Studies on the protective role of probiotics and milk calcium on Salmonella Typhimurium infection in mice : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Nutritional Science at Massey University, Palmerston North, New Zealand

Abstract

The current studies were carried out to evaluate the efficacy of a newly identified LAB strain - DR10TM (Bifidobacterium lactis) on host immunity and susceptibility to Salmonella typhimurium (S. typhimurium) infection in mice. In addition, the effect of elevated milk calcium levels combined with DR10TM was studied in mice infected with S. typhimurium. After initially establishing a murine infection model, the effect and efficacy of DR10TM in preventing S. typhimurium infection and stimulating immunity was examined. The results showed that DR10TM could significantly enhance resistance against S. typhimurium infection and stimulate a wide range of immune parameters including non-specific and specific immune responses. In another study the S. typhimurium infection model was used to examine the effect of milk calcium and the combination of different amounts of milk calcium with DR10TM on host immunity and prevention of S. typhimurium infection in mice. These results demonstrated that milk calcium was very effective in reducing the severity of infection and a high amount of milk calcium combined with DR10TM increased the ability of DR10TM to prevent S. typhimurium infection. The findings of the current study were significant in that they demonstrated the effect and efficacy of DR10TM on promoting enhanced resistance to enteric infection and stimulating immunity, provided additional evidence of the role played by the enhanced immune system in protecting against enteric infection, and ascertained the synergism between milk calcium and LAB in the prevention of S. typhimurium infection.