• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.72-80
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• 2023

Melons, a rich source of vitamins and fibers, are commonly grown in the soil. Hydroponic cultivation could improve yield and quality of melon and selection of substrate volume and the kind of substrates is important for hydroponic cultivation of melons. This study investigated the effect on melon growth according to volume of granular rockwool and substrates of coir and rockwool slab. 'Geumsegye' melon (Cucumis melo L. cv. Geumsegye) was cultivated hydroponically according to volume of granular rockwool to 1.0, 1.5, 2.0, 3.0, and 4.0 L, and was also cultivated using coir and rockwool slabs. Logistic model was applied to estimate the growth characteristics of melons such as plant height, leaf length, leaf width, and the characteristics of fruit. The growth characteristics of melons were significantly increased at 4.0 L compared to those grown of 1.0 L volume of on granular rockwool, and the results were the highest in coir and rockwool slabs. Melons grown in rockwool slabs showed the largest fruit fresh weight, fruit length, and fruit width. During hydroponic cultivation, growth characteristics of melon appropriate at the 4.0 L volume of granular rockwool, and the highest at coir and rockwool slabs. This study provides a basis for understanding the effect of root zone environment to the growth characteristics and fruit quality of non-netted melon.

• Microbiology and Biotechnology Letters
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• v.49 no.3
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• pp.329-336
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• 2021

Cellulophga sp. J9-3, is a gram-negative, aerobic marine bacterium belonging to the family Flavobacteriaceae. In addition to cellulose degradability, the J9-3 strain is also capable of hydrolyzing agar in the solid and liquid medium, and the production of agarase in the presence of agarose can be remarkably induced by the bacterium. From the cell culture broth of Cellulophga sp. J9-3, ammonium sulfate precipitation and three kinds of column chromatography were successively performed to purify a specific agarase protein, the AgaJ93. Purified AgaJ93 showed the strongest hydrolyzing activity towards agarose (approximately 22%), and even displayed activity towards starch. AgaJ93 hydrolyzed agarose into neoagarotetraose and neoagarohexaose via various oligosaccharide intermediates, indicating that AgaJ93 is an endo-type β-agarase. AgaJ93 showed maximum activity at a pH of 7.0 and temperature of 35 ℃. Its activity increased by more than six times in the presence of Co²⁺ ions. The N-terminal sequence of AgaJ93 showed 82% homology with the heat-resistant endo-type β-agarase Aga2 of Cellulophaga sp. W5C. However, the biochemical properties of the two enzymes were different. Therefore, AgaJ93 is expected to be a novel agarose, different from the previously reported β-agarases.

• Microbiology and Biotechnology Letters
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• v.38 no.1
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• pp.24-31
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• 2010

For the research of the natural marine antioxidant, an antioxidant-producing marine actinomycetes was isolated from sea water in Jeju coastal area. The strain was identified based on 16S rDNA sequencing, the morphology by a method of scanning electron microscopy, physiological and biochemical characteristics and cellular fatty acid analysis. The isolated strain ACT-18 was gram positive, aerobic, non-motile spores. Substrate mycelia are dark green and yellow gray aerial mycelia. The cell size of the strain was $0.5{\sim}1.0\;{\mu}m$. 16S rDNA sequence analysis showed that were Gram-positive bacteria grouped on Streptomyces sp. Results of cellular fatty acid analysis showed that major cellular fatty acids were $C_{15:0}$ anteiso (39.33%), $C_{16:1}$ cis 9 (11.96%), $C_{16:0}$ (13.08%) and $C_{17:0}$ anteiso (10.99%). The antioxidant activity of methanol extract from Streptomyce sp. ACT-18 was evaluated by measuring 1,1-diphenyl- 2-picrylhydrazyl (DPPH), hydroxyl, and alkyl radical scavenging activity using an electron spin resonance (ESR) spectrometer. DPPH radical scavenging activity of SBME (Streptomyces Broth Methanol Extract) A-18 was 46% at 0.1 mg/mL. Hydroxyl radical scavenging activity of SBME A-18 was 63% at 0.1 mg/mL. Alkyl radical scavenging activity of SBME A-18 was 39% at 0.1 mg/mL.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.84-89
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• 2014

In this work, Ag-$TiO_2$ nanocomposites were prepared via the sonochemical deposition of Ag nanometals on $TiO_2$ nanoparticles. The size of deposited Ag nanometals was ranged in 1~3 nm and the number of Ag nanometals deposited on $TiO_2$ increased in proportion to the dosage amounts of Ag precursors. As-prepared Ag-$TiO_2$ was loaded on the sterilized agar plate together with an aliquot volume of diluted E-coli, followed by 30 min irradiation of the solar simulated light ($600{\sim}1800{\mu}w/cm^2$). Finally, the agar plate was incubated for 24 h at $37^{\circ}C$ and the number of survived colonies were counted. It was experimentally confirmed that Ag-$TiO_2$ exhibited the higher antimicrobial activity than that of pure $TiO_2$, based on measuring the colony number of control sample. The survived colony numbers on the agar plate decreased with the increase of dosage amounts of Ag-$TiO_2$ and the irradiated intensity of solar simulated light for 30 min before incubating. The increase of Ag nanometal doposition induced the progressive enhancement of antimicrobial activity, but rather reduced the photocatalytic activity of Ag-$TiO_2$ probably due to the excessive presence of Ag nanometals on $TiO_2$ matrix.

• Research in Plant Disease
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• v.28 no.4
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• pp.231-236
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• 2022

Oxypetalum coeruleum, commonly known as Tweedia, is a perennial herbaceous plant of the Apocynaceae family native to southern Brazil and Uruguay. Tweedia plants are grown as one of the most popular ornamental flowers for floral arrangement in Korea. In May 2021, several tweedia plants in a single greenhouse in Gimje, Jeollabuk-do were found to show virus-like symptoms including necrotic rings, vein-clearing, chlorotic mottle, and mosaic on the leaves, and necrosis on the stems. Here, we have identified tomato spotted wilt virus (TSWV) in symptomatic tweedia leaves by applying high-throughput RNA sequencing. In the result, a single infection by TSWV was verified without mixed infections of different virus species. To confirm the presence of TSWV, a reverse transcription polymerase chain reaction was performed with a specific primer set to the N gene of TSWV. The complete genomic sequence of L, M, and S segments of TSWV 'Oxy' isolate were determined and deposited in GenBank under accession numbers LC671525, LC671638, and LC671639, respectively. In the phylogenetic tree analysis by maximum likelihood method, 'Oxy' isolate showed a high relationship with TSWV 'Gumi' isolate from Gerbera jamesonii in Gyeongsangbuk-do, Korea; for all three RNA segments. To our knowledge, this is the first report of TSWV infection of O. coeruleum in Korea.