Fig. 3
Resistance of encapsulated bacteria to Artificial Gastric Juice (AGJ). a After encapsulation of overnight pre-cultures of bacteria at fairly low bacterial density (2 × 106 CFU/mL), the CS capsules containing L. casei (b, c), L. acidophilus (d, e) and B. infantis (f, g), were incubated under standard bacterial growth conditions (appropriate medium and temperature with agitation) for 1 or 2 days to allow the encapsulated bacteria to multiply. The encapsulated bacteria were then exposed to AGJ + P for 1, 2 or 3 h. The capsules were microscopically observed at ×40 (b, d and f) or ×100 (c, e and g) magnification after three hours exposure to AGJ + P. Encapsulated L. casei were decapsulated without exposure (0 min), or after 1, 2 and 3 h exposure to AGJ, submitted to limiting titration and plated on MRS agar plates (h). The titres of decapsulated L. casei measured as CFU/capsule after exposure of the encapsulated L. casei to AGJ + P (blue diamonds, blue line) or to MRS (orange squares, orange line) are shown