• Journal of Microbiology and Biotechnology
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• v.15 no.4
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• pp.895-898
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• 2005

In the course of searching for potent chitin synthase 1 inhibitors from natural resources, Streptomyces sp. A6705 was found to exhibit potent inhibitory activity against the chitin synthase 1 from C. albicans (CaCHS1p). As a result, the inhibitor was isolated and identified using a series of chromatographies. Through chemical analyses with UV spectrophotometry, MS spectrometry, and various NMR techniques, the inhibitor was identified as N,N-bis(2-phenylethyl)urea. The compound exhibited strong inhibitory activity against the chitin synthase 1 from C. albicans with an $IC_{50}$ of 14 ${\mu}g$/ml, representing a similar inhibitory activity to that of the well-known chitin synthase inhibitor, polyoxin D ($IC_{50}$ 15 ${\mu}g$/ml). However, the compound showed no inhibitory activity against the chitin synthase 2 of Saccharomyces cerevisiae up to 280 ${\mu}g$/ml, which is structurally and functionally analogous to CaCHS 1 p. In addition, the compound exhibited weak antifungal activities against Cryptococcus neoformans and Rhizoctonis solani.

• Applied Biological Chemistry
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• v.46 no.2
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• pp.69-73
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• 2003

A novel antifungal antibiotic for azole-resistant Candida albicans was purified from the culture broth of Bacillus subtilis LAM 97-44 by butanol extraction, Diaion HP-20 and Dowex-50 adsorption chromatography, silica gel flash chromatography followed by HPLC and designated LAM-44A. LAM-44A was stable for 60 min at $100^{\circ}C$, and pH range from 2 to 10. MIC values were observed at $0.5-3.5\;{\mu}g/ml$ against various Candida albicans strains. The antibiotic showed no cytotoxicity for S180, MKN-45, P388, HeLa and 373 at the concentration of 1 mg/ml. LAM-f4A was colorless powder soluble in water, methanol, ethanol, butanol and negative to ninhydrin reaction. The antibiotic had maximum absorption at 273 nm in methanol, and melting point was $202^{\circ}C$. The molecular weight and formula were determined to be 282 and $C_{14}H_{34}O_5$ by $^1H-NMR,\;^{13}C-NMR$, IR spectrum and elemental analysis.

• Microbiology and Biotechnology Letters
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• v.44 no.1
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• pp.98-105
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• 2016

The presence of bacterial strains showing antagonistic activity to common pathogens found in a variety of fermented foods in Korea was explored. A bacterium inhibiting the growth of pathogens such as Aspergillus terreus (KCTC6178), A. flavus (KCTC6984), Staphylococcus aureus (KCCM12214), Escherichia coli O157:H7 (KCCM40406), Bacillus cereus (KCTC1012), Cryptococcus neoformans (ATCC208821), Salmonella typhimurium (ATCC19430), and Listeria monocytogenes (KCTC3569) was isolated from Makgeolli, a Korean traditional rice wine. The strain showing high antipathogenic activity was identified as B. amyloliquefaciens based on the nucleotide sequence of the 16S ribosomal RNA gene. Compared with B. amyloliquefaciens KCTC1660, whose genome has been sequenced, the isolate exhibited significantly low activities of starch-degrading enzymes and high resistance to high temperature and low pH.

• Journal of Microbiology and Biotechnology
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• v.27 no.5
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• pp.1010-1022
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• 2017

Hybrid histidine kinase is part of a two-component system that is required for various stress responses and pathogenesis of pathogenic fungi. The Tco1 gene in human pathogen Cryptococcus neoformans encodes a hybrid histidine kinase and is important for pathogenesis. In this study, we identified a Tco1 homolog, UmTco1, in the maize pathogen Ustilago maydis by bioinformatics analysis. To explore the role of UmTco1 in the survival of U. maydis under environmental stresses and its pathogenesis, ${\Delta}umtco1$ mutants were constructed by allelic exchange. The growth of ${\Delta}umtco1$ mutants was significantly impaired when they were cultured under hyperosmotic stress. The ${\Delta}umtco1$ mutants exhibited increased resistance to antifungal agent fludioxonil. In particular, the ${\Delta}umtco1$ mutants were unable to produce cytokinesis or conjugation tubes, and to develop fuzzy filaments, resulting in impaired mating between compatible strains. The expression levels of Prf1, Pra1, and Mfa1, which are involved in the pheromone pathway, were significantly decreased in the ${\Delta}umtco1$ mutants. In inoculation tests to the host plant, the ${\Delta}umtco1$ mutants showed significantly reduced ability in the production of anthocyanin pigments and tumor development on maize leaves. Overall, the combined results indicated that UmTco1 plays important roles in the survival under hyperosmotic stress, and contributes to cytokinesis, sexual development, and virulence of U. maydis by regulating the expression of the genes involved in the pheromone pathway.

