• Korean Journal of Microbiology
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• v.41 no.4
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• pp.293-299
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• 2005

Many isolates from soil of Korean ginseng rhizosphere did not show remarkable growth on full strength of the conventional nutrient broth (NB medium) but grew on its 100-fold dilution (DNB medium). Six hundred-forty strains were isolated as oligotrophic bacteria. In the course of screening for new bioactive compounds from oligotrophic bacteria from soil, 8 strains which had appeared to form of clear zone on a medium containing colloidal chitin as a sole carbon source were selected for further studies. Strain CR42 hydrolyzed a fluorogenic analogue of chitin, 4-methylumbelliferyl-D-glucosaminide (MUF-NAG) . Mo st of the culture supernatant of these isolates hydrolyzed 4-methylumbelliferyl-D-N,N'-diacetylchitobioside (MUF-diNAG). The isolates were heterogeneous and categorized to gamma- and beta-proteobacteria, Bacillaceae, Actinobactepia, and Bacteroides by 16S rRNA analysis. Two strains, WR164 and CR18, had a 16S rRNA sequence of $95-96\%$ identical to uncultured bacteria. It was observed that CR2 and CR75 could inhibit the growth of Colletotrichum gloeosporioides with hyphal extention-inhibition assay on PDA plate supplemented with $1\%$ colloidal chitin.

• Korean Journal of Microbiology
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• v.36 no.3
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• pp.203-208
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• 2000

A Baczllus circdans KCTC3004 $\alpha$-amylase gene contained in a recombinant plasmid pAL850 was transferred into a new shuttle vector plasmid pALSIlI by ligating linearlzed DNAs of pUC19 and pUB110. B. subtilis RM125 and B. megatenurn ATCC14945 transfonned with pALS111 produced the $\alpha$-amylase substantially Most of the enzyme was produced during the exponential growth period. The maxiinurn activities of the $\alpha$-amylase produced by the Bucillus transformants were compared with that of the B. circulans gene donor strain. The B. subtilis RM125(pALS111) enzyme showed the actlvicy 95 times higher than that of the gene donor cells, followed by the B, nzegaterium ATCC14945(pALSlll) enzyme with activity 34 limes higher than that of the gene donor cells. While E coli secreted about 10% of the produced enzyme, B. subtilis excreted the enzyme inlo the medium wholly and B. megaterirun about 98% ofthe total product. The plasmid pALSI11 was quite stable inB. nzegaterium (92%), inoderately stable in B. subtilis (76%), but was unstable in E. coli (38%). The SDS-PAGE and zymogram of this enzyme produced in E. coli(pALS111), B. subtilis( pALS111) or B. megateril~m (pALS111) indicated a molecular weight of 55,000. The enzymes overproduced in three different host cells hydrolyzed starch to produce mainly maltoaiose and mallooligosaccharides.

• Journal of Mushroom
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• v.18 no.2
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• pp.145-150
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• 2020

A new cultivar, 'Bambithyang', was bred from monokaryotic strains of Sanbaekhyang and SANJO 707ho using the mono-mono hybridization method. Its incubation period was determined to be 100 days and its optimum temperature for fruit body flushing, 11-20℃. The mushrooms had a convex cap (diameter, 69.6 mm; thickness, 15.2 mm) and stipes in their center. The color of their upper sides was chestnut brown; their gills were arranged in a ripple style and had medium density. Their scales were cream-colored and fully distributed; the stipes were cream-colored and cylindrical (thick upper part). They also had cream colored fluffs and sporadic fruiting bodies. Zone lines were present when they were cultivated with mother and father varieties. Their stipe lengths and caps were 9% shorter and 16.9% thicker, respectively, than those of Sanbaekhyang.

• Research in Plant Disease
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• v.12 no.2
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• pp.134-138
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• 2006

