• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.318-326
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• 2002

The pathogenic marine bacterium Vibrio vulnificus is the causative agent of food-borne diseases such as life-threatening septicemia. To better understand this organism's strategies to survive osmotic stress, a mutant that was more sensitive to high osmolarity was screened from a library of mutants constructed by a random transposon mutagenesis. By a transposon-tagging method, putAP genes encoding a proline dehydrogenase and a proline permease were identified and cloned from V. vulnificus. The amino acid sequences deduced from nucleotide sequences of putAP from V. vulnificus were 38 to $59\%$ similar to those of PutA and PutP reported from other Enterobacteriaceae. Functions of putAP genes were assessed by the construction of mutants, whose putAP genes were inactivated by allelic exchanges. When proline as the sole carbon or nitrogen source was used, the putA mutant was not able to grow to the substantial level, revealing the proline dehydrogenase is the only enzyme for metabolic conversion of proline into other amino acids. Although the growth rate of the putP mutant on proline as the sole carbon or nitrogen source was significantly reduced, the mutant still grew. This indicated that at least one more proline permease is produced by V. vulnificus. The putP mutant decreased approximately $2-log_10$ CFU/ml after a hyperosmotic challenge, while the parent strain decreased approximately $l-log_10$ CFU/ml. This result suggests that the gene product of putP contributes to the osmotic tolerance of V. vulnificus.

• Strategy21
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• s.44
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• pp.177-212
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• 2018

The purpose of this article is to examine the 'Discussion of maritime defense' which began to be discussed from the late Goryeo dynasty to the early Joseon dynasty and the process of establishing a maritime defense system. Also it can identify changes in the aspects of the naval ship operation and their strategic tactics during the reign of King Sejong. Japanese raiders began a full-scale invasion from 1350 at the late Goryeo Dynasty, So the government realized the need to raise the 'Sea power' and to organize the maritime defense system for defending enemy invasion. for example, the reinforcement of naval forces, construction of warships, develoment of weapon systems and so on. which have achieved remarkable growth while continuing, have also been used to carry out a three-time 'Conquest of Daemado' in 1389, 1396, 1419. Until then, however, it is difficult to interpret that the naval forces had a systematic and organizational combat operation system. According to fighting patterns on combat reports before the early days of King Sejong's reign, Our naval forces had no advantage over the Japanese raiders in terms of their capabilities and tactics. Then, the period of King Sejong marked a watershed in maritime defense history. Based on accumulated experience of naval battles and force Projections, The paradigm shift of the naval strategic tactics for maritime defense has occurred. First, the capability of the naval vessels has improved. for example, ship speed, durability, and weather resistance. Through these efforts, navy forces were able to pursue and attack, destroy enemy's ships by taking advantage of the 'Ship speed superiority'. This has led to tactical shifts from defensive to offensive. Second, purpose to support offensive tactics, the government put a strategic plan into practice that is the forward depolyment of naval bases from the inland to the coast, considering the 'sea environment' and 'threat'. By doing so, Joseon dynasty was able to secure 'the command of the sea'. This may be a little different from the perception of the so-called 'peace period' that King Sejong's era. We need to remember that Joseon dynasty was working hard for its defense. When studying history of maritime defense, these strategic and tactical elements must be fully considered. Only then we can have a coherent understanding of the many naval battles in the past, including the Imjin War(1592-1598).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.926-932
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• 2004

This study deals with the statistical analyses on the relationship between the red tide formation and the meteorological factors in the Korean coastal waters. From 1995 to 2002, the red tide was observed every year and the number of occurrences increased as well. The red tide mostly occurred in July, August, September and October. from multiple linear regression, the meteorological factors governing the mechanisms of the increase in the number of red tide occurrences are found to be a water temperature, rainfall, sunshine duration and wind velocity. But water temperature as the limited factor controlling the growth of phytoplankton (Cochlodinium polykrikoids) in 15∼$30^{\circ}c$. NO ＝ 8.089 - 0.319WT + 0.019RF + 0.141SD + 0.l19WV (R ＝ 0.897) in August NO = 7.531 - 0.327WT + 0.027RF + 0.208SD + 0.208WV (R ＝ 0.894) in September Here, NO is the number of occurrence for red tide, WT is water temperature, RF is rainfall, SD is sunshine duration and WV is wind velocity, respectively. The necessary times till the day of red tide occurrence verse the day when water temperature reaches $15^{\circ}c$ are 78∼104 days, then it should be divided the coastal waters into 4 areas by the comparison among the accumulated sunshine duration, water temperature and rainfall as follows； the South West Coast (SW), South Middle Coast (SM), South East Coast(SE) and East South Coast (ES). The coastal areas that red tide occurs were complicated and various by change of marine environments. Usually red tide with a high concentrations (individual number, cells/ml) appeared in SM and SE. It was found that the general situations for the frequencies of red tide formation are mainly concentrated to 24.5∼$25^{\circ}c$ (high water temperature) and eve. 1000 cells/ml (high individual number) such as the category of red tide warning.

