• Food Science and Preservation
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• v.22 no.6
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• pp.908-914
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• 2015

The objectives of this study were to isolate and characterize low temperature adaptation yeast and to obtain suitable yeasts strains for manufacturing Yakju. In this study, we isolated 482 wild yeasts from fermented foods. Out of these, 5 yeast strains were selected based on increased growth at low temperature ($15^{\circ}C$) and high ${\beta}$-glucosidase activity. To screen the aromatic level of isolates, media containing cerulenin and 5,5,5-trifluor-DL-leucine (TFL) were used. Y297 strain demonstrated tolerance against TFL and produced more than 13% alcohol. Y297 strain was identified a Saccharomyces cerevisiae based on the 26S rDNA gene sequences. Maximum cell growth was observed after 19 hr and 38 hr of incubation at $25^{\circ}C$ and $15^{\circ}C$, respectively. The exponential phase was followed by a lengthy stationary phase, at $15^{\circ}C$, when the cells remained high viable. Y297 strain demonstrated tolerance against alcohol (10%), glucose (60%) and salt(NaCl, 8%). ${\beta}$-glucosidase and esterase activity in Y297 were higher than those of controls at $15^{\circ}C$. Overall, these results indicated that using wild yeast strain, isolated from fermented food, affects the chemical characteristics of the brewed Yakju.

• The Korean Journal of Mycology
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• v.43 no.1
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• pp.47-52
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• 2015

Several kinds of yeasts were isolated from wild flowers collected from Muju resort of Deogyu mountain in Korea and identified by comparison of nucleotide sequences of D1/D2 region of 26S rDNA using BLAST. Totally twenty-two strains of eight species were isolated and Cryptococcus magnus (9 strains) and Cryptococcus flavescenes (6 strains) were dominant species. The supernatant and cell-free extracts were prepared and their antioxidant activity, anti-gout xanthine oxidase inhibitory activity and whitening tyrosinase inhibitory activity were investigated. Anti-gout xanthine oxidase inhibitory activities of Sporobolomyces phaffii JS00583 and Rhodotorula graminis JS00581 were 40.4% and 39.1%, respectively and also was 36.1% whitening tyrosinase inhibitory activity in the supernatant of Cryptococcus magnus JS00570.

• The Korean Journal of Mycology
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• v.46 no.3
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• pp.315-323
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• 2018

The goal of this study was to isolate wild yeasts from the fields of medicinal plants and investigate its tyrosinase inhibitory activities. Wild yeasts isolated from soil in the ginseng and Korean angelica fields of Geumsan, Chungcheongnam-do, Korea were identified by comparing the nucleotide sequences of the D1/D2 domain of 26S rDNA. In total, 43 yeast strains belonging to 21 species were isolated from 50 soil samples obtained from two medicinal plant fields. From the ginseng field, six strains of Rhodotorula glutinis and four strains of Sampaiozyma ingeniosa were isolated, out of which Rhodotorula glutinis strains were dominant. In the Korean angelica field, six strains of Cyberlindnera saturnus, three strains of Piskurozyma taiwanensis, and three strains of Saitozyma podzolica were isolated, out of which Cyberlindnera saturnus strains were dominant. We prepared cell-free extracts of the isolated wild yeasts and their tyrosinase inhibitory activities were investigated. Among 43 yeast strains, cell-free extracts of Naganishia globosa G1-7 showed the highest tyrosinase inhibitory activity (28.0%).

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.1
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• pp.50-58
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• 2013

A facultative bacterium producing cellulolytic and hemicellulolytic enzymes was isolated from the rumen of a native Korean goat. The bacterium was identified as a Bacillus licheniformis on the basis of biochemical and morphological characteristics and 16S rDNA sequences, and has been designated Bacillus licheniformis JK7. Endoglucanase activities were higher than those of ${\beta}$-glucosidase and xylanase at all temperatures. Xylanase had the lowest activity among the three enzymes examined. The optimum temperature for the enzymes of Bacillus licheniformis JK7 was $70^{\circ}C$ for endoglucanase (0.75 U/ml) and $50^{\circ}C$ for ${\beta}$-glucosidase and xylanase (0.63 U/ml, 0.44 U/ml, respectively). All three enzymes were stable at a temperature range of 20 to $50^{\circ}C$. At $50^{\circ}C$, endoglucanse, ${\beta}$-glucosidase, and xylanase had 90.29, 94.80, and 88.69% residual activity, respectively. The optimal pH for the three enzymes was 5.0, at which their activity was 1.46, 1.10, and 1.08 U/ml, respectively. The activity of all three enzymes was stable in the pH range of 3.0 to 6.0. Endoglucanase activity was increased 113% by $K^+$, while $K^+$, $Zn^+$, and tween 20 enhanced ${\beta}$-glucosidase activity. Xylanase showed considerable activity even in presence of selected chemical additives, with the exception of $Mn^{2+}$ and $Cu^{2+}$. The broad range of optimum temperatures (20 to $40^{\circ}C$) and the stability under acidic pH (4 to 6) suggest that the cellulolytic enzymes of Bacillus licheniformis JK7 may be good candidates for use in the biofuel industry.

• The Plant Pathology Journal
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• v.25 no.1
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• pp.86-90
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• 2009

In November 2008, typical powdery mildew symptoms were observed on leaves of Arabidopsis thaliana ecotype Col-0 plants in a growth room under controlled laboratory conditions at Korea University, Seoul. The disease was characterized by the appearance of white powder-like fungal growth on the surface of infected leaves. As the disease progressed, infected leaves exhibited chlorotic or necrotic brown lesions, and leaf distortion and senescence. Conidiophores of the causal fungus were hyaline, unbranched, 3-4 celled, cylindrical, and $80-115{\times}6-9{\mu}m$ in size. Singly produced conidia (pseudoidium type) were hyaline, oblong to cylindrical or oval in shape, and $26-55{\times}15-20{\mu}m$ in size with a length/width ratio of average 3, angular/rectangular wrinkling of outer wall and no distinct fibrosin bodies. Appressoria on the hyphae were multi-lobed. These structures are typical of the powdery mildew Oidium subgenus Pseudoidium, anamorph of the genus Erysiphe. The measurements of the fungal structures coincided with those of Erysiphe cruciferarum. The phylogenetic analysis using ITS rDNA sequences revealed that the causal fungus Erysiphe sp. KUS-F23994 is identical to E. cruciferarum. The isolated fungus incited powdery mildew symptoms on the inoculated Arabidopsis leaves, which proved Koch's postulates. Taken all data together, we first report the occurrence of powdery mildew disease of A. thaliana caused by Erysiphe cruciferarum in Korea.