• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.5
• /
• pp.726-731
• /
• 2003

The aim of this research was to identify candidate probiotic lactic bacteria among indigenous dadih lactic isolates. Dadih is an Indonesian traditional fermented milk of West Sumatra which is fermented naturally. Viability of the strain is critical in determining the capacity of lactic bacteria to induce immune stimulation as well as to colonize in the intestinal tract. Therefore, LAB are proposed to exert health promoting or probiotic effects in human, such as inhibition of pathogenic microflora, antimutagenic, and the reduction of cholesterol levels. This manuscript reports in vitro probiotic properties of indigenous dadih lactic bacteria, especially some important colonization factors in GI tract, such as lysozyme, acid and bile tolerance. Bile Salt Hydrolase (BSH) activity, spectrum of bacteriocin, and antimutagenic activity of bacterial cells were also assessed. Twenty dadih lactic isolates were screened further for their tolerance to low pH, at pH 2 and 3 as well as their bile tolerance. There were ten isolates classified as acid and bile acid tolerant, and further screened for lysozyme tolerance, BSH activity. The spectrum of bacteriocin activity of isolates was assayed using cell-free neutralized supernatants by agar spot test against variety of pathogens. Lc. lactis subsp. lactis IS-10285, IS-7386, IS-16183, IS-11857 and IS-29862, L. brevis IS-27560, IS-26958 and IS-23427, Leu.mesen.mesenteroides IS-27526, and L. casei IS-7257 each has good survival rate at low pH values and in the presence of lysozyme, and short lag time in the presence of 0.3 % oxgall. Lc. lactis subsp. lactis IS-11857 and IS-29862 each has high BHS activity, Lc. lactis subsp. lactis IS-10285 and IS-16183 each had a positive spectrum of bacteriocin activity against E. coli 3301 and Lysteria monocytogenes ATCC 19112, while L. brevis IS-26958 has high BHS activity as well as positive spectrum of bacteriocin against E. coli 3301, Lysteria monocytogenes ATCC 19112, and S. aureus IFO 3060. All of the ten dadih lactic strains performed in vitro acid and bile tolerance, indicating a possibility to reach the intestine alive, and display probiotic activities.

• Applied Biological Chemistry
• /
• v.42 no.2
• /
• pp.83-90
• /
• 1999

Four strains of lactic acid bacteria which had cholesterol lowering activities were selected from foreign fermented milk. The strains were identified as Lactobacillus(L.) rhamnosus 2084, L. casei 0781, Lactococcus (Lacto.) lactis spp. 204, and Enterococcus(E.) faecium 402. We observed that the L. rhamnosus 2084 was the most tolerant against pH 1.5, L. casei 0781 against pH 2.0, but not significantly different in the tolerance against pH 3.0. The L. rhamnosus 2084 was the most tolerant against bile acid and prominent in the degree of lowering cholesterol level. All four strains were used as starters in producing yogurt, and then investigated physico-chemical characteristics, such as pH, titratable acidity, and viable cell counts of yogurt base. L. casei 0781, L. rhamnosus 2084, Lacto. lactis 204, and E. faecium 402 were incubated for 6 hours at $40^{\circ}C$, 4 hours at $40^{\circ}C$, 6 hours at $37^{\circ}C$, and 12 hours at $37^{\circ}C$ and $40^{\circ}C$, respectively, for the optimum conditions of fermented milk.

• Korean Journal of Food Science and Technology
• /
• v.46 no.2
• /
• pp.165-172
• /
• 2014

Mixed fermentation of cow milk was performed by sequential co-cultures with Bacillus subtilis and Lactococcus lactis. After a first fermentation step with B. subtilis for 6 h, the number of viable cells increased to $2.5{\times}10^8$ CFU/mL. The second fermentation step with L. lactis resulted in increased viable cells $1.09{\times}10^{10}$ CFU/mL for 3 days and increased acidity. However, the number of viable B. subtilis cells was decreased greatly to $5{\times}10^1$ CFU/mL following fermentation with L. lactis. Milk proteins were markedly hydrolyzed by the first fermentation after 2 h, and the second fermentation induced curd formation in milk. However, after 4 h, the first fermentation resulted in higher whey separation and 80 mg% tyrosine content. Gamma-aminobutyric acid (GABA) production was dependent upon the degree of protein hydrolysis by first fermentation. Second fermentation resulted in 0.14% GABA. The milk fermented by B. subtilis indicated the rough surface of yogurt depended upon the degree of protein hydrolysis. In conclusion, set-type yogurt was efficiently produced by co-culturing of milk, and fortifying with peptides, GABA, and probiotics.

