Figure 4

Adhesion of treated B. bifidum S17 in comparison to untreated bacteria. (A) SDS-PAGE of cell wall fractions of B. bifidum S17 after 30 min treatment with 1 mM periodate, 1 mg/ml lipase or 1 mg/ml pronase. 50 μg of protein were loaded in each lane. (B) Viability of untreated B. bifidum S17 (black circles) or during treatment with 1 mM pronase (white circles), 1 mg/ml lipase (black triangles) or 1 mg/ml periodate (white triangles). Samples were taken after 0 (pre-treatment control), 15, 30, 45, and 60 minutes and colony forming units were determined after growth on MRSC agar plates. (C) Adhesion of B. bifidum S17 treated for 30 min with either 1 mM periodate, 1 mg/ml lipase or 1 mg/ml pronase to T84 (black bars), Caco-2 (light grey bars) and HT29 (dark grey bars) cells. 10⁸ cfu/well of treated bacteria were added to IECs. Adherent bacteria were determined after growth on MRSC agar plates and expressed as percentage relative to untreated bacteria. Values are mean ± standard deviation of one representative of at least three independent experiments performed in triplicate measurements. Statistical analysis was performed by pairwise comparison to the respective positive control (i.e. adhesion of untreated B. bifidum S17) using Students t-test. Letters above bars indicate statistical significance (a: p < 0.05; b: p < 0.01; c: p < 0.001).