The United States probiotics industry is a growing multi-billion-dollar industry. With promises of improving overall digestive health, more research is needed to assess survivability of probiotic strains in reaching target colonization sites. Understanding the survivability of probiotics throughout the gastrointestinal (GI) tract is crucial for optimizing their therapeutic efficacy. This study focuses on the survival of Lactobacillus rhamnosus GG (LGG), a commonly used probiotic, while it progresses through each phase of a simulated GI tract. Using a modified in vitro model, this study simulated physical, chemical, and biological conditions of the mouth, stomach, and small intestine to measure LGG survival. This modified in vitro model is a mechanical process that allows for the study of the GI tract outside of the human body. Environmental factors such as pH, enzymatic activity, and mechanical forces were implemented to mimic digestion. Results revealed a decline in LGG viability, as visualized by microscopy and growth measured as CFU/mL, particularly in the stomach phase (mean 5.2 X 103 CFU/mL) as compared to the control (mean 1.17 X 109 CFU/mL). This reduction is most likely due to the harsh conditions of this region (low pH and enzymatic activity). It is hypothesized that LGG can survive passage through the GI tract, with attrition in CFU/mL due to harsh simulated environmental conditions. Our findings show that LGG is capable of surviving in a simulated digestive system to reach the small intestines albeit in smaller numbers which could influence intestinal colonization and thus probiotic effectiveness.
*Primary authors