Influence of cross-protection on the survival of Lactobacillus casei ATCC 393

Objective: In this study, we investigated the cross-protection of Lactobacillus casei ATCC 393 under multi-stress conditions.

Methods: Cells pre-adapted to mild conditions (heat, H2O2, acid or bile salts) were then treated at lethal temperature (> 60 degrees C) or hydrogen peroxide stress (> 5 mmol/L). Furthermore, the changes of survival rate intracellular pH and membrane fatty acid under lethal conditions with or without acid adaption were compared.

Results: The cross-protection in Lactobacillus casei ATCC 393 were affected by different stress conditions. Acid pre-adaption, especially hydrochloride treatment, would increase the resistance of cells to lethal heat and peroxide stresses significantly, with the survival rate of 305-fold and 173-fold, respectively. Further study suggested that the effect of acid pre-adaption might be related to the regulation on intracellular pH and the saturation of cell membrane.

Conclusions: Hydrochloride adaption was the best inducer for the cross-protection of Lactobacillus casei ATCC 393 to maintain relatively stable physiological status of cells. The results supplied a novel way to investigate the relationship between different protective mechanisms in L. casei under different kinds of stresses.