• KSBB Journal
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• v.30 no.5
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• pp.239-244
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• 2015

Bacterial vaginosis (BV) is caused by microbial imbalance of the vaginal ecosystem and overgrowth of anaerobic bacteria. The antibiotic treatment often results in very high recurrence of BV because it disturbs the vaginal ecosystem. The high recurrence rates suggest a need for alternative therapeutic methods and probiotics are being recognized as alternative or additional treatment method for BV. The purpose of this study was to investigate how human vaginal isolates of Lactobacillus spp. inhibit the BV-associated pathogen Gardnerella vaginalis. Results show that selected strains significantly reduced the viability of G. vaginalis. Among these selected strains KLB410 and KLB416 were further selected based on acid/bile tolerance and identified through 16S rRNA gene sequencing being Lactobacillus plantarum. Further studies are underway to demonstrate that the selected strain can be applied as potential probiotics for recovering vaginal ecosystem.

• Microbiology and Biotechnology Letters
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• v.47 no.2
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• pp.211-219
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• 2019

The effect of microencapsulation on previously isolated Lactobacillus delbrueckii 94/L4 as starter culture for yogurt, and Lactobacillus casei 97/L3 as a probiotic candidate was investigated. Preliminary results showed that L. delbrueckii 94/L4 exhibited tolerance to bile, unlike L. casei 97/L3. Freeze drying significantly (p < 0.05) reduced the viability of both isolates by log 0.71-2.70. Although microencapsulation preserved the viability of L. casei 97/L3 cells exposed to simulated gastrointestinal tract conditions for 120 min, it did not impart significant (p < 0.05) protection against loss of viability during the first 30 min of exposure. Conversely, microencapsulated L. delbrueckii 94/L4 with the addition of Streptococcus thermophilus 24/S1 as starter culture was successfully incorporated into milk to form yogurt, yielding a significantly (p < 0.05) improved product quality.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.348-354
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• 2003

This study was conducted to confirm the availability of lactic acid bacteria as probiotics haying inhibitory effects to cancer cell line. Five lactic acid bacteria showing anti-cancer activity were compared by acid tolerance, bile tolerance, antibiotics resistance, milk fermentation, stability, and cell adherence activity to colon epithelial cell. The results obtained are as follows : In acid tolerance, all strains did not have a resistance below pH 3.0 and 3.5 except Lactobacillus plantarum KCTC3099. In antibiotics resistance, Lactococcus lactis and L. plantarum KCTC3099 were resistant to cotrimoxazol (128 mg/1), and Bifidobacterium adolescentis Maeil-K8 and B. infantis Maeil-K9 were resistant to doxycylin and gentamycin (4 mg/1). In case of cell adherence ability to Caco-2 cell, B. infantis Maeil-K9 was found to be superior to others as 3.1%, while the others were less than 0.5%. When the strains were cultured to milk base, viable counts of the strains tested increased more 1 log cycle than inoculation, but acid production was very low except L. plantarum KCTC3099. Also, L. plantarum KCTC3099, B. adolescentis Maeil-K8, and B. infantis Maeil-K9 were stable in fermented milk base during storage. In conclusion, L. plantarum KCTC3099 and B. infantis Maeil-K9 were confirmed to be superior for the availability as probiotics.

• Journal of Life Science
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• v.33 no.11
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• pp.915-922
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• 2023

