Acid Tolerance ofLactobacillus plantarumfromKimchi

Acid tolerance ofLactobacillus plantarumKFRI 815, isolated fromkimchi, was investigated in terms of Mg and K release, viable cell count, proton permeability, glycolysis, and membrane ATPase activity. The release of Mg from whole cells occurred significantly at pH values below about 3 and rapidly increased at a pH value of about 2. The injured cells significantly increased with time by losing their salt tolerance at a pH of below 4. The proton permeability was minimal at a pH value of about 4, at which the average half time for pH equilibration across the cell membrane was about 70 min. The pH profile for glycolysis of intact cells showed thatL. plantarumcompletely consumed glucose at the pH range of 4.0 to 6.0 and that glucose degradation was reduced by over 50% at pH 2.0. The maximal specific activity of membrane ATPase was about 3.6 units per mg of protein at a pH value close to 5.0. Overall, acid tolerance ofL. plantarumwas found to be closely related to the gross membrane damage and proton permeability of whole cells as well as the specific activity of membrane ATPase.