Myung-Ji Seo

Expression and Characterization of a Glutamate Decarboxylase from Lactobacillus brevis 877G Producing γ-Aminobutyric Acid

The glutamate decarboxylase of γ-aminobutyric acid-producing Lactobacillus brevis 877G (LbGAD) was expressed in Escherichia coli. The optimal pH and temperature for the purified LbGAD activity were respectively determined to be pH 5.2 and 45 °C. CaCl2 was shown to be a potent activator of this LbGAD activity. The kinetic parameters for LbGAD were a Km value of 3.6 mmol/L and a Vmax value of 0.06 mmol/L/min for L-monosodium glutamate.

Characterization of antimicrobial lipopeptides produced by Bacillus sp. LM7 isolated from chungkookjang, a Korean traditional fermented soybean food

A wild-type microorganism exhibiting antimicrobial activities was isolated from the Korean traditional fermented soybean food Chungkookjang and identified as Bacillus sp. LM7. During its stationary growth phase, the microorganism secreted an antimicrobial substance, which we partially purified using a simple two-step procedure involving ammonium sulfate precipitation and heat treatment. The partially purified antimicrobial substance, Anti-LM7, was stable over a broad pH range (4.0-9.0) and at temperatures up to 80 °C for 30 min, and was resistant to most proteolytic enzymes and maintained its activity in 30% (v/v) organic solvents. Anti-LM7 inhibited the growth of a broad range of Gram-positive bacteria, including Bacillus cereus and Listeria monocytogenes, but it did not inhibit lactic acid bacteria such as Lactobacillus plantarum and Lactococcus lactis subsp. Lactis. Moreover, unlike commercially available nisin and polymyxin B, Anti-LM7 inhibited certain fungal strains. Lastly, liquid chromatography-mass spectrometry analysis of Anti-LM7 revealed that it contained eight lipopeptides belonging to two families: four bacillomycin D and four surfactin analogs. These Bacillus sp. LM7-produced heterogeneous lipopeptides exhibiting extremely high stability and a broad antimicrobial spectrum are likely to be closely related to the antimicrobial activity of Chungkookjang, and their identification presents an opportunity for application of the peptides in environmental bioremediation, pharmaceutical, cosmetic, and food industries.

Weissella cibaria WIKIM28 ameliorates atopic dermatitis-like skin lesions by inducing tolerogenic dendritic cells and regulatory T cells in BALB/c mice.

The occurrence of atopic dermatitis (AD), a chronic inflammatory skin disease, has been increasing steadily in children and adults in recent decades. In this study, we evaluated the ability of the lactic acid bacterium Weissella cibaria WIKIM28 isolated from gatkimchi, a Korean fermented vegetable preparation made from mustard leaves, to suppress the development of AD induced by 2,4-dinitrochlorobenzene in a murine model. Oral administration of W. cibaria WIKIM28 reduced AD-like skin lesions, epidermal thickening, and serum immunoglobulin E levels. Furthermore, the production of type 2 helper T (Th2) cytokines such as interleukin (IL)-4, IL-5, and IL-13 decreased in peripheral lymph node cells. Moreover, the intake of W. cibaria WIKIM28 increased the proportion of CD4+CD25+Foxp3+ regulatory T (Treg) cells in mesenteric lymph nodes (MLNs) and IL-10 levels in polyclonally stimulated MLN cells. In conclusion, the oral administration of W. cibaria WIKIM28 isolated from gatkimchi ameliorated AD-like symptoms by suppressing allergic Th2 responses and inducing Treg responses. These results suggest that W. cibaria WIKIM28 may be applicable as a probiotic for the prevention and amelioration of AD.

Characterization of an L-Arabinose Isomerase from Bacillus thermoglucosidasius for D-Tagatose Production

L-Arabinose isomerase from Bacillus thermoglucosidasius KCTC 1828 (BTAI) was expressed in Escherichia coli. The optimal temperature and pH for the activity of the purified BTAI were 40 °C and pH 7.0. The Mn(2+) ion was an activator of BTAI activity. The kinetic parameters of BTAI for D-galactose were a K(m) of 175 mM and a k(cat)/K(m) of 2.8 mM(-1)min(-1). The conversion ratio by BTAI to D-tagatose reached 45.6% at 40 °C.

Isolation of the Putative Biosynthetic Gene Cluster of 1-Deoxynojirimycin by Bacillus amyloliquefaciens 140N, Its Production and Application to the Fermentation of Soybean Paste

The 1-deoxynojirimycin (DNJ) biosynthetic gene cluster of Bacillus amyloliquefaciens 140N isolated from traditional Korean fermented food was isolated by PCR screening. It showed 78.9% inhibitory activity against α-glucosidase and produced 0.8 g/L of DNJ in an optimized medium containing 2% soluble starch, 1% tryptone, 0.05% KH(2)PO(4), and 0.05% (NH(2))(4)SO(4). Soybean paste fermented with B. amyloliquefaciens 140N produced DNJ with 84.4% inhibitory activity.

