• Korean Journal of Microbiology
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• v.21 no.1
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• pp.7-14
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• 1983

In order to study the effects of cropping system and fungicide (Dachigaren) on soil microbes, the seasonal fluctuations of soil microbes in the fields of radish and Chinese cabbage including soil pH, Soil moisture content and soil temperature were investigated on every 15 day interval from the begining of March to late October in 1981. The population of total fungus peaked at the begining of July, while that of total bacteria, at the begining of August. They were affected by soil temperature, however pathogenic microbes seemed to be more related with host plants than the soil temperature, because pathogens showed high density through the whole cultivation period. The pathogenic microbes showed the density of order ; Xanthomonas, Erwinia, Pseudomonas, Agrobacterium and Corynebacterium. Xanthomonas, Erwinia and Pseudomonas, which induced radish and Chinese cabbage diseases were higher than Agrobacterium and Corynebacterium in population densigy. Bacterial soft rot occured at the density of Erwinia $5.9{\sim}6.6{\times}10^5/dry$ soil 1 gram. The density of microbes on continuous fields were higher than that of rotating fields, but there were no significant difference between treated fungicide plot and non treated in the density of microbes, also no difference between Chinese cabbage and radish growing fields.

• Journal of Microbiology
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• v.45 no.1
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• pp.53-57
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• 2007

A number of essential oils from Mongolian aromatic plants are claimed to have antimicrobial activities. The essential oil of Dracocephalum foetidum, a popular essential oil used in Mongolian traditional medicine, was examined for its antimicrobial activity. Eight human pathogenic microorganisms including B. subtilis, S. aureus, M. lutens, E. hirae, S. mutans, E. coli, C. albicans, and S. cerevisiae were examined. The essential oil of Dracocephalum foetidum exhibited strong antimicrobial activity against most of the pathogenic bacteria and yeast strains that were tested; by both the agar diffusion method and the minimum inhibitory concentration (MIC) assay ($MIC\;range\;was\;26-2592{\mu}g/ml$). Interestingly, Dracocephalum foetidum even showed antimicrobial activity against methicilin-resistant Staphylococcus aureus (MRSA) strains. We also analyzed the chemical composition of the oil by GC-MS and identified several major components, including n-Mentha-1,8-dien-10-al, limonene, geranial, and neral.

• Journal of Microbiology
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• v.41 no.4
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• pp.312-319
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• 2003

In an attempt to develop a method for rapid and accurate identification of six Vibrio species that are clinically important and most frequently detected in Korea, 16S rDNA restriction fragment length polymorphism (RFLP) of Vibrio type strains, as well as environmental isolates obtained from the Korean coastal area, was analyzed using ten restriction endonucleases. Digestion of the 16S rDNA fragments amplified by polymerase chain reaction (PCR) with the enzymes gave rise to 2~6 restriction patterns for each digestion for 47 Vibrio strains and isolates. An additional 2~3 restriction patterns were observed for five reference species, including Escherichia coli, Aeromonas hydrophila, A. salmonicida, Photobacterium phosphoreum, and Plesiomonas shigelloides. A genetic distance tree based on RFLP of the bacterial species correlated well with that based on 16S rDNA sequences. The very small 16S rDNA sequence difference (0.1%) between V. alginolyticus and V. parahaemolyticus was resolved clearly by RFLP with a genetic distance of more than 2%. RFLP variation within a species was also detected in the cases of V. parahaemolyticus, V. proteolyticus, and V. vulnificus. According to the RFLP analysis, six Vibrio and five reference species were assigned to 12 genotypes. Using three restriction endonucleases to analyze RFLP proved sufficient to identify the six pathogenic Vibrio species.

• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1324-1329
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• 2007

Resveratrol (3,5,4'-trihydroxystilbene) is a naturally occurring, multi-biofunctional chemical existing in grapes and various other plants as a polyphenol type, and it is one of the best known natural anticancer and antiatherosclerosis reagents. In this study, we investigated the antifungal action by resveratrol in Candida albicans, which is a human infectious fungi as an agent of candidiasis. Resveratrol displayed potent fungicidal activity in an energy-dependent manner, without any hemolytic effects against human erythrocytes. It was found that the serum-induced mycelial forms, which playa crucial role in the pathogenesis of C. albicans during host tissue invasion, were disrupted by resveratrol. To understand the correlation between lethal effects and resveratrol action, we examined the physiological changes of C. albicans. A significant accumulation of intracellular trehalose was induced by stress responses to resveratrol action, and a remarkable arrest of cell-cycle processes at the S-phase in C. albicans occured. Therefore, the fungicidal effects of resveratrol demonstrate that this compound is a potential candidate as an antifungal agent in treating infectious diseases by candidal infections.

• Journal of Microbiology
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• v.44 no.5
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• pp.523-529
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• 2006

OSH3 is one of the seven yeast homologues of the oxysterol binding proteins (OSBPs) which have the major binding affinity to the oxysterols and function as regulator of cholesterol biosynthesis in mammals. Mutational analysis of OSH3 showed that OSH3 plays a regulatory role in the yeast-to-hyphal transition through its oxysterol-binding domain in Saccharomyces cerevisiae. The OSH3 gene was also identified in the pathogenic yeast Candida albicans. Deletion of OSH3 caused a defect in the filamentous growth, which is the major cause of the C. albicans pathogencity. The filamentation defect of the mutation in the MAPK-associated transcription factor, namely $cph1{\Delta}$ was suppressed by overexpression of OSH3. These findings suggest the regulatory roles of OSH3 in the yeast filamentous growth and the functional conservations of OSH3 in S. cerevisiae and C. albicans.

• The Journal of the Korean Society for Microbiology
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• v.34 no.5
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• pp.471-478
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• 1999

Spirochetes were isolated from the midgut of Ixodes persulcatus ticks captured at Chungju, Korea and identified as Borrelia afzelii strains by polymerase chain reaction. To determine the pathogenicity of the B. afzelii strains isolated in Korea, the microbiological and pathological features of Lyme disease were observed in C3H/He mice after intraperitoneal inoculation of the fresh isolate of B. afzelii strain. The results are summarized as follows 1) The Borrelia were detected in the tissues of heart, spleen, kidney, urinary bladder and knee joint within 7 days after inoculation of infection by dark field microscopic examination. The isolation rate from heart, urinary bladder and joint was significantly higher than the rate from spleen, kidney, and blood samples. 2) The Borrelia was detected in heart muscle by indirect immunofluorescent antibody test. 3) Antibody to the Borrelia was detected as early as one week after inoculation. 4) The marked tropism of the Borrelia was observed in myocardial, urinary tract and joint tissue. The main pathological features are inflammation in tissues of heart, kidney, joint and urinary bladder. From these results, the Borrelia afzelii strain isolated in Korea were determined as pathogenic strain.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.3
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• pp.1571-1578
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• 2013

Cancer is a leading cause of death worldwide. Recently, the demand for more effective and safer therapeutic agents for the chemoprevention of human cancer has increased. As a white rot fungus, Inonotus obliquus is valued as an edible and medicinal resource. Chemical investigations have shown that I. obliquus produces a diverse range of secondary metabolites, including phenolic compounds, melanins, and lanostane-type triterpenoids. Among these are active components for antioxidant, antitumoral, and antiviral activities and for improving human immunity against infection of pathogenic microbes. Importantly, their anticancer activities have become a hot recently, but with relatively little knowledge of their modes of action. Some compounds extracted from I. obliquus arrest cancer cells in the G0/G1 phase and then induce cell apoptosis or differentiation, whereas some examples directly participate in the cell apoptosis pathway. In other cases, polysaccharides from I. obliquus can indirectly be involved in anticancer processes mainly via stimulating the immune system. Furthermore, the antioxidative ability of I. obliquus extracts can prevent generation of cancer cells. In this review, we highlight recent findings regarding mechanisms underlying the anticancer influence of I. obliquus, to provide a comprehensive landscape view of the actions of this mushroom in preventing cancer.

