• Journal of fish pathology
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• v.33 no.2
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• pp.111-118
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• 2020

The genus Edwardsiella belonging to the family Enterobacteriaceae is a member of Gram-negative rod-shaped bacteria that cause disease in diverse aquatic organisms such as fish, amphibians and reptiles as well as avians and mammals including human throughout the world. This genus had been composed of three species, E. hoshinae, E. ictaluri and E. tarda, but recent researches erected two novel species, E. anguillarum and E. piscicida that were conventionally identified as E. tarda. In this study, we isolated seven strains belonging to the genus Edwardsiella from freshwater fishes that had been reared at inland fish farms in South Korea and investigated their biochemical characteristics and molecular phylogenetic relationships. The seven strains showed typical characteristics of four Edwardsiella species, E. anguillarum, E. ictaluri, E. piscicida and E. tarda, by biochemical analyses of Gram staining, indole and hydrogen sulfide (H2S) production, and API (Analytic Profile Index) 20E test. Molecular phylogenetic analyses inferred from DNA sequence data of both 16S ribosomal RNA (rRNA) and DNA gyrase subunit B (gyrB) genes were congruent with the biochemical characteristics. As a result, both biochemical and molecular phylogenetic analyses identified four strains isolated from three Anguilla species as E. anguillarum, E. piscicida and E. tarda, two strains from Pelteobagrus fulvidraco and Silurus asotus as E. ictaluri, and one strain from Moroco oxycephalus as E. piscicida. In this study, we isolated and successfully identified recently newly erected species, E. anguillarum and E. piscicida in addition to historically notorious pathogenic species, E. ictaluri and E. tarda. In the future study, systematic and comprehensive monitoring of the four Edwardsiella species are required for studying differences in pathogenicity among freshwater fishes.

• Biomedical Science Letters
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• v.18 no.1
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• pp.79-82
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• 2012

Acinetobacter infections are of great concern in clinical settings because of multi-drug resistance (MDR) and high mortality of the infected patients. The MDR Acinetobacter baumannii has emerged as a significant infectious agent in hospitals worldwide. The purpose of this study was to determine for molecular characterization of MDR A. baumannii clinical isolates obtained from the Wonju Christian Hospital in Gangwon province of Korea. A total of seventy nonduplicate A. baumannii isolates were collected from the Wonju Christian Hospital in Korea from March to April in 2011. All of the MDR A. baumannii isolates were encoded by $bla_{OXA-23-like}$ gene and all isolates with the $bla_{OXA-23-like}$ gene had the upstream element ISAba1 to promote increased gene expression and subsequent resistance to carbapenem. 16S rRNA methylase gene (armA) was detected in 44 clinical isolates which were resistant to amikacin, and phosphotransferase genes encoding aac(3)-Ia and aac(6')-Ib were the most prevalent. A combination of 16S rRNA methylase and aminoglycoside-modifying enzyme genes (armA, aac(3)-Ia, aac(6')-Ib, and aph(3')-Ia) were found in 31 isolates. The sequencing results for the quinolone resistance-determining region (QRDR) of gyrA and parC revealed the presence of Ser (TCA) 83 Leu (TTA) and Ser (TCG) 80 Leu (TTG) substitutions in the respective enzymes for all MDR. Molecular typing for MDR A. baumannii could be helpful in confirming the identification of a common source or cross-contamination. This is an important step in enabling epidemiological tracing of these strains.