• The Korean Journal of Food And Nutrition
• /
• v.14 no.2
• /
• pp.126-131
• /
• 2001

Microbiological, pH and sensory evaluations of pork loins treated with lactic acid cultures (Lactococcus lactis subsp. lactis ATCC 11454 grown in 10% milk solids) during storage at 4$^{\circ}C$ were assessed. Pork loins were immersed in solutions containing 3.96 log units, 4.10 log units, or 4.23 log units of individual lactic acid cultures for 2 min. Pork loins treated with lactic acid cultures had a inhibitory effect (P<0.05) on the growth of aerobic palate counts during storage of 3 days at 4$^{\circ}C$. Pork loins treated with lactic acid cultures during storage of 3 days at 4$^{\circ}C$ significantly (P<0.05) decreased pH values compared to those of controls. Sensory evaluations for odor and appearance of pork loins treated with lactic acid cultures during storage of 9 days at 4$^{\circ}C$ were a "liked less" to "typical" category compared to those of controls.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.11
• /
• pp.1471-1480
• /
• 2010

An extremely thermostable xylanase gene, xynB, from the hyperthermophilic bacterium Thermotoga maritima MSB8 was successful expressed in Kluyveromyces lactis. The response surface methodology (RSM) was also applied to optimize the medium components for the production of XynB secreted by the recombinant K. lactis. The secretion level (102 mg/l) and enzyme activity (49 U/ml) of XynB in the optimized medium (yeast extract, lactose, and urea; YLU) were much higher than those (56 mg/l, 16 U/ml) in the original medium (yeast extract, lactose, and peptone; YLP). The secretory efficiency of mature XynB was also improved when using the YLU medium. When the mRNA levels of 13 characterized secretion-related genes in the K. lactis cultured in YLP and YLU were detected using a semiquantitative RT-PCR method, the unfolded protein response (UPR)-related genes, including ero1, hac1, and kar2, were found to be up-regulated in the K. lactis cultured in YLU. Therefore, the nutrient ingredients, especially the nitrogen source, were shown to have a significant influence on the XynB secretory efficiency of the host K. lactis.

• The Korean Journal of Ecology
• /
• v.22 no.1
• /
• pp.45-50
• /
• 1999

A bacteriocin-producing strain was isolated from kimchi at the early stage of kimchi fermentation. It was identified as Lactococcus lactis by morphological, cultural and physiological characteristics and partial sequence of 16S rDNA. The bacteriocin from isolate had antimicrobial activity against gram positive pathogenic bacteria, such as Listeria monocytogenes. Staphylococcus aureus and several strains of lactic acid bacteria but not to gram negative bacteria, Yersinia enterocolitica. The bacteriocin was sensitive to protease, protease ⅩⅣ, a-chymotrypsin and pepsin but not to lipase, trypsin and lysozyme. The bacteriocin activity was stable at pH 2-11 and temperature of 100 for 10 min. Thus, Listeria monocytogenes could be inhibited by Lactococcus lactis at early stage of fermentation.

• Korean Journal of Microbiology
• /
• v.43 no.2
• /
• pp.124-129
• /
• 2007

We evaluated the use of citrus fruit fermented by lactic acid bacteria, as a feed supplement for flounder (Paralichthys olivaceus) cultivation. For the fermentation, a lactic acid bacterial strain W-44 showing antibacterial activity was isolated from kimchi. From the phylogenetic analysis based on, 16S rDNA sequence, the strain W-44 was identified as Lactococcus lactis. After the fermentation of citrus fruit with L. lactis W-44, the contents of naringenin and hesperetin, bioactive flavonoid aglycones, were increased about ten-fold and six-fold, respectively. The effects of fermented citrus fruit-based feed additives (CFBFA) were tested on the growth of flounder, Paralichthys olivaceus. There were significant differences in average total length and body weight between the experimental and control group. The growth rate of the experimental group fed with the 0.2% CFBFA-supplemented diet was increased 4.5% and 20.9% more than the control group in total length and body weight, respectively. These results suggest that the fermented citrus fruit could be used as a functional feed additive for flounder cultivation.

