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

• Journal of Microbiology and Biotechnology
• /
• 제6권6호
• /
• pp.386-390
• /
• 1996

The ${\beta}$-galactosidase gene from Lactococcus lactis subsp. lactis ATCC 7962 was cloned and its enzymatic properties were characterized, with a view to assessing its potential use as a selection marker in the food-grade cloning vector. Chromosomal DNA from L. lactis subsp. lactis 7962 was cleaved with PstI and ligated into pBR322 for transformation into Escherichia coli TGl. Transformants showing ${\beta}$-galactosidase activity possessed the pBR322 plasmid containing a 10 kilobase (kb) PstI fragment and this plasmid was named pCKL11. The cloned ${\beta}$-galactosidase gene came from the chromosomal DNA of L. lactis subsp. lactis 7962 was confirmed by Southern hybridization. A restriction map of pCKL11 was constructed from the cleavage of both pCKL11 and the purified 10kb insert fraqment. The. optimum pH of the ${\beta}$-galactosidase determined with the E. coli harboring the pCKL11 was 7.0. The optimum temperature was $50^{\circ}C$, while the pI of the enzyme was 7.4. These values were the same as those of the enzyme from the parent strain.

• Journal of Microbiology and Biotechnology
• /
• 제9권1호
• /
• pp.39-43
• /
• 1999

A flocculent aggregate produced by Lactococcus lactis subsp. lactis in broths containing Tween 80, including MRS broth, had a microscopic structure of intertwined thread-like filaments. The filamentous structure was not elongated bacterial cells, but consisted of an organic solvent-soluble portion and an insoluble solid. L. lactis subsp. lactis grown at $25^{\circ}C$ for 15 days in tryptic soy broth with 0.1% Tween 80 and 1.0% malt extract produced 13 mg/l of flocculent aggregate, which contained 0.84 g/g of organic solvent-soluble component. The organic solvent-soluble part was identified as 10-hydroxyoctadecanoic acid.

• Journal of Microbiology and Biotechnology
• /
• 제9권6호
• /
• pp.732-736
• /
• 1999

The superoxide dismutase (SOD) in Lactococcus lactis was measured quantitatively and qualitatively under various culture conditions. The L. lactis SOD was induced by oxidative stress. As the concentration of paraquat to produce superoxide radicals increased, the growth of L. lactis decreased with concomitant increase of SOD activity. The SOD activity was found to be growth-phase dependent: when aerobically grown cells entered to the stationary phase, the activity increased gradually until the late stationary phase. From inhibition studies, L. lactis SOD was found to be insensitive to KCN and $H_2O_2$ which are known to inhibit Cu/ZnSOD and FeSOD, respectively. Moreover, as the concentration of manganese in the medium increased, the activity of SOD also increased. These data strongly suggested that L. lactis possessed a single manganese-containing SOD (MnSOD). Finally, a putative sod gene fragment of 510 bp was identified in L. lactis using a polymerase chain reaction (PCR) with degenerate primers designed from the deduced DNA sequences of known SOD genes.

• Journal of Microbiology and Biotechnology
• /
• 제6권6호
• /
• pp.381-385
• /
• 1996

Three distinct plasmids, with approximate molecular weights of 1, 4.5, and 33 megadaltons, were found in Lactococcus lactis subsp. lactis (L. lactis) ML8. Slow acid-producing mutants of L. lactis ML8, isolated by plasmid curing with acriflavine treatment, lacked the 33-megadalton plasmids. The plasmid-cured mutant showed lactose-negative (Lac) characteristics and the alteration of extracellular proteinase pattern. The possible involvement of extracellular proteinase with the 33-megadalton plasmid is highlighted in this research.

• Asian-Australasian Journal of Animal Sciences
• /
• 제17권12호
• /
• pp.1741-1745
• /
• 2004

Administration of milk and fermented milks produced from indigenous dadih lactic acid bacteria on serum lipids and bile acids, fecal bile acids and microflora was estimated in hypercholesterolemic rats. Anaerobic lactic acid bacteria decreased and coliforms increased in the feces of the control group; however, the number of fecal lactic acid bacteria remained unchanged when rats were administered milk and fermented milks. Only fermented milk made from Lc. lactis subsp. lactis IS-10285 significantly reduced serum total cholesterol, LDL cholesterol and total bile acids. Milk and fermented milks did not influence the HDL cholesterol. Triglyceride and phospholipid levels were significantly lower in the rats fed fermented milk of Lc. lactis subsp. lactis IS-10285 than rats fed milk and fermented milk of Lc. lactis subsp. lactis IS-29862, but not significantly different from the control group. Hypocholesterolemic effect of Lc. lactis subsp. lactis IS-10285 was attributed to its ability to suppress the reabsorption of bile acids into the enterohepatic circulation and to enhance the excretion of bile acids in feces of hypercholesterolemic rats.

• 미생물학회지
• /
• 제54권4호
• /
• pp.445-447
• /
• 2018

한국의 전통시장에서 구입한 김치에서 분리된 Leuconostoc lactis CCK940은 sucrose와 maltose를 이용하여 중합도가 4이상인 올리고당을 생산하였다. L. lactis CCK940의 유전체는 1,741,511 bp의 2개 contig로 구성된 염색체로 조합되었으며 G + C의 비율은 43.33%로 나타났다. 염색체 DNA에서 1,698개의 코딩 유전자, 12개의 rRNA, 68개의 tRNA 유전자가 확인되었다. L. lactis CCK940은 올리고당을 생산할 수 있는 sucrose phosphorylase, maltose phosphorylase, ${\beta}$-galactosidase 등의 glucosyltransferase 생합성 유전자들을 지니고 있었다.

