EFFECT OF FREEZING AND THAWING ON THE VIABILITY AND UPTAKE OF AMINO-ACIDS BY L-DELBRUECKII SSP BULGARICUS

Freezing and thawing damaged the cell membrane of Lactobacillus delbrueckii ssp. bulgaricus, thus rendering the microorganism sensitive to NaCl and liver extract. These substances had no inhibitory effect on the unfrozen cells. The amino acids transport system was also depressed in all the freezing regimens tested, a fact that indicates the existence of a close relationstrip between this system and the viability of the cells. Cell injury proved reversible and could be partially repaired with a solution of KH2PO4, pyruvate, and MgSO4. © 1993 by Academic Press, Inc.