• Journal of Life Science
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• v.27 no.2
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• pp.202-210
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• 2017

As an effort to find a potential biopreservative, we isolated bacterial strains producing bacteriocin from fermented foods. A strain was finally selected and characteristics of the bacteriocin were investigated. The selected strain was identified as Bacillus subtilis E9-1 based on the 16S rRNA gene analysis. The culture supernatant of B. subtilis E9-1 showed antimicrobial activity against Gram-positive bacteria. Subtilisin A, ${\alpha}$-chymotrypsin, trypsin and proteinase K inactivated the antimicrobial activity, which means its proteinaceous nature, a bacteriocin. The bacteriocin activity was fully retained at the pH range from 2.0 to 8.0 and stable at up to $100^{\circ}C$ for 60 min. Solvents such as ethanol, isopropanol and methanol had no effect on the antimicrobial activity at the concentration of 100% but acetone and acetonitrile reduced the activity at up to 100% concentration. Cell growth of four indicator strains was dramatically decreased in dose-dependent manner. Listeria monocytogenes was the most sensitive, but Enterococcus faecium was the most resistant. Bacillus cereus and Staphylococcus aureus showed the medium sensitivity. The bacteriocin showed its antimicrobial activity against B. cereus and L. monocytogenes via bactericidal action. The number of viable cells of L. monocytogenes started to reduce after addition of bacteriocin to the minced beef. The bacteriocin was purified through acetone concentration, gel filtration chromatography and RP-HPLC. The whole purification step led to a 6.82 fold increase in the specific activity and 6% yield of bacteriocin activity. The molecular weight of the purified bacteriocin was determined to be 3.3 kDa by MALDI-TOF/TOF mass spectrometry.

• Food Science and Preservation
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• v.22 no.3
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• pp.443-451
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• 2015

This study was carried out to investigate the quality characteristics and identification of acetic acid bacteria for black waxy rice vinegar. Eight (8) strains of acetic acid bacteria were isolated for the production of acetic acid and their acidities were then compared with commercial acetic acid bacteria. Among them, F1, H4, and two types of commercial bacteria (four best strains by vinegar zymogen) were selected. After analyzing the 16S rRNA sequence, both F1 and H4 strains were identified as acetobacter genus. Therefore, the F-1 and H-4 strains were named as Acetobacter sp. F-1 and Acetobacter sp. H-4, respectively. Acidity of black waxy rice vinegar during fermentation was steadily increased up to 16 days and the acidity was then constant. Total acidity content was higher when used FV-1 strain. In the results of Hunter's color value of black waxy vinegar, L value was at 75.01 to 80.11, while (+a) value was at 3.34 to 3.92, and (+b) value was at 12.84 to 18.09. The major organic acid of the black waxy vinegar was acetic acid. The total organic acid content was high when used H-4, F-1, C-2 and C-1 strains. The total free amino acid content of the black waxy vinegar by strain was the highest (351.43 mg%) of F-1 vinegar strain, and the lowest (247.74 mg%) of C-2 vinegar strain. A sensory evaluation of black waxy vinegar indicated that F-1 vinegar strain was better than the other samples in aspect of flavor, color, and overall preference.

• Journal of Life Science
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• v.20 no.3
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• pp.336-344
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• 2010

