• Korean Journal of Microbiology
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• v.45 no.2
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• pp.208-214
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• 2009

To avoid ambiguity in counting the number of colony, about 1,500 of colonies grown on B. cereus selective agar plates were grouped into 12 types by morphological difference and then identified by biochemical and 16S rDNA nucleotide sequence. Among them, seven colony types with 11 to 15 mm diameters of halo were identified as B. cereus or B. cereus subsp. cytotoxis. Five mm sized colonies with no halo, which have not been considered as B. cereus according to the manufacturer's manual, were identified as B. cereus. A colony type with double halos of only 6 mm in diameter was also B. cereus. Other three types were proven to be Enterococcus sp., Brevibacillus sp., and B. subtilis, respectively. PCR results showed that only 9 types that are identified as B. cereus strains harbor at least one of B. cereus toxin genes.

• Journal of Microbiology and Biotechnology
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• v.11 no.1
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• pp.85-91
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• 2001

To construct an efficient Bacillus subtilis expression vector, strong promoters were isolated from the chromosomal DNA libraries of Clostridium acetobutylicum ATCC 4259, Thermoactinomyces sp. E79, and Bacillus thermoglucosidasius KCTC 3400. The $P_{C27}$ promoter cloned from the clostridial chromosmal DNA showed a 5-fold higher promoter strength than the $P_{SP02}$ promoter in the expression of the cat gene, and its sequence was estimated as an upstream region of the predicted hypothetical gene (tet-R family bacterial transcription regulator gene) in C. acetobutylicum. As a promoter element, $P_{C27}$ exhibited putative nucleotide sequences that can bind with bacterial RNAP and the 3'end of the 16S rRNA just upstream of the start codon. In addition, the promoter activity of $P_{C27}$ was distinctively repressed in the presence of glucose. Using $P_{C27}$ as the promoter element, a glucose controllable B. subtilis expression vector was constructed and the lipase gene from Staphylococcus haemolyticus KCTC 8957P was expressed in B. subtilis. When compared with the lipase expression by the T7 promoter induced by IPTG in E. coli, the $P_{C27}$ promoter showed about a 1.5-fold higher expression level in B. subtilis than that without induction.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.339-346
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• 2014

A bacterial strain was isolated from homemade doenjang (Korean fermented soybean paste) as a producer of the extracellular ${\beta}$-galactosidase, capable of hydrolyzing lactose to liberate galactose and glucose residues. The isolate YB-1414 has been identified as Bacillus licheniformis on the basis of its 16S rDNA sequence, morphology and biochemical properties. The production of ${\beta}$-galactosidase by B. licheniformis YB-1414 reached maximum levels of 6.2 U/ml in culture medium containing wheat bran (1%) and yeast extract (2.5%) as carbon and nitrogen sources, respectively. Particularly, the insoluble fraction was more effective for ${\beta}$-galactosidase production than the soluble extract of wheat bran. The enzyme exhibited maximum activity for hydrolysis of para-nitrophenyl-${\beta}$-D-galactopyranoside (pNP-${\beta}Gal$) under reaction conditions of pH 6.0 and $55-60^{\circ}C$. Its hydrolyzing activity for pNP-${\beta}Gal$ was drastically decreased by the addition of low concentrations of galactose, but only slightly decreased by glucose, with 85% of maximal activity in the presence of 400 mM glucose.

• Microbiology and Biotechnology Letters
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• v.40 no.1
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• pp.17-22
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• 2012

A bacterial strain was isolated from homemade Cheongkookjang as a producer of the ${\beta}$-galactosidase, capable of hydrolyzing lactose to liberate galactose and glucose residues. The isolate YB-1105 has been identified as Bacillus licheniformis on the basis of its 16S rDNA sequence, morphology and biochemical properties. ${\beta}$-Galactosidase activity was detected in both the culture supernatant and the cell extract of B. licheniformis YB-1105. The enzymes of both fractions demonstrated maximum activity for hydrolysis of para-nitrophenyl-${\beta}$-D-galactopyranoside (pNP-${\beta}Gal$) under identical reaction conditions of pH 6.5 and $50^{\circ}C$. However, ${\beta}$-galactosidase activity from the culture filtrate was affected more than that from the cell free extract at acidic pHs and high temperatures. The hydrolyzing activity of both ${\beta}$-galactosidases for pNP-${\beta}Gal$ was dramatically decreased by the addition of low concentrations of galactose, but was only marginally decreased by high concentrations of glucose or mannose.

