Cryotolerance and cold adaptation in Lactococcus lactis subsp lactis IL1403

The physiology of the cold-shock response in Lactococcus lactis subsp, lactis IL1403 at a subzero temperature, and cold-induced adaptation to heat shock, were investigated. Preincubation of cells at 8 degrees C led to the development of cryotolerance, i.e., an enhanced capacity to survive exposure to freezing temperature (-20 degrees C). Pretreatment with chemicals considered to be chaotropic agents did not induce cryotolerance or, in contrast, led to a decrease in survival capacity at -20 degrees C. Interestingly, preincubation at 8 degrees C led also to thermotolerance to a 52 degrees C challenge, but preincubation of cells at 42 degrees C for 30 min did not improve their capacity to survive freezing-thawing exposure. These results demonstrate that cold- and heat-shock responses are physiologically linked by a complex relation. Furthermore, food processing at low temperature before subzero or heat treatment may need to be reconsidered. (C) 1995 Academic Press, Inc.