To assess population structure and genetic diversity among the Pacific cod (Gadus macrocephalus), we investigated mtDNA COI gene sequences of 7 populations. Samples were obtained from Sokcho, Wolsung, Geojedo, Yeosu, Geomundo and Westsouth in 2008 and 2009 (n=28). The sequence analysis of 28 individual samples showed 8 haplotypes, ranging in sequence divergence by pairwise comparisons from 0.2 to 2.2% (1 bp-11 bp). The Gal haplotype was found in Wolsung, Geojedo, Yeosu, Geomundo and Westsouth, and was regarded as the main haplotype of Korean Pacific cod. Ga2, Ga3, Ga6 and Ga7 haplotypes were found only in Sokcho. In the PHYLIP analysis, 8 haplotypes formed two independent groups: cladeA consisted of Ga2, Ga3, Ga6 and Ga7 haplotypes, whereas cladeB contained Gal, Ga4, Ga5 and Ga8 haplotypes. The genetic relationship between the two groups was weakly supported by bootstrap analysis(<50%). In pairwise comparisons between 6 populations other than that from Sokcho, a very high per generation migration ratio ($N_m$=infinite) and a very low level of geographic distance ($F_{sr}=-0.0123-(-0.0423)$) were observed. The estimates of genetic distance between Sokcho and the other localities were all statistically significant (p<0.05, p<0.01, p<0.001), indicating a limited mtDNA-based gene flow between Sokcho and other regions. The finding of the lowest genetic diversity in the Sokcho population (nucleotide diversity=0.00589) may be a result of relatively small population size and interrupted gene flow to other localities. Consequently, the overall considerable migration of Pacific cod population in Korea caused a genetically homogeneous structure to form, although a distinct population was found in this study.

• Journal of Life Science
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• v.23 no.3
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• pp.415-425
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• 2013

This study compared the characteristics of five Bacillus strains capable of aerobic and anaerobic growth, CBW3, CBW4, CBW9, CBW14 and EBW10. They were isolated and selected from a polychaete, Perinereis aibuhitensis, which is known as a good degrader of organic compounds in marine wetland. Based on a 16S rRNA sequence, CBW3 and CBW14 were found to share more than 99.8% similarity with B. nanhaiensis, B. arsenicus and B. barbaricus. CBW4, CBW9 and EBW10 shared 92.7%, 99.8%, and 99.8% similarity with B. anthracis, B. algicoa and B. thuringiensis, respectively. The temperature, salinity, and pH ranges of the cell growth of the Bacillus strains were $4-45^{\circ}C$, 0-17%, and pH 5-pH 9, respectively. All Bacillus strains were found to exhibit enzyme activities for the degradation of casein and starch. Notably, strain EBW10 exhibited the enzyme activities for all the tested macromolecules, DNA, casein, starch, cellulose, and four kinds of Tweens, which suggests the possibility that it had protease, amylase, cellulose, and lipase. All five Bacillus strains had alkaline phosphatase activities, and the strains CBW3, CBW4, and EBW10 also had acid phospatase. Strains CBW3 and EBW10 exhibited the enzyme activities both for esterase (C4) and esterase lipase (C8). The analysis of fatty acids revealed that in all strains, major fatty acids were anteiso $C_{15:0}$ and iso $C_{15:0}$.

• Korean Journal of Microbiology
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• v.38 no.2
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• pp.86-95
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• 2002

As a result of genome projects, the research to elucidate the function of a protein of interest has recently been well-recognized. In order to facilitate functional genomics, a useful mammalian gene expression vector is required. Using an infectious CDNA clone of BVDV pNADLclns-, we have developed a mammalian gene expression vector. In this study, a replication-competent full-length infectious CDNA clone containing puremycin acetyltransferase (pac) gene (pNADLclns-/pac) was successfully generated. The viral RNA replication and viral protein NS3 synthesis were examined by detecting metabollically $^{32}P$-labelled genomic viral RNA and immunoblotting with a mouse anti-NS3 antibody. To generate viral replicon as an expression vector, we examine if the viral structural genes (C, E0, El, E2) are required for viral replication by deletion analysis. As a result, all of the structural proteins are dispensable for viral replication per se, but essential for infectious viral particle formation. Based on our deletion analysis, we have generated a replication-competent BVDV viral replicon (pNADLclns-/pac/${\Delta}S$), whose structural genes are all deleted. In addition to NADLclns- /pac/${\Delta}S$, NADLclns-/ luc/${\Delta}S$ viral replicon containing luciferase gene as a reporter was constructed and fecund to be replication-compotent in HeLa and BHK cells as well as MDBK cells. Therefore, BVDV viral replicon developed in our study will be a useful tool to express a protein of interest in various mammalian cells.

