• Korean Journal of Microbiology
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• v.51 no.2
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• pp.156-168
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• 2015

The objective of this study is to investigate the anti-Helicobacter pylori and anti-cancer activities of the live cells (LC), cell-free culture supernatants (CFCS), and bacteriocin solution (BS) obtained from Lactobacillus acidophilus BK13 and Lactobacillus paracasei BK57 strains. After incubation for 30 h in MRS broth, the concentration of lactic acid produced by L. paracasei BK57 ($155.9{\pm}10.2mM$) was higher than in MRS broth using L. acidophilus BK13 ($126.8{\pm}7.9mM$). Maximum bacteriocin activity (128 AU/ml) of BK13 strain was observed after 30 h of cultivation at $37^{\circ}C$, however its magnitude was significantly lower than that of BK57 strain (256 AU/ml). The LC of L. acidophilus BK13 and L. paracasei BK57 were able to inhibit the growth of H. pylori ATCC 43504 at different incubation times, depending on the initial inoculum of the LAB. These CFCS and BS obtained from BK13 and BK57 strains dramatically inhibited the growth, adhesive ability, and enzymatic activity of H. pylori. Meanwhile, the anti-cancer effect of the lactic acid from L. acidophilus BK13 and L. paracasei BK57 strains on AGS cells had significant differences with the control group. Therefore, these antagonistic substances-producing strains are potentially useful as new potential antimicrobial agents for the management and prevention of H. pylori infections.

• Korean Journal of Microbiology
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• v.45 no.3
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• pp.281-285
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• 2009

In this study, we compared the BacT/Alert liquid culture system with Ogawa and $L\ddot{o}wenstein$-Jensen (L-J) media for sputum culture and drug susceptibility test (DST) of Mycobacterium tuberculosis. Rapid liquid culture systems have been widely employed both for primary cultures of M. tuberculosis from clinical specimens and for drug susceptibility test because of its greater sensitivity and faster turn-around time than the conventional egg-based culture methods (Ogawa, $L\ddot{o}wenstein$-Jensen media). Sputum specimens were decontaminated with N-acetyl-L-cysteine (NALC)-4% NaOH and inoculated into the BacT/Alert culture bottles and Ogawa media. 95 from among 135 sputa were smear-positive, 97 (71.9%) were culture-positive by the BacT/Alert culture system, while 89 (65.9%) were positive by Ogawa media. The mean time to culture-positive by the BacT/Alert process system was about 11.3 days, which was significantly shorter than that by Ogawa media (22.4 days). Of 32 M. tuberculosis cultures examined for drug sensitivity, the concordant rate between the two methods (BacT/ Alert liquid culture system, $L\ddot{o}wenstein$-Jensen media) ranged from 87.5% for isoniazid and 90.6% for rifampicin.

• Korean journal of food and cookery science
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• v.14 no.3
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• pp.232-240
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• 1998

The effect of various levels of perilla seed powder on physicochemical, microbiological, and sensory characteristics of Puchukimchi during fermentation was investigated. Puchukimchi is a kind of korean kimchi made with Leek (Allium odorum L.). In a laboratory model of Puchukimchi made with various levels (0, 1, 2, 3, 5%) of perilla seed powder fermentated at 10$^{\circ}C$ up to 45 days. As a fermentation progressed, the initial high decrease in pH has been retarded in all the treatments, of which the delaying extent was noted from Puchukimchi made with perilla seed powder. The pH dropped with accumulation of total acidity. The total vitamin C content increased sharply at the palatable period of Puchukimchi during initial fermentation and then, especially from the 8th-day, gradually decreased later following sigmoidal changing pattern. And the total vitamin C content was the highest in the Puchukimchi made with 5% perilla seed powder. The lactic acid bacteria count increased remarkably and then decreased gradually after optimum ripening period, i.e., the palatable period of Puchukimchi during fermentation. During the early stage of fermentation, sensory evaluation showed the higher scores on the overall taste of Puchukimchi made with 3, 5% on the 2nd-day, 1, 2% on the 5th-day of fermentation. However, the trend of acceptability has been reversed by the Puchukimchi made with little amount of perilla seed powder, more notably 2% at the later stage of fermentation.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.219-222
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• 2010

