• Korean Journal of Microbiology
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• v.45 no.2
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• pp.163-169
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• 2009

This study was performed to investigate the type of extended-spectrum $\beta$-lactamases (ESBL) produced by bacteria isolated from the sewage of wastewater treatment plant at Minragdong, Suyong-gu in Busan. The facility is located at sushi restaurants and guides its drain water to the wastewater treatment plant at Yonghodong, Nam-gu in Busan. Samples were collected on January, 2009. A total of 19 strains were selected as potential ESBL positive strains through a double disk synergy test. On the basis of the results from biochemical tests including indole, methyl-red, Voges-Proskauer, Simmon's citrate, decarboxylase-dihydrolase and sugar-fermentation tests, the 19 strains were identified with 16 strains of Escherichia coli and 3 strains of Klebsiella pneumoniae. Out of 19 strains, 4 transconjugants against Escherichia coli J53, which is sodium azide resistant recipient strain, were obtained. The plasmids isolated from transconjugants were used for PCR analysis. The type of each extended-spectrum $\beta$-lactamase (ESBL) produced by the strains was determined on the basis of isoelectric focusing analysis and DNA sequencing. The results indicated that the types of ESBL from Klebsiella pneumoniae were SHV-12 (3 strains), and Escherichia coli was SHV-12/TEM-1 (1 strain), respectively.

• Journal of Microbiology and Biotechnology
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• v.27 no.11
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• pp.2019-2027
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• 2017

Recently, cabbage kimchi has occasionally been associated with the foodborne diseases of enteric viruses such as human norovirus (HuNoV). This study aimed to evaluate the correlation between microbial/physicochemical properties and persistence of HuNoV in experimentally contaminated cabbage kimchi fermented and stored at $4^{\circ}C$ or $10^{\circ}C$ for 28 days. Changes in organic acid content, lactic acid bacteria (LAB), acidity, pH, and salinity were analyzed. The recovery of structurally intact HuNoV was examined for up to 28 days post-inoculation, using a NoV GII.4 monoclonal antibody-conjugated immuno-magnetic separation method combined with quantitative real-time reverse transcription polymerase chain reaction. On day 0, LAB loads were $4.70log_{10}$ colony forming units/g and HuNoV GII.4 titers were $2.57log_{10}\;genomic\;copies/{\mu}l$, at both temperatures. After 28 days, intact HuNoV titers decreased to 1.58 ($4^{\circ}C$) and $1.04(10^{\circ}C)log_{10}\;genomic\;copies/{\mu}l$, whereas the LAB density increased. This correlated with a gradual increase in lactic acid and acetic acid at both temperatures. Our findings support a statistical correlation between changes in physicochemical properties and the recovery of structurally intact HuNoV GII.4. Moreover, we determined that the production of organic acid and low pH could affect HuNoV GII.4 titers in cabbage kimchi during fermentation. However, HuNoV GII.4 was not completely eliminated by microbial/physicochemical factors during fermentation, although HuNoV GII.4 was reduced. Based on this, we speculate that the persistence of HuNoV GII.4 may be affected by the continually changing conditions during kimchi fermentation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.1
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• pp.1-7
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• 2002

To study the increased resistance in fish against Vibrio vulnificus known as an important agent of vibrio septicemia in human, we analyzed specific and nonspecific immune response in flounder after administration of V. vulnificus bacterins by oral route. It contained the comparison of antibody concentrations in the sera of flounder after oral administration by two different protocols with uncoated heat killed bacterin of V vulnificus (UHKB, 20 mg/kg body weight), i.e., 4 weeks continuously (group 4W) and taking 2 weeks resting period between the 1st and last week of administration (group 1-2-1W). Even though, 1-2-1W group showed significantly increased level of specific antibody in serum, it did not reach to that of 4W group. Certainly, flounder vaccinated twice a week for four weeks (20 mg/kg b.w.) showed increased concentration of specific antibody against V. vulnificus at week 2 after last administration by oral route and maintained throughout the experimental period. It also was confirmed by the increased numbers of specific antibody secreting cells (SASC) in the leukocytes isolated from the splenocytes of the flounder of 4W group at week 1 after last administration until the end of experimental period. However, enteric, acid-resistant film coated heat killed bacterin (ECHB) did not show both greater immune reaction for antibody production and faster elimination of a challenge dose of V. vulnificus compared with those of the UHKB. These results suggested that UHKB administered by oral route was very effective method to prevent the contamination of V vulnificus in flounder, and did not show the increased antigenicity by coating the surface with acid-resistant film.