• Microbiology and Biotechnology Letters
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• v.40 no.3
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• pp.243-249
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• 2012

This study was conducted to screen an alginate-degrading microorganism and to investigate the characteristics of the alginate-degrading activity of its crude enzyme. A marine bacterium which produces extracellular alginate-degrading enzymes was isolated from the brown alga Sargassum thunbergii. 16S rRNA sequence analysis and physiological profiling resulted in the bacterium's identification as a Vibrio crassostreae strain, named Vibrio crassostreae PKA 1002. Its optimal culture conditions for growth were pH 9, 2% NaCl, $30^{\circ}C$ and a 24 hr incubation time. The optimal conditions for the alginate degrading ability of the crude enzyme produced by V. crassostreae PKA 1002 were pH 9, $30^{\circ}C$, a 48 hr incubation time and 8% alginic acid. The alginate degrading crude enzyme produced 3.035 g of reducing sugar per liter in 4% (w/v) alginate over 1 hr.

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.424-431
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• 2011

BACKGROUND: Tributyltin chloride is among the most toxic compounds known for aquatic ecosystems. Microorganisms are responsible for removal of TBTCl. Nevertheless, only a limited number of marine bacteria were investigated for biodegradation of TBTCl in Korea. METHODS AND RESULTS: The number of TBTCl resistant bacteria ranged from $2.5{\times}10^3$ to $3.8{\times}10^3$ cfu/mL in the seawater, and ranged from $3.2{\times}10^5$ to $9.1{\times}10^5$ cfu/g in the surface sediment, respectively. The morphological, physiological, and biochemical characteristics of TBTCl resistant bacteria were investigated by API 20NE and other tests. The most abundant species of TBTCl resistant bacteria were Vibrio spp. (19.2%), Bacillus spp. (16.2%), Aeromonas spp. (15.2%), and Pseudomonas spp. (13.1%), etc. Eleven TBTCl resistant isolates also had a resistance to heavy metals (Cd, Cu, Hg, and Zn). Among them, isolate T7 showing the strong TBTCl-resistance was selected. This isolate was identified as the genus Pantoea by 16S rRNA gene sequencing and designated as Pantoea sp. T7. In addition, this bacterium was cultivated up to the growth of 50.7% after 60 hrs at TBTCl concentration of $500{\mu}M$. TBTCl-degrading activity of Pantoea sp. T7 was measured by GC-FPD analysis. As a result of biological TBTCl-degradation at TBTCl concentration of $100{\mu}M$, TBTCl-removal efficiency of Pantoeasp. T7 was 62.7% after 40 hrs. CONCLUSION(S): These results suggest that Pantoea sp. T7 is potentially useful for the bioremediation of TBT contamination.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1058-1067
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• 2000

In this study, eel, puffer and snake head fish, which are widely taken and highly valued for processing into baked fish, soup or fish juice were studied by classifying them into wild fish and cultured fish, and evaluated in terms of taste. The samples were gathered in the area including Kimhae, Samchonpo and Haman in Kyungsangnam-do, Kangsu-Gu in Pusan and Bukcheju-Gun in Cheju-do. Proximate compositions, the content of nucleotides and their related compounds, total and free amino acids, organic acids and fatty acids of the fishes were analysed. Generally, as for the compositions, wild fish had a higher crude fat content and a lower moisture content as compared with cultured fish, while there was no great difference between them in terms of crude protein and ash contents. Nucleotides and their related compounds including ATP, ADP, AMP, IMP, HxR, Hx were detected, and the amounts of which were nearly the same with respect to the growth conditions. IMP content was high in all of the samples, while ATP content was extremely low. Total 17 amino acids were detected from the samples, and most of the samples had high contents of glutamic acid, aspartic acid, lysine, leucine, glycine, alanine and arginine, and low contents of cystein, isoleucine and methionine. As for the other amino acids, generally same level of contents were detected for each samples. In cases of eel and snake head fish, the wild fish had higher total amino acid contents in comparison with cultured fish. And the result to the contrary was obtained for the case of puffer. Sample fishes had nearly the same compose distribution of free amino acid though the contents of which were a little different according to the samples. Each sample had high contents of taurine, hydroxyproline, glutamic acid, glycine, cystathionine, ${\beta}-aminoisobutyric$ acid and lysine. Total organic acid contents of cultured fish was higher than that of wild fish. All fishes commonly had high contents of lactic acid, iso-valeric acid, oxalic acid and fumaric acid. High levels of $C_{16:0},\;C_{16:1},\;C_{18:1(cis)},\;C_{18:3},\;and\;C_{22:6}$ were shown in all of the samples and ${\omega}-3$ polyunsaturated fatty acid content of cultured fish was higher than that of wild fish, and as for the essential fatty acid, wild fish has higher content in comparison with cultured fish.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3785-3791
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• 2012

