• Journal of Microbiology and Biotechnology
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• 제26권9호
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• pp.1579-1585
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• 2016

Sugar esters are valuable compounds composed of various sugars and fatty acids that can be used as antibacterial agents and emulsifiers in toothpaste and canned foods. For example, fructose fatty acid esters suppress growth of Streptococcus mutans, a typical pathogenic bacterium causing dental caries. In this study, fructose laurate ester was chosen as a target material and was synthesized by a transesterification reaction using Candida antarctica lipase B. We performed a solvent screening experiment and found that a t-butanol/dimethyl sulfoxide mixture was the best solvent to dissolve fructose and methyl laurate. Fructose laurate was synthesized by transesterification of fructose (100 mM) with methyl laurate (30 mM) in t-butanol containing 20% dimethyl sulfoxide. The conversion yield was about 90%, which was calculated based on the quantity of methyl laurate using high-performance liquid chromatography. Fructose monolaurate (M_r 361) was detected in the reaction mixture by high-resolution mass spectrometry. The inhibitory effect of fructose laurate on growth of oral or food spoilage microorganisms, including S. mutans, Bacillus coagulans, and Geobacillus stearothermophilus, was evaluated.

• Journal of Microbiology and Biotechnology
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• 제24권5호
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• pp.614-618
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• 2014

Resveratrol, which is a polyphenolic antioxidant, is dose-dependent when used to provide health benefits, to enhance stress resistance, and to extend lifespans. However, even though resveratrol has therapeutic benefits, its clinical therapeutic effect is limited owing to its low oral bioavailability. An Escherichia coli system was developed that contains an artificial biosynthetic pathway that produces resveratrol glucoside derivatives, such as resveratrol-3-Oglucoside (piceid) and resveratrol-4'-O-glucoside (resveratroloside), from simple carbon sources. This artificial biosynthetic pathway contains a glycosyltransferase addition (YjiC from Bacillus) with resveratrol biosynthetic genes. The produced glucoside compounds were verified through the presence of a product peak(s) and also through LC/MS analyses. The strategy used in this research demonstrates the first harnessing of E. coli for de novo synthesis of resveratrol glucoside derivatives from a simple sugar medium.

• Journal of Microbiology and Biotechnology
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• 제26권10호
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• pp.1808-1816
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• 2016

As a scaffolding subunit of the PIK3C3/VPS34 complex, Beclin 1 recruits a variety of proteins to class III phosphatidylinositol-3-kinase (VPS34), resulting in the formation of a distinct PIK3C3/VPS34 complex with a specific function. Therefore, the investigation of a number of Beclin 1 domains required for the protein-protein interactions will provide important clues to understand the PIK3C3/VPS34 complex, of which Beclin1-VPS34 interaction is the core unit. In the present study, we have designed a bacterial overexpression system for the Beclin 1 domain corresponding to VPS34 binding (Vps34-BD) and set up the denaturing purification protocol due to the massive aggregation of Vps34-BD in Escherichia coli. The expression and purification conditions determined in this study successfully provided soluble and functional Vps34-BD.

• Journal of Microbiology and Biotechnology
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• 제28권3호
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• pp.454-464
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• 2018

Salivary microbiota alterations can correlate with dental caries development in children, and mechanisms mediating this association need to be studied in further detail. Our study explored salivary microbiota shifts in children and their association with the incidence of dental caries with dentine involvement. Salivary samples were collected from children with caries and their subsequently matched caries-free controls before and after caries development. The microbiota was analyzed by 16S rRNA gene-based high-throughput sequencing. The salivary microbiota was more diverse in caries-free subjects than in those with dental caries with dentine involvement (DC). Although both groups exhibited similar shifts in microbiota composition, an association with caries was found by function prediction. Analysis of potential microbiome functions revealed that Granulicatella, Streptococcus, Bulleidia, and Staphylococcus in the DC group could be associated with the bacterial invasion of epithelial cells, phosphotransferase system, and ${\text\tiny{D}}-alanine$ metabolism, whereas Neisseria, Lautropia, and Leptotrichia in caries-free subjects could be associated with bacterial motility protein genes, linoleic acid metabolism, and flavonoid biosynthesis, suggesting that functional differences in the salivary microbiota may be associated with caries formation. These results expand the current understanding of the functional significance of the salivary microbiome in caries development, and may facilitate the identification of novel biomarkers and treatment targets.

• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.957-963
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• 2001

Bacillus subtilis YL-1004 was isolated from soil for the development of agents to control dental caries. This strain produced an extracellular lytic enzyme that hydrolyzed the Streptococcus mutans cell wall. The lytic enzyme was purified to homogeneity by affinity chromatography and gel permeation chromatography to give a single band on SDS-PAGE and non-denaturing polyacrylamide gel electrophoresis. The molecular weight of the enzyme was deduced from SDS-PAGE and gel chromatography to be 38 kDa and the PI to be 4.3 from isoelectric focusing. Sirty $\%$ of its lytic activity remained after incubation at $50^{\circ}C$ for 30 min, and its optimal temperature was $37^{\circ}C$ . The enzyme showed its highest activity at pH 8.0 and was stable at pHs ranging from 4.0 to 9.0. Treatment with several modifiers showed that a cysteine residue was involved in the active site of the enzyme. This lytic enzyme from Bacillus subtilis YL-1004 exhibited specificity towards Streptococci and also showed autolytic activity on Bacillus subtilis YL-1004.

