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Kim M.K.,Environment Friendly Research Division | Seo W.T.,Gyeongnam National University of Science and Technology | Lee Y.B.,Gyeongsang National University | Cho K.M.,Gyeongnam National University of Science and Technology
Food Science and Biotechnology | Year: 2013

The archaeal diversity in the soybean fermented food was analysed by culture-independent methods based on the 16S rRNA sequences. The 21 doenjang archaea - clones from the doenjang library were grouped into 5 groups: uncultured archaeon clone AE34 (42. 8%), uncultured archaeon clone AS17 (28. 6%), uncultured compost archaeon clone 4A29 (4. 8%), uncultured compost archaeon clone 0A10 (19. 0%), and uncultured compost archaeon clone 5A16 (4. 8%). The 21 ganjang archaea - clones from the ganjang library were grouped into 5 groups: Halophilic archaeon MH1-34-1 (19. 0%), H. archaeon MH1-16-3 (61. 9%), Halococcus thailandensis (4. 8%), Haloplanus sp. RO5-8 (9. 5%), and H. archaeon MH1-136-2 (4. 8%). © 2013 The Korean Society of Food Science and Technology and Springer Science+Business Media Dordrecht. Source


Lee J.H.,Nakdong River Basin Environmental Office | Nam S.H.,Gyeongnam National University of Science and Technology | Seo W.T.,Gyeongnam National University of Science and Technology | Yun H.D.,Gyeongsang National University | And 3 more authors.
Food Chemistry | Year: 2012

Bacillus subtilis CSY191, the potential probiotics and surfactin-like compound producer, was isolated from doenjang (Korean traditional fermented soybean paste).The survival rate of this strain appeared to be the 58.3% under artificial gastric conditions after 3 h at pH 3.0. Surfactin was purified from the strain CSY191. Three potential surfactin isoforms were detected, with protonated masses of m/z 1030.7, 1044.7, and 1058.71. These different structures were detected in combination with Na+, K+ and Ca 2+ ions by MALDI-TOF mass spectrometry. Upon 500 MHz 1H NMR analysis, the surfactin isoforms had identical amino acids (GLLVDLL) and hydroxy fatty acids (of 13-15 carbons in length). The MTT assay showed that surfactin inhibited growth of MCF-7 human breast cancer cells in a dose-dependent manner, with an IC50 of approximately 10 μg/ml at 24 h. Additionally, the surfactin contents, during cheonggukjang fermentation with strain CSY191, increased from 0.3 to 48.2 mg/kg over 48 h of fermentation, while the level of anticancer activity increased from 2.6- to 5.1-fold. © 2011 Elsevier Ltd. All rights reserved. Source


Kang Y.M.,Korea Institute of Oriental Medicine | Kim M.G.,Environment Friendly Research Division | Yun H.D.,Gyeongsang National University | Cho K.M.,Gyeongnam National University of Science and Technology
Journal of the Korean Society for Applied Biological Chemistry | Year: 2013

A shotgun method was adopted to clone the β-xylanase and lichenase genes from a genomic library of a Paenibacillus polymyxa GS01 genome library. Also, a fusion enzyme, Xyn3A-Lin16A, was designed by overlap extension polymerase chain reaction (PCR). The cloned Xyn3A and Lin16A proteins were successfully expressed and exhibited both xylanase and lichenase activities. The xyn43A and lin16A gene amplicons were 1,917 bp and 714 bp in size and encoded proteins of 635 and 238 amino acids, respectively. The Xyn43A and Lin16A gene products showed predicted molecular masses of 65 and 24 kDa with respective calculated pIs of 5.97 and 5.77, respectively. Furthermore, the fusion enzyme gene, Xyn43A-Lin16A, was 4,466 bp in length and encoded a protein of 847 amino acids, with apparent molecular mass of 89 kDa and a calculated pI of 5.93. This fusion enzyme showed optimum activity at pH 6.0-7.0 and 50°C. Thus, the xyn43A and lin16A genes from P. polymyxa GS01were able to exist in tandem, and recombinant DNA technologies can be used to improve enzyme productivity. Therefore, the development of functional fusion enzymes (xylanase-lichenase) using recombinant DNA technologies may lead to further improvements and their successful enzyme engineering in industrial application. © 2013 The Korean Society for Applied Biological Chemistry. Source


