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KMID : 1007519980070010066
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Food Science and Biotechnology
1998 Volume.7 No. 1 p.66 ~ p.70
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The Relationship between Cell Surface Hydrophobicity (CSH) and Stress Tolerance in Bifidobacterium spp .
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Park, Hee Kyung
SO, JAE SEONG/HEO, TAE RYEON/Lim, Nam Kyu/Yoo, Ji Chul
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Abstract
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In this study, the relationship was examined between cell surface hydrophobicity (CSH) and tolerance of environmental stresses in Bifidobacterium spp. First, the CSH of 7 species of Bifidobacterium was determined by hydrocarbon assay (BATH assay). Among Them, B. infantis ATCC 25962 and B. longum ATCC 15707 was found to have the highest and the lowest CSH, respectively. In order to examine the possible relationship between CSH and stress tolerance, the two strains were exposed to a number of stresses such as bile salt (0.6% oxgall), H₂O₂(1,000 ppm), heat (62℃), cold storage (-20℃) and acid (pH 2, 2.5, 3, 4, 5). Compared with B. longum, B. infantis was found significantly more resistant to various stresses examined. In the presence of bile salt (0.6%), B. infantis and B. longum showed 80% and 9% survivability, respectively. When exposed to H₂O₂(1,000 ppm) for 20 min, viable cell counts of B. infantis and B. longum dropped from 2.0×10^8 CFU/mL to 6.7×10³CFU/mL and from 1.6×10^7 CFU/mL to 0 CFU/mL, respectively. After 90 min incubation upon temperature shift to 62℃, viable cell count of B. infantis dropped from 1.45×lO^8CFU/mL to 3× 10^5CFU/mL whereas that of B. longum dropped markedly to 0CFL/mL. In addtion, during cold storage at -20℃ over the two weeks period, B. infantis and B. longum exhibited 30% and 0.02% survivability, respectively. After 30 min incubation at pH 2, B. infantis survived at a level of 5%, while B. longum exhibited 0% survivability. Higher ATPase activity was observed within the B. infantis than B. longum. These data strongly suggest that there is a close relationship between the CSH and stress tolerance in Bifidnbacterium spp.
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KEYWORD
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