• Horticultural Science & Technology
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• v.31 no.5
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• pp.626-632
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• 2013

In the course of a developing screening method for resistant radish to Fusarium oxysporum f. sp. raphani, we found that the fungus produces phytotoxic compound against Raphanus sativus. The culture filtrate of F. oxysporum f. sp. raphani KR1 represented the strongest phytotoxicity when the fungus was incubated in the malt extract broth with 150 rpm at $25^{\circ}C$ for 14 days. Under bioassay-guided purification, we isolated a substance from liquid culture of F. oxysporum f. sp. raphani KR1, with phytotoxic effect against R. sativus. The compound was identified as fusaric acid by mass and nuclear magnetic resonance spectral analyses. Phytotoxicity of the compound against cruciferous vegetable crops, including radish, cabbage, and broccoli, was investigated. Fusaric acid represented phytotoxicity on radish seedlings by concentration dependant manner. And the phytotoxin demonstrated strong phytotoxicity on the resistant cultivars as well as susceptible cultivars of radish to F. oxysporum f. sp. raphani. In addition, fusaric acid isolated from the fungus also showed a potent phytotoxic efficacy against non-host Brassicaceae crops of the fungus such as cabbage and broccoli. The results demonstrate that fusaric acid produced by F. oxysporum f. sp. raphani is non-host-specific toxin and for screening of resistant radish to the fungal pathogen, spore suspension of the fungus without the phytotoxin has to be used.

• Research in Plant Disease
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• v.26 no.3
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• pp.159-169
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• 2020

Pectobacterium carotovorum subsp. carotovorum (Pcc) causes bacterial soft rot on a wide range of crops worldwide, especially in countries with warm and humid climates. This study was conducted to establish an efficient screening method for resistant cultivars of Chinese cabbage to bacterial soft rot. Resistance degrees of 65 commercial Chinese cabbage cultivars to the Pcc KACC 10225 isolate were investigated. For further study, three Chinse cabbage cultivars (Taebong, Hadaejangkun, CR Alchan) showing different level of resistance to the bacterium were selected. The development of bacterial soft rot on the cultivars was tested according to several conditions such as growth stage of Chinse cabbage seedling, inoculum concentration, and incubation temperature after inoculation. On the basis of the results, we suggest that an efficient screening method for resistant Chinses cabbage to Pcc is to inoculate twenty one-day-old seedlings with a bacterial suspension of Pcc at a concentration of 1×10⁷ cfu/ml, and to incubate the plants in a dew chamber at 25℃ for 24 hr and then to cultivate in a growth room at 25℃ and 80% relative humidity with 12-hr light per day.

• Research in Plant Disease
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• v.24 no.3
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• pp.193-201
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• 2018

Pectobacterium carotovorum subsp. carotovorum (Pcc) causes bacterial soft rot on a wide range of crops worldwide, especially in countries with warm and humid climates. This study was conducted to establish an efficient screening method for resistant cultivars of radish (Raphanus sativus) to bacterial soft rot. Resistance degrees of 60 commercial radish cultivars to the Pcc KACC 10421 isolate were investigated. For further study, six radish cultivars (Awooriwoldong, YR Championyeolmu, Jeonmuhumu, Bitgoeunyeolmu, Sunbongaltari, Housecheongok) showing different level of resistance to the bacterium were selected. The development of bacterial soft rot on the cultivars was tested according to several conditions such as incubation temperature, seedling stage of radish, inoculum concentration to develop the disease. On the basis of the results, we suggest that an efficient screening method for resistant radish to Pcc is to inoculate twenty-day-old seedlings with a bacterial suspension of Pcc at a concentration of $8{\times}10^5cfu/ml$ and then to cultivate the plants in a growth room at $25^{\circ}C$ and 80% RH with 12-hour light per day.

