• The Korean Journal of Ecology
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• 제22권1호
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• pp.45-50
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• 1999

김치 발효 초기에 bacteriocin 생성 유산균을 분리하고자 하였다. 분리 유산균은 형태, 배양 및 생리학적인 특징과 16S rDNA의 부분적인 염기서열로부터 Lactococcus lactis로 동정되었다. 분리균주가 생성한 bacteriocin은 Listeria monocytogenes, Staphylococcus aureus와 같은 그람 양성 병원성 세균과 몇몇 유산균에 대해 항균활성이 있었고, 그람음성균인 Yesinia에는 활성이 없었다. bacteriocin의 활성은 protease, protease ⅩⅣ, a-chymotrypsin과 pepsin에 대해서 활성이 소실되었으나, lipase, trypsin, lysozyme에 대해서는 활성이 유지되었다. bacteriocin의 활성은 pH 2∼11에서 안정적이며 l00℃에서 10분간 열처리시에도 변하지 않았다. 따라서 L. monocytogenes는 발효초기에 L. lactis에 의하여 억제될 수 있다.

• 한국미생물·생명공학회지
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• 제40권4호
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• pp.310-318
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• 2012

유세포 형광분석에 의한 유산균의 면역증진 효과와 황색포도상구균에 대한 유산균의 항균활성을 확인하여 항아토피 기능성이 있는 유산균을 탐색하고 그 배양법을 검토하였다. T cell에서 CD4+/CD25+/foxp3+ 증가는 Lactobacillus plantarum, Lactococcus lactis subsp. lactis (Lc. lactis)의 순으로 면역증진효과를 보였고, 황색포도상구균에 대한 항균력은 Lc. lactis, Lb. plantarum의 순으로 나타냈다. Lc. lactis 배양액 첨가배지에 Lb. plantarum을 배양한 실험에서는 항균력의 증가가 없었으나 Lb. plantarum 배양액 첨가배지에 Lc. lactis를 배양한 실험에서 황색포도상구균의 항균활성 증대가 나타났다. 항균력을 증가시키는 유산균 첨가배지법의 최적조건은 Lb. plantarum 배양상층액 10%를 첨가하고 가열살균한 배지에서의 Lc. lactis 배양으로 나타났다. 이때 유산균의 항균역가는 Lc. lactis 순수배양 시보다 대수기 말기에 급격히 증가하여, 황색포도상구균의 증식 억제력이 1.29배 높아졌다.

• Journal of Microbiology and Biotechnology
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• 제17권9호
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• pp.1521-1526
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• 2007

A maltogenic amylase gene from Lactobacillus gasseri ATCC33323 (LGMA) was expressed in Lactococcus lactis MG1363 using the P170 expression system. The successful production of recombinant LGMA (rLGMA) was confirmed by the catalytic activity of the enzyme in liquid and solid media. The N-terminal amino acid sequencing analysis of the rLGMA showed that it was Met-Gln-Leu-Ala-Ala-Leu-, which was the same as that of genuine protein, meaning the signal peptide was efficiently cleaved during secretion to the extracellular milieu. The optimal reaction temperature and pH of rLGMA ($55^{\circ}C$ and pH 5, respectively) and enzymatic hydrolysis patterns on various substrates (${\beta}$-cyclodextrin, starch, and pullulan) supported that rLGMA was not only efficiently secreted from the Lactococcus lactis MG1363 but was also functionally active. Finally, the branched maltooligosaccharides were effectively produced from liquefied com starch, by using rLGMA secreted from Lactococcus lactis, with a yield of 53.1%.

• 한국식품영양학회지
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• 제14권1호
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• pp.59-64
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• 2001

돼지고기 등심의 표면에 Lactococcus lactis subsp. Jactis ATCC l1454 유산균 배양액 3.96 log units의 처리구는 4$^{\circ}C$ 저장 1일 이후 대조구의 TBA가와 유의적 차이가 없었다 (P>0.05). 유산균 배양액 3.96 log units 처리구의 Hunter color L*과 b*가는 저장 동안 대조구와 유의적 차이가 없었다. 그러나 유산균 배양액 4.10과 4.23 log units 처리구의 Hunter a*가는 4$^{\circ}C$ 저장 1일과 6일 이후 대조구와 유의적 차이 (P<0.05)를 나타내었다. 유산균 배양액 4.10과 4.23 log units 처리구의 육즙유출율은 4$^{\circ}C$ 저장 4일 이후부터 처리구와 대조구 사이에 유의적 차이를 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제30권9호
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• pp.1404-1411
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• 2020