In this study, we evaluated Vi-passive hemagglutination (Vi-PHA), SD Salmonella Typhi IgG/IgM ($SD^{(R)}$ kit) and Widal test for the rapid laboratory diagnosis of typhoid fever patients. A total of 36 serum samples from febrile patients in Korea from 2005 to 2006 were used. Among 36 patients, 27 were fever patients without typhoid, 9 were typhoid fever. Vi-PHA showed 8 positive results out of 9 typhoid fever patients (sensitivity 88.9%) and 1 positive and 26 negative results out of 27 febrile patients without typhoid (specificity 96.3%). The sensitivity and the specificity of $SD^{(R)}$ kit were 100% and 92.6%, respectively. However, the sensitivity and the specificity of Widal O & H tests were 88.9%, 100%, and 77.8%, 70.4%, respectively. Consequently, Widal H and $SD^{(R)}$ kit showed higher sensitivity and Vi-PHA showed higher specificity. To efficient diagnosis, Vi-PHA may be sufficient diagnosis method in acute cases and $SD^{(R)}$ kit and Widal test may be sufficient in sporadic area and high risk group.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.262-269
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• 2010

To investigate a quantitative evaluation of the actinobacteria, we have collected samples from various kinds of bamboo forest soil. Each different layers contained $2.7{\times}10^6-2.7{\times}10^8$ CFU/g of actinobacteria which was the highest in litter layers of Sasa boreali forest soil. We obtained 330 actinobacteria from different layers of bamboo forest soil; litter (100 strains), humus (70 strains), and rhizosphere soil (160 strains). Based on the colony morphology (aerial mycelium, substrate mycelium, and soluble pigment), isolates were divided into thirty-six groups and we selected 50 representative isolates. 16S rRNA gene sequence analysis showed Streptomyces was major actinobacteria (94%) and they were categorized as cluster I (2 strains), II (35 strains), III (6 strains), and IV (7 strains), respectively. The diversity index of 50 Streptomyces collected from the bamboo forest soil was calculated with the Shannon-Wiener method. Bamboo litter showed higher diversity index level of 3.33 than that of humus and rhizosphere soil. Also, antibiotic activities of our isolates were investigated against Botrytis cinerea, Xanthomonas campestris, Xanthomonas axonopodis pv. vesicatoria, and Bacillus cereus and found in 74, 16, 25, and 24 strains, respectively.

• Food Science of Animal Resources
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• v.25 no.1
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• pp.13-19
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• 2005

The radio-sensitivity of pathogens and the effect of irradiation on microbiologican safety and mutagenicity of meat products such as seasoned and cooked beef and ham were investigated. Samples were radiation-sterilized and inoculated at 10/sup 7/ cfu/g with each of the four pathogens including Salmonella typhimurium, Escherichia coli, Staphylcoccus aureus, and Listeria ivanovii. No viable cells of pathogens were observed in the sample irradiated with 3 kGy. The D/sub 10/ value of inoculated pathogens in seasoned and cooked beef and ham were 0.24∼0.48 and 0.39∼0.45, respectively. Results of Ames test performed with non-irradiated and irradiated seasoned and cooked beef and ham were both negative at the level of 625, 1,250, 2,500, 50,000, and! 10,000 ㎍ sample/plate, respectively. Results indicate that low dose (2∼3 kGy) irradiation is effective to ensure safety for seasoned and cooked beef and ham with toxicological wholesomeness.

• Food Science of Animal Resources
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• v.22 no.3
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• pp.247-251
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• 2002

This study was carried out to investigate the keeping quality of market milks collected from several dairy processing companies. Microbiological, chemical, and sensory properties of Intra-high temperature(UHT) treated milks stored at 5, 10, 15t were evaluated during the storage of 154days. No significant difference during the storage was shown in bacterial counts, pH and titratable acidity. Standard plate count(SPC) was remained less than 20,000 cfu/ml after 15 day storage at 5, 10, 15$^{\circ}C$. Also, Psychrotrophic bacterial count and Coliform count were not detected or detected at low level. The pH ranged from 6.55 to 6.83 and the titratable acidity ranged from 0.13% to 0.16%. In sensory evaluation, UHT milks showed normal flavor until 10days, but thereafter off-flavor was slightly developed. Consequently, UHT milks remained in good quality when stored at 5$^{\circ}C$,10$^{\circ}C$t until 15days except sensory properties. According to this experiment, the shelf-life of UHT milk can be extended to 10 days, even though maintaining the storage temperature strictly below 10 t in milk market is not easy.