• Korean Journal of Food Science and Technology
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• v.20 no.1
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• pp.112-118
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• 1988

The effect of gamma irradiation of microbiological and physicochemical properties of raw ingredients (thirteen kinds of protein sources) for the mixed feed were investigated. The total aerobic bacteria counts in the samples was ranged from $10^2$ to $10^7$cells/g. After 5 to 7 kGy irradiation, the total count was reduced by 3 to 4 log cycles. Coliforms were detected in seven samples and the range was from $10^4$ to $10^6$cells/g. Enteric pathogens were found only in fish meal and poultry byproduct as $10^2$ to $10^6$cells/g. They were sensitive to radiation and completely sterilized by 3 to 5 kGy irradiation. Total fungi count was ranged from $10^1$ to $10^4$cells/g in all samples. They were osmophiles such as Aspergillus, Penicillium, Cladosporium, Aureobasidium and Rhizopus and were destroyed by 3 to 7 kGy irradiation. Five species of potential mycotoxin producers including Aspergillus flavus were also identified. Physicochemical properties, such as total amino acid content, TBA value, POV and color difference showed that irradiation with optimum does was less detrimental than autoclaving.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.735-746
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• 2016

This study was conducted to investigate the antibacterial, antioxidant, and in vitro greenhouse gas mitigation activities of fermented Scutellaria baicalensis Georgi extract. Seven starter cultures were used, comprising four of lactic acid bacteria and three of Saccharomyces cerevisiae. Ten grams of S. baicalensis Georgi powder was diluted in 90 mL autoclaved MRS broth. Each seed culture was inoculated with 3-10% (v/v) S. baicalensis Georgi MRS broth and incubated at $30^{\circ}C$ for 48 h. Among the starter cultures used, only Lactobacillus plantarum EJ43 could withstand the fermentation conditions. This fermentation broth was dried and extracted with ethanol to assess its antibacterial, antioxidant, and in vitro methane mitigation activities. The extract of S. baicalensis Georgi fermented by L. plantarum EJ43 (SBLp) showed higher antibacterial activity (bigger clear zone) compared to the unfermented S. baicalensis Georgi extract (SB0). SBLp also presented 1.2 folds higher antioxidant activity than SB0. During in vitro rumen fermentation, SBLp showed reduction in methane production compared to SB0 or the control. In conclusion, fermentation by L. plantarum EJ43 may enhance antibacterial and antioxidant activities of S. baicalensis Georgi and decrease enteric methane production.

• Pediatric Infection and Vaccine
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• v.27 no.2
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• pp.90-101
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• 2020

Purpose: The multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) test developed recently can help detect enteric pathogens of acute gastroenteritis (AGE). This study aimed to investigate the epidemiology of pathogens in children with AGE using the multiplex RT-PCR. Methods: From May 2015 to June 2018, multiplex RT-PCR tests were performed to identify pathogens in the feces of pediatric patients diagnosed with AGE at a secondary hospital in Seoul, Korea. Results: Of the 1,366 stool samples examined for viral pathogens, 483 (35.3%) tested positive for ≥1 pathogen. Group A rotavirus (RV) was detected in 106 cases (7.8%). The positivity rate increased annually from 3.0% (8/263) to 16.7% (48/288) and surged in 2018 (P<0.001). Norovirus (NoV) GII was the most common viral pathogen (263/1,366, 19.3%), and the positivity rate did not increase during the 3 years. Of the 304 stool samples tested for bacterial pathogens, Campylobacter spp. was the most common bacterial pathogen (32/304, 10.5%), followed by Clostridium difficile (22/304, 7.2%) and Salmonella spp. (17/304, 5.6%). The positivity rate of these bacterial pathogens did not change significantly during the study period. Conclusions: NoV GII is the main pathogen in childhood AGE since the introduction of RV vaccine, yet the number of rotavirus-infected patients increased during our study, especially in 2018. Therefore, further research is needed including the possibility of emergence of novel RV strains. Campylobacter spp. is the predominant cause of bacterial AGE in children. For proper treatment, the clinical characteristics of the bacteria should be taken into consideration, and continuous monitoring is necessary.

• Journal of Ginseng Research
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• v.7 no.2
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• pp.102-107
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• 1983

