• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2418-2422
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• 2011

The enantiomeric separation of lactic acid for its absolute configuration has become important task for understanding its biological origin and metabolic process involved in the formation of lactic acid. It involves the conversion of enantiomers as diastereomeric O-pentafluoropropionylated (S)-(+)-3-methyl-2-butyl ester and the direct separation by gas chromatography-mass spectrometry on a achiral capillary column. The (R)- and (S)-lactic acids were completely separated with a high resolution of 1.9. The newly developed method showed good linearity (r ${\geq}$ 0.999), precision (% relative standard deviation = 3.4-6.2), and accuracy (% relative error = -7.7-1.4) with the detection limit of 0.011 ${\mu}g/mL$. When the method was applied to determine the absolute configuration of lactic acid in Lactobacillus delbrueckii subsp. lactis 304 (LAB 304), the composition (%) of (R)-lactic acid in the cell pellet and in the culture medium were $89.0{\pm}0.1$ and $78.2{\pm}0.4$, respectively. Thus, it was verified that the present method is useful for the identification and composition test of lactic enantiomers in microorganisms.

• Journal of Microbiology and Biotechnology
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• v.30 no.5
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• pp.726-732
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• 2020

Indonesian kefir grains are potential sources of lactic acid bacteria (LAB) that may act as probiotics with specific functional properties. In this study we explored the potential of the probiotic and cholesterol-lowering effect of LAB isolated from Indonesian kefir grains obtained from Bogor, Bandung, Jakarta, and Yogyakarta. The results revealed that 10 isolates showed considerable survivability at low pH and bile salt with total cell reduction of ~3 log colony-forming units per milliliter after exposure to pH 2.5 and 0.5% (w/v) bile salt for 1 and 3 h, respectively. All strains exhibited strong antimicrobial activities against pathogenic bacteria and were sensitive to a wide spectrum of antibiotics but exhibited weak bile salt hydrolase activity. Identification based on 16S RNA suggested that nine isolates were Lactobacillus kefiri and one was Lactobacillus rhamnosus. The ability of the isolates to reduce cholesterol from the media varied, ranging from 22.08% to 68.75% with the highest reduction shown by L. kefiri JK17. The ability to remove cholesterol from the media decreased greatly in resting and dead cells, ranging from 14.58% to 22.08% in resting cells and from 7.89% to 18.17% in dead cells. It can be concluded that Indonesian kefir grains contain LAB potentially acting as probiotics capable of reducing cholesterol. The cholesterol-lowering effect especially occurs when the cells are metabolically active.

• Applied Biological Chemistry
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• v.38 no.2
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• pp.95-99
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• 1995

The distribution of lactic acid bacteria and total bacteria in 27 samples of Nuruk (traditional Korean rice wine starter) were investigated, and lactic acid bacteria isolated from those samples were identified. The average number of lactic acid bacteria and total bacteria were $2,11{\times}10^7$ and $2.08{\times}10^8\;cfu/g$, respectively. There was no appreciable differences in the number of lactic acid bacteria among those samples, meanwhile the number of total bacteria varied significantly from sample to sample. Among the lactic acid bacteria, more cocci were counted than rods in those samples. Thirty-two strains of lactic acid bacteria obtained from those samples were identified as Leuconostoc mesenteroides subsp. mesenteroides (11 strains), Pediococcus acidilactici (7 strains), Lactobacillus plantarum (3 strains), L. murinus (7 strains) and Enterococcus faecium (4 strains).

• Korean Journal of Veterinary Research
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• v.56 no.1
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• pp.1-7
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• 2016

Lactic acid bacteria (LAB) are commonly used as probiotics in poultry. The present study employed in vitro and in vivo methods to select and test LAB isolated from Muscovy duck ceca as potential probiotics. In the in vitro study, 50 LAB were isolated from Muscovy duck ceca and tested for growth inhibition against Salmonella (S.) Enteritidis. Eleven isolates strongly inhibited S. Enteritidis and only 1 isolate (MD5-2) showing the strongest inhibition was selected for identification. This isolate was called as Lactobacillus (L.) reuteri MD5-2. For the in vivo investigation, 90 1-day-old Muscovy ducks were randomly assigned into three groups of 30 animals each (group 1, control; group 2, treated with $10^8$ colony-forming unit (CFU) of L. reuteri MD5-2 orally once on day 1; and group 3, treated with $10^8CFU$ of L. reuteri MD5-2 orally once daily from days 1 to 5). The ducks were housed in three large cages and raised for 50 days, after which body weight, duodenal villus height and crypt depth were measured. Both villus height and villus height to crypt depth ratio were significantly greater in group 3 than in groups 1 and 2. In conclusion, further investigation of L. reuteri MD5-2 as a potential probiotic strain is warranted.