• Korean Journal of Microbiology
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• v.36 no.2
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• pp.142-149
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• 2000

It had been evaluated the recombinant Circumsporozoite(CS) protein of Plasmodium viva in serologic diagnosis of vivax malaria. Western blot was done to analyse the sera of malaria patients according to the days after onset. The sera which have the terms within 15 days were shown 43.8%(14/32) of positive rates and the sera over the 16 days were shown 94.4%(17/18) of positive rates. So the total positive rate was 62%(31/50). It was 22.6%(7/31) which was shown negative response in Western blot, even though they were shown positive response in Immuuofluorescent antibody test(1FAT) using whole blood stage antigens. The positive rate of non-epidemic area(Yechon-gun, Kyongsangbuk-do) was 10.7%(3/28), and epidemic area(Kangwha-gun, Inchon-shi) was 27.6%(13/47) in Western blot analysis using recombinant CS protein. In order to applicate the recombinant CS protein in seroepidemiological survey, blood samples of 422 inhabitants were collected who lived in malaria epidemic areas, Chosm-ri, Majeong-ri, Hyangyang-ri and Noejo-n in Paju-shi, Kyonggi-do. All of them were negative in microscopic examination and two(0.5%) of them were positive in Polymerase Chain Reaction. 42(10.0%) of them were seropositive in FAT using whole blood antigens and 71(16.8%) of them were seropositive in Enzyme-linked immunosorbent assay using recombinant CS protein. It was figured out the positive rates were much higher according to the distances of villages which were closed to the demilitalized zone(DMZ) in all kind of diagnostic methods, respectively.

• Korean Journal of Microbiology
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• v.39 no.3
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• pp.181-186
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• 2003

This study was performed to analyze quantitatively the number of living bacteria in forest soil samples collected from Mt. Keryong using improved direct viable count (DVC) and plate count (PC) methods. The number of living bacteria by DVC comprised 18～44% of the total direct count (TDC), whereas the number of living bacteria by PC was less than 1% of TDC. These results showed that viable but non-culturable (VBNC) bacteria existed in the soil with high percentages. Besides, DVC was proved to make it possible to make a quantitative detection of the VBNC bacteria. On the other hand, upon measuring the value from the conventional nutrient broth (NB) and $10^{-2}$ folded diluted nutrient broth (DNB), the values from the DNB showed 5 to 10 times higher than those from the conventional NB medium. These results indicate that oligotrophic bacterial groups, which could multiply in the low nutrient broth, abundantly exist in the soil ecosystem. It would also be possible to apply this kind of method to other substrate to make a quantitative detection of soil bacterial groups.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.2
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• pp.121-130
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• 2010

Metals and sulfate can be considerably dissolved at low pH condition in the acid mine drainage(AMD) and it would make an environmental problems. There are only few of acid mine drainage treatment systems in Korea which are operating, but these still have an effect on the surrounding stream. In this study, quantification of indicator microorganisms was conducted to judge the environmental impact of AMD on microflora by quantitative real-time PCR in the drainage samples of four mines and the water samples of each surrounding stream. Two species of iron reducing bacteria(Rhodoferax ferrireducens T118 and Acidiphilium cryptum JF-5) were selected for indicator bacteria based on 16S rRNA cloning analysis, and sulfate reducing bacteria(Desulfosporosinus orientus), iron and sulfur oxidizing bacteria(Acidothiobacillus ferrooxidans) and iron oxidizing bacteria(Leptosprillum ferrooxidans) were included into indicator since these were found in the previous studies on the mining area. Thereafter, the comparative analysis of four mines were established by the microbiological variation index and it was determined that the biological environment effect of AMD is highest in Samtan mine which doesn t contain treatment system by the value.