• The Korean Journal of Mycology
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• v.45 no.4
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• pp.259-269
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• 2017

In order to investigate the diversity of yeasts from major rivers (the Daejeoncheon, Gapcheon and Yudeungcheon) located in Daejeon city, we isolated wild yeasts by plating diluents of samples collected during the summer and winter of 2016 onto yeast extract-peptone-dextrose (YPD) medium, then identified them using Basic Local Alignment Search Tool (BLAST) analysis to compare the nucleotide sequences of the PCR amplicons for the D1/D2 domain of 26S rDNA. In total, we isolated 191 yeast strains belonging to 104 species from 148 soil or water samples from the rivers and their junctions. Candida spp. (45 strains) including Candida tropicalis (22 strains) were the most abundantly isolated strains from the Daejeoncheon. Candida spp. (16 strains) including Candida vartiovaarae (8 strains) and Candida spp. (18 strains) such as Candida sake (4 strains) were also the dominant isolates from the Gapcheon and Yudeungcheon, respectively. In conclusion, Candida spp. and Cryptococcus spp. were the most dominant strains, corresponding to 42% and 7% of the 191 yeast strains isolated in this study, respectively.

• Tuberculosis and Respiratory Diseases
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• v.42 no.1
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• pp.93-98
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• 1995

Cryptococcosis is a systemic infection caused by the yeast-like fungus Cryptococcus neoformans. Respiratory tract is the usual portal of infection but relatively few cases of pulmonary cryptococcosis have been reported. Recently the incidence of the disease are increasing because the perception to seek the disease is increasing and immunocompromised hosts are more widespread with introduction of immune-suppressants, steroids and advent of AIDS. Because of nonspecific pattern of clinical manifestation, radiologic findings, differentiating the other diseases is essential and it needs fungal culture and biopsy. We describe a patient in the state of bilateral adrenalectomy due to bilateral ACTH-independent macronodular hyperplasia who developed pulmonary cryptococcosis and was later infected with pulmonary tuberculosis.

• Journal of Korean Academy of Nursing
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• v.23 no.4
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• pp.528-543
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• 1993

Vitamin E, which has its advocates in the treatment of diabetes mellitus. autoimmune disease, cancer and peripheral vascular and thromboembolic disease, has now been alleged to have a powerful antioxident effect and to affect various biological activities such as fertility factor, inhibition of human platelet aggregation and stabilization of biological membranes. The present study was designed to test whether vitamin I(alpha-tocopherol) can : (1) enhance the hemagglutinin response to sheep red blood cells (SRBC), (2) modulate Arthus and delayed type hypersensitivity(DTH) to SRBC and contact hypersensitivity to dinitrofluorobenzene (DNFB). (3) enhance the mitogenic response of murine splenocyte, (4) decrease the recovery of Cryptococcus neoformans from brain, lung, liver, spleen and kidney of infected mice and (5) have an inhibitory or enhancing effect on the induction of active systemic anaphylaxis(ASA) induced by chicken-gamma globulin (CGG) in mice. Mice were given either intramuscular injections of 0.3ml (300mg) of vitamin I before immunization or were infection for 10 consecutive days or were given by vitamin I esophageal intubation, 0.1ml(100mg), for 20 days before sacrifice for the mitogenic response experiments. It was found that vitamin E treated mice showed a significant enhancement in hemagglutinin response, Arthus reaction and DTH to SRBC and contact hypersensitivity to DNFB. There was no significant difference in the mitogenic response to phytohemagglutinin(PHA), but the response to concanavalin A(ConA) or pokeweed mitogem(PWM) was increased in vitamin E-treated mice. Interestingly, the vitamin E administration before C. neoformans infection decreased significantly the recovery of C. neoformans from brain lung, liver, spleen and kidney of the infected mice as compared with that of the control mice, strongly suggesting that vitamin E pretreatment may increase the resistance of mice to the fungal infection. Unexpectedly, vitamin E administration enhanced the production of CGG -induced ASA. Taken together, it can be concluded that vitamin I administration may in-crease the humoral and cellular immune response and resistance. to C. neoformans infection, but enhance the induction of ASA to CGG. Further studies are necessary to clarify the underlying mechanism accounting for these effects.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.129-134
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• 2017

