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Featured researches published by Dae Young Kwon.


International Journal of Food Microbiology | 2009

Development of a RAPD-PCR method for identification of Bacillus species isolated from Cheonggukjang.

Gun-Hee Kwon; Hwang-A Lee; Jae-Young Park; Jong Sang Kim; Jinkyu Lim; Cheon-Seok Park; Dae Young Kwon; Yong-Suk Kim; Jeong Hwan Kim

A RAPD-PCR (Randomly Amplified Polymorphic DNA-PCR) method was developed for rapid identification of Bacillus species, especially B. subtilis, B. licheniformis, and B. amyloliquefaciens, the most frequently isolated organisms from fermented soy foods such as Cheonggukjang, a Korean traditional food. A RAPD-PCR using a 10-mer (S-30) produced species specific bands reproducibly. All B. subtilis strains tested produced common bands of 0.5 and 0.88 kb in size. All B. amyloliquefaciens strains generated 1.1 and 1.5 kb bands together with 0.5 kb fragment whereas B. licheniformis strains produced 1.25, 1.70, and 1.9 kb bands with an occasional 0.5 kb band. Using the RAPD-PCR protocol, six bacilli strains isolated from Cheonggukjang were identified to the species level, which was difficult by 16S rRNA gene and recA gene sequencing for some isolates. The 0.5 kb fragment, the major band for B. subtilis strains, was an internal part of a ytcP gene encoding a hypothetical ABC-type transporter. A B. subtilis species specific primer pair was designed based on ytcP sequences and PCR using the primer pair produced a 0.46 kb fragment only from B. subtilis strains.


Bioscience, Biotechnology, and Biochemistry | 2010

Metabolite Profiling of Cheonggukjang, a Fermented Soybean Paste, Inoculated with Various Bacillus Strains during Fermentation

Jin Gyeong Baek; Soon-Mi Shim; Dae Young Kwon; Hyung-Kyoon Choi; Choong Hwan Lee; Young-Suk Kim

Metabolite profiling of Cheonggukjang inoculated with different Bacillus strains including Bacillus amyloliqueciens CH86-1, Bacillus licheniformis 58, and Bacillus licheniformis 67 during fermentation, was performed using gas chromatography-time of flight-mass spectrometry after derivatization, combined with multivariate statistical analysis. A total of 20 amino acids, 10 sugars, five sugar alcohols, and seven organic acids were identified in three Cheonggukjang samples. With fermentation time, most of the amino acids showed increasing amounts. On the other hand, most of the sugars including sucrose, fructose, and glucose decreasing patterns, and the amounts of organic acids varied. In order to observe differences in metabolites with fermentation time and inoculated Bacillus strains, principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were carried out, respectively. On PCA plots, some sugars and organic acids including sucrose, fructose, glucose, mannose, succinic acid, and malonic acid, as well as most of the amino acids, contributed mainly to differentiation of the Cheonggukjang samples fermentation time. On the other hand, on PLS-DA, mannose, xylose, glutamic acid, and proline were mainly responsible for differentiating the Cheonggukjang among into various inoculated strains.


Bioscience, Biotechnology, and Biochemistry | 2011

Correlation between Antioxidative Activities and Metabolite Changes during Cheonggukjang Fermentation

Jiyoung Kim; Jung Nam Choi; Daejung Kang; Gun Hee Son; Young-Suk Kim; Hyung-Kyoon Choi; Dae Young Kwon; Choong Hwan Lee

Liquid chromatography mass spectrometry and multivariate analysis were employed to investigate the correlation between fermentation time-dependent metabolite changes in cheonggukjang, a traditional fermented soybean product, and changes in its antioxidant activity over 72 h. The metabolite patterns were clearly distinguished not by strains but by fermentation time, into patterns I (0–12 h), II (12–24 h), and III (24–72 h), which appeared as distinct clusters on principal component analysis. The compounds that significantly contributed to patterns I, II, and III were soyasaponins, isoflavonoid derivatives, and isoflavonoid aglycons respectively. Partial least square analysis for metabolite to antioxidant effects showed correlations between the ferric reducing/antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay during 24–36 h, and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) test and total phenol content (TPC) during 36–72 h. Compared with the strong negative correlations of glucosylated-isoflavonoids with DPPH, ABTS and TPC during fermentation, the isoflavonoid aglycon displayed strong positive correlations with these compounds during fermentation.


Nutrition | 2009

Kochujang, a Korean fermented red pepper plus soybean paste, improves glucose homeostasis in 90% pancreatectomized diabetic rats

Dae Young Kwon; Sang Mee Hong; Il Sung Ahn; Young-Suk Kim; Dong Wha Shin; Sunmin Park