• Microbiology and Biotechnology Letters
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• v.38 no.2
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• pp.216-221
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• 2010

This study shows an application of microbiologically induced carbonate precipitate for strength improvement and crack remediation of cement-sand mortar. Seven calcium carbonate-forming bacteria (CFB) were isolated from Dok-do and partially identified by DNA sequence analysis of the 16s rRNA gene. Crystal aggregates were apparent around the bacterial colonies grown on an agar medium. These strains showed strain specific $CaCO_3$ precipitation on urea-$CaCl_2$ medium. Among 7 isolates, Arthrobacter nicotinovorans KNUC601, Microbacterium resistens KNUC602, Agrobacterium tumefaciens KNUC603, Exiguobacterium acetylicum KNUC604, and Bacillus thuringiensis KNUC606 showed a repairing of artificial forced cracks in cement-sand mortar. Compressive strength of cement-sand mortar consolidated with Stenotrophomonas maltophilia KNUC605 was increased around 14.07% compared with that of negative control.

• Microbiology and Biotechnology Letters
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• v.42 no.2
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• pp.99-105
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• 2014

A Bacillus strain capable of hydrolyzing locust bean gum was isolated as a producer of extracellular mannanase by way of an enrichment culture in an acidic medium from homemade soybean pastes. The isolate YB-1401 showed a biochemical identity of 61.1% with Brevibacillus laterosporus, while the nucleotide sequence of its 16S rDNA had the highest similarity with that of Bacillus amyloliquefaciens. The mannanase productivity of the Bacillus sp. YB-1401 was drastically increased by mannans. Particularly, maximum mannanase productivity was reached at approximately 265 U/ml in LB medium supplemented with konjac glucomannan (4.0%). The mannanase was the most active at $55^{\circ}C$ and pH 5.5. Mannanase activity was completely maintained after pre-incubation at pH 3.5 to 11.0 for 1 h. The predominant products resulting from the mannanase hydrolysis were mannobiose and mannotriose for LBG, guar gum or mannooligosaccharides. A small amount of mannose was also detected in the hydrolyzates.

• Korean Journal of Organic Agriculture
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• v.26 no.4
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• pp.649-660
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• 2018

To control the pepper anthracnose caused by Colletotrichum acutatum, antifungal bacterium strains which was selected among bacterium from natural soil, was tested the antimicrobial activity against various pathogens and its control efficacy on anthracnose disease in the fields. We confirmed that antagonistic activity of CAB13001 strain to pathogens such as Sclerotinia cepivorum, Sclerotinia sclerotium and Botrytis cinerea including Colletotrichum acutatum was remarkable superior with the dual culture method in the artificial medium. In vitro bioassay using the green pepper fruit, CAB13001 strain suppressed the lesion development of Anthracnose disease, and its control value compared to the untreated one was 82.4% on pepper fruit in field test. These results suggested that CAB13001 strain could be a very useful biological control agents to anthracnose disease caused by air born plant pathogens of pepper. By the way, analysis of nucleotide sequence of the gene 16S rDNA, antagonistic bacterium CAB13001 strain used in this study was identified as Burkholderia lata.

• Journal of Species Research
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• v.11 no.3
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• pp.155-161
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• 2022

