Fig. 4
Relative viability of non-encapsulated versus encapsulated bacteria after exposure to Artificial Gastric Juice (AGJ). a After overnight culture of bacteria, or encapsulation of overnight pre-cultures of bacteria at fairly low bacterial density (2 × 106 CFU/mL), the free or CS encapsulated L. acidophilus (b), L. johnsonii (c), B. infantis (d) and L. casei shirota (e) were incubated under standard bacterial growth conditions (appropriate medium and temperature with agitation) for 1 or 2 days to allow the bacteria to multiply. The viability of the bacteria was then measured in an AlamarBlue® assay. The relative viability of each bacterial species, free or encapsulated, was set at 100% and all subsequent measured viabilities calculated as a relative percentage to this initial 100%. The free (black up-pointing triangle—green lines, filled diamond—blue lines) and encapsulated (filled square—red lines) bacteria were then exposed to AGJ + P (black up-pointing triangle —green lines, filled square—red lines) or to AGJ without acid (filled diamond—blue lines) for 1, 2 or 3 h before being subjected to alamarBlue® metabolic activity measurement. b–e Time course of the relative viability of encapsulated (filled square—red lines) or free, non-encapsulated (black up-pointing triangle—green lines) L. acidophilus (b), L. johnsonii (c), B. infantis (d) and L. casei shirota (e) expressed as a percentage of the initial viability set as 100%, after 2 h exposure to artificial gastric juice plus pepsin and lysozyme (AGJ + P). For comparison the time course of viability of free bacteria (filled diamond—blue lines) L. acidophilus (b), L. johnsonii (c), B. infantis (d) and L. casei shirota (e) after 2 h exposure to artificial gastric juice without acid (AGJ) is also shown. The mean and the standard deviation are indicated