithmic phase cells.