• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2100-2105
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• 2015

Probiotic bacteria must have not only tolerance against bile salt but also no genes for antibiotic resistance. Leuconostoc citreum is a dominant lactic acid bacterium in various fermented foods, but it is not regarded as a probiotic because it lacks bile salt resistance. Therefore, we aimed to construct a bile salt-resistant L. citreum strain by transforming it with a bile salt hydrolase gene (bsh). We obtained the 1,001 bp bsh gene from the chromosomal DNA of Lactobacillus plantarum and subcloned it into the pCB4170 vector under a constitutive P710 promoter. The resulting vector, pCB4170BSH was transformed into L. citreum CB2567 by electroporation, and bile salt-resistant transformants were selected. Upon incubation with glycodeoxycholic acid sodium salt (GDCA), the L. citreum transformants grew and formed colonies, successfully transcribed the bsh gene, and expressed the BSH enzyme. The recombinant strain grew in up to 0.3% (w/v) GDCA, conditions unsuitable for the host strain. In in vitro digestion conditions of 10 mM bile salt, the transformant was over 67.6% viable, whereas only 0.8% of the host strain survived.

• Korean journal of food and cookery science
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• v.31 no.2
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• pp.128-135
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• 2015

Blueberry juice extraction (JE), hot water extract (HE), and 50% ethanol extract (EE) were fermented with Lactobacillus plantarum CGKW3. We investigated the quality characteristics and antioxidative activities of yanggaeng prepared with different amounts of fermented blueberry extract (JE, HE, EE). The viable cells in fermented HE was higher (7.49 log CFU/mL) than JE (7.28 log CFU/mL) and EE (6.99 log CFU/mL), during the fermentation period. The viable cells and acidity in yanggaeng increased significantly with increasing levels of fermented blueberry extract (p<0.05). In terms of color, the lightness and yellowness decreased significantly, but redness increased with increasing levels of fermented blueberry extract. In the texture profile analysis, control showed the highest result in hardness. Cohesiveness did not show significant differences, according to amount of fermented blueberry extract. The springiness decreased with the increasing levels of fermented blueberry extract. Antioxidant activity, which was measured by DPPH and reducing power, was significantly higher than those of control; and it increased proportionally according to the amount of fermented blueberry extract. Anthocyanin contents were increased proportionally with the increasing levels of fermented blueberry extract. Sensory evaluation showed that the color, taste, flavor, texture, and overall acceptability of yanggaeng containing the JE, HE, and EE were higher than those of the control.

• Food Science of Animal Resources
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• v.33 no.3
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• pp.335-340
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• 2013

This study screened for radio-resistant strains lactic acid bacteria (LAB) by evaluating their capability to survive exposure to ionizing radiation. Ten strains of LAB - Lactobacillus bulgaricus, Lactobacillus paracasei, Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus delbruekii, Lactococcus lactis, Streptococcus thermophilus, Bifidobacterium breve, and Pediocuccos pentosaceus - were selected and subcultuted twice. The LAB was then further cultured for 3 d at $37^{\circ}C$ to reach 7-10 Log colony-forming units (CFU)/mL prior to irradiation and immediately exposed to gamma rays or electron beams with absorbed doses of 0, 1, 2, 3, 4, 5, 6, 8, and 10 kGy. Gamma irradiation gradually decreased the number of the tested viable LAB, and the effect was irradiation dose dependent. A similar effect was found in electron beam-irradiated LAB. Radiation sensitivity of LAB was calculated as $D_{10}$ values, which ranged from 0.26 kGy to 0.9 kGy and 0.5 kGy to 1.44 kGy with exposure to gamma and electron beam irradiation, respectively, in all tested LAB. L. acidophilus was the most resistant to gamma and electron beam irradiation, with $D_{10}$ values of 0.9 kGy and 1.44 kGy, respectively. These results suggest that L. acidophilus might be suitable for the preparation of probiotics as direct-fed microbes for astronauts in extreme space environments.

• International journal of advanced smart convergence
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• v.10 no.1
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• pp.197-208
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• 2021

