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J. Microbiol. Biotechnol. 2000; 10(2): 147-153

Published online April 28, 2000

Copyright © The Korean Society for Microbiology and Biotechnology.

Comparative Evaluation of Probiotic Activities Bifidobacterium longum MK - G7 with Commercial Bifidobacteria Strains

Hoo-Kil Jung , Eung-Ryool Kim , Geung-Eog Ji 1, Jong-Hyun Park 2, Seong-Kwan Cha 3 and Suk-Lak Juhn 3

R&D Central Research Institute Maeil Dairy Industry Co. Ltd. Pyungtaek 451-860 Korea, 1Department of Food Science and Nutrition Seoul National University Seoul 151-742 Korea, 2Department of Food and Bioengineering Kyungwon University Sungnam 461-701 Korea, 3Korea Food Research Institute Sungnam 463-420 Korea

Abstract

This study was conducted to compare probiotic activities and physiological functions of Bifidobacterium longum Mk-G7 with weveral commercial and type strains of bifidobacteria. bif. longum MK-G7 showed the highest acid tolerance against HCl and acetic acid, whereas bif. infantis Y-1 showed the lowest acid tolerance and more than 4 log cycles of viable cell count decreased due to acid injuty. Viable cell counts of bifidobacteria strains decreased more than 1.5 log cycles owing to oxygen toxicity, with the exception of Bif. longum MK-G7, Bif. infantis Y-2, Bif. longum Y-3, Bif. longum Y-6, and Bif. longum RD-13 showed the highest bile tolerance, whereas Bif. longum MK-G7 showed a medium level of bile tolerance. Only Bif. longum MK-G7 howed much higher antibiotic resistance against both tetracycline and penicillin-G in the MIC(minimum inhibitory concentration) level of 24.8 mg/I and 0.52mg/I, respectively. Bif longum Y-6, and Bif. bifidum ATCC 29539 showed more than 80% of anti-mutagenicity against NQO(4-nitroquinolinel-oxide). Since the production of cytokines such as $TNF(tumor necrosis factor)-{\alpha}$ and IL (interleukin)-6, and NO(nitric oxide) in the macrophage cell line Raw 264.7 cells increased as Bif. longum MK-G7 cell concentration increased, ti was suggested that Bif. longum MK-G7 is able to enhance immunopotentiating activity in vitro. When freeze-dred Bif. longum MK-G7 was administered to mice at the dose of 1,2,4, and 6 g/kg of body weight, all of the mice survived in all feeding groups, proving the GRAS(generally recognized as safe) status of Bif. longum MK-G7. When fermented milk containing Bif. longum MK-G7 was administered to human volunteers, viable cell count of total bifidobacteria and anaerobes in the feces increased up to 0.5 log cycles more than before the administration. In particular, Bif. logum MK-G7 ingibited the growth of Bacteroides at the level of 1.0-1.5 log cycles.

Keywords: BifidobacteriumlongumMK-G7, probioticactivity, physiologicalfunctionality, Koreanorigin