• Journal of Food Hygiene and Safety
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• v.16 no.4
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• pp.264-273
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• 2001

Antimicrobial activities of ave different probiotics (Lactobacillus reuteri, L. acidophillus, L. bulgaricus, L. casei and Bifidobacterium longum) against 8 bacterial pathogens were determined on the Mueller Hinton Agar containing supernatant of probiotics obtained from 3 different growth conditions (MRS without glycerol, MRS with 0.5 M glycerol or 0.25 M glycerol solution). Though antimicrobial activity of L. reuteri in the first two conditions was not better than the others', the activity was significantly higher than that of others in 0.25 M glycerol solution. This prominent effect might be attributable to reuterin, produced by L. reuteri using glycerol. We could detect the presence of reuterin in the supernatant of 0.25 M glycerol solution with 500 MHz Nuclear Magnetic Resonance (NMR). The result of minimum bactericidal concentration (dilution fold) has revealed that reuterin showed pan-bactericidal effects against 8 major food-borne pathogens. To examine any changes of antimicrobial activities of the probiotics, the probiotics were treated with different pH conditions, pepsin or trypsin digestion. Antimicrobial activity of reuterin was not entirely affected by any of these treatments, while the activities of the other probiotics were significantly decreased.

• Journal of Food Hygiene and Safety
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• v.35 no.4
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• pp.319-325
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• 2020

Widespread consumption of fresh-cut vegetables without cooking results in ingestion of major foodborne pathogens including Bacillus cereus. In this study, we aimed to develop a method to rapidly detect B. cereus in fresh-cut vegetables by combining commercial PCR analysis with enrichment of the pathogenic levels. A mixture of B. cereus strains (KCTC1013, KCTC1014, KCTC1092, KCTC1094, and KCTC3624) was inoculated on the surface of fresh-cut cabbage lettuce (20 g) and baby leafy vegetables (10 g) to concentration 1, 2, 3, 4, and 5 log CFU/g. Eighty milliliters of TSB with 0.15% polymyxin B was used for cabbage lettuce, and 90 mL of medium was used for baby leafy vegetables and incubated at 42℃ for 0, 2, 3, 4, 5, 6, and 7 h. One milliliter of the enriched media was plated on mannitol-egg yolk-polymyxin agar for quantification, and another 1 mL was used for DNA extraction for PCR analysis. Additionally, the minimum number of sub-samples to be tested from a pack of fresh-cut vegetable samples was determined using 5 sub-samples. The results from this study showed that for detecting B. cereus in fresh-cut cabbage lettuce, 3, 4, 5, 6, and 7 h enrichment were required to at least detect 5, 4, 3, 2, and 1 log CFU/g of B. cereus, respectively. B. cereus in fresh-cut baby leafy vegetables could be detected after 2, 3, 4, 5, and 6 h of enrichment at 5, 4, 3, 2, and 1 log CFU/g, respectively, using a combination of enrichment and PCR analysis. To determine if a pack of fresh-cut vegetable is positive, the minimum number of sub-samples should be 3. These results can be used to develop a rapid detection method to semi-quantify B. cereus in fresh-cut vegetable samples combining enrichment and PCR.

• Journal of Veterinary Clinics
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• v.29 no.2
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• pp.141-147
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• 2012

This work describes the characteristics of $Malassezia$ $pachydermatis$ isolated from dog ear canals and the effect of essential oils on the growth of this organism. Sterile cotton swabs were used to collect specimens from the external ear canal and culture tests were performed to detect the population size of $Malassezia$ yeast. Using three different isolation media, included Sabouraud dextrose agar (SDA) to isolate common $M.$ $pachydermatis$, and SDA supplemented with olive oil (SDAO) and Leeming's medium (LM) to detect lipophilic yeast, $Malassezia$ spp were isolated from 14 of 18 dogs (77.8%); isolation rates were 33.3% in SDA, 72.2% in SDAO and 66.7% in LM media. All $Malassezia$ spp isolates were identified as $M.$ $pachydermatis$ according to results of PCR amplification, but gross colony morphology and SDA growth rates suggested four different subtypes. Large (LC) and medium colony (MC) types respectively describe large colony (diameter > 3 mm) and medium colony (around 2 mm) after 72 hour incubation, and small (SC) type refers to smaller colony (< 1 mm) even after 5 days incubation; lipid dependent colonies did not grow onto SDA. Large Colony type strains were isolated from 4, 11, and 11 samples, MC type strains from 2, 3 and 1 and SC type strains from 1, 2 and 1 in SDA, SDAO and LM, respectively. Lipid-dependent $M.$ $pachydermatis$ (Lipo) were isolated from 3 samples each in SDAO and LM. Anti-$M.$ $pachydermatis$ activity testing was done using disc-diffusion assays and well diffusion tests. Most essential oils inhibited the growth of $M.$ $pachydermatis$ in a range from 0.5% to 1.0% of essential oils. MIC90 and MIC50 were variable depending upon the nature of essential oils. Thyme oil was found to be highly effective in inhibiting the growth of $M.$ $pachydermatis$ in a range from 0.125% to 0.0625% while marjoram and then tea tree oil exhibited lower inhibitory capacity.

