• 대한미생물학회지
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• 제35권1호
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• pp.77-85
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• 2000

Streptococcus mutans is the most important causative bacteria of dental caries among the oral bacteria. Lactococcus lactis 1370 was isolated from the oral cavity of child. The effect of Lactococcus lactis 1370 on the formation of artificial plaque by Streptococcus mutans was studied. 1. The insoluble substances and bacteria were much more attached on the wall of disposable cuvette in the culture of Streptococcus mutans than in the combined culture of Streptococcus mutans and Lactococcus lactis 1370. 2. The mean weight of produced artificial plaque on the wires in the beaker was 131.7 mg in the culture of Streptococcus mutans only, whereas being reduced to 6.4 mg in the combined culture of Streptococcus mutans and Lactococcus lactis 1370 (p<0.05). The viable cell didn't show the significant difference between them after culturing. 3. When Streptococcus mutans was cultured in the media containing culture supernatant of Lactococcus lactis 1370 cultured in M17 broth containing 0.5% yeast extract and 5% sucrose, the mean weight of produced artificial plaque was 8.0 mg on the wires, whereas being 125.4 mg in the media without culture supernatant of Lactococcus lactis 1370 (p<0.05). The viable cell didn't show the significant difference between them after culturing. 4. When Streptococcus mutans was cultured in the media containing soluble polymer produced by Lactococcus lactis 1370, the mean weight of produced artificial plaque was significantly reduced compared with being cultured in the media without soluble polymer (p<0.05). The viable cell didn't show the significant difference between them after culturing. 5. The soluble polymer produced by Lactococcus lactis 1370 was glucan. 6. The glucan produced by Lactococcus lactis 1370 was water-soluble glucan containing ${\alpha}$-1,6-glucose linkage as the main linkage. These results suggest that the artificial plaque formed by Streptococcus mutans is inhibited by water-soluble glucan produced by Lactococcus lactis 1370.

• 대한임상검사과학회지
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• 제53권3호
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• pp.277-283
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• 2021

Lactococcus속은 조건무산소성 그람양성알균으로 catalase 음성, 비운동성이며 10~40℃에서 배양된다. Lactococcus속은 16개의 종으로 구성되어 있으며, 그 중 Lactococcus garvieae와 Lactococcus lactis가 인간질병에 주로 관여하는 것으로 알려져 있다. 본 연구는 발열, 구토, 옆구리 통증으로 내원한 74세 여자의 소변 배양에서 Lactococcus garvieae가 배양된 사례를 최초 보고한다. 상기 환자는 의료기관에서 시행한 혈액검사, 미생물 배양검사, 컴퓨터단층촬영 등의 검사를 통해 급성 요로감염의 소견을 확인하였다. 신장내과 병동에 입원 후 수액처치 및 에리스로마이신 항생제 치료를 시행하였고 5일 후 환자는 퇴원하였다. 본 증례는 우리나라에서 처음으로 요로감염 환자의 소변에서 L. garvieae가 분리된 사례로서 향후 L. garvieae 감염 환자의 치료에 도움이 될 것이다.

• 한국미생물·생명공학회지
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• 제22권5호
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• pp.522-530
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• 1994

Bacteriocin-producing lactic acid bacteria, Lactococcus sp. HY 449, was isolated from dairy products. Using response surface methodology, the various concentrations of medium compo- nents (tryptone, glucose, yeast extract, tween 80, and initial pH) were tested to find the optimum conditions for maximum bacteriocin production and growth of Lactococcus sp. HY 449. Central composite design was used to control the concentrations of medium components in the experiment. Bacteriocin production and cell growth of Lactococcus sp. HY 449 were most affected by glucose and yeast extract. Estimated optimum growth conditions of Lactococcus sp. HY 449 were as follows; tryptone 1.08%, glucose 1.129%, yeast extract 0.674%, tween 80 0.11%, and initial pH 7.19. Also estimated optimum conditions for bacteriocin production were tryptone 0.937%, glucose 1.108%, yeast extract 0.163%, tween 80 0.09%, and initial pH 6.98.