Acetic acid bacteria (AAB) convert ethanol to acetic acid through oxidation, and the fermentation pathway of AAB is important in the vinegar industry. The genus Acetobacter is the representative one of AAB, and several Korean traditional vinegars are produced using Acetobacter strains. Until now, four species in the genus Acetobacter were reported as native species in Korea. During the past two years, we isolated several AAB strains from fruits, flowers and fermented foods, and several AAB species unrecorded in Korea were found on the basis of 16S rRNA gene sequence analyses. In this study, we report eight Acetobacter species as native ones which are A. fabarum C10-3 (=KACC 21483) isolated from plumcot fruit (Naju-si), A. lovaniensis KDG-EC1 (=KACC 22697) isolated from diced radish kimchi (Naju-si), A. okinawensis GAM12-M2 (=KACC 22696) isolated from persimmon fruit (Sangju-si), A. orientalis FR32C4 (=KACC 22370) isolated from fruit of Cudrania tricuspidata (Jeonju-si), A. papaya FR35B3 (=KACC 22046) isolated from grape fruit (Yeongdong-gun), A. suratthaniensis GAM15-R2 (=KACC 22694) isolated from persimmon fruit(Gimje-si), A. syzygii C25-1 (=KACC 22048) isolated from peach fruit (Namwon-si) and A. thailandicus JDF1-M1 (=KACC 22693) isolated from plum fruit(Seoul).

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.99-99
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• 2002

The hormone resistin is associated with typeII diabetes mellitus in rodent model. Resistin impairs glucose tolerance and insulin action. A new class of anti-diabetic drugs were called thiazolidinediones (TZDs) downregulates a resistin which is induced during adipocyte differentiation. But the connection between increased adiposity and resistin remains unknown. The objectives of this study was to clone a mouse resistin cDNA and to generate transgenic mice overexpressing mouse resistin gene. The 555 bp of mouse resistin was amplified from mob cDNAS by polymerase chain reaction (PCR) and cloned into pCR$\^$(R)/ 2.1 TOPO T-vector. Mouse resistin mRNA on the basis of Genbank sequence (acession no. AF323080). Then, the PCR product was cloned into pTargeT$\^$TM/ mammalian expression vector that has pCMV promoter and chimeric intron. Restriction enzyme analysis with BamH I and Not I was carried out to determine an orientation of the insert in the vector. The pCMV-mus/resistin gene was prepared from previous recombinant pTargeT$\^$TM/-mus/resistin by digestion of Bgl II, and has used for microinjection into pronuclei of one cell embryos. The microinjected embryos were transfered to pseudopregnant foster-mother. Mouse resistin expression was detected in transgenic F1 mice by Reverse Transcriptase- Polymerase Chain Reaction (RT-PCR). Resistin gene expression mouse has heavier body weight which was measured higher level of plasma glucose than that of normal mouse. And in diet-induced experiments, the abdominal fat pads were isolated from each 24h starvation and re-feeding after fasting group mice that were assessed by RT-PCR analysis. In fasting group mice, resistin expression was higher than that of re-feeding group mice. This result suggests that the resistin gene overexpressing mice may be became to obesity and be useful as an animal disease model to be diabetes mellitus caused by insulin resistance of resistin.

• Genomics & Informatics
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• v.21 no.4
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• pp.52.1-52.10
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• 2023

Accurate and efficient microbial diagnosis is crucial for effective molecular diagnostics, especially in the field of human healthcare. The gold standard equipment widely employed for detecting specific microorganisms in molecular diagnosis is quantitative real-time polymerase chain reaction (qRT-PCR). However, its limitations in low metagenomic DNA yield samples necessitate exploring alternative approaches. Digital PCR, by quantifying the number of copies of the target sequence, provides absolute quantification results for the bacterial strain. In this study, we compared the diagnostic efficiency of qRT-PCR and digital PCR in detecting a particular bacterial strain (Staphylococcus aureus), focusing on skin-derived DNA samples. Experimentally, specific primer for S. aureus were designed at transcription elongation factor (greA) gene and the target amplicon were cloned and sequenced to validate efficiency of specificity to the greA gene of S. aureus. To quantify the absolute amount of microorganisms present on the skin, the variable region 5 (V5) of the 16S rRNA gene was used, and primers for S. aureus identification were used to relative their amount in the subject's skin. The findings demonstrate the absolute convenience and efficiency of digital PCR in microbial diagnostics. We suggest that the high sensitivity and precise quantification provided by digital PCR could be a promising tool for detecting specific microorganisms, especially in skin-derived DNA samples with low metagenomic DNA yields, and that further research and implementation is needed to improve medical practice and diagnosis.