Response of Lactobacillus casei to short bile salts exposure revealed by two-dimensional electrophoresis

Tolerance to bile salts is one of essential properties for probiotic bacteria during passage through the gastrointestinal tract. Using proteomics techniques, protein patterns of a new probiotic bacterium, Lactobacillus casei Zhang, were constructed after exposure to bile salts (1.0%, w/v) for 30 min. The study observed that twelve proteins were induced by bile salts stress, including nine up-regulated proteins (DnaK, CysK, LacC, etc.) and three down-regulated proteins (PyrD and PepC) by bile salts stress. Further analysis showed that two proteins belonged to amino acid biosynthesis, and one protein was involved in carbohydrate, general stress response, fatty acid metabolism and transport system each. The differential expressed proteins might contribute to the survival of L. casei Zhang in the gastrointestinal tract.