• Food Science of Animal Resources
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• v.29 no.1
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• pp.15-23
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• 2009

In order to develop a new starter for fermented milk, 2082 bacteria were isolated from raw milk. The strain that showed excellent acid forming and ${\gamma}$-aminobutyric acid (GABA) production ($711.40{\mu}g/g$ D.W) characteristics after incubation at $37^{\circ}C$ for 18 hr was selected and identified as Lactobacillus acidophilus by the result of API carbohydrate fermentation pattern and 16S rDNA sequence. L. acidophilus RMK567 was investigated for its physiological characteristics. RMK67 strain showed good GABA production compared with commercial lactic acid bacteria. The optimum growth temperature of L. acidophilus RMK567 was $40^{\circ}C$ and cultures took 15 hr to reach pH 4.3. L. acidophilus RMK567 showed higher sensitivity to penicillin-G, novobiocin, as compared to other 14 different antibiotics. However, it showed more resistance to kanamycin, neomycin, streptomycin. It showed higher leucine arylamidase and ${\beta}$-galactosidase activities compared to 16 other enzymes. It was comparatively tolerant to bile juice and able to survive at pH 2 for 3 hr. It showed resistence to Escherichia coli, Salmonella typhimurium and Staphylococcus aureus with rates of 29.2%, 39.1% and 51.4%, respectively. Based on these and previous results, L. acidophilus RMK567 could be an excellent starter culture for fermented milk with excellent GABA contents.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.834-841
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• 1997

A lactic acid bacteria which showed antimicrobial activity was isolated from dairy products and identified as Lactobacillus sp. according to the morphological, physiological and biochemical properties, which was named Lactobacillus sp. SH 7311. The bacteriocin of Lactobacillus sp. GM 7311 showed a broad range of inhibitory spectrum against some gram positive and negative bacteria. Especially, Proteus mirabilis was highly sensitive to bacteriocin and used as indicator strain for further investigation. The optimal condition for the production of bacteriocin was showed on MRS broth at $37^{\circ}C$ and pM 6.0. Bacteriocin production of this strain cultured under optimal condition was increased late logarithmic phase to early stationary phase. This bacteriocin was fully active at the pH range $2.0\~5.0$, also was stable at $100^{\circ}C$ for 60 min. at pH 5.0, But about $40\%$ of bacteriocin activity was diminished by the treatment of acetone, ethanol, iso-butanol and ethyl ether during 2 hours at $4^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.51 no.1
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• pp.53-58
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• 2023

The glutamic acid producing strain for development savory taste enhancing foods was identified the possibility through application into soybean fermentation. To check the effects on glutamic acid production during soybean fermentation, Lactococcus lactis HY7803 was introduced as a starter. The soybean samples were analyzed on days 0, 7, 14 and 21. The numbers of bacteria decreased gradually, while the content of amino-type nitrogen increased during fermentation in the soybean with L. lactis HY7803. Glutamic acid content in soybeans with L. lactis HY7803 increased from 114.99 ± 9.37 pmol/ul on day 0 to 138.14 ± 1.76 pmol/ul on day 21, showing an overall higher amino acid content than soybeans without L. lactis HY7803 and similar content to soybeans with Aspergillus oryzae SNU-G. It was clearly distinguished through principal component analysis. Consequently, our results indicate that L. lactis HY7803 is available as a fungus replacement and may be a good starter strain for enhancing savory taste in vitro as well as soybean fermentation.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.218-224
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• 2011

Lactic acid bacteria (LAB) OA18 was isolated from yogurt prepared by using Kefir Grain as a starter. The OA18 strain was a Gram-positive, cocci-type bacterium, and able to grow anaerobically with $CO_2$ production. The OA18 strain grew well on MRS broth supplemented with 50 mM arginine at $30-37^{\circ}C$ and pH of 7.0-9.0. The optimum temperature and pH for growth are $37^{\circ}C$ and pH 7.0. The isolate fermented ribose, D-glucose, cellobiose, D-trehalose, but not L-xylose, D-melibiose, and inositol. The 16S rRNA gene sequence of the isolate showed 99.8% homology with the Enterococcus faecalis 16S rRNA gene (Access no. AB012212). Based on the biochemical characteristics and 16S rRNA gene sequence analysis data, it was identified and named as E. faecalis OA18. The E. faecalis OA18 strain showed a high ornithine-producing capacity in the presence of arginine and also showed an antimicrobial activity against Streptomyces strains such as Streptomyces coelicolor subsp. Flavus, S. coeruleorubidus, S. coeruleoaurantiacus, S. coelicolor, S. coeruleoprunus. The cell growth of E. faecalis OA18 strain was maintained in MRS broth with a NaCl concentration of 0-7%.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.231-240
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• 2011