• Food Science of Animal Resources
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• v.41 no.6
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• pp.967-982
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• 2021

Probiotics are living microorganisms that, when administered in adequate amounts, provide a health benefit to the host and are considered safe. Most probiotic strains that are beneficial to human health are included in the "Lactic acid bacteria" (LAB) group. The positive effects of probiotic bacteria on the host's health are species-specific and even strain-specific. Therefore, evaluating the probiotic potential of both wild and novel strains is essential. In this study, the probiotic characteristics of Lactobacillus brevis KT38-3 were determined. The strain identification was achieved by 16S rRNA sequencing. API-ZYM test kits were used to determine the enzymatic capacity of the strain. L. brevis KT38-3 was able to survive in conditions with a broad pH range (pH 2-7), range of bile salts (0.3%-1%) and conditions that simulated gastric juice and intestinal juice. The percentage of autoaggregation (59.4%), coaggregation with E. coli O157:H7 (37.4%) and hydrophobicity were determined to be 51.1%, 47.4%, and 52.7%, respectively. L. brevis KT38-3 produced β-galactosidase enzymes and was able ferment lactose. In addition, this strain was capable of producing antimicrobial peptides against the bacteria tested, including methicillin and/or vancomycin-resistant bacteria. The cell-free supernatants of the strain had high antioxidant activities (DPPH: 54.9% and ABTS: 48.7%). Therefore, considering these many essential in vitro probiotic properties, L. brevis KT38-3 has the potential to be used as a probiotic supplement. Supporting these findings with in vivo experiments to evaluate the potential health benefits will be the subject of our future work.

• Journal of Dairy Science and Biotechnology
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• v.31 no.2
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• pp.153-159
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• 2013

Lactic acid bacteria are microorganisms that are closely associated with human and/or animal environments, and are categorized as generally recognized as safe (GRAS) organisms due to their ubiquitous appearance in foods and their contribution to the healthy microflora of mucosal surfaces. This study was performed to isolate and identify lactic acid bacteria with antagonistic effects against food-borne pathogens. A total of 3,000 acid-producing bacteria were isolated from infant feces, cattle feces, goat feces, dog feces, pig feces, vaginal tracts, vegetables, fruits, Kimchi, Jeotgal, fermented sausages, raw milk, cheese, yogurt, Cheonggukjang, Meju, and Makgeolli cultured on MRS agar with 0.05% bromocresol purple. For the isolation of bacteriocin-producing bacteria, the diameter of the clear zone was measured on MRS agar plates. Twenty-six isolates exhibited strong antibacterial activity against indicator strains such as Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica serovar Enteritidis. Lactic acid bacteria were identified as Enterococcus faecalis, Enterococcus faecium, Enterococcus hirae, Lactobacillus acidophilus, Lactobacillus amylovorus, Lactobacillus curvatus, Lactobacillus plantarum, and Pediococcus acidilactici by 16S rDNA gene sequence analysis. The results of this study suggest that the isolates could be used as potential probiotic starters for functional food applications.

• Korean Journal of Microbiology
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• v.47 no.4
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• pp.308-315
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• 2011

The purpose of this work was to examine the antimicrobial activity derived from the lactic acid bacterium, UK-3 isolated from the vaginas of women of childbearing age. Various physiological and biochemical properties of this strain were characterized. Both the BIOLOG system and phylogenetic analysis using 16S rRNA sequencing were utilized for identification, and the strain was designated as Lactobacillus plantarum UK-3, and registered in GenBank as [JK266589]. Growth rate, production of organic acids (e.g., lactic acid and acetic acid), and pH during growth were monitored. The maximum concentrations of lactic acid and acetic acid were approximately 684.11 mM and 174.26 mM, respectively, and pH changed from 7.0 to 3.7 after 72 h of incubation. High performance liquid chromatography was used to confirm lactic acid and acetic acid production. Significant antimicrobial activity of the concentrated supernatant was demonstrated against various Gram-positive (e.g., Staphylococcus aureus, Staphylococcus epidermidis, Methicillin-resistant Staphylococcus aureus, Enterococcus faecalis, Neisseria species., Listeria monocytogenes), Gram-negative bacteria (e.g., Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis), and yeast (e.g., Candida albicans) by the plate diffusion method. As a result, the concentrated L. plantarum UK-3 cultures had lower acidity and inhibited the growth of all microorganisms tested, whereas the growth of L. acidophilus was not affected.