• Journal of The Korean Astronomical Society
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• v.46 no.1
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• pp.1-32
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• 2013

We construct several Milky Way-like galaxy models containing a gas halo (as well as gaseous and stellar disks, a dark matter halo, and a stellar bulge) following either an isothermal or an NFW density profile with varying mass and initial spin. In addition, galactic winds associated with star formation are tested in some of the simulations. We evolve these isolated galaxy models using the GADGET-3 N-body/hydrodynamic simulation code, paying particular attention to the effects of the gaseous halo on the evolution. We find that the evolution of the models is strongly affected by the adopted gas halo component, particularly in the gas dissipation and the star formation activity in the disk. The model without a gas halo shows an increasing star formation rate (SFR) at the beginning of the simulation for some hundreds of millions of years and then a continuously decreasing rate to the end of the run at 3 Gyr. Whereas the SFRs in the models with a gas halo, depending on the density profile and the total mass of the gas halo, emerge to be either relatively flat throughout the simulations or increasing until the middle of the run (over a gigayear) and then decreasing to the end. The models with the more centrally concentrated NFW gas halo show overall higher SFRs than those with the isothermal gas halo of the equal mass. The gas accretion from the halo onto the disk also occurs more in the models with the NFW gas halo, however, this is shown to take place mostly in the inner part of the disk and not to contribute significantly to the star formation unless the gas halo has very high density at the central part. The rotation of a gas halo is found to make SFR lower in the model. The SFRs in the runs including galactic winds are found to be lower than those in the same runs but without winds. We conclude that the effects of a hot gaseous halo on the evolution of galaxies are generally too significant to be simply ignored. We also expect that more hydrodynamical processes in galaxies could be understood through numerical simulations employing both gas disk and gas halo components.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.285-287
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• 2016

Background: The efficacy of standard treatment of Helicobacter pylori (H. pylori) is declining because of antibiotic resistance. Clarithromycin resistance is also increasing in many Asian countries. The aim of this study was to determine the antibiotic susceptibility patterns of H. pylori infection and clinical association in Laos. Materials and Methods: A total of 329 Lao dyspeptic patients who underwent gastroscopy at Mahosot Hospital, Vientiane, Laos during December 2010-March 2012 were enrolled in this study. During gastroscopy, 4 biopsies were collected (2 each from the antrum and body) for CLO-test and histopathology. Only the positive CLO-test gastric tissues was stored at $-80^{\circ}C$ in a freezer until DNA was extracted and a GenoType$^{(R)}$HelicoDR test was conducted for detecting mutations in the rrl gene encoding 23S rRNA (clarithromycin resistance) and mutations in gyrA gene (fluoroquinolone resistance). Results: Of the total, 119 Lao patients (36.2%) were infected with H. pylori including 59 males (49.6%) and 60 females (50.4%) with a mean age of 46 years. Clarithromycin and fluoroquinolone resistance of H. pylori infection was demonstrated in 15 (12.6%) and 16 strains (13.4%) respectively. In clarithromycin resistance, the number of patients who had education above primary school and $BMI{\geq}25kg/m^2$ were significantly higher than those who had education below primary school and BMI<$25kg/m^2$ (23.1% vs 7.5%, P-value= 0.036 and 20.5% vs 8%, P-value= 0.048, respectively). In fluoroquinolone resistance, the number of lowland Lao was significantly higher than those of non-lowland (highland and midland) Lao ethnic groups (16.7% vs 0%, P-value= 0.039). Conclusions: H. pylori infections remain common in Laos. Clarithromycin and fluoroquinolone resistance with H. pylori infection are growing problems. Education above primary school and $BMI{\geq}25kg/m^2$ might be predictors for clarithromycin resistance and lowland Lao ethnicity might be predictors for fluoroquinolone resistance with H. pylori infection in Laos.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.606-611
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• 2015

As Salmonella enterica serovar Pullorum remains a major economic problem for the poultry industries of countries with no efficient control measures, we presented a multidrug resistance strain S06004 (isolated from a clinically sick chicken in China in 2006) for genome sequencing. The genome comparison showed that the strain contained two prophages, the ST104 and prophage-4 (Fels2) of E. coli LF82, which were not detected in the only published genomes of S. Pullorum RKS5078 and CDC1983-67. In addition, the GyrA Ser83 point mutation, drugresistant genes, and many antibiotic pump systems that are present in S06004 may be contributing to the multidrug resistance of this strain.