• Research in Plant Disease
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• v.30 no.2
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• pp.124-130
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• 2024

Leaf blight caused by Stemphylium vesicarium is one of the most important fungal diseases of garlic (Allium sativum L.) worldwide, which results in a reduction of quality and yield. The breeding of resistant cultivars is an efficient approach to decrease the use of chemical fungicides and minimize crop losses. In this study, to find the resistant garlic resources against S. vesicarium, we evaluated the resistance degree of 20 garlic germplasms. To do this, garlic seedlings at four-leaf stage were rubbed with nonabsorbent cotton and then inoculated with spore suspension (3.0×10⁵ spores/ml of potato dextrose broth) of S. vesicarium by spray method. Three to seven days after inoculation, the infected leaf area (%) of garlic seedling was measured. 'Daeseo' and 'Namdo' were included as susceptible and resistant control cultivars, respectively. After 3 to 7 days of incubation, the infected leaf area (%) of garlic seedling was measured. Our results showed that IT245512, IT245528, and IT244068 lines exhibited the highest resistance against S. vesicarium, whereas IT257134 and IT253043 lines were more susceptible than the susceptible cultivar 'Daeseo'. Based on the results, the resistant genetic resources selected in this study can be used a basic material for resistant garlic breeding system against leaf blight.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.81-88
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• 1993

For searching the photosynthetic electron transport(PET) inhibitors, bio-rational screening system using thylakoid membranes extracted from wild and mutant cyanobacteria(Anacystis nidulans $R_2$) was developed. Generally, thylakoid membrane was more sensitive to the tested herbicides than the chloroplast from spinach in the Hill reaction. Higher resistant characteristics appeared in mutant D-5, Di-22 to diuron and mutant G-264 to atrazine as compared to wild type. To test the reaction of thylakoid membrane to herbicides, diuron and atrazine were applied simultaneously. Diuron and atrazine competed each other for binding with substituted amino acids, while diuron and dinoseb were non-competitive, and inhibiting activity was increased. Conclusively, bio-rational screening system using cyanobacteria was proved to be fast and efficient screening method for the development of PET inhibitors.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.410-416
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• 2008

The gene SfXyn10, which encodes a protease-resistant xylanase, was isolated using colony PCR screening from a genomic library of a feather-degrading bacterial strain Streptomyces fradiae var. k11. The full-length gene consists of 1,437bp and encodes 479 amino acids, which includes 41 residues of a putative signal peptide at its N terminus. The amino acid sequence shares the highest similarity (80%) to the endo-1,4-${\beta}$-xylanase from Streptomyces coelicolor A3, which belongs to the glycoside hydrolase family 10. The gene fragment encoding the mature xylanase was expressed in Escherichia coli BL21 (DE3). The recombinant protein was purified to homogeneity by acetone precipitation and anion-exchange chromatography, and subsequently characterized. The optimal pH and temperature for the purified recombinant enzyme were 7.8 and $60^{\circ}C$, respectively. The enzyme showed stability over a pH range of 4.0-10.0. The kinetic values on oat spelt xylan and birchwood xylan substrates were also determined. The enzyme activity was enhanced by $Fe^{2+}$ and strongly inhibited by $Hg^{2+}$ and SDS. The enzyme also showed resistance to neutral and alkaline proteases. Therefore, these characteristics suggest that SfXyn10 could be an important candidate for protease-resistant mechanistic research and has potential applications in the food industry, cotton scouring, and improving animal nutrition.

• Pediatric Infection and Vaccine
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• v.6 no.2
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• pp.261-266
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• 1999

Vancomycin-resistant enterococcus(VRE) was first isolated from various specimens of patients with renal failure or leukemia in 1988. Thereafter VRE has been increasing gradually and became one of the clinically important palhogenic organisms currently. We experienced a case of E. faecalis sepsis in a 4 day old neonate. She was born at 39 weeks gestational age with 2,900gm weight by Cesarean section delivery due to breech presentation. She had had swelling and motion limitation of the left knee joint with fever for one day at age of 4 day and was transfered to our hospital. Ultrasonographic examination of her left knee joint showed some inflammatory change. E. faecalis was isolated from the blood. The organism showed resistance to vancomycin on drug susceptibility test using BHI agar screening test and disk diffusion method. After treatment with ampicillin-sulbactam for 3 weeks the baby was improved. Although VRE infection has been considered rare in Korea. considerable number of demonstrative studies about VRE isolation have been reported recently thus adequate countermeasures are needed to reduce the emergence and prevent nosocomial spreading of this organism.