A new bacterial disease of broccoli (Brassica oleracea var. italica) was observed on field-grown plants in Pyungchang during 2003 and 2004. Seedling infections first appeared as a blackening along the margins of the cotyledon. Cotyledon shriveled and dropped off. Infected seedlings were stunted and yellowed and eventually died. The disease was easily recognized by the presence of yellow, V-shaped, or U-shaped areas extending inward from margin of the leaf. As the disease progressed, the yellow lesions turned brown and the tissues died. Isolations made from diseased leaves on yeast extract dextrose calcium carbonate agar yielded nearly pure cultures of a yellow-pigmented bacterium typical of a xanthomonad. Two bacterial strains were purified and used for further tests. Pathogenicity of strains was confirmed on 3-week-old crucifer (cabbage, Chinese cabbage, kale, radish and broccoli) plants cut by scissors with bacterial suspensions containing $10^8 cfu/ml$ of phosphate buffered saline. The Biolog and fatty acid analyses and 16S rDNA sequencing of two strains (SL4797 and SL4800) from broccoli black rot showed that they could be identified as X. campestris pv. campestris because of their high similarity to the tester strain (X. campestris pv. campestris NCPPB528) with a match probability of 100%. This is the first report of black rot of broccoli in Korea.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.278-285
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• 2008

An efficient transformation method for soybean [Glycine max (L.) Merr.] using meristematic tissues of germinating seeds has been established. The embryonic axes were excised from germinating seeds of Korean soybean cultivar, Iksannamulkong and 0.5-2 cm long segment containing meristematic tissues were prepared by cutting hypocotyl region. The explants were inoculated with Agrobacterium tumefaciens strain LBA4404 harboring a binary vector with the bar gene as a selectable marker gene and a ${\beta}-glucuronidase$ (GUSINT) reporter gene, and then co-cultured for 7 days on co-cultivation medium (CCM). The meristematic tissues were cultured on shoot induction medium (SIMP6) supplemented with 0.4 mg/l $N_6-benzylaminopurine$ (BAP) and 0.1 mg/l indolebutyric acid (IBA) in the presence of 6 mg/l L-phosphinotricin (PPT) for 2 weeks and the surviving explants were transferred to shoot elongation medium (SEMP6). Transformation was confirmed by Southern blot analysis and the transformation efficiencies ranged from 1.48 to 2.07%. The new modified transformation method was successfully implemented for obtaining several transgenic lines with SMV-CP gene. It is expected that this method could efficiently be used for the transformation of recalcitrant soybean cultivars.

• Journal of the Korean Applied Science and Technology
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• v.36 no.1
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• pp.355-361
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• 2019

The red pigment extracted from Serratia marcescens 2354 (ATCC 25419) was prodigiosin (PG), which was dissolved in methanol and measured for ultraviolet and visible light absorption spectra. It was the typical absorption spectrum of PG in an acid solution with ${\lambda}_{max}=537nm$. When the concentration of PG was increased from $1.0{\times}10-5M$ to $9.0{\times}10-5M$ in the methanol solution, the absorption intensity at 537 nm was increased, the absorption intensity at 467 nm was decreased, and the isosbestic point at 500 nm was observed. This phenomenon can be regarded as a result of reversible acid-base equilibrium reaction considering 537 nm and 467 nm of PG absorption band in acid and base solution respectively and isosbestic point of 500 nm. On the other hand, when the concentration of PG was reduced from $6.0{\times}10-4$ to $1.0{\times}10-4M$ in acetic acid buffer solution at pH 4.75, a new absorption band with ${\lambda}$ max at 500 nm appeared. This absorption band appears only in the aqueous solution of pH 4.75 and does not appear in the pure methanol solution of the same pH. This is due to the conversion of the PG molecule from the ${\alpha}$-isomer to the ${\beta}$-isomer by $H_2O$. In other words, it was confirmed that the color change of the PG can be caused by the concentration of the solution and the characteristics of the solvent.

• Journal of Life Science
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• v.31 no.1
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• pp.52-58
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• 2021

Pseudomonas syringae pv. actinidiae, which causes bacterial canker in kiwifruit, is divided into five biovars (1, 2, 3, 5, 6) on the basis of genetic characteristics and toxin productivity. Among them, biovar 3 is responsible for the current global outbreak, and has been isolated in Korea since 2011. Biovar 3 strains isolated from Korea are subdivided into six genetically different lineages (subgroup I, IV, V, VI, VII, and VIII) based on random amplified polymorphic DNA (RAPD) analysis. In this work, the subgroup-specific sequence characterized amplified region (SCAR) primers were developed from sequenced differential RAPD bands. Distribution of the subgroups of the biovar 3 strains collected in Korea from 2011-2017 were examined using these subgroup-specific primer sets. Among the 54 strains tested, 35 strains (64.8%) belonged to subgroup V, 9 strains (16.7%) belonged to subgroup IV, 4 strains (7.4%) belonged to subgroup VI, 3 strains (5.6%) belonged to subgroup VII, 2 strains (3.7%) belonged to subgroup VIII, and 1 (1.9%) strain belonged to subgroup I. Strains belonging to subgroups IV, V, and VI were shown to be related to strains isolated from China, New Zealand, and Chile, respectively. The study revealed that the biovar 3 strains in Korea are genetically diverse and are estimated to have been introduced through pollen sourced from foreign countries.