The objective of this study was to evaluate the acid and bile tolerance, bile salt hydrolase (BSH) activity, and cholesterol assimilation ability of lactic acid bacteria isolated from mustard leaf kimchi. MLK11, MLK22, MLK27, MLK41, and MLK67 were relatively acid- and bile-tolerant strains, with more than $10^5$ CFU/ml after incubation in simulated gastric juice and intestinal fluid, while MLK53 was the most sensitive strain to acid and bile. Strains MLK22 and MLK67 deconjugated the highest level of sodium glycocholate with more than 3.5 mM of cholic acid released, while deconjugation was lowest by strains MLK13 and MLK41 which released only 1.35 mM and 1.16 mM, respectively. Specially, strains MLK22 and MLK67 showed higher deconjugation of sodium glycocholate compared to sodium taurocholate and conjugated bile mixture. Although strains MLK22 and MLK67 exhibited maximal BSH activity at the stationary phase, MLK22 had somewhat higher total BSH activity compared to MLK67 towards both sodium glycocholate and sodium taurocholate. Meanwhile, cholesterol removal varied among tested strains (p<0.05) and ranged from 5.22 to 39.16 ${\mu}g$/ml. Especially, MLK67 strain assimilated the highest level of cholesterol in media supplemented with 0.3% oxgall, cholic acid, and taurocholic acid (p<0.05). According to physiological and biological characteristics, pattern of carbohydrate fermentation, and 16S rDNA sequence, strain MLK67 that may be considered as probiotic strain due to acid and bile tolerance and cholesterol-lowering effects was identified as Pediococcus pentosaceus MLK67.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.1
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• pp.89-95
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• 2013

Biological and functional characteristics of lactic acid bacteria (LAB) were investigated in mustard stem/leaf kimchi (MK), cabbage kimchi (CK), young radish kimchi (YRK), and cubed radish kimchi (CRK). LAB of young radish kimchi were mainly composed of bacilli in contrast to the other kimchi. 89.2% LAB isolated from all kimchi harbored plasmids. However, LAB had an average of $4.1{\pm}0.5$ plasmid bands in YRK, more than MK, CK, and CRK. Exopolysaccharides were produced by 10.9~11.1% of LAB, and were especially by LAB isolated from radish kimchi. A significant percentage of LAB (69.5%) had antibacterial activity against one sensitive strain or more. LAB from CK, YRK and CRK had antimicrobial activities against Bacillus sp., Listeria monocytogenes, and Salmonella Typhimurium, while the LAB from MK had activities against Vibrio parahaemolyticus higher than those from the other kimchi. In YRK and CRK, acid-tolerant LAB were twice as prevalent as those in MK and CK. Bile-tolerant LAB isolated from CRK were more prevalent than other kimchi. When $10^8$ CFU of LAB were added to Caco-2 cells, 12.1% of LAB isolated from all kimchi showed similar adherent activity to Lactobacillus rhamnosus GG. LAB of MK particularly adhered to Caco-2 cells, 2.0~4.1 fold higher than LAB in the other kimchi. From these results, biological and functional characteristics of LAB varied according to the type of kimchi and LAB existing in kimchi were limited to their respective species.

• Microbiology and Biotechnology Letters
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• v.49 no.4
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• pp.552-558
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• 2021

Traditional foods are manufactured according to the characteristics of each region for the nations of the world. Korea has mainly farmed, and seasonings have developed around rice and vegetables. In fermented foods, lactic acid bacteria such as Lactobacillus sp. and Pediococcus sp. and Bacillus sp. were isolated and identified from fermented foods. In this study, lactic acid bacteria were isolated and identified from commercially available traditional Korean fermented foods, and candidate strains were selected through antibacterial activity tests on human and fish disease bacteria. Thereafter, the final strain was selected by examining the resistance to simulated gastric and intestinal fluids, and hemolysis. The three (M1, K1, C13) final selected latic acid bacteria were miced with prebiotics and the antibacterial activity of synbiotics was evaluated. As for the fist antibacterial activity result, C13 showed high antibacterial acitivity in human diseases and fish diseases. Then, M1, K1 and C13, which did not produce β-haemolysis and were resistant to simulated gastric and intestinal fluids, were subjected to the second antibacterial activity of synbiotics. When the three prebiotics (FOS, GOS, Inulin) and probiotics (M1, K1, C13) were mixed, the antibacterial activity was increased or inhibited. Based on the 16S rRNA gene sequencing results, K1 and M1 were analyzed as Bacillus tequiensis 99.72%, Bacillus subtilis 99.65%, Bacillus inaquosorum 99.72%, Bacillus cabrialesii 99.72%, Bacillus stercoris 99.58%, Bacillus spizizenii 99.58%, Bacillus halotolerans 99.58%, and Bacillus mojavensis 99.51%. And C13 was analyzed as Bacillus velezensis 99.71%, Bacillus nematocida 99.36%, Bacillus amyloliquefaciens 99.44%, Bacillus atrophaeus 99.22%, and Bacillus nakamurai 99.44%.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.7
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• pp.1027-1032
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• 2008