• Korean journal of applied entomology
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• v.49 no.4
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• pp.417-422
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• 2010

Cultural characteristics Lecanicillium lecani Btab01 and its insecticidal activity against tobacco whitefly (Bemisia tabaci) were investigated. On potato dextrose agar, tryptic soy agar and SDA+Y media, mycelial growth of L. lecani Btab01 was best at $20{\sim}25^{\circ}C$ and suppressed above $28^{\circ}C$. Both solid culture and liquid culture of L. lecani Btab01 showed high insecticidal activity, 93.9 and 98.3% respectively, against nymph of tobacco whitefly, but there is no significant difference. When culture of L. lecani Btab01 was treated at the concentration of $10^5$, $10^6$, $10^7$ and $10^8$ cfu/ml, their insecticidal activity were 5.8%, 33.8%, 77.3% and 98.5% respectively, and $LT_{50}$ values were 16.1 days, 7.3 days, 5.1 days and 3.5 days respectively. When nymphs were treated by the cultures of L. lecani Btab01 and maintained under saturated condition for zero hour, 24 hours and 168 hours, their control activities were 0%, 20.3% and 100% respectively. Spore germination of L. lecani Btab01 was increased about two times by adding edible oil. When L. lecani Btab01 was treated to control nymph with 0.1% edible oil, it showed high control activity(98.6%) compared to single treatment of L. lecani Btab01 (79.9%).

• Journal of Life Science
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• v.23 no.2
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• pp.197-206
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• 2013

The present study investigated whether leukemia-maintaining cells reside in a differentiation-resistant fraction using a megakaryocytic differentiation model of K562 cells. Treatment with phorbol-12-myristate-13-acetate (PMA) significantly inhibited the colony-forming efficiency of the K562 cells. At a PMA concentration of 1 nM or higher, colony was not formed, but approximately 40% of K562 cells still survived in soft agar. Approximately 70% of colony-forming cells that were isolated following the removal of PMA after exposure to the agent were differentiated after treatment with 10 nM PMA for 3 days. The differentiation rate of the colony-forming cells was gradually increased and reached about 90% 6 weeks after colony isolation, which was comparable to the level of a PMA-treated K562 control. Meanwhile, imatinib-resistant variants from the K562 cells, including K562/R1, K562/R2, and K562/R3 cells, did not show any colony-forming activity, and most imatinib-resistant variants were CD44 positive. After 4 months of culture in drug-free medium, the surface level of CD44 was decreased in comparison with primary imatinib-resistant variants, and a few colonies were formed from K562/R3 cells. In these cells, Bcr-Abl, which was lost in the imatinib-resistant variants, was re-expressed, and the original phenotypes of the K562 cells were partially recovered. These results suggest that leukemia-maintaining cells might reside in a differentiation-resistant population. Differentiation therapy to eliminate leukemia-maintaining cells could be a successful treatment for leukemia if the leukemia-maintaining cells were exposed to a differentiation inducer for a long time and at a high dose.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.323-328
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• 2015

Control efficacy was investigated with fungicides as 3 copper compound, 3 antibiotic fungicides and one fungicide containing to quinolone against the growth of Ralstonia solanacearum on NA medium and the disease occurrence on pepper seedlings. Among 7 fungicides, oxytetracycline was shown the highest activity against a growth of the pathogen in the agar diffusion method, but validamycin showed no activity against the pathogen. With $1000{\mu}g\;mL^{-1}$ of each copper fungicide as copper hydroxide, copper oxychloride+ dithianone and copper sulfate, 2.2, 1.3 and 1.5 mm in size of clear zone only could be found, respectively. In pepper seedling test, oxytetracycline showed a perfect activity in all treatments 7 days after inoculation. However, its activity was decreased from $500{\mu}g\;mL^{-1}$ of treatment over the time. Copper fungicides showed the control efficacy lower than antibiotic fungicides except for validamycin. Based on the results, it was suggested that it would be better to use antibiotic fungicides than copper fungicides to control pepper bacterial wilt in the fields.