• 한국미생물·생명공학회지
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• 제22권3호
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• pp.259-265
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• 1994

A bacteriocin-producing lactic acid bacteria was isolated from contaminated milk products, which was identified by using the API50 CH kit as Lactococcus lactis subsp. lactis with reliability of 98%. Fatty and analysia of the cell membrane showed that this strain contained same fatty acids profiles as type strain, Lactococcus lactis subsp. lactis ATCC 19435. The bacteriocin of Lactococcus sp. HY 449 showed relatively wide range of inhibition spectrum against gram positive and some gram negative bacteria such as Escherichia coli and maintained the inhibitory activity between pH2.0 and pH9.0 The thermostability of this bacteriocin was higher in acidic solution than in distilled water and was stable at 60$\circ $C for 1 hour.

• 생명과학회지
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• 제9권1호
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• pp.111-120
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• 1999

우리 고유의 전통 발효 음식인 김치로부터 bacteriocin 생성능이 우수한 Lactococcus sp. J-105균주를 분리하였다. Lactococcus sp. J-105의 생육 및 bacteriocin 생성에 대한 최적 조건을 검토한 결과 bacteriocin 생성은 대수 증식기 말기에서 정지기 초기에 가장 많이 생성되었다. Lactococcus sp. J-105의 생육 및 bacteriocin 생성 최적 탄소원 및 질소원은 각각 maltose와 polypeptone이었다. 균의 생육 및 bacteriocin 생성 최적 온도는 $25^{\circ}C$였으며 생육 최적 pH는 pH 8 부근이었다. bacteriocin 생성 또한 pH 8에서 최고를 나타내었다. 한편 NaCl은 오히려 균체 증식과 bac-tericoin 생성을 저해하였다. Lactococcus sp. J-105가 생산하는 bacteriocin의 pH 및 열에 대한 안정성을 검토한 결과 pH 2~4, $121^{\circ}C$ 15분에서 각각 안정하였다. 또한 J-105의 항균 spectrum을 검토한 결과 Lactobacillus sp. Leuconostoc s 그리고 Bacillus subtilis 등의 Gram 양성균에 대해서 항균활성 나타내었으며 Gram 음성균인 Acetobacter acid에 대해서도 항균 활성을 나타내었으나 E. coli에 대해서는 항균 활성을 나타내지 않았다. 본 bacteriocin은 trypsin, protease와 같은 peptide 분해효소에 대해서는 안정한 반면, pepsin에 의해서는 활성이 상실되는 특이한 성질을 나타내었다

• Journal of Animal Science and Technology
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• 제63권1호
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• pp.191-193
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• 2021

Lactococcus lactis is a fermentative lactic acid bacterium that is used extensively in food fermentations. The L. lactis strain K_LL005 was isolated from the grasshopper (Oxya chinensis sinuosa) gut in Korea. In this study, we reported the complete genome sequence of Lactococcus lactis K_LL005. The final complete genome assembly consist of one circular chromosome (2,375,093 bp) with an overall guanine + cytosine (G + C) content of 35.0%. Annotation results revealed 2,281 protein-coding sequences (CDSs), 19 rRNAs, and 68 tRNA genes. Lactococcus lactis K_LL005 has a gene encoding xylose metabolism such as xylR, xylA, and xylB (xylRAB).

• 대한소아치과학회지
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• 제28권4호
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• pp.583-592
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• 2001

치태 억제효과가 있는 것으로 알려진 Lactococcus lactis 1370으로 제조한 양치용액이 실제 소아들의 구강내에서 치태의 형성을 억제하는지 여부와 이들 균주의 시간경과에 따른 구강내 잔류율을 알아보고자 소아 30명을 대상으로 위양치액 (Lactobacillus casei)과 유산균 양치액 (Lactococcus lactis 1370)으로 양치하도록 한 뒤 시간경과에 따른 치태지수, 치태부착면적을, 그리고 Lactococcus lactis 1370의 생균수를 count하여 다음과 같은 결과를 얻었다. 1. 대조군과 실험군에서 24시간후 치태지수는 각각 평균 2.43과 2.06으로 양치에 의해 치태지수는 평균 0.37 감소하였으며 치태형성억제율은 약 15%로 유의한 감소를 보였다 (P<0.05). 2. 48시간 후 치태지수는 대조군과 실험군에서 각각 평균 2.95와 2.17로 양치에 의해 치태지수는 평균 0.78 감소하였으며 치태형성 억제율은 약 26%로 24시간후에 비해 좀더 많은 감소를 보였다(P<0.05). 3. 대조군과 실험군에서 24시간후 치태부착면적율은 각각 평균 21.2%와 15.6%로 양치에 의해 치태부착면적율은 평균 5.63% 감소하였으며 치태형성억제율은 약 26%로 유의한 감소를 보였다(P<0.05). 4. 48시간후 치태부착면적율은 대조군과 실험군에서 각각 평균 33%와 17.8%로 양치에 의해 치태부착면적율은 평균 15.1% 감소하였으며 치태형성 억제율은 약 46%로 24시간 후에 비해 좀 더 많은 감소를 보였다(P<0.05). 5. 양치후 시간에 따른 구강내 생균수를 count한 결과 1시간 이후까지는 급격한 감소를, 3시간 후에는 약간의 감소를 보였으며 3시간부터 6시간 사이에는 약간의 증가추세를 보였다.

