원문정보
초록
영어
Two Lactobacillus spp., KLB295 and KLB275, were selected from 108 lactobacilli which had been isolated from human because KLB295 showed the highest resistance in salt stress(1.8M NaCl) and KLB 275 showed the lowest(0.5M NaCl). KLB295 was identified as L. rhamnosus and KLB275 as L. jensenii using 16S rDNA sequencing and PCR-RFLP(polymerase chain reaction-restriction fragment length polymorphism). When the cell were exposed to various stresses: acid (pH 3.0, pH 5.0), heat (55℃, 65℃), cold(4℃), ethanol (10%), oxidative stress (0.01% H2O2), both strains maintained similar cell number. In adaptation test, salt-adapted(0.3M, 30min) KLB295 showed 10-fold increase in osmotic tolerance (2M NaCl) but there were no changes against other stresses and cross protection. Surface proteins of cells grown under various stress conditions were analyzed by SDS-PAGE, and different protein profiles were observed compared with control cells. From these results it is likely that there is specific gene related to osmotic stress. Several NTG mutants which showed low osmotic resistance were made from the high osmotic resistant strain KLB295 to compare the mutant and parental strains using SDS-PAGE and PCR.