• Tuberculosis and Respiratory Diseases
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• v.80 no.2
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• pp.201-209
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• 2017

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infection is a severe and life-threatening disease in patients with community-onset (CO) pneumonia. However, the current guidelines lack specificity for a screening test for MRSA infection. Methods: This study was retrospectively conducted in elderly patients aged ${\geq}65years$, who had contracted CO-pneumonia during hospitalization at the Jeju National University Hospital, between January 2012 and December 2014. We analyzed the risk factors of MRSA in these patients and developed a scoring system to predict MRSA infection. Results: A total of 762 patients were enrolled in this study, including 19 (2.4%) with MRSA infection. Healthcare-associated pneumonia (HCAP) showed more frequent MRSA infection compared to community-acquired pneumonia (4.4% vs. 1.5%, respectively; p=0.016). In a multivariate logistic regression analysis, admissions during the influenza season (odds ratio [OR], 2.896; 95% confidence interval [CI], 1.022-8.202; p=0.045), chronic kidney disease (OR, 3.555; 95% CI, 1.157-10.926; p=0.027), and intensive care unit admission (OR, 3.385; 95% CI, 1.035-11.075; p=0.044) were identified as predictive factors for MRSA infection. However, the presence of HCAP was not significantly associated with MRSA infection (OR, 1.991; 95% CI, 0.720-5.505; p=0.185). The scoring system consisted of three variables based on the multivariate analysis, and showed moderately accurate diagnostic prediction (area under curve, 0.790; 95% CI, 0.680-0.899; p<0.001). Conclusion: MRSA infection would be considered in elderly CO-pneumonia patients, with three risk factors identified herein. When managing elderly patients with pneumonia, clinicians might keep in mind that these risk factors are associated with MRSA infection, which may help in selecting appropriate antibiotics.

• Research in Plant Disease
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• v.16 no.3
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• pp.290-293
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• 2010

Bacterial canker, caused by Clavibacter michiganensis subsp. michiganensis, is a very damaging disease to tomato (Lycopersicon esculentum) farm in Korea. It infects tomato, spreads through the xylem and causes bacterial wilt and canker. Selection of resistant cultivar is the best way to prevent or reduce the occurrence of the disease. Thirty-nine tomato cultivars, twenty-one cherry tomato cultivars and thirteen rootstock tomato cultivars were inoculated with Clavibacter michiganensis subsp. michiganensis, to evaluate tomato cultivarspecific resistance against bacterial canker. In the evaluation of 73 major commercial cultivars, 'Sunmyung', 'Sweet', 'Akiko', 'Dadaki', 'Match', 'Magnet', 'Friend', and 'Greenpower' were found to have a high level of resistance to bacterial canker of tomatoes.

• Food Science of Animal Resources
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• v.30 no.4
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• pp.634-640
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• 2010

The principal objective of this study was to screen and select acid-tolerant Lactobacillus strains from chicken feces, feeds, and other sources. Fourty six strains evidencing acid tolerance (pH 3.5) were isolated in this study. Among them, nine strains exhibited marked immunostimulatory effects. Therefore, nine candidate strains were characterized for probiotic use. In order to evaluate macrophage activation, NO production was measured using RAW 264.7 cells. In particular, three strains (FC812, FC222, and FC113) evidenced the highest levels of NO production measured at $38.39{\pm}20.01,\;35.06{\pm}27.73$, and $33.88{\pm}15.99{\mu}M$, respectively, at a concentration of $10^{8}CFU/mL$. The majority of strains, with the exception of strain FC322, evidenced marked resistance to artificial gastric juice (pH 2.5 with 1%(w/v) pepsin). Additionally, strains FC222, FC421, FC511, and FC721 were highly resistant to artificial bile acid (0.1%(w/v) oxgall), whereas strains FC113, FC322, FC422, FC621, and FC812 were the least resistant to bile. All nine strains exerted antimicrobial effects against chickenrelated pathogens. Additionally, all nine strains were found to be resistant to several antibiotics. The isolated strains, except for strain FC322, were tentatively identified as Lactobacillus salivarius, using an API 50 CHL kit. These results demonstrate that some probiotic organisms may potentially probiotic properties, and thus may serve as an effective alternative to antibiotics in animal applications.