• Food Science and Preservation
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• v.14 no.2
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• pp.188-193
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• 2007

The purpose of this study was to isolate lactic acid bacteria, useful in the fermentation industry from Hahyangju Nuruk. Five strains were isolated, and identified as Lactobacillus based on growth inhibition by 10% (v/v) alcohol at pH 4.0. Isolated strains were identified to species, and named Lactobacillus plantarum L-3, L. sakei L-10, and L. curvatus strains L-8, L-11, and L-12. Morphological characteristics, physiological data, carbohydrate fermentation patterns, and 16S rRNA sequence data, were all used to characterize the bacterial isolates. L. plantarum L-3 showed the highest lactic acid productivity of all isolates, but grew only poony in the presence of 10% (v/v) alcohol at pH 4.0. The other strains exhibited lower lactic acid productivity than did L. plantarum L-3 and did not grow in the presence of 10% (v/v) alcohol at pH 4.0. The optimal temperature and pH for lactic acid production were $30^{\circ}C$ and pH 6.0 7.0, respectively. The lactic acid productivity of L. plantarum L-3, L. sakei L-10 and the three L. curvatus strains L-8, L-11, and L-12 were (% v/v of culture supematant) 1.55, 1.0, 1.06, 1.0, and 0.99, respectively, at $30^{\circ}C$ and pH 6.0. While L. plantarum L-3 suffered growth inhibition in the presence of 10% (v/v) alcohol, growth of the other strains was inhibited at 8% (v/v) alcohol.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.495-505
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• 1995

The purpose of this study was to identify the psychrotrophic lactic acid bacteria isolated from kimchi, a Korean traditional fermented vegetable food. Thirty isolates of psychrotrophic lactic acid bacteria were isolated randomly from kimchi-A and kimchi-B which were fermented at $5{\sim}7^{\circ}C$ for 20 days and 50 days, respectively. Among 30 isolates of lactic acid bacteria isolated from kimchi-A, 14 isolates were identified as Leuconostoc mesenteroides subsp. mesenteroides, 12 as Leuconostoc mesenteroides subsp. dextranicum and 4 as Lactobacillus bavaricus. Among 30 isolates isolated from kimchi-B, 20 isolates were identified as Lactobacillus bavaricus, 3 as Leuconostoc mesenteroides subsp. mesenteroides, 3 as Leuconostoc lactis, 2 as Leuconostoc paramesenteroides and 2 as Lactobacillus homohiochii. Though these strains were identified as above, there were many strains whose sugar fermenting patterns and $NH_3$ producing ability from arginine were inconsistent with those described in Bergey's Manual of Systematic Bacteriology, and some strains identified as Leuconostoc mesenteroides subsp. mesenteroides and Leuconostoc mesenteroides subsp. dextranicum even disclosed such contradictions as the comparisons of sugar fermenting patterns between the strains of different subspecies were much more coincident than those between the same subspecies. As there were difficulties in classifying these psychrotrophic lactic acid bacteria according to the current taxonomic system, further studies were needed to solve these problems.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.68-76
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• 2006

Despites many attempts to explore the microbial diversity in kimchi fermentation, the predominant flora remains controversial to date. In the present study, major lactic acid bacteria (LAB) were investigated in Chinese cabbage kimchi in the early phase of fermention. For the samples over pH 4.0, viable cell counts of Leuconostoc and Pediococcus were $10^6\;cfu/ml$ and below $10^2\;cfu/ml$, respectively, and 20 isolates out of 172 were subjected to a biochemical identification (API 50 CH kit) as well as molecular-typing methods including ITSPCR with a RsaI digestion and 16s rRNA gene sequence analysis for species confirmation. Seven isolates were nicely assigned to Lb. brevis, 6 to Leuconostoc spp. (2 mesenteroides, 2 citreum, I carnosum, I gasicomitatum), 4 to Weissella (3 kimchii/cibaria, 1 hanii) and 2 to other Lactobacillus spp. (1 farciminis, 1 plantarum). On the other hand, the biochemical identification data revealed 9 strains of Lb. brevis, 6 strains of Leuconostocs,2 strains of Lb. plantarum and 1 strain each of Lb. coprophilus and Lactococcus lactis. However, a single isolates, YSM 16, was not matched to the ITS-PCR database constructed in the present study. Two Lb. brevis strains by API 50 CH kit were reassigned to W kimchii/cibaria, Lb. coprophilus or W hanii, respectively, judging from the results by the above molecular typing approaches. As a whole, the identification data obtained by the biochemical test were different from those of ITS-PCR molecular method by about $63\%$ at genus-level and $42\%$ at species-level. The data by the ITS-PCR method conclusively suggest that predominant LAB species is probably heterolactic Lb. brevis, followed by W kimchii/cibaria, Leuc. mesenteroides, and Leuc. citreum, in contrast to the previous reports [3] that Leuc. mesenteroides is the only a predominant species in the early phase kimchi fermentation.