• Food Science of Animal Resources
• /
• v.27 no.4
• /
• pp.522-530
• /
• 2007

This experiment was carried out to measure the content of lactoferrin, IgA, $IgG_1,\;IgG_2$, in Holstein colostrum, and to test the effect of it's colostrum on the antibacterial activity to pathogenic bacteria and the growth stimulation of lactic acid bacteria. Colostrum was collected at the first, second, and third day after parturition in summer and winter season. The levels of lactoferrin, IgA, $IgG_1,\;and\;IgG_2$ in Holstein cow colostrum were 0.30 mg/mL, 0.37 mg/mL, 4.00 mg/mL, 0.37 mg/mL, respectively, on the first day of the summer season whereas they were 1.16 mg/mL, 2.60 mg/mL, 13.35 mg/mL, 1.30 mg/mL on the first day of the winter season, postpartum. Heat treated ($65^{\circ}C$ for 30 min) or non-treated colostrum showed antibacterial activity toward Escherichia coli. The growth of commercial mixed strains (Bifidobacterium longum, Lactobacillus acidophilus, Streptococcus themophilus), L. acidophilus, L. casei, L. bulgaricus, and L. lactis subsp. cremoris were improved in first, second and third day colostrum compared to normal milk. Commercial miked strains (B. longum, L. acidophilus S. themophilus) lowered the pH to 4.97-5.22 and 4.89 while increasing the titratable acidity to 0.75-0.88% and 0.70% in colostrum and normal milk, respectively. However, L. casei, L. bulgaricus, L. lactis subsp. cremoris lowered the pH to 5.96-6.47 and 6.5-6.8 while increasing the titratable acidity to 0.29-0.48% and 0.20-0.25% in colostrum and normal milk, respectively.

• Microbiology and Biotechnology Letters
• /
• v.19 no.5
• /
• pp.536-541
• /
• 1991

To enhance the productivity of fruit flavor compounds from whey by the lactose fermenting yeast, Kluyveromyces lactzs ATCC 8585 was treated with N-methyI-N'-nitro-N-nitrosoguanidine (NTG). After the NTG treatments, a mutant showing resistance to antifungal activity of geraniol, and strong fruity but low yeasty flavor was selected and named as K. lactis 450 K. Flavor compounds from 3-day culture broth were extracted with pentane-dichloromethane (2:l) and the concentrated oleoresins were analyzed by gas chromatography. The mutant strain produced more classes and larger amount of flavor compounds than the parent stlain. Tentatively identified volatile compounds from the culture of the mutant were: terpenes such as myrcenol; alcohols such as cis-3-hexenol, n-hexanol; esters such as ethyl isovalerate, cis- 3-hexenyl n-butyrate, n-amyl-n-hexanoate, phenyl ethyl n-propioate; ketones such as methyl vinyl ketones; other compounds such as vanillin, 3-methylcoumarin.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.11
• /
• pp.1799-1808
• /
• 2006

A food-grade integration vector based on site-specific recombination was constructed. The 5.7-kb vector, pIMA20, contained an integrase gene and a phage attachment site originating from bacteriophage A2, with the ${\alpha}$-galactosidase gene from Lactobacillus plantarum KCTC 3104 as a selection marker. pIMA20 was also equipped with a controllable promoter of nisA ($P_{nisA}$) and a signal peptide-encoding sequence of usp45 ($SP_{usp45}$) for the production and secretion of foreign proteins. pIMA20 and its derivatives mediated site-specific integration into the attB-like site on the Lactococcus lactis NZ9800 chromosome. The vector-integrated recombinant lactococci were easily detected by the appearance of blue colonies on a medium containing $X-{\alpha}-gal$ and also by their ability to grow on a medium containing melibiose as the sole carbon source. Recombinant lactococci maintained these traits in the absence of selection pressure during 100 generations. The ${\alpha}-amylase$ gene from Bacillus licheniformis, lacking a signal peptide-encoding. sequence, was inserted downstream of $P_{nisA}\;and\;SP_{usp45}$ in pIMA20, and the plasmid was integrated into the L. lactis chromosome. ${\alpha}-Amylase$ was successfully produced and secreted by the recombinant L. lactis, controlled by the addition and concentration of nisin.