Effects of addition of sucrose and salt, and of starvation upon thermotolerance and survival during storage of freeze-dried Lactobacillus delbrueckii ssp bulgaricus

Increased survival of freeze-dried cells of Lactobacillus bulgaricus was observed when the drying medium was supplemented with sucrose; however, the magnitude of such protection was dependent on the growth medium used. Supplementing the growth medium with NaCl markedly increased survival of dried cells, and only a small effect was exerted by the composition of the drying medium or prior to starvation of cells. The D₅₇ values of Lactobacillus bulgaricus cells grown in MRS were about half of those of cells grown in MRS supplemented with sucrose, with sucrose plus NaCl, or with NaCl.