Influence of cross-protection on the survival of Lactobacillus casei ATCC 393
交互保护对干酪乳杆菌ATCC 393~(TM)存活的影响

Abstract: Objective] In this study, we investigated the cross-protection of Lactobacillus casei ATCC? 393TM under multi-stress conditions. Methods] Cells pre-adapted to mild conditions (heat, H2O2, acid or bile salts) were then treated at lethal temperature (>60 oC) 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 393TM were affected by different stress conditions cell encountered. 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. Conclusion] In this study, hydrochloride adaption was the best inducer for the cross-protection of Lactobacillus casei ATCC 393TM to maintain relatively stable physiological status of cells. The results above supplied a novel way to investigate the relationship between different protective mechanisms in L. casei under different kinds of stresses.