A study was conducted to evaluate the effects of dietary yeast derived ${\beta}$-glucan and single-strain probiotics on the growth performance and antibody response in broiler chicks. Six hundred and thirty 1-d-old male broiler chicks were divided into seven groups, placed into three pens per group (30 birds per pen) and fed one of seven non-medicated corn-SBM based experimental diets containing 0.025, 0.05 or 0.1% Saccharomyces cerevisiae ${\beta}$-glucan and 0.05, 0.1 or 0.2% Bacillus amyloliquefaciens (BA-pro, $1.3{\times}10^9/g$) or devoid of them for 5 wk. The body weight gains in groups fed diets containing 0.025 or 0.1% ${\beta}$-glucan, 0.1% or 0.2% BA-pro were significantly higher (p<0.05) than the control over 1-35 d. Feed conversion rates of groups fed ${\beta}$-glucan and BA-pro tended to be improved compared to the control group. There were no significant differences in the relative weights of liver, abdominal fat and breast muscle. No significant differences were observed in the activities of serum enzymes and concentrations of various cholesterol fractions. The antibody titers against Newcastle disease or infectious bronchitis virus in the chicks fed diets containing ${\beta}$-glucan and BA-pro were significantly higher (p<0.05) than in the control. The concentrations of cecal lactic acid bacteria in all groups fed BA-pro were significantly increased (p<0.05) compared to the control. These results indicated that dietary yeast derived ${\beta}$-glucan and BA-pro exerted growth-promoting and immune-enhancing effects in broiler chickens. In addition, BA-pro added to the diets modulated the profiles of cecal microflora, reflecting a potential to be beneficial microorganisms in chickens.

• Food Science of Animal Resources
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• v.29 no.5
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• pp.640-646
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• 2009

Lactic acid bacteria (LAB) are typical probiotic microbes that are used in various industries including fermented foods, feed additives, and pharmaceuticals. The purpose of this study was to compare the ability of isoflavone biotransformation and antioxidative activity of 17 LAB. Six strains including the Lactobacillus species exhibited a 100% hydrolysis rate for daidzein during fermentation. The content of total genistein in soymilk fermented with these strains was $872-943\;{\mu}g/g$. The DPPH (1, 1-diphenyl-2-picrylhydrazyl) radical scavenging ability of the LAB was widely variable and ranged from 23-78%. A selected strain was isolated from kimchi and the strain was identified as Lactobacillus plantarum ssp. through the API carbohydrate fermentation pattern and 16S rDNA profile. The strain exhibited excellent acid tolerance in an artificial gastric solution. L. plantarum YS712 showed high $\beta$-glucosidase activity in fermentation. The concentration of genistein and daidzein in soymilk fermented with L. plantarum YS712 increased from 3.64 to $917.3\;{\mu}g/g$ and from 58.18 to $1062.17\;{\mu}g/g$, respectively. These results demonstrate the potential of L. plantarum YS712 as a probiotic culture that can be utilized in the manufacturing of fermentation foods and dietary supplements.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.157-161
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• 2002

A lactic acid bacteria with ${\beta}$-gal activity was isolated from Kimchi, a traditional fermented vegetable food in Korea. The isolate was identified as a Lactococcus lactis strain and named L. lactis A2. The gene encoding ${\beta}$-gal of L. lactis A2 was cloned as a 5.8 kb PstI fragment. DNA sequencing identified the complete lacA (galactoside acetyltransferase)-lacZ (${\beta}$-galactosidase) genes together with the 3' part of upstream galT (galactose-1-phosphate uridyltransferase), and the 5'region of downstream galE (UDP-galactose-4-epimerase) genes. L. lactis A2 had the same gal/lac operon structure as in L. lactis subsp. lactis 7962. Other genes of the Leloir pathway are most likely to be located in the 5'upstream of the 5.8 kb fragment on the A2 chromosome. Sequences downstream of galE were different from those of L. lactis subsp. lactis 7962.