• Journal of Microbiology and Biotechnology
• /
• 제33권6호
• /
• pp.823-830
• /
• 2023

Lactococcus lactis is a lactic acid bacterium and used in the dairy food industry. The ameliorating effects of Lactobacillus species on atopic dermatitis (AD) have been extensively studied, but the specific effect of L. lactis strains has not yet been investigated. In this study, the efficacy of L. lactis LB 1022, isolated from natural cheese, was evaluated using RAW 264.7, HMC-1 and HaCaT cell lines and an ovalbumin-sensitized AD mouse model. L. lactis LB 1022 exhibited nitric oxide suppression and anti-allergy and anti-inflammatory activity in vitro. Oral administration of L. lactis LB 1022 to AD mice significantly reduced the levels of IgE, mast cells, and eosinophils, and a range of T cell-mediated T helper Th1, Th2, and Th17-type cytokines under interleukin (IL)-10, transforming growth factor-β (TGF-β), thymus and activation-regulated chemokine (TARC), and thymic stromal lymphopoietin (TSLP). In addition, L. lactis LB 1022 treatment increased the concentration of short-chain fatty acids. Overall, L. lactis LB 1022 significantly modulated AD-like symptoms by altering metabolites and the immune response, illustrating its potential as candidate for use in functional food supplements to alleviate AD.

• 한국식품저장유통학회지
• /
• 제6권4호
• /
• pp.442-447
• /
• 1999

섬유질이 풍부하고 enthocyanin색소가 풍부한 자색 고구마를 이용하기 위하여 탈지유와 설탕이 들어있는 기본배지에 증자, 박피한 고구마를 첨가한 후 5종(Lactebacillus bulgaricis, Lactobacillus delbruchii sub. sp. lactis, Streptococcus lactis, Bifidobacterium bifidum, Leuconostoc lactis) 의 젖산균주를 배양, 접종하여 호상 요쿠르트를 만들고 자색고구마가 젖산균의 생육과산 생성, 색도에 미치는 영향 및 저장성 등을 조사한 결과 L. bulgaricus균을 배양한 경우가 젖산균의 증식과 산 생성이 가장 빨라 발효개시 12시간만에 1.04 $\times$$10^{9}$CFU/$m\ell$의 생균수와 pH 4.22를 나타냈고 B. bifidum균은 발효개시 24시간까지는 젖산균의 증식이 느리게 이루어져 발효개시 36시간에 달할 때 3.3 $\times$ $10^{8}$ CFU/$m\ell$의 생균수와 pH 5.1을 나타냈다. 발효종료 후 자색고구마를 첨가한 요쿠르트의 자색은 B. bifdum균에 의한 요쿠르트제조시 색도가 가장 안정하였고 Leuc. lactis, L. delbruechii sub. sp. lactis, L bulgaricus순으로 안정하였으며 St. lactis균에 의한 요쿠르트는 자색의 색소 소실이 가장 많았다. 2~3$^{\circ}C$에서 저장시 저장 2주까지 pH의 변화는 거의 없었고 생균수의 변화는 L. bulgaricus와 L. delbruechii sub. sp. lactis균에 의해 제조된 요쿠르트는 저장 1주까지는 변화가 없었으나 그 이후는 약간 감소하였으며 St. lactis균과 B. bifidum 균은 저장 1주까지 저온에서도 생균수가 소량 증가함을 보여주었다. 색도는 저장 2주 후 B. bifidum균에 의한 요쿠르트 제조시 자색도가 많이 소실되었고 L. delbruechii sub. sp. lactis균에 의한 요쿠르트가 가장 안정하였다.

• Journal of Microbiology and Biotechnology
• /
• 제2권2호
• /
• pp.73-77
• /
• 1992

The effect of a nisin-producing Lactococcus lactis spp. lactis (L. lactis) on the growth and attachment of Listeria monocytogenes Scott A and Brie 1 on stainless steel and their growth in Brain Heart Infusion broth was determined. Viable cells of Listeria decreased rapidly after 9~12 hr of incubation at $21^{\circ}C$ and after 6~9 hr of incubation at $32^{\circ}C$ in the presence of L. lactis. The number of L. monocytogenes Scott A attached to stainless steel in pure culture was $2.5{\times}10^3/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}2.3{\times}10^3/\textrm{cm}^2{\;}at{\;}32^{\circ}C$ after 48 hr of incubation, but was only $10/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}1.1{\times}10/\textrm{cm}^2{\;}at{\;}32^{\circ}C$ in the presence of L. lactis. Results from L. monocytogenes strain Brie 1 were similar to those from strain Scott A. The population of L. monocytogenes Scott A which attached to stainless steel with previously adherent L. lactis was $1.8{\times}10^2/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}8.2{\times}10^2/\textrm{cm}^2{\;}at{\;}32^{\circ}C$, whereas the population attached to sterile stainless steel was $1.2{\times}10^3/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}2.1{\times}10^2/\textrm{cm}^2{\;}at{\;}32^{\circ}C$. For L. monocytogenes Brie 1, the attached population of the control was $1.6{\times}10^4/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}3.2{\times}10^2/\textrm{cm}^2{\;}at{\;}32^{\circ}C$, and on stainless steel with adherent L. lactis, it was $1.1{\times}10/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}6.9{\times}10/\textrm{cm}^2{\;}at{\;}32^{\circ}C$. Surface adherent L. lactis was less inhibitory to attachment of L. monocytogenes on stainless steel than a liquid culture inoculum. Listeria attached to stainless steel survived dry storage for 20 days both in the presence and absence of adherent lactococci.