• 한국환경과학회지
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• 제31권3호
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• pp.265-274
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• 2022

Lipoxygenase is an enzyme, mainly produced by plants, capable of converting unsaturated fatty acids to fatty acids. It has vast application potential in the food, pharmaceutical and agricultural industries. The aim of this study was to isolate novel lipoxygenase-producing bacteria from the environment and to investigate the lipoxygenase enzymatic properties for industrial production. The strain, NC1, isolated from cultivation soils, was identified as Bacillus subtilis based on the phenotypic characteristics and 16S rRNA gene sequencing. This strain formed a pink color around the colony when cultured on indamine dye formation plates. The production of lipoxygenase by B. subtilis NC1 was influenced by the composition of the medium and linoleic acid concentrations. The optimum temperature and pH for lipoxygenase activity was determined to be 40 ℃ and pH 6, respectively. The enzyme showed relatively high stability at temperatures ranging from 20-50 ℃ and acid-neutral regions. In addition, the lipoxygenase produced by B. subtilis NC1 was able to degrade commercially available oils including sunflower seed oil and Perilla oil. In this study, a useful indigenous bacterium was isolated, and the fundamental physicochemical data of bacterial lipoxygenase giving it industrial potential are presented.

• 한국환경과학회지
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• 제31권8호
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• pp.715-725
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• 2022

Lactic Acid Bacteria (LAB) are among the representative probiotics that have been used for a long time in fermented food. Although there are many studies on detecting the radical scavenging activity of LAB, few studies have been conducted on the environmental factors that improve scavenging activity. This study investigated the environmental factors affecting the DPPH radical scavenging and various antioxidant activities of Kimchi-derived Lactobacillus plantarum K-21 with antihypertensive and radical scavenging activities. The optimal conditions for scavenging DPPH radicals were glucose 2%, bactopeptone 0.5%, Tween 80 0.05%, L-cysteine 0.05%, and an initial pH 6.5 at 35℃. Under optimal conditions, the DPPH radical scavenging activity was 94.8±2.2%, which was 1.5 times higher than that of the basic medium. In addition, L. plantarum K-21 had other antioxidant activities; ABTS radical scavenging (93.6±1.5%), hydroxyl radical scavenging (8.5±0.9%), metal chelating (65.9±0.5%), NO scavenging (53.1±19%), SOD-like (25.1±1.5%), and reducing power (11.7±1.4%) activities were detected. Therefore, L. plantarum K-21 may act not only as a starter for lactic acid-fermented foods with improved functionality but also as a drug for various diseases caused by oxidative stress.

• 한국동물위생학회지
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• 제46권3호
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• pp.211-218
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• 2023

This study was carried out to investigate the prevalence and antimicrobial resistance of Salmonella serotypes in duck farms of Jeollanam-do Province, South Korea. A total of 1112 samples (breeder ducks, 286; broiler ducks, 826) were collected from 196 duck farms (breeder duck farms, 25; broiler duck farms, 171) between January 2018 and November 2019. The total prevalence of Salmonella serotypes was 45.4% (89/196) in the duck farms, with no significant difference between prevalence in breeder and broiler duck farms (48% and 45%, respectively; P>0.05). The most prevalent serotype among the 127 Salmonella isolates was Salmonella Typhimurium (20.5%) followed by Salmonella Albany (17.3%), Salmonella Hadar (15.7%), and Salmonella Enteritidis (11.8%). Maximum resistance was observed against penicillin (78.74%), followed by tetracycline (68.50%), and kanamycin (65.35%). Of the 127 isolates, 117 (92.13%) were resistant to ≥3 antimicrobials and 2 to all 18 antimicrobials. Our results demonstrate the presence of Salmonella strains and their resistance to multiple antimicrobials, thus indicating a public health concern in South Korea. The emergence of Salmonella stains that are resistant to multiple drugs highlight the need for careful use of antimicrobials in duck farms.