Dissolved oxygen is one of the most important factors controlling growth in aquatic organisms. Hypoxia is generally defined as dissolved oxygen less than 2.8 mg $O_2/L$ (equivalent to 2 mL $O_2/L$ or 91.4 mM). Therefore, hypoxia zone can cause a serious problem in marine ecosystem. In this study, to investigate embryotoxic (fertilization and embryo development rates) effects of hypoxia on sea urchin Strongylocentrotus nudus were exposed to dissolved oxygen levels of 7.6 mg $O_2/L$ (normoxia) and 1.8 mg $O_2/L$ (hypoxia) for 2 days at $15^{\circ}C$ and 33 ‰. Also, Expression levels of stress related gene (HSP70) and antioxidant related gene (glutathione reductase) in the sea urchins exposed to hypoxia were confirmed by Immunoblotting and RT-PCR analysis. In results, we showed that developmental rates were dramatically reduced in hypoxia condition. Molecular analysis demonstrated that higher HSP70 (5.5 fold) and glutathione reductase gene (2.79 fold) were present in the sea urchin exposed to hypoxia. Our results suggested that hypoxia can cause the abnormal development and elicits a stress and antioxidant response on sea urchin.

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.373-378
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• 2019

In the marine area, the salt concentration in the soil increases, and the inland heavy metal pollution increases the damage of plants. In the inland industrial development area, researches on the genetic resources of plants together with the heavy metal accumulation of Co, Ni, Zn, and so on are required. Both of these problems have caused scientists to work hard to find plants that are likely to cause stress in plant roots. In this study, seeds of Arabis stelleri var. japonica collected near the shore were used for germination. The growth and development and tolerance of both Arabis and Arabidopsis seeds were investigated under laboratory culture conditions. As a result, Arabis showed resistance about 3 times in 250 mM nickle and cobalt, and more than 4 times in 1 mM zinc when compared to Arabidopsis. The tolerance of Arabis to Na salts increased by 20% or more at 50 mM concentration and Arabis was resistant to heavy metals and salt concentration. The accumulation of Na ions in the body was measured as a preparation for studying the intracellular mechanism. As a result, it showed a further decrease in resistance to ground water roots. It is considered that the activity of the exporting gene is important rather than the mechanism of accumulation.

• Korean Journal of Environment and Ecology
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• v.33 no.2
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• pp.228-236
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• 2019

This study investigated the effect of the sediment phosphorus fraction sampled from the southern coast of Korea on the release characteristics of sediments by environmental changes of water quality. We conducted the release experiment in the laboratory for 20 days and measured the phosphorus fraction properties, the environmental factors of water quality, and the release rate of total phosphorus. The results showed a decrease in dissolved oxygen by the growth of microorganisms in the water layer, leading to the anaerobic condition in which the redox potential of the sediments decreased. As such, the decreasing variability of phosphates bonded to iron oxide in the sediment phosphorus was higher after 20 days of the release experiment than the first day. It means that the metal ions and the separated inorganic phosphorus transfer into the water when the iron oxide is reduced. The separated inorganic phosphorus is easily absorbed by the plankton. The analysis of total phosphorus in the water layer showed that it continuously increased to up to 0.304 mg/L for 20 days, and the release rate had a high correlation with the decrease of dissolved oxygen after 5 days of culture. Therefore, it is necessary to pay attention to the characteristics of iron bonded to phosphorus in the phosphorus fraction and dissolved oxygen to manage the eutrophication of the system.

• Journal of Life Science
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• v.29 no.1
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• pp.97-104
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• 2019

Streptococcus iniae is a typical fish pathogen causing streptococcosis and it can also cause zoonotic infectious diseases. We studied S. iniae FP5228 isolated from infected olive flounder in Wando, Korea. In a study to find virulence factors in FP5228, we found that the number of live bacteria decreased dramatically in culture medium containing S. iniae FP5228 for more than 24 hr. This phenomenon was hypothesized to be related to Toxin ${\zeta}$ and Antitoxin ${\varepsilon}$ genes, components of the Toxin/ Antitoxin (TA) system on the 14 kb plasmid of FP5228. We used a protein overexpression system to identify it. The pBP1140 vector system was constructed to regulate the expression of Toxin ${\zeta}$ and Antitoxin ${\varepsilon}$ by IPTG and Arabinose. E. coli/pBP1140 strain grew slowly in early growth under toxin expression condition, and it was confirmed by microscopic observation that the strain became longer. S. iniae CK287, lacking a 14 kb plasmid of S. iniae FP5228 strain, was constructed. CK287 bacterial cells did not show rapid killing during culture, and the ability to produce biofilm was also decreased, and toxicity was weakened in cytotoxicity test and fish test. These results suggest that the TA system is involved in physiological regulation and expression of virulence factors in S. iniae FP5228.