The deer antler has been used as a major drug in oriental medicine for a long time. Recently, the demand for easy-to-take health functional foods is increasing due to economic development and changes in diet. As part of research on the development of functional materials for antlers, lactic acid fermentation of antler extract was performed. It was intended to develop a functional material with enhanced total polyphenol and flavonoid content and enhanced antioxidant activity. Lactic acid bacteria fermentation was performed by adding 4 types of lactic acid bacteria starter products, B. longum, Lb. Plantarum, Lb. acidophilus and mixture of 8 types of lactic acid bacteria to the antler water extract substrate, respectively. During the fermentation of lactic acid bacteria, the number of proliferation, total polyphenol and total flavonoid content, DPPH radical scavenging and antioxidant activity were quantified and evaluated. As a result of adding these four types of lactic acid bacteria to the antler water extract substrate, the number of lactic acid bacteria measured was 2.04~5.00×107. Meanwhile, a protease (Baciullus amyloliquefaciens culture: Maxazyme NNP DS) was added to the antler extract to decompose the peptide bonds of the contained proteins. Then, these four types of lactic acid bacteria were added and the number of lactic acid bacteria increased to 2.84×107 ~ 2.21×108 as the result of culture. The total polyphenol contents were 4.82~6.26 ㎍/mL in the lactic acid bacteria fermentation extracts, and after the reaction of protease enzyme and lactic fermentation, increased to 14.27~20.58 ㎍/mL. The total flavonoid contents were 1.52~2.21 ㎍/ml in the lactic acid bacteria fermentation extracts, and after the protease reaction and fermentation, increased to 5.59 ~ 8.11 mg/mL. DPPH radical scavenging activities of lactic acid bacteria fermentation extracts was 17.03~22.75%, but after the protease reaction and fermentation, remarkably increased to 32.82~42.90%.

• Journal of Microbiology and Biotechnology
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• v.31 no.4
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• pp.550-558
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• 2021

Lactobacillus kefiranofaciens contains two types of β-galactosidase, LacLM and LacZ, belonging to different glycoside hydrolase families. The difference in function between them has been unclear so far for practical application. In this study, LacLM and LacZ from L. kefiranofaciens ATCC51647 were cloned into constitutive lactobacillal expression vector pMG36e, respectively. Furtherly, pMG36n-lacs was constructed from pMG36e-lacs by replacing erythromycin with nisin as selective marker for food-grade expressing systems in Lactobacillus plantarum WCFS1, designated recombinant LacLM and LacZ respectively. The results from hydrolysis of o-nitrophenyl-β-galactopyranoside (ONPG) showed that the β-galactosidases activity of the recombinant LacLM and LacZ was 1460% and 670% higher than that of the original L. kefiranofaciens. Moreover, the lactose hydrolytic activity of recombinant LacLM was higher than that of LacZ in milk. Nevertheless, compare to LacZ, in 25% lactose solution the galacto-oligosaccharides (GOS) production of recombinant LacLM was lower. Therefore, two β-galactopyranosides could play different roles in carbohydrate metabolism of L. kefiranofaciens. In addition, the maximal growth rate of two recombinant strains were evaluated with different temperature level and nisin concentration in fermentation assay for practical purpose. The results displayed that 37℃ and 20-40 U/ml nisin were the optimal fermentation conditions for the growth of recombinant β-galactosidase strains. Altogether the food-grade Expression system of recombinant β-galactosidase was feasible for applications in the food and dairy industry.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.2
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• pp.129-136
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• 2024

Lactic acid bacteria (LAB) growth in processed meat products produces slime. In this study, 10 different biofilm-forming LAB, including Leuconostoc mesenteroides, Lacticaseibacillus paracasei, Levilactobacillus brevis, Lactiplantibacillus plantarum, Leuconostoc citreum, Weissella viridescens, and Latilactobacillus sakei, were isolated from various meat products and identified based on 16S rRNA gene analysis. To inhibit biofilm formation by LABs, Eisenia bicycles methanolic extract (EB) and ethyl acetate soluble fraction (EA) were used as antibacterial and antibiofilm agents, respectively. Furthermore, EA and EB were employed to synthesize gold nanoparticles (AuNPs) such as EB-AuNPs and EA-AuNPs, which could serve as antibiofilm agents against the isolated LAB. These findings demonstrate that EA, EB-AuNPs, and EA-AuNPs exhibit significant antibacterial activity against the isolated LAB. Furthermore, EB-AuNPs reduced L. citreum biofilm production, whereas EA-AuNPs inhibited L. mesenteroides and L. brevis biofilm formation. The current results suggest that EB-AuNPs and EA-AuNPs can be used as nanomaterials to inhibit LAB that form biofilms on meat products.

• Korean Journal of Food Science and Technology
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• v.42 no.2
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• pp.155-159
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• 2010

The antimicrobial activity of Sargassum fulvellum (SF) was investigated using the agar diffusion assay and MIC test. In addition, the stability of this activity under extreme heat and pH conditions was examined. The SF ethanol extract was shown to display strong antimicrobial activities against B. subtilis, C. perfringens, L. plantarum, S. aureus, L. monocytogenes, S. cerevisae and C. tropicalis in the agar diffusion assay at the concentration of 4 mg/mL. The MIC value of the SF ethanol extract against the tested microbes ranged from 0.05 to 0.0063%. In the heat and pH stability test, the antimicrobial activity of the SF ethanol extract was not altered when the temperature was maintained at $121^{\circ}C$ for 15 min, and it was also not affected in the pH range of 2-10. These results suggest that the SF ethanol extract is highly stable against drastic changes in temperature and pH.