• 한국임상수의학회지
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• 제41권1호
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• pp.8-17
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• 2024

This study was conducted to explore the efficacy of bee venom as a treatment for mastitis and to determine the optimal dosage and treatment period. When 6 mg or 12 mg of bee venom was administered to each experimental quarter of mastitis in dairy cow, the clinical symptoms in the 12 mg quarter were noticeably improved compared to those in the 6 mg quarter. There was no significant difference in the somatic cell count (SCC) in the milk between normal and mastitis quarters between the 6 and 12 mg doses, but there was a steady decrease in the 12 mg-treated quarter (p = 0.34). To determine the treatment period, bee venom was administered for 2, 4, and 7 days. After administering 12 mg of bee venom for 7 days, the SCC in the milk was compared before 6 days and after 7 days, and the SCC was significantly decreased to less than 100,000 SC/mL after 7 days (p = 0.01). In addition, to investigate the efficacy of bee venom, the minimum inhibitory concentration for S. aureus, E. coli, and coagulase negative staphylococci was measured, and the results showed that Gram-positive bacteria were more sensitive to bee venom than Gram-negative bacteria, and treatment for Gram-negative bacteria was limited. As a result of this study, it was confirmed that a dose of 12 mg of bee venom and a treatment period of more than 7 days were required to treat mastitis, and that treatment with bee venom alone against Gram-negative bacteria was negative.

• 농촌계획
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• 제19권4호
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• pp.137-147
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• 2013

Most of livestock houses are concentrated in certain area with mass rearing system resulting in rapid spread of infectious diseases such as HPAI (highly pathogenic avian influenza). The livestock-related vehicles which frequently travel between farms could be a major factor for disease spread by means of transmission of airborne aerosol including pathogens. This study was focused on the quantitative measurement of aerosol concentration by field experiment while vehicles were passing through the road. The TSP (total suspended particle) and PM10 (particle matter) were measured using air sampler with teflon filter installed downward the road with consideration of weather forecast and the direction of road. And aerosol spectrometer and video recorders were also used to measure the real-time distribution of aerosol concentration by its size. The results showed that PM2.5 was not considerable for transmission of airborne aerosol from the livestock-related vehicle. The mass generated from the road during the vehicle movement was measured and calculated to 241.4 ${\mu}g/m^3$ by means of the difference between TSP and PM2.5. The dispersion distance was predicted by 79.6 m from the trend curve.

• 한국동물위생학회지
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• 제36권2호
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• pp.79-86
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• 2013

Mycobacterium (M.) bovis, a member of the M. tuberculosis complex (MTC), is a re-emerging, zoonotic agent of bovine tuberculosis whose prevalence probably depends on variations in direct exposure to cattle and ingestion of raw milk. Accurate species differentiation of M. bovis and M. tuberculosis is needed to distinguish between human and zoonotic tuberculosis. This study successfully developed a loop-mediated isothermal amplification (LAMP) assay for rapid detection and differentiation of M. bovis and M. tuberculosis, however showed negative reactions in eight non-tuberculous mycobacteria (NTM) samples and ten other bacterial species. Sensitivity of this assay for detection of genomic M. bovis DNA was 10 $fg/{\mu}l$. And this assay successfully detected M. bovis in bovine clinical specimens. In conclusion, the LAMP assay is a simple and powerful tool for rapid detection of M. bovis in both pure bacterial culture and in clinical samples.

• 한국임상수의학회지
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• 제36권1호
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• pp.15-22
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• 2019

Highly pathogenic avian influenza (HPAI) is among the top infectious disease priorities in Korea and the leading cause of economic loss in relevant poultry industry. An understanding of the spatial epidemiology of HPAI outbreak is essential in assessing and managing the risk of the infection. Though previous studies have reported the majority of outbreaks occurred clustered in what are preferred to as densely populated poultry regions, especially in southwest coast of Korea, little is known about the spatial distribution of risk areas vulnerable to HPAI occurrence based on geographic information system (GIS). The main aim of the present study was to develop a GIS-based risk index model for defining potential high-risk areas of HPAI outbreaks and to explore spatial distribution in relative risk index for each 252 Si-Gun-Gu (administrative unit) in Korea. The risk index was derived incorporating seven GIS database associated with risk factors of HPAI in a standardized five-score scale. Scale 1 and 5 for each database represent the lowest and the highest risk of HPAI respectively. Our model showed that Jeollabuk-do, Chungcheongnam-do, Jeollanam-do and Chungcheongbuk-do regions will have the highest relative risk from HPAI. Areas with risk index value over 4.0 were Naju, Jeongeup, Anseong, Cheonan, Kochang, Iksan, Kyeongju and Kimje, indicating that Korea is at risk of HPAI introduction. Management and control of HPAI becomes difficult once the virus are established in domestic poultry populations; therefore, early detection and development of nationwide monitoring system through targeted surveillance of high-risk spots are priorities for preventing the future outbreaks.