The effects of saponin, one of major components (Panax ginseng C.A. Meyer), on the growth of E. coli K-12 and the formation of siderphore was observed The following results were obtained. 1. When E. coli was grown on medium containing 1${\times}$10-5%-11${\times}$10-1% of the saponin, the rate of growth was stimulated at 10-1% of the saponin significantly compared to that of control. 2. When E. coli K-12 was grown on medium containing 1${\times}$10-1% of the saponin, the amount of siderphore was two times as much as the control. 3. The growth of E. coli was observed to be dependent on the concentration of siderophore when siderophore was added to medium. 4. The effect of saponin on the formation of siderophore in vitro was observed to reach maximum at 1${\times}$10-3% of the saponin. Such results suggest that the growth rate of E. coli K-12 could be enhanced by ginseng saponin fraction through stimulation of siderphore formation. We have described the fast growth of E. coli, K-12 and B. subtilis, rapid uptake of 14C-glucose, and high level of other metabolites such as lipids and proteins of E. coli, and B. subtilis in medium containing saponing fraction compared to that of microorganisms without saponin fraction.1∼3Such differences were claimed to be due to rapid uptake of 14C-glucose by widened periplasmic region throught unknown mechanism in the prescence of saponin fraction in medium3 and have raised a question whether there is another possible factor, siderophore4(Greek for iron bears), since microorganisms must secure a sufficient amount of iron for normal growth. These are known to be synthesized by the cells under iron-deficient condition and in most case, excreted into the medium5, where they can complex and solubilize any iron present there. It is generally believed that these complexes are then taken into the cells presumably by specific transport systems, thus providing iron for cell metabolism. Within the group of enteric bacteria, only three species (E. coli, S. typhimurium, and A. aerogense) have, so far, been studied in a ny detail. The main iron-binding compound produced by these species is enterochelin, and its role in iron transport is now well established. And biosynthesis of enterochelin from 2, 3- dihydroxybenzoate and serine in the prescence of magnesium ions and ATP was reported6. 2, 3-dihydroxybenzoate was also shown to involve isochorismate and 2, 3-dihydro-2, 3-dihydroxybenzoate as intermediate.7∼11 The present paper deals with the effect of ginseng saponin fraction on growth, the level of enterochelin formation in vivo and the conversion of 2, 3-dihydroxybenzoate and serine into entrochelin in vitro, and entrochelin obtained on the growth in relation to possible explanation of ginseng saponin fraction on the rapid growth of E. coli, K-12.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.342-348
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• 2007

In a previous study, a new antibacterial activity was found from Paenibacillus polymyxa DY1 isolated from Korean soil, which showed a good growth inhibition against various multidrug resistant enteric bacteria. Thus the effect of nutritional factors and physicochemical conditions on the growth of P. polymyxa DY1 cells and the production of antibacterial activity were evaluated in this study. For the growth of P. polymyxa DY1 cells the optimum condition reaches by incubating at $35^{\circ}C$ for 48 hours by shaking at 180 rpm in the basal medium containing 0.6% dextrose, 1.4% ammonium phosphate dibasic, 0.9% peptone, 2.4% glutamine, and 2 mM sodium molybdate with initial pH 8.0. A maximum level of antibacterial activity was obtained when P. polymyxa DY1 was incubated at $35^{\circ}C$ for 48 hours by shaking at 180 rpm in the basal medium with initial pH 8.0 containing 1% dextrose, 1.5% ammonium sulfate, 1.1% casamino acid, 1.9% aspartic acid, and 2 mM ferrous sulfate.

• Journal of Life Science
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• v.23 no.1
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• pp.143-156
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• 2013

Due to the high incidence of cancer and cancer-related mortality in Korea, there is increased concern and psychological anxiety about this disease, leading to increasing numbers of cancer studies. Despite these, the trend of the cancer incidence rate has shown a significant increase. The detection of colorectal cancer, which has a high incidence rate, often tends to be delayed, causing a high mortality rate. Therefore, the prevention of colorectal cancer has become an important emergent issue. The cause of this cancer has not been confirmed. However, it may be attributable to westernized dietary patterns, which include consuming a high quantity of red meat. Consumption of dietary fiber promotes the production of butyrate short-chain fatty acids by enteric bacteria. In the treatment of cancer, anticancer medications have been shown to lead to the apoptosis of tumor cells, and a strong relationship between apoptosis mechanisms of tumor cells and cancer treatment has been confirmed. The results of many studies have confirmed that butyrate can directly promote the apoptosis of colorectal cancer cells. Therefore, increased consumption of dietary fiber, which promotes the production of butyrate shortchain fatty acids, can be expected to have an effect on the prevention and treatment of colorectal cancer.

• Korean Journal of Food Science and Technology
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• v.19 no.5
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• pp.403-408
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• 1987

The effects of gamma irradiation on microbiological and chemical qualities of four kinds of poultry feeds were investigated. The viable counts of total bacteria in the samples were $10^5\;to\;10^6/g$. They were reduced by 2 to 3 log cycles after 3 to 5 kGy irradiation, and were completely eliminated with irradiation of 7 kGy. Coliforms and enteric pathogens were contaminated in high levels in all samples, ranging from $1.2{\times}10^4\;to\;1.7{\times}10^5/g\;and\;4.0{\times}10\;to\;2.6{\times}10^3/g$, respectively, They were sterilized by 3 to 5 kGy irradiation. Fungi, ranging from $10^{2}\;to\;10^4/g$, mainly osmophiles were identified as Aspergillus and Penicillium. They were eliminated to a undetectable level by 5 to 10 kGy irradiation. Six kinds of species, including Aspergillus flavus, were potential mycotoxin producers. Chemical components, such as proximate compositions, and mineral contents were not affected by the gamma irradiation. However, TBA values and amino acid content seemed to be affected by gamma irradiation.