Testing in vitro viability of a thermophilic probiotic bacterial strain in simulated gastrointestinal conditions

Abstract

The preservation of the viability of Streptococcus salivarius ssp. thermophilus strain IL 5.1 under gastrointestinal conditions is one of the more important microbial features for its use in probiotic products. The aim of this study was to test the viability of the bacterium under various gastrointestinal stressor conditions. The influence of pepsin at various pH levels and of pancreatin in the presence of bile salts was also determined in order to demonstrate the influence of these substances on the viability of the microorganism. Under identical conditions, the effect of both casein and mucin was also determined. Mucin was found to preserve microbial viability better than casein based on calculated mathematical parameters relating to viability and mortality. © 2013 Springer-Verlag Berlin Heidelberg and the University of Milan.