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항생물질 Nisin 을 생산하는 Lactococcus lactis KCTC2184 의 특성
이경욱(K . W . Lee),장영호(Y . H . Jang),김현욱(H . U . Kim) 한국축산학회 1990 한국축산학회지 Vol.32 No.10
Lactococcus lactic KCTC2184 was found to be lactose-negative lactic acid bacteria. Antimicrobial agent produced by Lactococcas lactic KCTC2184 inhibited the growth of Lactococcas lactis NCDOl404. Lactococcus lactic subsp. cremoris CH-14. and Lactobacillus casei YIT9018 in modified M17 medium. The antimicrobial activity was not inactivated by boiling in water for 10 min and by trypsin digestion, and was stable at pH 2.0, but was inactivated at pH 11.0 and by α-chymotrypsin digestion. The overall characteristics indicate the antimicrobial activity due to $quot;nisin$quot;. The quantity of nisin produced by Lactococcas lactic KCTC2184 was examined in four different media; M17 medium, Ml7glc medium, Elliker medium, and LTB medium. After 8 hours of incubation, LTB medium and M17glc medium supported good nisin production. Lactococcas lactic KCTC2184 produced more nisin in LTB medium with pH control between pH 6.5 and pH 6.8 than without pH control. Lactococcas lactic KCTC2184 produced nisin rapidly after 3 hours of inoculation and stopped producing nisin in 8 to 10 hours after inoculation.
Lactobacillus casei LM -1 의 Bacteriophage 저항성 기작에 관한 연구
임광세(K . S . Lim),장영호(Y . H . Jang),백영진(Y . J . Baek),김현욱(H . U . Kim) 한국축산학회 1991 한국축산학회지 Vol.33 No.10
This study was carried out to elucidate the phage defense mechanism of Lactobacillus casei LM-1, the phage-resistant mutant of L. cased S-1, and to obtaine the basic knowledge for developing a better lactic starter bacteria resistant to the phages. The results obtained are summarized as follows ; 1. No differences were found in growth, acid production, and carbohydrate fermentation between L. casei S-1 and L. casei LM-1 in the MRS broth. and transmission electron microscopic studies of L. case; LM-1 revealed that cells were covered with the hairly capsular layer, that is presumed to cover up the phage receptor sites on the surface of the cells. 2. When the cells of L. casei S-1 were treated with mutanolysin, the adsorption rate of phage J-I and ø-I was decreased rapidly. In case of L. casei LM-l, the adsorption rate of phage J-1 and ø-1 was increased around 30 minutes after addition of mutanolysin and then decreased. 3. Based upon the knowledge obtained from enzymatie treatment; and electron micrographs of L. casei LM-I, it is safe to say that the phage-resistant harrier of L. case; LM-1 is the extension of the modified pep-tidoglycan layer of the normal cell wall. 4. Treatment of L. casei LM-1 with 3 kinds of enzymes (subtilisin. α-amylase, β-amylase) did not affect the low adsorption of phage J-I and ø-1 on the host cells. which tells the capsular layer of L. casei LM-1 was not hydrolyzed by these enzymes. 5. No plasmids of L. casei S-1 and L. easei LM-1 were found on agarose gel electrophoresis, which suggests that the gene responsible for the formation of capsular layer was possibly induced due to the chromosomal mutation.
Lactococcus lactis KCTC 2184 의 Nisin Plasmid 에 관한 연구
이경욱(K . W . Lee),장영호(Y . H . Jang),김현욱(H . U . Kim) 한국축산학회 1991 한국축산학회지 Vol.33 No.9
The plasmids of Lactococcus lactis KCTC 2184 producing nisin were studied to find out the nisin plasmid. Lactococcus lactis KCTC 2184 did not ferment lactose and produced raisin, and possessed 9 plasmids and their sizes are 25.1 Mdal, 21.0 Mdal, 17.0 Mdal, 9.2 Mdal. 5.2 Mdal, 3.4 Mdal, 2.7 Mdal, 1.8 Mdal and 1.4 Mdal. Seventeen Mdal plasmid of Lactococcus lactis KCTC 2184 was found to code both raisin production and sucrose-fermenting ability.
Lactobacilli에 의한 Bacillus cereus 의 생장억제에 관한 연구
김현욱,안영태,김용희,장영호 한국동물자원과학회 2000 한국축산학회지 Vol.42 No.3
The growth inhibition effect of Bacillus cereus by lactobacilli has been studied. As L. acidophilus HF 04 or L. acidophilus NCFM was co-incubated with B. cereus in skim milk, the germination and sporulation of B. cereus were inhibited without affecting the growth of L. acidophilus strains. The growth curve of lactobacilli reached stationary phase after IS hours of incubation and the number of B. cereus cells decreased drastically after 10 hours of incubation. The growth of B. cereus was not observed in the skim milk medium lower than pH 4.3. The organic acids produced by lactobacilli were confirmed to inhibit the growth of B. cereus. Acetic acid was more effective growth inhibitor of B. cereus LTDM03 in skim milk medium and thermoduric spores were not germinated after 10 hours of incubation in the skim milk medium adjusted to pH 4.63 by acetic acid.