Lactic acid bacteria (LAB) play an important role in dairy fermentations, notably as cheese starter cultures. During the cheese production and ripening period, various enzymes from milk, rennet, starter cultures, and non-starter LABs are involved in flavor formation pathways, including glycolysis, proteolysis, and lipolysis. Among these three pathways, starter LABs are particularly related to amino acid degradation, presumably as the origins of major flavor compounds. Therefore, we used several enzymes as major criteria for the selection of starter bacteria with flavor-forming ability. Lactococcus lactis subsp. lactis LDTM6802 and Lactococcus lactis subsp. cremoris LDTM6803, isolated from Korean raw milk and cucumber kimchi, were confirmed by using multiplex PCR and characterized as starter bacteria. The combinations of starter bacteria were validated in a miniature Gouda-type cheese model. The flavor compounds of the tested miniature cheeses were analyzed and profiled by using an electronic nose. Compared to commercial industrial cheese starters, selected starter bacteria showed lower pH, and more variety in their flavor profile. These results demonstrated that LDTM6802 and LDTM6803 as starter bacteria have potent starter properties with a characteristic flavor-forming ability in cheese.

• Journal of Microbiology and Biotechnology
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• 제6권2호
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• pp.137-141
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• 1996

Acetoin and ammonia, the precursors of tetramethylpyrazine (TMP) having "meaty" or "roasted" flavors, were produced by the culture of Lactococcus lactis ssp. lactis biovar. diacetilactis FC1 in free and immobilized cell systems. Cells were immobilized using k-carrageenan and then were incubated at $34^{\circ}C$. The TMP productivity (0.34 g/l) and the conversion ratio (9.3%) of acetoin to TMP of the immobilized cell system were higher than those (0.24 g/l, 7.0%) of the free cell system. When the beads were activated for 12 h, the productivity of acetoin and TMP increased slightly.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.554-557
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• 2000

Strain JV3 was isolated from commercial Swiss cheese products and identified as a bacteriocin producer, which has bactericidal activity against Leuconostoc mesenteroides KCCM 11324. Strain JW3 was identified tentatively as Lactococcus lactis by the API test. The activity of lacticin JW3, named tentatively as the bacteriocin produced by Lactococcus lactis JW3, was detected during the mid-log growth phase, and reached a maximum during the early stationary phase, and decreased after the late stationary phase. Its antimicrobial activity on sensitive indicator cells was completely disappeared by protease IV. The inhibitory activities of lacticin JW3 were detected during treatments of up to $121\'^{circ}C$ for 15 min. Lacticin JW3 was very stable over a pH range of 2.0 to 9.0 The apparent molecular mass of lacticin JW3 was estimated to be in the region of 3-3.5kDa, which was determined by the direct detection of bactericidal activity after SDS-PAGE.

• 한국미생물·생명공학회지
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• 제26권6호
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• pp.562-565
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• 1998

Nisin-producing and nisin resistant L. lactis subsp. lactis ATCC7962 harbored six plasmids. To find a plasmid containing a nisin resistant gene, these plasmids were transformed into L lactis LM0230 of plasmid-free and nisin sensitive strain. After screening on nisin selection media containing nisin (150 $\mu\textrm{g}$/$m\ell$), several nisin resistant transformants were obtained and the level of nisin resistance was very similar to that of wild type L lactis subsp. lactis ATCC7962. A 26.5 kb plasmid, named as pCS100, which confers resistance to nisin, was identified in transformants. The pCS100 was digested with EcoRI and Southern blot hybridization was done with nisI probe to localize the nisin resistant gene. A 4 kb EcoRI fragment showed a strong positive signal, and it was cloned into pBluescript for the potential selection marker.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.697-700
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• 2003

젓갈에서 분리한 유용 유산균인 Lactococcus lactis NK24, Lactobacillus plantarum NK181, 효모인 strain HW161를 대상으로 항산화능과 콜레스테롤 저해능을 검토 하였다. 항산화능을 조사한 결과, DPPH의 free radical 소거능은, strain HW161, Lactococcus lactis NK24, Lactobacillus plantarum NK181 순서로 나타났다. TCA를 이용한 실험의 결과, 과산화물질 저해능을 확인할 수 있었다. 또한, 콜레스테롤 저하 실험의 결과 는 strain NK181이 가장 우수하게 나타났다. 따라서 본 실험에서 사용된 균주들은 프로바이오틱 생균제로서의 가능성을 보여 주었다.

• Journal of Microbiology and Biotechnology
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• 제4권3호
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• pp.191-194
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• 1994

Acetoin and ammonia, the precursors of tetramethylpyrazine (TMP) having "nutty " or "roasted" flavors, were produced by cultivating Lactococcus lactis ssp. lactis biovar. diacetilactis FC1. The effects of the volume concentration ratio (VCR) of cell-free medium on the formation of TMP were investigated using a rotary evaporator at $70^{\circ}C than at 80^{\circ}C$. As the VCR increased, the formation of TMP and the conversion ratio of acetoin to TMP increased. More TMP were formed at $70^{\circ}C than at 80^{\circ}C$. As the VCR increased, the concentration of acetoin decreased implying the formation of TMP from acetoin and ammonia.