• Journal of Microbiology and Biotechnology
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• 제10권4호
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• pp.488-495
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• 2000

Strain SA72 was isolated from Jeot-gal and identified as producer of a bacteriocin, which showed some bactericidal activity against Lactobacillus delbrueckii ATCC 4797. Strain SA72 was tentatively identified as Lactococcus lactis according to the AOI test. Lactococcus lactis SA72 showed a broad spectrum of microorganisms, tested by the modified deferred method. The activity of lacticion SA72, named tentatively as a bacteriocin produced by Lactococcus lactis SA72, was detected during the mid-lon growth phase, reached a maximum during the early stationary phase, and then declined after the late stationary phase. Lacticin SA72 also showed a relatively broad spectrum of activity against non-pathogenic and pathogenic microorganisms when assessed by the spot-on-lawn method. Its anitimicrobial activity on sensitive indicator cells disappeared completely by protease XIV treatment. The inhibitory activity of lacticin SA72 remained after treatment for 15 min at $121^{\circ}C$, 문 was stable in a pH range of 2.0 to 9.0 and all organic solvents examined. It demonstrated a typical bactericidal mode of inhibition against Lactobacillus delbrueckii ATCC 4797. The apparent molecular mass of lacticin SA72 was in the region of 3-3.5 kDa, determined by SDS-PAGE.

• Journal of Microbiology and Biotechnology
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• 제20권9호
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• pp.1307-1313
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• 2010

An extracellular ${\alpha}$-amylase from Lactococcus lactis IBB500 was purified and characterized. The optimum conditions for the enzyme activity were a pH of 4.5, temperature of $35^{\circ}C$, and enzyme molecular mass of 121 kDa. The genome analysis and a plasmid curing experiment indicated that $amy^+$ genes were located in a plasmid of 30 kb. An analysis of the phylogenetic relationships strongly supported a hypothesis of horizontal gene transfer. A strong homology was found for the peptides with the sequence of ${\alpha}$-amylases from Ralstonia pikettii and Ralstonia solanacearum. The protein with ${\alpha}$-amylase activity purified in this study is the first one described for the Lactococcus lactis species, and this paper is the first report on a Lactococcus lactis strain belonging to the amylolytic lactic acid bacteria (ALAB).

• Journal of Microbiology and Biotechnology
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• 제13권2호
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• pp.202-206
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• 2003

To determine the effect of immunopotentiating activity of cellular components of Lactococcus lactis ssp. lactis, the immune function was analyzed in vitro using mice cells. When stimulated with mitogens, productions of $IFN-{\gamma}$, IL-12, $TNF-{\alpha}$, and IL-6 were enhanced in spleen cells treated with cellular components, with IL-4 production being the highest in spleen cells treated with cytoplasm fraction. Without mitogen stimulation, the productions of $IFN-{\gamma}$ and IL-12 were the highest in spleen cells treated with heat-killed whole cell. $TNF-{\alpha}$ and IL-6 productions were also high in spleen cells treated with all cellular components. Only heat-killed whole cell showed significant enhancement in natural killer cell activity. In peritoneal exudates cells, $TNF-{\alpha}$ production was enhanced significantly by all cellular components of Lactococcus lactis ssp. lactis These results indicate that the cellular components of Lactococcus lactis ssp. lactis are capable of stimulating immune cells to produce cytokines, and that both their cell walls and cytoplasm fraction contribute to these capacities.