• Korean Journal of Microbiology
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• v.39 no.3
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• pp.166-174
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• 2003

Microcystin produced by cyanobacteria in surface waters, such as eutrophic lake and river, is a kind of serious environmental problems due to its toxicity to human and wild animals. Microcystin is synthesized nonribosomally by the large modular multi-functional enzyme complex known as microcystin synthetase encoded by the mcy gene cluster. Amplification of mcy genes by PCR from cultures and environmental samples is a simple and efficient method to detect the toxigenic Microcystis. In order to evaluate primers designed to detect toxic microcystin-producing strains, 17 cyanobacterial strains and 20 environmental samples were examined by PCR with 7 pairs of primers. Some microcystin-producing cyanobacteria were not detected with FAA-RAA, TOX4F-TOX4R and FP-RP primers. The fragment of unexpected size was amplified with NSZW2-NSZW1 primers in Microcystis strains isolated from the lakes in Korea. TOX1P-TOX1F primers failed in amplification of toxin-producing strains. Only MSF-MSR and TOX2P- TOX2F primers amplified the fragments of mcy genes from 11 strains of microcystin-producing Microcystis. The water samples taken from 20 lakes in Korea were analyzed by PCR using each of the primers. In all the water samples, cyanobacteria capable of producing microcystin were detected by the PCR with TOX2P-TOX2F primers. These results indicate that TOX2P-TOX2F primers are better than the other primers for detection of microcystin-producing Microcystis strains in Korea. The nucleotide sequences of mcy gene in Microcystis aeruginosa NIER10010 suggest genetic diversity of Korean isolates.

• Applied Biological Chemistry
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• v.39 no.6
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• pp.443-448
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• 1996

In order to investigate the function of xylA promoter(Pxyl) as regulatory region Pxyl-lacZ fusion gene was constructed by the insertion of xylA promoter to the multiple cloning site of upstream of lacZ gene in a multicopy numbered plasmid pMC1403 containing promoterless lac operon, which was designated pMCX191, and Pxyl-lacZ fragment from pMCX191 was inserted to low copy numbered plasmid pLG339, designated pLGX191. The expressions of ${\beta}-galactosidase$ in these recombinant plasmids containing Pxyl-lacZ fusion gene were induced strongly by the addition of xylose, repressed by the addition of 0.2% glucose in the presence of xylose. The catabolite repressions were derepressed by the addition of 1 mM cAMP as same as native xylA gene. The fragment of xylA promoter was partially deleted from the upstream of xylA promoter by exonuclease III to investigate the regulation site of xylA promoter and the degrees of deletion derivatives of xylA promoter were analyzed by the DNA base sequencing. By the investigations of the induction by xylose, repression by glucose and derepression by cAMP on xylose isomerase production, the regulation site of xylA promoter may be located in segment between -165 and -59 bp upstream from the initiation site of xylA translation.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.317-323
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• 2014

Violacein has received much attention due to its various important biological activities, including broad-spectrum antibacterial and antifungal activity, anti-malarial, anti-tumoral, anti-oxidant, and anti-diarrheal activities. EP15224 strain isolated from forest soils in Korea was found to be a new species belonged to the genus Massilia based on its 16S ribosomal DNA sequences. The 16S ribosomal DNA of strain EP15224 displayed 97% homology with Massilia sp. BS-1, the nearest violacein-producing bacterium. Strain EP15224 produced bluish-purple pigment well in a synthetic MM2 medium containing glucose, $(NH_4)_2SO_4$, $Na_2HPO_4{\cdot}7H_2O$, $KH_2PO_4$, $MgSO_4{\cdot}7H_2O$, and 1 mM $\small{L}$-tryptophan. The chemical analysis of the pigment by LC/MS/MS showed that it is violacein with molecular weight of 343.34. This is the second report on the production of violacein by a Massilia species. In this study, the optimal culture conditions for violacein production were established under which 280 mg/l crude violacein was produced : glucose 2 g/l, $(NH_4)_2SO_4$ 1 g/l, $Na_2HPO_4{\cdot}7H_2O$ 2 g/l, $KH_2PO_4$ 1 g/l, $MgSO_4{\cdot}7H_2O$ 0.1 g/l, L-tryptophan 0.24 g/l, 25 ml medium in a 250 ml flask, with an inoculumn size of 10% (v/v), 72 h of cultivation with 250 rpm at $25^{\circ}C$.