• Korean Journal of Food Science and Technology
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• v.14 no.1
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• pp.57-62
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• 1982

The possibility of developing new kinds of lactic acid beverage from a malt syrup was studied. The optimum sugar concentration of malt syrup for the cultivation of lactic acid bacteria was $10^{\circ}Bx$. The acidity of the fermented malt syrup was improved by the supplement of yeast extract(0.5%) or sodium citrate(0.08%). Though the activity of Lactobacillus lactis in malt syrup was superior to other strains, sensory test indicated that the mixed culture of Lactobacillus lactis and Streptococcus diacetilactis was better because of masking malt flavour. The changes in acidity and viable cells of malt syrup during the lactic fermentation were not so good as skim milk medium, but malt syrup medium containing milk(50 : 50) was nearly similar to skim milk medium. In the sensory scores among samples, no significant differences(P<0.05) were noted between fermented milk and fermented malt syrup containing milk, but fermented malt syrup showed a poor quality. However fermented malt syrup was not inferior to marketing lactic fermented fruit juices with regards to the lactic acid fermented beverage type.

• Journal of Animal Science and Technology
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• v.64 no.1
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• pp.166-182
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• 2022

Deer antler velvet is widely used in traditional medicine for its anti-aging, antioxidant, and immunity-enhancing effects. However, few studies have reported on the discovery of probiotic strains for deer antler fermentation to increase functional ingredient absorption. This study evaluated the ability of probiotic lactic acid bacteria to enhance the concentrations of bioactive molecules (e.g., sialic acid and gamma-aminobutyric acid [GABA]) in extracts of deer antler velvet. Seventeen strains of Lactobacillus spp. that were isolated from kimchi and infant feces, including L. sakei, L. rhamnosus, L. brevis, and L. plantarum, and those that improved the life span of Caenorhabditis elegans were selected for evaluation. Of the 17 strains, 2 (L. rhamnosus LFR20-004 and L. sakei LFR20-007) were selected based on data showing that these strains increased both the sialic acid and GABA contents of deer antler extract after fermentation for 2 d and significantly improved the life span of C. elegans. Co-fermentation with both strains further increased the concentrations of sialic acid, GABA, and metabolites such as short-chain fatty acids and amino acids. We evaluated the biological effects of the fermented antler velvet (FAV) on the antibacterial immune response in C. elegans by assessing worm survival after pathogen infection. The survival of the C. elegans conditioned with FAV for 24h was significantly higher compared with that of the control worm group fed only normal feed (non-pathogenic E. coli OP50) exposed to E. coli O157:H7, Salmonella typhi, and Listeria monocytogenes. To evaluate the protective effects of FAV on immune response, cyclophosphamide (Cy), an immune-suppressing agent was treated to in vitro and in vivo. We found that FAV significantly restored viability of mice splenocytes and immune promoting-related cytokines (interleukin [IL]-6, IL-10, inducible nitric oxide synthase [iNOS], interferon [IFN]-γ, and tumor necrosis factor [TNF]-α) were activated compared to non-fermented deer antlers. This finding indicated the protective effect of FAV against Cy-induced cell death and immunosuppressed mice. Taken together, our study suggests that immune-promoting antler velvet can be produced through fermentation using L. rhamnosus LFR20-004 and L. sakei LFR20-007.

• Journal of The Korean Society of Grassland and Forage Science
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• v.28 no.3
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• pp.229-236
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• 2008

This experiment was conducted to study on the evaluation of fermentation ability of microbes for whole crop rice silage Inoculant at National Institute of Animal Science, RDA from 2004 to 2005. We collected 28 strains of microbes from whole crop rice silage. According to acidity and growth ability, 5 strains of microbes was isolated (R4-1, R7-1, R7-2, R10-1, R12-1). The cultures of 4 strains were identified to be Lactobacillus plantarum (R4-1, R7-1, R7-2 and R10-1) and one was identified to be Lactobacillus pentosus (R12-1). Whole crop rice was harvested at the yellow ripen stage. It was ensiled in experimental silos (20ℓ capacity) with or without microbial additives (R4-1, R7-1, R7-2, R10-1, R12-1 and three commercial inoculant) and stored at room temperature for 60d. The pH value and acetic acid content of additivetreated silages were lower and lactic acid content was higher than those of the control (p<0.05). There was a trend for acetic acid content to be lowest and lactic acid to be highest in R7-1 treated silage. Crude protein (CP) contents of R7-2 treated silage was higher and acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents of R7-1 treated silage was lower (p<0.05). Although some strains of inoculant could improve silage quality, L. plantarum R7-1 was more effective as an inoculant for whole crop rice silage. This microbe was named NLRI 401 and registered in the Korea Agricultural Culture Collection.