• Journal of fish pathology
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• v.36 no.2
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• pp.277-286
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• 2023

Korean rockfish, Sebastes schlegelii, is a representative bony fish that belongs to the family Scorpaenidae and the order Scorpaeniformes. It has high ecological and economic value and is widely cultivated in many East Asian countries, including South Korea, Japan and China. One of streptococci, Streptococcus iniae, is Gram-positive cocci with a negative reaction for catalase and oxidase. The Korean rockfish shows clinical signs when infected with S. iniae, such as body darkening, bleeding, enlarged kidneys, blurred eyes, abdominal distension, etc., ultimately leading to death. The Korean rockfish causes significant economic losses every year in South Korea due to streptococcosis. In this study, we identified bacteria from the fish using polymerase chain reaction and conducted analyses of hemolytic activity and biochemical tests using API 20 STREP and API ZYM systems. Results of confirming the hemolytic activity (n=4) observed in alpha-type hemolysis (25%), beta-type hemol- ysis (50%), and gamma-type hemolysis (25%) of isolates. The biochemical test results exhibited sig- nificant variation among S. iniae. Additionally, we performed intraperitoneal injection with S. iniae in the fish and analyzed the phylogenetic tree using housekeeping genes of S. iniae, including cpsD, arcC, glnA, groEL, gyrB, mutS, pheT, prkC, rpoB, and tkt, via multilocus sequence typing (MLST). The lethal dose (LD₅₀) showed strong pathogenicity, such as 3.34 × 10 colony-forming unit (CFU)/ml for 23FBStr0601 strain and 7.16 × 10 CFU/ml for 23FBStr0602 strain. 23FBStr0603 strain showed relatively low pathogenicity at 1.73 × 10⁵ CFU/ml. The strains 23FBStr0601 and 23FBStr0602, which showed strong pathogenicity, clustered into one monophyletic group. The 23FBStr0603 strain showed weak pathogenicity and formed a monophyletic group with KCTC 3657.

• The Plant Pathology Journal
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• v.40 no.1
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• pp.48-58
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• 2024

The oldest and most extensively cultivated form of millet, known as pearl millet (Pennisetum glaucum (L.) R. Br. Syn. Pennisetum americanum (L.) Leeke), is raised over 312.00 lakh hectares in Asian and African countries. India is regarded as the significant hotspot for pearl millet diversity. In the Indian state of Haryana, where pearl millet is grown, a new and catastrophic bacterial disease known as stem rot of pearl millet spurred by the bacterium Klebsiella aerogenes (formerly Enterobacter) was first observed during fall 2018. The disease appears in form of small to long streaks on leaves, lesions on stem, and slimy rot appearance of stem. The associated bacterium showed close resemblance to Klebsiella aerogenes that was confirmed by a molecular evaluation based on 16S rDNA and gyrA gene nucleotide sequences. The isolates were also identified to be Klebsiella aerogenes based on biochemical assays, where Klebsiella isolates differed in D-trehalose and succinate alkalisation tests. During fall 2021-2023, the disease has spread all the pearl millet-growing districts of the state, extending up to 70% disease incidence in the affected fields. The disease is causing considering grain as well as fodder losses. The proposed scale, consisting of six levels (0-5), is developed where scores 0, 1, 2, 3, 4, and 5 have been categorized as highly resistant, resistant, moderately resistant, moderately susceptible, susceptible, and highly susceptible disease reaction, respectively. The disease cycle, survival of pathogen, and possible losses have also been studied to understand other features of the disease.

