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Chi W.-J.,National Institute of Biological Resource | Youn Y.S.,Myongji University | Kim J.-H.,University of Seoul | Hong S.-K.,Myongji University
Korean Journal of Microbiology and Biotechnology | Year: 2015

An agarolytic marine bacterium (H9) was isolated from the coastal seawater of the West Sea, South Korea. The isolate, H9, was gram-negative and rod-shaped with a smooth surface and polar flagellum. Cells grew at 20-30°C, between pH 5.0 and 9.0, and in ASW-YP (Artificial Sea Water-Yeast extract, Peptone) media containing 1-5% (w/v) NaCI. The G+C content was 41.56 mol%. The predominant isoprenoid quinone in strain H9 was ubiquinone-8. The major fatty acids (>10%) were C16:1ω7c (34.3%), C16:0(23.72%), and C18;1ω7c (13.64%). Based on 16S rRNA gene sequencing, and biochemical and chemotaxo- nomic characterization, the strain was designated as Pseudoalteromonas sp. H9 (=KCTC23887). In liquid culture supplemented with 0.2% agar, the cell density and agarase activity reached a maximum level of OD = 4.32 (48 h) and OD = 3.87 (24 h), respectively. The optimum pH and temperature for the extracellular crude agarases of H9 were 7.0 and 40°C, respectively. Thin-layer chromatography analysis of the agarase hydrolysis products revealed that the crude agarases hydrolyze agarose into neoagarotetraose and neoagarohexaose. Therefore, the new agar-degrading strain, H9, can be applicable for the production of valuable neoagarooligosaccharides and for the complete degradation of agar in bio-industries. © 2015, The Korean Society for Microbiology and Biotechnology.


Chi W.-J.,National Institute of Biological Resource | Lee C.-R.,Myongji University | Dugerjonjuu S.,Myongji University | Park J.-S.,Myongji University | And 2 more authors.
FEMS Microbiology Letters | Year: 2015

A putative agarase gene (agaH92) encoding a primary translation product (50.1 kDa) of 445 amino acids with a 19-amino-acid signal peptide and glycoside hydrolase 16 and RICIN superfamily domains was identified in an agarolytic marine bacterium, Pseudoalteromonas sp. H9 ( = KCTC23887). The heterologously expressed protein rAgaH92 in Escherichia coli had an apparent molecular weight of 51 kDa on SDS-PAGE, consistent with the calculated molecular weight. Agarase activity of rAgaH92 was confirmed by a zymogram assay. rAgaH92 hydrolyzed p-nitrophenyl-β-D-galactopyranoside, but not p-nitrophenyl-α-D-galactopyranoside. The optimum pH and temperature for rAgaH92 were 6.0 and 45°C, respectively. It was thermostable and retained more than 85% of its initial activity after heat treatment at 50°C for 1 h. rAgaH92 required Fe2+ for agarase activity and inhibition by EDTA was compensated by Fe2+. TLC analysis, mass spectrometry and NMR spectrometry of the GST-AgaH71 hydrolysis products revealed that rAgaH92 is an endo-type β-agarase, hydrolyzing agarose into neoagarotetraose and neoagarohexaose. © FEMS 2015.


You Y.-H.,Kyungpook National University | Seo Y.,Kyungpook National University | Yoon H.,Kyungpook National University | Kim H.,Kyungpook National University | And 5 more authors.
Korean Journal of Microbiology and Biotechnology | Year: 2013

The coastal sand-dune plants of eight species; Argusia sibirica, Calystegia soldanella, Elymus mollis, Lithospermum zollingeri, Raphanus sativus, Salsola collina, Zoysia macrostachya, and Zoysia sinica were collected from the Shindu-ri coastal sand dune. Ninety-eight endophytic fungal strains were isolated from the roots of these plants, analyzed, and identified by sequences in their internal transcribed spacers (ITS) at the ITS1, 5.8S, and ITS2 regions. The diversity of endophytic fungi isolated from coastal sand-dune plants was confirmed with various diversity indices. The fungal strains belonged to thirteen orders: Capnodiales (3.09%), Eurotiales (70.10%), Glomerellales (1.03%), Helotiales (3.09%), Hypocreales (9.28%), Mortierellales (2.06%), Onygenales (1.03%), Ophiostomatales (1.03%), Pleosporales (1.03%), Polyporales (1.03%), Russulales (1.03%), Saccharomycetales (2.06%), and Xylariales (1.03%). Of the endophytic fungal strains collected, Penicillium (59.18% in Eurotiales) and Fusarium (5.10% in Hypocreales) were the most abundant in coastal sand-dune plants. The endophytic fungal strains isolated from C. soldanella were more diverse compared to strains from the other coastal sand-dune plants. © 2013, The Korean Society for Microbiology and Biotechnology.


Lee C.-R.,Myongji University | Chi W.-J.,National Institute of Biological Resource | Bae C.-H.,National Institute of Biological Resource | Hong S.-K.,Myongji University
Korean Journal of Microbiology and Biotechnology | Year: 2015

Agar-hydrolyzing bacteria were isolated from the coastal sea water of Jeju Island. One isolate, designated as S4, was selected for further study. The S4 cells were Gram-negative and rod-shaped with smooth beige surfaces and single polar flagellum. Cells were grown at 15-42°C, 0.5-5% (w/v) NaCI, between pH 6.0 and 9.0, and in media containing 0.5-5% (w/v) NaCI. The G+C content was 49.93 mol%. The major fatty acids (>15%) were C18:1ω7c, C16:0 and Summed feature 3 (comprising C16:1ω7c/iso-C15:0 2-OH). Based on 16S rRNA sequencing and biochemical and chemotaxonomic characteristics, the strain was designated as Vibrio sp. S4. In liquid culture supplemented with 0.1% agar the cell density and agarase activity reached a maximum level in 72 h, while agarase activity in the culture without agar was negligible, implying agarose expression is induced by agar. The optimum pH and temperature for the extracellular crude agarase of S4 were 7.0 and 45°C, respectively. However, it also exhibited 98.6% and 87.6% at 40°C and 50°C, respectively, of the maximum activity seen at 45°C. The crude agarase hydrolyzed agarose into (neo)agarotetraose and (neo)agarohexaose. © 2015, The Korean Society for Microbiology and Biotechnology.


Soon-Ok R.,Kyungpook National University | You Y.-H.,Kyungpook National University | Yoon H.,Kyungpook National University | Kim Y.-E.,Kyungpook National University | And 5 more authors.
Journal of Microbiology and Biotechnology | Year: 2013

Gibberellins (GAs) are a group of phytohormones that control many developmental processes in higher plants. We report the cloning and expression pattern of gibberellin biosynthesis genes from a new GA-producing fungus, Fusarium proliferatum (strain KGL0401). These genes sequences are deposited in the National Center for Biotechnology Information (NCBI) under accession numbers EF119831, EF119832, DQ313173, DQ313174, DQ313175, DQ313176, and DQ313177. The expression level of these genes was maximal at a 0.5 M: 0.17 M carbon: nitrogen ratio, and minimal at a 0.25 M: 0.47 M carbon: nitrogen ratio.

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