Induction of the acid tolerance response in Leuconostoc mesenteroides ATCC 8293 by pre-adaptation in acidic condition

Leuconostoc mesenteroides is a commercially important lactic acid bacterium which is used as a starter culture in various fermentation processes. However, because of its sensitivity to acid stress, high cell-density culture has not been accomplished yet. Therefore, we investigated the effect of preadaptation of L. mesenteroides under mildly acidic conditions for resistance to normally lethal levels of acid stress. For this, the cells grown to the early-exponential phase at pH 7.0 were incubated at pH 6.5, 6.0, and 5.0 for 1 h, and then the survival rates of acid-adapted cells in pH 4.0 solution was determined. Acid-adapted cells at pH 5.0 exhibited maximum increase in tolerance, showing an increased survival of approximately 2,500 folds compared to the control (pH 7.0).