Lactic acid bacteria (LAB) are widespread in a variety of environments including fermented dairy products, gastroinstetinal and urogenital tracts of human and animals, plant, soil and water. Leuconostoc mesenteroides DB3 was detected by the strongest antibacterial activities among 24 Leuconostoc strains isolated from Camellia japonica flowers. Acid tolerance of L. mesenteroides DB3 existed up to pH 2.5, but the resistance did not show at pH 2.0, which relatively excellent acid resistance existed. Bile acid tolerance was very stable within the test range to 1.2%. L. mesenteroides DB3 exhibited the optimal growth at 30℃, and showed a slight slow growth when compared with L. mesenteroides KCTC3505, which reached a stationary phase at 18 hr. The pH was changed along with the growth curve, but was maintained above pH 3.98. L. mesenteroides DB3 had higher initial antibacterial activities when compared to L. mesenteroides KCTC3505, but it showed similar activities with the standard strain after the latter part of the logarithmic growth phase. Although lactic acid production in L. mesenteroides DB3 was induced by lower amount in the initial part to the standard strain, it was exhibited by similar amounts after the late logarithmic growth phase. Muicin adhesion of L. mesenteroides DB-3 maintained superior to L. mesenteroides KCTC3505. Both strains showed excellent emulsification ability for kerosene. In summary, we evaluate that L. mesenteroides DB-3 has a high potential for application as probiotics owing to its excellent antibacterial activity, acid resistance, bile acid resistance, and muicin adhesion.

• Food Science of Animal Resources
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• v.27 no.3
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• pp.363-370
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• 2007

In order to identify probiotic microorganisms, 25 isolates of Lactobacillus sp. were selected from kimchi based on their growth rates, lactic acid production and salt tolerance. The isolate JK-01 was identified as Lactobacillus plantarum by the API kit and 16S rDNA analysis (99.9% of homology), and named as L. plantarum JK-01. The maximum number of L. plantarum JK-01 was reached at 18 hr fermentation in MRS broth and the pH gradually decreased to 4.5. L. plantarum JK-01 showed high enzyme activities for xylanase, amylase, protease, and phytase on MRS agar plates containing each substrate. L. plantarum JK-01 showed high resistance to acidic pH and bile salts, and grew well even at pH 2.0 and 1.0% bile salt. In particular, L. plantarum JK-01 showed high heat stability as shown by $3.3{\times}10^3$ CFU/mL at $60^{\circ}C$. The isolate showed remarkable antimicrobial activity against E. coli in MRS broth based on its disappearance after 18 hr and clear zone formation using a paper disk assay. These results suggest that L. plantarum JK-01 may be probiotic in nature.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.7
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• pp.1009-1016
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• 2014

This study investigated the probiotic and functional characteristics of Mukeunji starter, Lactobacillus curvatus ML17, isolated from Mukeunji. Lb. curvatus ML17 was confirmed as a safe microorganism due to its non-hemolytic activity and non-production of harmful ${\beta}$-glucuronidase and ${\beta}$-glucosidase. Tolerance to artificial gastric and bile juice of Lb. curvatus ML17 was investigated. After incubation in artificial gastric and bile juice, the number of surviving cells was $1.38{\times}10^8$ CFU/mL. According to the results of adhesion assay, this strain also exhibited good adhesion to Caco-2 cells. Lb. curvatus ML17 showed good antimicrobial activity against food borne pathogens, especially Micrococcus luteus, Bacillus cereus, Salmonella enterica subsp. enterica, and Pseudomonas aeruginosa. Cell-free extract of Lb. curvatus ML17 exhibited high levels of DPPH scavenging capacity and inhibitory effects on growth of AGS human gastric adenocarcinoma cells and HT-29 human colon carcinoma cells. These results suggest that Lb. curvatus ML17 has potential for application in functional foods.

• Journal of Animal Science and Technology
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• v.50 no.4
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• pp.509-518
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• 2008

This experiment was conducted to investigate enzyme activity, antimicrobial activity, and antibiotics susceptibility of Lactobacilli strain(Lactobacillus reuteri BLA5, Lactobacillus crispatus BLA7, Lactobacillus reuteri BLA9, Lactobacillus amylovorus LLA7, Lactobacillus crispatus LLA9, Lactobacillus vaginalis LLA11) isolated from chicken ceca and were selected by organic acid synthesis, acid tolerance, bile salt tolerance. The enzymes activities were different among strains of Lactobacilli. The amylase activity and lipase activity of Lactobacillus were high but cellulase activity and protease activity of that were low. Lactobacillus culture showed high antimicrobial activity against E. coli but low antimicrobial activity against Salmonella. The inhibitory factor of Lactobacilli isolated from chickens’ cecum on E. coli was low pH by organic acid. All of Lactobacillus isolated from chicken’s cecum were susceptible to ampicillin and amoxicillin but weren’t susceptible at the optimum level of feed additive antibiotics(virginiamycin and salinomycin).