Genome Sequence of Lysinibacillus boronitolerans F1182, Isolated from a Traditional Korean Fermented Soybean Product

Lysinibacillus is a Gram-positive, rod-shaped, and round-spore-forming bacterial genus of the family Bacillaceae. We analyzed the genome sequence of Lysinibacillus boronitolerans F1182, isolated from a traditional Korean fermented soybean product. The genome sequence contained 4.46 Mbp with a G+C content of 37.5%. This is the first report of an L. boronitolerans genome.

Enhanced Production of Gamma-Aminobutyric Acid by Optimizing Culture Conditions of Lactobacillus brevis HYE1 Isolated from Kimchi, a Korean Fermented Food.

This study evaluated the effects of culture conditions, including carbon and nitrogen sources, L-monosodium glutamate (MSG), and initial pH, on gamma-aminobutyric acid (GABA) production by Lactobacillus brevis HYE1 isolated from kimchi, a Korean traditional fermented food. L. brevis HYE1 was screened by the production analysis of GABA and genetic analysis of the glutamate decarboxylase gene, resulting in 14.64 mM GABA after 48 h of cultivation in MRS medium containing 1% (w/v) MSG. In order to increase GABA production by L. brevis HYE1, the effects of carbon and nitrogen sources on GABA production were preliminarily investigated via one-factor-at-a-time optimization strategy. As the results, 2% maltose and 3% tryptone were determined to produce 17.93 mM GABA in modified MRS medium with 1% (w/v) MSG. In addition, the optimal MSG concentration and initial pH were determined to be 1% and 5.0, respectively, resulting in production of 18.97 mM GABA. Thereafter, response surface methodology (RSM) was applied to determine the optimal conditions of the above four factors. The results indicate that pH was the most significant factor for GABA production. The optimal culture conditions for maximum GABA production were also determined to be 2.14% (w/v) maltose, 4.01% (w/v) tryptone, 2.38% (w/v) MSG, and an initial pH of 4.74. In these conditions, GABA production by L. brevis HYE1 was predicted to be 21.44 mM using the RSM model. The experiment was performed under these optimized conditions, resulting in GABA production of 18.76 mM. These results show that the predicted and experimental values of GABA production are in good agreement.

Genome Sequence of Kocuria atrinae C3-8, Isolated from Jeotgal, a Traditional Korean Fermented Seafood

Kocuria is a Gram-positive coccus, catalase-positive, coagulase-negative, strictly aerobic bacterial genus in the family Micrococcaceae. Kocuria atrinae C3-8 was isolated from a traditional Korean fermented seafood. This study describes the first genome sequence of K. atrinae strain C3-8, which has a 3.19-Mbp genome and a G+C content of 63.8%.

Thalassobius litorarius sp. nov., isolated from a tidal flat.

A Gram-stain-negative, aerobic, non-motile and rod-shaped bacterium, belonging to the family Rhodobacteraceae, designated strain MME-075T, was isolated from a tidal flat. Strain MME-075T grew with 1-5% (w/v) NaCl at 20-35 °C and at pH 7-9. Optimal growth occurred with 2% (w/v) NaCl at 25-30 °C and at pH 7. The dominant respiratory quinone was ubiquinone-10, whereas summed feature 8 (C18:1ω7c and/or C18:1ω6c), 11-methyl C18:1ω7c, and C16:0 were the major fatty acids. The major polar lipids were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and an unidentified lipid. The genomic DNA G+C content was 62.1 mol%. The highest 16S rRNA gene sequence similarity values were between strain MME-075T and Thalassobius aestuarii, Thalassococcus lentus, Thalassobius maritimus and Shimia marina and were 97.6, 97.5, 97.2 and 96.2%, respectively. Neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees, based on 16S rRNA gene sequences, revealed that strain MME-075T clustered with species of the genus Thalassobius. Based on phenotypic and phylogenetic taxonomic properties, this strain is proposed as a representative of a novel species of the genus Thalassobius, for which the name Thalassobius litorarius sp. nov. is proposed. The type strain is MME-075T (=KCCM 43143T=JCM 30758T).

Linarin down-regulates phagocytosis, pro-inflammatory cytokine production, and activation marker expression in RAW264.7 macrophages

Plant-extracted flavonoid glycosides have been reported to be bioactive compounds with pleiotropic functions, including antioxidant, anti-inflammatory, and anti-cancer effects. This study investigated the anti-inflammatory role of linarin (acacetin-7-rutinoside, which is found in Chrysanthemum indicum (Gam-Guk) and Dendranthema zawadskii (Gu-Jul-Cho)), on lipopolysaccharide-stimulated RAW264.7 macrophages. Linarin treatments exhibited no cytotoxicity up to a concentration of 30 μM, as assessed by MTT assay. The production of nitric oxide, an inflammatory mediator, was decreased by addition of linarin. The secretion of pro-inflammatory cytokines, interleukin-1β and interleukin-6, was significantly decreased in a dose-dependent manner. Linarin also decreased the phagocytic ability of macrophages following co-culture with fluorescent beads. In addition, expression levels of antigenpresenting surface markers, MHC II and CD80, were suppressed by linarin. Taken together, these results indicate that the flavonoid glycoside linarin has an anti-inflammatory effect, in part through the suppression of phagocytosis, cytokine production, and antigen presentation in macrophages.