• Korean journal of applied entomology
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• v.59 no.2
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• pp.93-107
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• 2020

Adults of seven noctuid potential pests (Spodoptera frugiperda, S. litura, S. exigua, Ctenoplusia agnata, Mythimna loreyi, Athetis dissimilis, and A. lepigone) of soybean and maize in Suwon, Korea were identified by their morphological characteristics in the wing pattern and male genitalia and partial mitochondrial DNA sequences of cytochrome c oxidase subunit 1 gene. The generation number of adults that emerge annually in six species (except A. lepigone) was estimated from the data on density fluctuations of adults caught in sex pheromone traps in 2019 and the forecasted data using temperature-associated development and reproduction models for those species. S. frugiperda adults were caught from July 27th to October 31st in 2019, and hence were initially estimated to emerge three times per year. But, it was finally expected that S. frugiperda adults could possibly emerge a total of four times per year in Suwon, considering larval emergence observed during mid- and late June in other areas. Adult emergence of S. litura, S. exigua, C. agnata, and M. loreyi in 2019 was observed from May 29th to November 6th, from May 14th to November 6th, from May 26th to October 25th, and from May 31st to November 23rd, respectively. Annual adult emergence of these four species was estimated as at least four times. Adults of A. dissimilis were caught from May 26th to September 11th in 2019, and adult emergence was estimated at only twice per annum. It was postulated that the first adult populations of five species except the two Athetis species were probably migrated from other areas.

• Tuberculosis and Respiratory Diseases
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• v.43 no.6
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• pp.842-851
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• 1996

Background : Rifampicin(RFP) is a key component of the antituberculous shon-course chemotherapy and the RFP-resistance is a marker of multi-drug resistant(MDR) M. tuberculosis. rpoB gene encodes the ${\beta}$-subunit of RNA polymerase of M. tuberculosis which is the target of RFP. Recent reports show that rpoB gene mutations are the cause of RFP resistance of M. tuberculosis and the main mechanism of rpoB gene mutation is point mutation. And PCR-SSCP is a rapid and easy method for detecting point mutations. So we performed PCR-SSCP of rpoB gene of M. tuberculosis and compared the result with traditional RFP sensitivity test. Method : The 27 RFP sensitive M. tuberculosis culture isolates and 25 RFP resistant isolates were evaluated. The RFP sensitivity test was done at the Korean Tuberculosis istitute. The DNA was extracted by bead beater method and was amplified with primers TR-8 and TR-9 in a 20ul PCR reaction containing 0.1ul(luCi) [${\alpha}-^{32}P$] - dCTP. After amplification, SSCP was done using non-denaturaring polyacrylamide gel electrophoresis. Then direct sequencing was done in cases of different eletrophoretic mobility compared with that of H37Rv. In 19 cases, we compared PCR-SSCP results with patient's clinical course and the results of traditional RFP sensitivity test. Results : 1) All 27 RFP sensitive M. tuberculosis isolates showed the same electrophoretic mobility compared with that of H37Rv. And all 25 RFP resistant M. tuberculosis isolates showed different electrophoretic mobility. 2) The mechanism of rpoB gene mutation of M. tuberculosis is mainly point mutation. 3) The PCR-SSCP results correlate well with traditional RFP sensitivity and patient's clinical response to antituberculous treatment. Conclusion: The PCR-SSCP of rpoB gene is a very sensitive and rapid mehod in detecting RFP- resistant M. tuberculosis.