• Food Science and Biotechnology
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• v.14 no.4
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• pp.503-508
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• 2005

Screening for antilisterial activity was performed in about three thousand isolates of lactic acid bacteria (LAB) from Chinese cabbage kimchi, and finally based on the relatively stronger antilisterial activities eight bacterial strains were selected. The bacteria were further characterized in terms of their tolerance to artificial gastric juice, pH 2.5, bile salts (0.3% oxgall), and to the different NaCl concentrations. Of the isolates, YK005 was especially investigated for its physiological characteristics due to its inhibitory activity against gram-positive Listeria monocytogenes as well as gram-negative Escherichia coli O157:H7, as they have been constantly reported to be resistant against bacteriocins produced by a number of LAB strains. YK005 was found to be rod-shaped, $3.8\;{\mu}m$ long ${\times}\;0.5\;{\mu}m$ wide, non-sporeforming, non-motile, catalase-negative, and produced gas from glucose (heterolactic). Based on the biochemical data obtained by API 50 CHL medium, the isolate was tentatively identified as Lactobacillus brevis. To validate the result obtained by the biochemical identification, rRNA-based PCR experiments using a pair of species-specific primers for L. brevis were conducted and a single band of 1400 bp was observed, which strongly indicated that YK005 belongs to L. brevis. The LAB isolates are potentially exploited as human probiotic organisms and are employed to control some food-borne pathogens like L. monocytogenes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.10
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• pp.1481-1487
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• 2016

Lactic acid bacteria showing alginate-degrading and cellulolytic activity were isolated and identified as a starter for seaweed fermentation. A total of 331 strains of lactic acid bacteria isolated from various Korean traditional foods, such as Kimchi, Jeotgal, and Makgeolli, were examined alginate-degrading and cellulolytic activity by the plate assay method. Six strains showed strong alginate-degrading and cellulolytic activity among the isolated 331 strains. Among these six strains, four strains (strain No. 162, 164, 192, and 196) showed probiotic properties (antimicrobial activity, tolerance to simulated gastric juice, artificial bile acid, and NaCl). No. 192 strain (Gram-positive cocci, catalase negative, and homofermentative) showed the best probiotic properties among selected strains and was identified as Enterococcus faecium by 16S rRNA sequencing. Strain No. 192 (E. faecium) showed the best growth and antioxidative activity during seaweed (sea mustard and sea tangle) fermentation for 72 h at $37^{\circ}C$ among the four selected strains.

• Food Science of Animal Resources
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• v.38 no.5
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• pp.878-888
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• 2018

In the current study, the probiotic potential of approximately 250 strains of lactic acid bacteria (LAB) isolated from piglet fecal samples were investigated; among them Lactobacillus plantarum strain JDFM LP11, which possesses significant probiotic potential, with enhanced acid/bile tolerance, attachment to porcine intestinal epithelial cells (IPEC-J2), and antimicrobial activity. The genetic characteristics of strain JDFM LP11 were explored by performing whole genome sequencing (WGS) using a PacBio system. The circular draft genome have a total length of 3,206,883 bp and a total of 3,021 coding sequences were identified. Phylogenetically, three genes, possibly related to survival and metabolic activity in the porcine host, were identified. These genes encode p60, lichenan permease IIC component, and protein TsgA, which are a putative endopeptidase, a component of the phosphotransferase system (PTS), and a major facilitator in the gut environment, respectively. Our findings suggest that understanding the functional and genetic characteristics of L. plantarum strain JDFM LP11, with its candidate genes for gut health, could provide new opportunities and insights into applications in the animal food and feed additive industries.