OBJECTIVES Red pepper and soybeans have been reported to modulate energy and glucose metabolism. However, the antidiabetic effect of kochujang, the fermented product of red pepper plus soybeans, has not been studied. We examined whether kochujang affected insulin secretion from beta-cells and/or peripheral insulin resistance in 90% pancreatectomized diabetic rats fed high-fat diets. METHODS Diabetic rats consumed a high-fat diet containing two different kinds of 5% kochujang powder or the equivalent amount of nutrients for 8 wk. Two types of kochujang were made through the fermentation of two different kinds of meju (soybeans), red peppers, glutinous rice, and malts. Meju was produced by fermenting soybeans in a traditional method (TMK) or in a more modern method in which soybeans are inoculated with Bacillus subtilus and Aspergillus sojae (MMK). RESULTS TMK and MMK decreased body weight, visceral fat, and serum leptin levels without modulating caloric intake in diabetic rats compared with the control. TMK and MMK also improved glucose tolerance by enhancing insulin sensitivity but did not potentiate glucose-stimulated insulin secretion. The improvement in hepatic insulin sensitivity caused by TMK and MMK was explained by the potentiated phosphorylation of signal transducer and activator of transcription-3 --> adenosine monophosphate kinase --> acetyl-coenzyme A carboxylase and decreased phosphoenolpyruvate carboxykinase expression. Kochujang diets reduced hepatic glucose output and triacylglycerol accumulation and increased glycogen storage. CONCLUSION The combination of red pepper and fermented soybeans in kochujang improves glucose homeostasis by reducing insulin resistance, not by enhancing beta-cell function, in diabetic rats. The improvement is associated with decreased hepatic fat storage by the activation of adenosine monophosphate kinase.


Genes and Nutrition | 2008

Extracts of Rehmanniae radix, Ginseng radix and Scutellariae radix improve glucose-stimulated insulin secretion and β-cell proliferation through IRS2 induction

Sun Min Park; Sang Mee Hong; So Ra Sung; Ji Eun Lee; Dae Young Kwon

Recent studies have revealed that β-cell dysfunction is an important factor in developing type 2 diabetes. β-cell dysfunction is related to impairment of the insulin/IGF-1 signaling cascade through insulin receptor substrate-2 (IRS2). The induction of IRS2 in β-cells plays an important role in potentiating β-cell function and mass. In this study, we investigated whether herbs used for treating diabetes in Chinese medicine—Galla rhois, Rehmanniae radix, Machilus bark, Ginseng radix, Polygonatum radix, and Scutellariae radix—improved IRS2 induction in rat islets, glucose-stimulated insulin secretion and β-cell survival. R. radix, Ginseng radix and S. radix significantly enhanced glucose-stimulated insulin secretion compared to the control, i.e., by 49, 67 and 58%, respectively. These herbs induced the expression of IRS2, pancreas duodenum homeobox-1 (PDX-1), and glucokinase. The increased level of glucokinase could explain the enhancement of glucose-stimulated insulin secretion with these extracts. Increased PDX-1 expression was associated with β-cell proliferation, which was consistent with the cell viability assay. In conclusion, R. radix, Ginseng radix and S. radix had an insulinotropic action similar to that of exendin-4.


Bioscience, Biotechnology, and Biochemistry | 2007

A New Colorimetric Method for Determining the Isomerization Activity of Sucrose Isomerase

Sang-Eun Park; Mee-Hyun Cho; Jin Kyu Lim; Jong-Sang Kim; Jeong Hwan Kim; Dae Young Kwon; Cheon-Seok Park

A new colorimetric method for determining the isomerization activity of sucrose isomerase was developed. This colorimetric method is based on the enzymatic reactions of invertase and glucose oxidase-peroxidase (GOD-POD). The main scheme for assaying sucrose isomerase activity is to degrade sucrose in the reaction mixture to glucose and fructose by invertase and to detect the concentration of glucose generated using GOD-POD. The concentrations of trehalulose and isomaltulose, reaction products of sucrose isomerase, are calculated from the concentration of glucose. This method allows rapid and accurate determination of the isomerization activity of sucrose isomerase without inhibition by hydrolysis activity.


European Journal of Nutrition | 2007

Long-term consumption of fermented soybean-derived Chungkookjang enhances insulinotropic action unlike soybeans in 90% pancreatectomized diabetic rats

Dae Young Kwon; Jin Sun Jang; Sang Mee Hong; Ji Eun Lee; So Ra Sung; Hye Ryeo Park; Sunmin Park


Biofactors | 2006

The isoflavonoid aglycone-rich fractions of Chungkookjang, fermented unsalted soybeans, enhance insulin signaling and peroxisome proliferator-activated receptor-γ activity in vitro

Dae Young Kwon; Jin Sun Jang; Ji Eun Lee; Yong-Suk Kim; Dong-Hwa Shin; Sunmin Park


Food Science and Biotechnology | 2008

Metabolism of Isoflavone Derivatives During Manufacturing of Traditional Meju and Doenjang

Chan Ho Jang; Chun Seok Park; Jin Kyu Lim; Jeong Hwan Kim; Dae Young Kwon; Yong-Suk Kim; Dong Hwa Shin; Jong-Sang Kim


Journal of Microbiology and Biotechnology | 2007

Cloning of fibrinolytic enzyme gene from Bacillus subtilis isolated from Cheonggukjang and its expression in protease-deficient Bacillus subtilis strains.

Seon-Ju Jeong; Gun-Hee Kwon; Jiyeon Chun; Jong Sang Kim; Cheon-Seok Park; Dae Young Kwon; Jeong Hwan Kim

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Jong-Sang Kim

Kyungpook National University

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Jinkyu Lim

Kyungpook National University

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Yong-Suk Kim

Chonbuk National University

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Gun-Hee Kwon

Gyeongsang National University

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Jin Kyu Lim

Kyungpook National University

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