The viability of the Lactobacillus paracasei IL2 and Lactobacillus plantarum IL3 strains in simulated gastrointestinal conditions

The viability maintenance of Lactobacillus paracasei IL2 and Lactobacillus plantarum IL3 strains in gastrointestinal conditions represents one of the most important characteristics regarding their use for obtaining probiotic products. The tests were performed with a cell suspension kept in 0.5% NaCl. The influences of pepsin (3 g/l) at pH values of 1.5, 2, 2.5 and 3.0, as well as of pancreatin (1 g/l) in the presence of bile salts (1.5, 2, 3 and 5 mg/ml) were determined. The influence of casein and mucin, in a concentration of 1 g/l, were also established in the aforementioned conditions. It was observed that casein presented a longer viability maintenance; a fact also confirmed by the calculation of the mathematical parameters of viability and mortality, when mucin was either used or not, especially in the case of gastric transit. The results proved that the tested strains maintained their viability even at pH between 1.8 and 2.0 and at an even higher concentration, of 2 mg/ml, of bile salts, but up to two hours as of the exposure to the conditions of the simulated small intestinal juice. Such results were also confirmed by the cumulated effect of the simulated gastric and small intestinal juice, the strains thus increasing their viability with an average of 15% in the presence of casein.