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.259-271
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• 2021

Many bacteria metabolize aromatic compounds via catechol as a catabolic intermediate, and possess multiple genes or clusters encoding catechol-cleavage enzymes. The presence of multiple isozyme-encoding genes is a widespread phenomenon that seems to give the carrying strains a selective advantage in the natural environment over those with only a single copy. In the naphthalene-degrading strain Pseudomonas putida ND6, catechol can be converted into intermediates of the tricarboxylic acid cycle via either the ortho- or meta-cleavage pathways. In this study, we demonstrated that the catechol ortho-cleavage pathway genes (catBICIAI and catBIICIIAII) on the chromosome play an important role. The catI and catII operons are co-transcribed, whereas catAI and catAII are under independent transcriptional regulation. We examined the binding of regulatory proteins to promoters. In the presence of cis-cis-muconate, a well-studied inducer of the cat gene cluster, CatRI and CatRII occupy an additional downstream site, designated as the activation binding site. Notably, CatRI binds to both the catI and catII promoters with high affinity, while CatRII binds weakly. This is likely caused by a T to G mutation in the G/T-N11-A motif. Specifically, we found that CatRI and CatRII regulate catBICIAI and catBIICIIAII in a cooperative manner, which provides new insights into naphthalene degradation.

• Korean Journal of Poultry Science
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• v.48 no.4
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• pp.217-225
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• 2021

This study compares the physicochemical characteristics and fatty acid composition of three Korean native chickens and broilers. Ten whole raw broiler chickens and ten each from the three Korean native chickens (KNCs), Hanhyup 3 (HH3), Woormatdak 1 (WRMD1), and Woormatdak 2 (WRMD2), were purchased from the meat market. Their breast and thigh meat were used as samples. The proximate composition, pH, color, water-holding capacity (WHC), shear force, collagen content, and fatty acid composition were determined. In breast meat, the moisture content of HH3 (74.94%) and WRMD1 (74.74%) was lower than that of the broilers (77.1%, P<0.05). No significant difference was found in crude protein, lipids, and ash contents. The crude fat from thigh meat from HH3 and WRMD2 was lower than that of broilers (P<0.05). The redness of WRMD1 was the highest in both breast and thigh meat (P<0.05). The WHC of the breast meat of WRMD1 was lower than that of HH3 and WRMD2. In thigh meat, the WHC of the broilers was significantly higher than that of the KNCs. In breast meat, the shear force of WRMD2 was significantly lower than that of the broilers, HH3, and WRMD1, while no significant difference was found in thigh meat. The collagen content and arachidonic acid levels of the KNCs were significantly higher than those of the broilers for breast and thigh meats. No significant differences were observed among the KNCs. This result can be used to improve the quality of KNC but further studies on the bioactive compounds, taste, and volatile compounds of KNCs are required.

• Journal of Life Science
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• v.31 no.12
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• pp.1072-1078
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• 2021

The oral pathogen Streptococcus mutans is considered a major causative agent of dental caries in humans. The use of dental hygiene products, including toothpaste and mouthwash, is used for caries control. However, food intake can lead to the recurrence of oral microorganisms. This study aimed to explore why this bacterium dies so quickly during prolonged incubation and to assess whether this growth characteristic is closely associated with the secretion of metabolic products. Notably, the number of live S. mutans cells rapidly declined after 24 hr during the entire period tested, whereas the number of Escherichia coli cells, an indicator strain, remained steady over the same period. To test whether the S. mutans supernatants contained possible signals that accelerated the death of neighbor cells, we obtained the individual supernatants at the above time points. Following pH neutralization, the cells in which the supernatant was supplemented with glucose grew well. However, pH adjustment alone could not fully recover cell growth in conditions in which the supernatant was supplemented, with or without glucose. These phenotypes of S. mutans may be associated with signaling, not only resulting from nutrient depletion. The findings on the survival phenotype of S. mutans provide new insights into cell-cell communication in the biology of this bacterium.