• Journal of Microbiology and Biotechnology
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• 제30권4호
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• pp.599-603
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• 2020

In the present study, we examined the effects of interleukin (IL)-10 expression-inducing bacteria Bifidobacterium adolescentis HP1, Lactobacillus mucosae HP2, and Weissella cibaria HP3 on high-fat diet (HFD)-induced obesity and liver steatosis in mice. Oral gavage of HP1, HP2, and HP3 reduced HFD-induced bodyweight gain, triglycerides, and total cholesterol levels in the blood and liver. They also suppressed HFD-induced colitis and the fecal δ,γ-Proteobacteria population. Of the tested bacteria, HP2, which most potently inhibited IL-10 expression, also suppressed HFD-induced bodyweight gain, liver steatosis, and colitis most effectively. These findings suggest that IL-10 expression-inducing gut bacteria can suppress obesity and liver steatosis.

• Journal of Microbiology and Biotechnology
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• 제30권1호
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• pp.71-78
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• 2020

Lactobacillus sakei S1 strongly inhibits the expression of interleukin (IL)-6 and IL-1β in lipopolysaccharide-induced peritoneal macrophages by a mechanism for which lactic acid bacteria from kimchi that inhibit tumor necrosis factor-alpha (TNF-α) were isolated. Therefore, we further evaluated the protective effect of this strain on the colitis mouse model induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS). TNBS significantly elevated myeloperoxidase (MPO) expression, macroscopic scores, and colon shortening. Oral L. sakei S1 administration resulted in reduction of TNBS-induced loss in body weight, colon shortening, MPO activity, expression of cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS) and nuclear factor-kappa B (NF-κB). L. sakei S1 inhibited the expression of inflammatory cytokines IL-1β, IL-6 and TNF-α, induced by TNBS, but enhanced IL-10 expression. L. sakei S1 showed resistance to artificial digestive juices and adherence to intestinal epithelial Caco-2 cells. Thus, L. sakei S1 may inhibit the NF-κB pathway and be used in functional food to treat colitis.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.998-1001
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• 2002

Potential antitumor activity of Lactobacillus plantarum cytoplasm was examined using F9 teratocarcinoma-bearing BALB/C mice. The cytoplasmic fraction of L. plantarum was separated by sonication followed by ultracentrifugation. The fraction at a dose of 100 or 200 mg/kg/day was orally administered for 7 consecutive days before or after tumor inoculation to 16 mice. As a control, heat-killed whole cell was used at a dose of 100 mg/kg/day. Upon oral administrations of both the cytoplasm and heat-killed whole cell, when performed after and before tumor inoculation, the survival of F9-bearing mice prolonged more effectively. Administration of the cytoplasm after tumor inoculation extended the average survival days by 30 and $40\%$ at daily dosages of 100 and 200 mg/kg/day, respectively. This result suggests that the cytoplasmic fraction of L. plantarum has strong antitumor activity against mouse F9 teratocarcinoma in vivo.

• Journal of Microbiology and Biotechnology
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• 제18권2호
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• pp.308-313
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• 2008

Ixeris dentata (ID, family Asteraceae), called Seumbakuy in Korea, was fermented with lactic acid bacteria (LAB) and their antiallergic activities were investigated. Fermentation of ID with Bifidobacterium breve or Lactobacillus acidophilus increased its inhibition of degranulation in RBL-2H3 cells induced by the IgE-antigen complex. Oral administration of these extracts to mice inhibited the passive cutaneous anaphylaxis (PCA) reaction induced by the IgE-antigen complex and scratching behaviors induced by compound 48/80. The fermented ID more potently inhibited the PCA reaction and scratching behaviors than the non-fermented one. These extracts also inhibited mRNA expression of TNF-${\alpha}$ and IL-4, as well as NF-${\kappa}B$ activation in RBL-2H3 cells induced by the IgE-antigen complex. These findings suggest that LAB fermentation improves ID-mediated inhibition of IgE-induced allergic diseases such as rhinitis and asthma, and that ID works by inhibiting degranulation and NF-${\kappa}B$ activation in mast cells and basophils.

• Journal of Microbiology and Biotechnology
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• 제24권10호
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• pp.1438-1444
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• 2014

Lactic acid bacteria (LAB) are probiotics that provide numerous beneficial effects on the host body, especially on the intestine. Combining several strains of LAB, we prepared a formulation containing four different LAB and studied its anti-inflammatory activity both in vitro and in vivo. The formulation significantly reduced NO production from RAW 264.7 cells treated with bacterial lipopolysaccharide, indicating that the formulation might include anti-inflammatory activity. The formulation also suppressed inflammatory change induced by trinitrobenzene sulfonic acid (TNBS) in mice, where oral or rectal administration of the formulation protected the colon tissue from the damage by TNBS. Expressions of the IL-6 and FasL genes appeared to be down-regulated by the formulation in TNBS-treated colon tissues, suggesting that the suppression of those genes may be involved in the anti-inflammatory activity of the formulation.