• Mycobiology
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• v.41 no.4
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• pp.252-255
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• 2013

Fungal pathogens have caused severe damage to the commercial production of Pleurotus eryngii, the king oyster mushroom, by reducing production yield, causing deterioration of commercial value, and shortening shelf-life. Four strains of pathogenic fungi, including Trichoderma koningiopsis DC3, Phomopsis sp. MP4, Mucor circinelloides MP5, and Cladosporium bruhnei MP6, were isolated from the bottle culture of diseased P. eryngii. A species-specific primer set was designed for each fungus from the ITS1-5.8S rDNA-ITS2 sequences. PCR using the ITS primer set yielded a unique DNA band for each fungus without any cross-reaction, proving the validity of our method in detection of mushroom fungal pathogens.

• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1401-1411
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• 2019

Mycobacterial cell walls comprise thick and diverse lipids and glycolipids that act as a permeability barrier to antibiotics or other chemical agents. The use of OH radicals from a non-thermal plasma jet (NTPJ) for the inactivation of mycobacteria in aqueous solution was adopted as a novel approach. Addition of water vapor in a nitrogen plasma jet generated OH radicals, which converted to hydrogen peroxide ($H_2O_2$) that inactivated non-pathogenic Mycobacterium smegmatis and pathogenic Mycobacterium tuberculosis H37Rv. A stable plasma plume was obtained from a nitrogen plasma jet with 1.91 W of power, killing Escherichia coli and mycobacteria effectively, whereas addition of catalase decreased the effects of the former. Mycobacteria were more resistant than E. coli to NTPJ treatment. Plasma treatment enhanced intracellular ROS production and upregulation of genes related to ROS stress responses (thiolrelated oxidoreductases, such as SseA and DoxX, and ferric uptake regulator furA). Morphological changes of M. smegmatis and M. tuberculosis H37Rv were observed after 5 min treatment with $N_2+H_2O$ plasma, but not of pre-incubated sample with catalase. This finding indicates that the bactericidal efficacy of NTPJ is related to the toxicity of OH and $H_2O_2$ radicals in cells. Therefore, our study suggests that NTPJ treatment may effectively control pulmonary infections caused by M. tuberculosis and nontuberculous mycobacteria (NTM) such as M. avium or M. abscessus in water.

• Journal of Microbiology and Biotechnology
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• v.34 no.2
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• pp.314-329
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• 2024

Fifteen cyclic dipeptides (CDPs) containing proline, one cyclo(Phe-Ala) without proline, and a non-peptidyl ᴅⳑ-3-phenyllactic acid were previously identified in the culture filtrates of Lactobacillus plantarum LBP-K10, an isolate from kimchi. In this study, we used Japanese quail (Coturnix japonica) eggs to examine the effects of probiotic supplementation on the antimicrobial CDPs extracted from quail eggs (QE). Eggshell-free QE were obtained from two distinct groups of quails. The first group (K10N) comprised eggs from unsupplemented quails. The second group (K10S) comprised eggs from quails supplemented with Lb. plantarum LBP-K10. The QE samples were extracted using methylene chloride through a liquid-liquid extraction process. The resulting extract was fractionated into 16 parts using semi-preparative high-performance liquid chromatography. Two fractions, Q6 and Q9, were isolated from K10S and identified as cis-cyclo(ⳑ-Ser-ⳑ-Pro) and cis-cyclo(ⳑ-Leu-ⳑ-Pro). The Q9 fraction, containing cis-cyclo(ⳑ-Leu-ⳑ-Pro), has shown significant inhibitory properties against the proliferation of highly pathogenic multidrug-resistant bacteria, as well as human-specific and phytopathogenic fungi. Some of the ten combinations between the remaining fourteen unidentified fractions and two fractions, Q6 and Q9, containing cis-cyclo(ⳑ-Ser-ⳑ-Pro) and cis-cyclo(ⳑ-Leu-ⳑ-Pro) respectively, demonstrated a significant increase in activity against multidrug-resistant bacteria only when combined with Q9. The activity was 7.17 times higher compared to a single cis-cyclo(ⳑ-Leu-ⳑ-Pro). This study presents new findings on the efficacy of proline-containing CDPs in avian eggs. These CDPs provide antimicrobial properties when specific probiotics are supplemented.