• Journal of Veterinary Science
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• 제23권3호
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• pp.36.1-36.14
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• 2022

Background: Since 2003, the H5 highly pathogenic avian influenza (HPAI) subtype has caused massive economic losses in the poultry industry in South Korea. The role of inland water bodies in avian influenza (AI) outbreaks has not been investigated. Identifying water bodies that facilitate risk pathways leading to the incursion of the HPAI virus (HPAIV) into poultry farms is essential for implementing specific precautionary measures to prevent viral transmission. Objectives: This matched case-control study (1:4) examined whether inland waters were associated with a higher risk of AI outbreaks in the neighboring poultry farms. Methods: Rivers, irrigation canals, lakes, and ponds were considered inland water bodies. The cases and controls were chosen based on the matching criteria. The nearest possible farms located within a radius of 3 km of the case farms were chosen as the control farms. The poultry farms were selected randomly, and two HPAI epidemics (H5N8 [2014-2016] and H5N6 [2016-2017]) were studied. Conditional logistic regression analysis was applied. Results: Statistical analysis revealed that inland waters near poultry farms were significant risk factors for AI outbreaks. The study speculated that freely wandering wild waterfowl and small animals contaminate areas surrounding poultry farms. Conclusions: Pet birds and animals raised alongside poultry birds on farm premises may wander easily to nearby waters, potentially increasing the risk of AI infection in poultry farms. Mechanical transmission of the AI virus occurs when poultry farm workers or visitors come into contact with infected water bodies or their surroundings. To prevent AI outbreaks in the future, poultry farms should adopt strict precautions to avoid contact with nearby water bodies and their surroundings.

• 한국동물위생학회지
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• 제36권4호
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• pp.243-248
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• 2013

Q fever is a rickettsial infection caused by Coxiella burnetii that is transmitted from animals to humans. Modes of transmission to humans include inhalation, tick bites and ingestion of unpasteurized milk or dairy products. This survey was aimed at monitoring the seroprevalence of C. burnetii in bulk-tank milk (BTM) in Gyeongbuk province. In addition, the seroprevalence of C. burnetii was investigated at the herd level of dairy cattle in eastern Gyeongbuk province in which many dairy cattle are reared. Among 324 BTM samples collected from 20 country areas, 175 (54%) BTM samples from 15 (75%) country areas were positive for C. burnetii by ELISA. By regions, the seroprevalence of BTM samples in eastern, central, western and northern areas of Gyeongbuk province were 62.7%, 48.4%, 45.1%, and 41.4%, respectively. When analyzed in the dairy cattle reared in the eastern area where high seroprevalence occurred in BTM samples, 119 (24.2%) out of 492 dairy cattle were positive for C. burnetii. Seroprevalence of C. burnetii in dairy cattle was increased with daily milk yield of farm (P<0.05) and age (P<0.001). Since seroprevalence of C. burnetii is relatively high in both BTM samples and dairy cattle reared in Gyeongbuk province, further studies on the high risk farms and herds are needed to evaluate infection status and appropriate control programs in this region.

• 대한의생명과학회지
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• 제24권3호
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• pp.183-195
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• 2018

Cryptococcosis, which is caused by the Cryptococcus species complex (including Cryptococcus neoformans and Cryptococcus gattii), is well known as one of the most important medical problems. However, the of the Cryptococcus species complex is still limited to pneumonia and meningitis. In particular, the differences in virulence among the five major serotypes of the Cryptococcus species complex are not fully understood. To elucidate the virulence of the Cryptococcus species complex when it is disseminated hematogenously, rats were infected by different strains of the Cryptococcus species serotype, and their histopathological characteristics were compared after infection. The cumulative mortality ratio of rats infected with serotype B strain was slightly higher than in the other experimental groups. In addition, the average recovery of the Cryptococcus species complex from rats infected with serotype B strain was significantly higher than in the other groups in almost all organ samples except spleen. The recovery of the Cryptococcus species complex was associated with the severity of histopathological lesions, including bleeding, inflammation, and tissue damage in all organs. In rats infected with serotype B strain, the virulence was the most severe, especially in the lungs and liver. These results indicate that the pathophysiology of the Cryptococcus species complex infection differs according to serotype.