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Low-temperature adaptation and cryoprotection were studied in Leuconostoc mesenteroides SY1, a strain isolated from Kimchi. L. mesenteroides SY1 cells grown in exponential growth phase at 30oC were exposed to 15oC, 10oC and 5oC for 2, 4 and 6 h, respectively, and then frozen at -70oC for 24 h. Survival ratio was measured after the cells were thawed. The freezing-thawing cycles were repeated four times. Preadapted cells survived better than non-adapted control cells, and the highest survival ratio (96%) was observed for cells preadapted for 2 h at 5oC, whereas control cells showed only 22%. The 2D gel showed that two proteins (spots A and B) were induced in cells preadapted at lower temperatures. Spots A and B have the same molecular weight (7 kDa), but the pI was 4.6 for spot A and 4.3 for spot B. The first 29 and 15 amino acid sequences from spots A and B were determined, and they were identical, except for one amino acid. A csp gene was cloned and nucleotide sequencing confirmed that the gene encoded spot A cold shock protein.
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