BACKGROUND: Yeasts are used in a variety of industries. However, most industries are biased toward Saccharomyces cerevisiae ; so we sought to explore non-conventional yeasts (NCY). This study aimed to isolate yeasts from seawater collected from the East Sea of Korea and to analyze the NCY. METHODS AND RESULTS: We first collected seawater and performed pure isolation using four kinds of medium (GPY, DOB + CSM, DG18, and SCG). In total, 314 strains and 17 genera were isolated by ITS sequencing, including Aureobasidum pullulans (236 strains), Cryptococcus (19 strains), Cystobasidium (18 strains), and Rhodotorula (9 strains). Upon in-depth analysis, A. pullulans, the most dominant genus (236 strains), was divided into Group II (147 strains), Unknown I (8 strains), and Unknown II (49 strains). CONCLUSION: In this study, a total of 314 strains were isolated from seawater; many of these yeasts have been found and reported in seawater previously. In-depth analysis of A. pullulans, showed the dominance of Group I (21 strains) and Group II (147 strains) We also discovered Unknown I (8 strains) and Unknown II (49 strains), which have not been reported previously.

• Microbiology and Biotechnology Letters
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• v.3 no.2
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• pp.69-72
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• 1975

Isolation of the toxic substance which was produced by Streptentyces sp. and it's biorhemical characterestics and toxicity to fishes were reported in the previous paper. The present report includes antibiotic activity of the substance, inhibitory activity of the substance on the succinic dehydrogenase of fishes, and its effect on the blood corpuscles of a rabbit. An evident antibiotic activity of this substance was observed on Candida yeasts, but n$ot^1$on molds or bacteria. The substance inhibited the growth of Candida japonica and C. utilis to the 50％ at the concentrations of 7.5 and 10.2ug per ml, respectively. The activity of succinic dehydrogenase obtained from various organs of Cyprinous carpio L. was also found to be inhibited by this substance. Original activities of the enzymes from tht brain, kidney, and liver, were inhibited by 75.4％, 38.2％, and 26.2％, respectively, but not the enzymes from the heart and spleen. Neither leukopenia nor leukocytosis was detected after the intravenous administration of the substince to the rabbit at the level of 6 mg per 2 kg body weight.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.87-96
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• 2014

In the present study, a yeast species isolated from CETP, Vellore, Tamilnadu was identified as Cryptococcus sp. VITGBN2 based on molecular techniques and was found to be a potent producer of acidic diacetate sophorolipid in mineral salt media containing vegetable oil as additional carbon source. The chemical structure of the purified biosurfactant was identified as acidic diacetate sophorolipid through GC-MS analysis. This sophorolipid was used as a stabilizer for synthesis of zinc oxide nanoparticles (ZON). The formation of biofunctionalized ZON was characterized using UV-visible spectroscopy, XRD, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy. The antimicrobial activities of naked ZON and sophorolipid functionalized ZON were tested based on the diameter of inhibition zone in agar well diffusion assay, microbial growth rate determination, protein leakage analysis, and lactate dehydrogenase assay. Bacterial pathogen Salmonella enterica and fungal pathogen Candida albicans showed more sensitivity to sophorolipid biofunctionalized ZON compared with naked ZON. Among the two pathogens, S. enterica showed higher sensitivity towards sophorolipid biofunctionalized ZON. SEM analysis showed that cell damage occurred through cell elongation in the case of S. enterica, whereas cell rupture was found to occur predominantly in the case of C. albicans. This is the first report on the dual role of yeast-mediated sophorolipid used as a biostabilizer for ZON synthesis as well as a novel functionalizing agent showing antimicrobial property.