• The Plant Pathology Journal
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• v.33 no.5
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• pp.488-498
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• 2017

The aim of this study was to identify volatile and agardiffusible antifungal metabolites produced by Bacillus sp. G341 with strong antifungal activity against various phytopathogenic fungi. Strain G341 isolated from four-year-old roots of Korean ginseng with rot symptoms was identified as Bacillus velezensis based on 16S rDNA and gyrA sequences. Strain G341 inhibited mycelial growth of all phytopathogenic fungi tested. In vivo experiment results revealed that n-butanol extract of fermentation broth effectively controlled the development of rice sheath blight, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew, and red pepper anthracnose. Two antifungal compounds were isolated from strain G341 and identified as bacillomycin L and fengycin A by MS/MS analysis. Moreover, volatile compounds emitted from strain G341 were found to be able to inhibit mycelial growth of various phytopathogenic fungi. Based on volatile compound profiles of strain G341 obtained through headspace collection and analysis on GC-MS, dimethylsulfoxide, 1-butanol, and 3-hydroxy-2-butanone (acetoin) were identified. Taken together, these results suggest that B. valezensis G341 can be used as a biocontrol agent for various plant diseases caused by phytopathogenic fungi.

• Tuberculosis and Respiratory Diseases
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• v.72 no.1
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• pp.44-49
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• 2012

Background: Multidrug-resistant tuberculosis (MDR-TB) is an increasing public health problem and poses a serious threat to global TB control. Fluoroquinolone (FQ) and aminoglycoside (AG) are essential anti-TB drugs for MDR-TB treatment. REBA MTB-FQ$^{(R)}$ and REBA MTB-KM$^{(R)}$ (M&D, Wonju, Korea) were evaluated for rapid detection of FQ and kanamycin (KM) resistance in MDR-TB clinical isolates. Methods: M. tuberculosis (n=67) were isolated and cultured from the sputum samples of MDR-TB patients for extracting DNA of the bacilli. Mutations in genes, gyrA and rrs, that have been known to be associated with resistance to FQ and KM were analyzed using both REBA MTB-FQ$^{(R)}$ and REBA MTB-KM$^{(R)}$, respectively. The isolates were also utilized for a conventional phenotypic drug susceptibility test (DST) as the gold standard of FQ and KM resistance. The molecular and phenotypic DST results were compared. Results: Sensitivity and specificity of REBA MTB-FQ$^{(R)}$ were 77 and 100%, respectively. Positive predictive value and negative predictive value of the assay were 100 and 95%, respectively, for FQ resistance. Sensitivity, specificity, positive predictive value and negative predictive value of REBA MTB-KM$^{(R)}$ for detecting KM resistance were 66%, 94%, 70%, and 95%, respectively. Conclusion: REBA MTB-FQ$^{(R)}$ and REBA MTB-KM$^{(R)}$ evaluated in this study showed excellent specificities as 100 and 94%, respectively. However, sensitivities of the assays were low. It is essential to increase sensitivity of the rapid drug resistance assays for appropriate MDR-TB treatment, suggesting further investigation to detect new or other mutation sites of the associated genes in M. tuberculosis is required.

• Research in Plant Disease
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• v.29 no.4
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• pp.390-398
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• 2023

Apple white rot, caused by Botryosphaeria dothidea, is one of the important diseases in Korea. B. dothidea can cause pre- and postharvest decay on apple fruit as well as canker and dieback of apple trees. In this study, we isolated bacteria from the trunk of apple trees and tested their antagonistic activity against B. dothidea. Five bacterial isolates (23-168, 23-169, 23-170, 23-172, and 23-173) were selected that were most effective at inhibiting the mycelial growth of the pathogens. The isolate 23-172 was identified as Bacillus amyloliquefaciens and four isolates 23-168, 23-169, 23-170, and 23-173 were identified as Bacillus velezensis by RNA polymerase beta subunit (rpoB) and DNA gyraseA subunit (gyrA) gene sequencing. All isolates showed strong antagonistic activity against B. dothidiea as well as Colletotrichum fructicola and Diaporthe eres. All isolates exhibited cellulolytic, proteolytic and phosphate solubilizing activities. In particular, two isolates 23-168, 23-169 were shown to significantly reduce the size of white rot lesions in pretreated apple fruits. These results will provide the basis for the development of a fungicide alternative for the control of white rot of apple.