Understanding the Competitive and Cooperative Interactions between Probiotics and Autochthonous Intestinal Bacteria

The present study combines the theory and the experimental data to predict the changes on intestinal bacterial populations during ingestion of beneficial probiotic bacteria. Our proposed model is a modified version of the LotkaVolterra model, which takes the probiotic administration into account. Using the linear stability analysis of the model, the conditions for coexistence of the probiotics with other bacteria are established. Using the model fitted to the data of C. coccoides species and Bifidobacterium species, the effects of oral probiotics on autochthonous bacterial cultures is investigated. The estimated parameter values suggest that C. coccoides and Bifidobacterium facilitate each other during the probiotics administration, whereas they compete in the absence of the probiotics administration. This may suggest the beneficial effect of probiotic administration as it promotes the growth of C. coccoides species. The results also confirm prior studies showing that once probiotic supplementation is discontinued, the probiotic population and the promoting effect within the digestive tract will diminish.