Kang Y.M.,Korea Institute of Oriental Medicine | Kim M.K.,Environment Friendly Research Division | An J.M.,Gyeongsang National University | Haque M.A.,Gyeongnam National University of Science and Technology | Cho K.M.,Gyeongnam National University of Science and Technology
Journal of Molecular Catalysis B: Enzymatic | Year: 2015

The metagenomes of complex microbial communities are rich sources of novel biocatalysts. Genetic engineering facilitates the artificial fusion of genes that encode functional proteins into a single open reading frame. The cloning of the cellulase and xylanase genes from the cow rumen metagenome resulted in the construction of a bifunctional fusion gene via site-directed mutagenesis for further specific industrial processes. The metagenome of cow rumen bacteria was the source of a gene that encodes an extracellular β-glucanase for cloning and expression in Escherichia coli DH5α. The cellulase (cel9E) gene of un-culturable rumen bacteria existed in tandem with the xylanase (xyn10A) gene. The genes were 2268 bp and 1.578 bp and encoded 756- and 526-aa proteins, respectively. BLAST analyses and domain predictions assigned Cel9E and Xyn10A to glycosyl hydrolase families 9 and 10. The molecular weight of the individual proteins Cel9E and Xyn10A were estimated to be approximately 76.0 kDa and 56.0 kDa by CMC-SDS-PAGE and OSX-SDS-PAGE, respectively. The 3909 bp cel9E-xyn10A fusion gene encoded a 1303-amino acid residue protein with a molecular weight of approximately 137.0 kDa according to CMC/OSX-SDS-PAGE. The maximum cellulase and xylanase activities from the fusion protein Cel9E-Xyn10A were observed at pH 6.0 and pH 8.0, respectively. The optimal temperature for the bifunctional enzyme was found to be 50 °C. The improved catalytic efficiency of the Cel9E-Xyn10A for the cellulase and xylanase activity was equivalent to 1.47- and 2.21-fold of the parental efficiency. We report the presence of the cel9E gene in tandem with the xyn10A gene in the metagenome of un-culturable cow rumen bacteria. The construction, expression and characterization of the cel9E-xyn10A bifunctional gene fusion obtained by site-directed mutagenesis are also reported. © 2015 Published by Elsevier B.V. Source


Kim B.,Gyeongnam National University of Science and Technology | Seo W.T.,Gyeongnam National University of Science and Technology | Kim M.G.,Environment Friendly Research Division | Yun H.D.,Gyeongsang National University | Cho K.M.,Gyeongnam National University of Science and Technology
Journal of the Korean Society for Applied Biological Chemistry | Year: 2012

Lactic acid bacterial diversity and the composition of individual bacterial communities during the fermentation of mulkimchi were examined using a polymerase chain recation (PCR)-based approach. Based on 16S rRNA sequence similarity values, a total of fifteen different lactic acid bacterial species were found in eight sampling sites, including Lactobacillus alimentarius, Lactobacillus brevis, Lactobacillus farciminis, Lactobacillus fabifermentans, Lactobacillus nantensis, Lactobacillus parabrevis, Lactobacillus plantarum, Lactobacillus versnoldensis, Lactobacillus zymae, and Lactobacillus sp., Leuconostoc pseudomesenteroides, Weissella cibaria, Weissella confusa, and Weissella sp. The prevalence of We. cibaria, belonging to the Weissella genus, was the highest (86. 7%) at 0 h (initial stages) and gradually decreased at 72 h (rancid stage). In contrast, La. plantarum was observed at 36 h (16. 7%, over-ripening stage) and gradually increased up to 84 h (70. 0%, rancid stage) during mulkimchi fermentation. We. cibaria was found to be associated with the microorganisms that were present during the initial stage of fermentation, whereas La. plantarum was associated with the production of lactic acid in the over-ripening and rancid stages during fermentation at 30°C±2. © 2012 The Korean Society for Applied Biological Chemistry. Source

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