The Effect of Cold-adaptation on Stress Responses and Identification of a Cold Shock Gene, cspA in Lactobacillus crispatus KLB46

초록

Lactobacilli have been considered to play important roles in the health of human vagina. They secrete inhibitory substances to prevent vaginal infection by pathogenic organisms. In a previous study, we isolated several lactobacilli from Korean women and one of them (KLB46) was selected and indentified as Lactobacillus crispatus which showed high antimicrobial activity. Formulated L. crispatus KLB46 can be used for ecological treatment of bacterial vaginosis. For pharmaceutical formulation, the lyophilization process is required. During lyophilization cells are routinely subjected to stresses such as freezing/thawing and dehydration. In this study, cold adaptation prior to stress exposure was examined whether the adapted cells undergoing the stresses maintain the viability better than the non-adapted ones. For cold adaptation, cultured L. crispatus KLB46 cells were exposed to 10℃ for 4 hrs. After pre-treatment at low temperature, the viable cell counts remained significantly higher in subsequent stress conditions. Upon exposure to various stresses such as freezing/thawing, dehydration, acid and heat, the viable cell numbers of adapted cells was 3 - 10 folds higher than those of non-adapted ones. It appeared that de novo protein synthesis is required during adaptation since a protein synthesis inhibitor, chloramphenicol abolished the increased stress tolerance. By using a degenerate PCR primer set, a cspA homolog was amplified from L. crispatus KLB46 genome and sequenced. The deduced amino acid sequence of the putative CspA shares a significant similarity with known CspA proteins of other bacteria.