• Korean Journal of Plant Resources
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• v.30 no.2
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• pp.133-143
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• 2017

This study was conducted to evaluate the contents of total polyphenol and flavonoid, and the effect of antioxidant, antimicrobial activities and cytotoxicity in vitro by different solvent fractions from Orostachys japonicus. The ethylacetate fraction extract for O. japonicus contained $634.48{\mu}g/g$ polyphenol and $205.20{\mu}g/g$ flavonoid. The ABTS radical scavenging ability of ethylacetate fraction extract at 1 mg/ml was higher than 95% which is comparable to ascorbic acid of 97%. The APX enzymatic activity and CAT activity were $1125.89{\mu}mol$ ascorbate oxidized/min/mg protein and 119.87 H2O2 decomposed/min/mg protein, respectively. In disc agar plate diffusion assay, the extract gave rise to a larger inhibition circle with Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus and Malassezia furfur strains compared with antibiotics kanamycin suggestive of high antibiotic activity. The cytotoxicity of extracts of O. japonicus was significant differences between solvent fractions. That is, the cytotoxic effect against human cancer cell was higher in ethylacetate fraction extract than other fraction extracts. These results suggest that fraction extract of O. japonicus might be very effective and economical in developing natural antioxidant and antimicrobial.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.218-226
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• 2016

Helicobacter pylori primarily colonizes the human stomach. Infection by this bacterium is associated with various gastric diseases, including inflammation, peptic ulcer, and gastric cancer. Although there are antibiotic regimens for the eradication of H. pylori, the resistance of this species against antibiotics has been continuously increasing. The natural compound plumbagin has been reported as an antimicrobial and anticancer molecule. In this study, we analyzed the inhibitory effect of plumbagin on H. pylori strain ATCC 49503 as well as the expression of various molecules associated with H. pylori growth or virulence by immunoblotting and reverse transcription polymerase chain reaction (RT-PCR) analyses. We demonstrated the minimal inhibitory concentration of plumbagin on H. pylori through the agar dilution and broth dilution methods. Furthermore, we investigated the effect of plumbagin treatment on the expression of the RNA polymerase subunits and various virulence factors of H. pylori. Plumbagin treatment decreased the expression of RNA polymerase subunit alpha (rpoA), which is closely associated with bacterial survival. Moreover, the mRNA and protein levels of the major CagA and VacA toxins were decreased in plumbagintreated H. pylori cells. Likewise, the expression levels of urease subunit alpha (ureA) and an adhesin (alpA) were decreased by plumbagin treatment. Collectively, these results suggest that plumbagin may inhibit the growth, colonization, and pathogenesis of H. pylori by the mechanism demonstrated in this study.

• Korean Journal of Medicinal Crop Science
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• v.4 no.2
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• pp.119-125
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• 1996

To improve the efficiency of mass propagation in vitro of Fritillaria thunbergii, bulb scale and nodes were cultured in LS medium supplemented with the combination of 2, 4-D and kinetin or NAA and BA. The number and size of bulb, the number of adventitious shoot, the ratio of callus formation, rooting, and the effects of light and dark on the culture, plant regeneration from calli, and the gelling substances were investigated. The combination of 2, 4-D and kinetin in media was more effective than the media of NAA and BA for the bulblet formation. The media supplemented with 2 mg/L 2, 4-D and 1 mg/L kinetin, $1{\sim}2\;mg/L$ 2, 4-D without kinetin and $1{\sim}3\;mg/L$ BAA only were effective in the adventitious shoot development. Callus formation and root formation, respectively were effective in the medium supplemented with 2mg/L 2, 4-D and 1mg/L kinetin. In bulb formation, the medium with 5 mg/L kinetin was effective, and the most of bulbs were formed from the axillary bud of node part. In bulb formation, shoot growth, callus and root formation, the light culture for 16 hours per day was better than that in the dark culture. Bulb was nicely formed in the medium with 0. 2 mg/L 2, 4-D, 1 mg/L kinetin. The medium without hormone was most effective for plant regeneration. The phytagel was more effective than agar in the medium as the gelling agent.

• Korean Journal of Environmental Agriculture
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• v.19 no.4
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• pp.284-293
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• 2000

For the artificial removal of air pollutants such as pesticides, environmental toxicants, and pathogenic microorganisms in the greenhouse or the living environment, the accelerated photodegradation and the biocidal effects of some photosensitizers (PS)/photocatalysts (PC) were tested under the sunlight and/or artificial light. The selected photosensitizers/photocatalysts included the semiconductors (PC-1 and PC-2), the oxidizers (PC-3, PC-4, PC-5 and PC-6), the aromatic ketone (PS-7) and the aromatic amine (PS-8). In the case of dichlorvos, all the photocatalysts selected showed more accelerated photodegradation than the control without photocatalysts under both the sunlight and artificial light. Whereas, only the photocatalyst PC-1 accelerated the degradation of methyl tert-butyl ether about 17 times more than the control under both the sunlight and artificial light. Procymidone was much more degraded by the photosensitizer PS-8 and the two photocatalysts (PC-1, PC-6) than by PS-7. In the preliminary experiments to diminish the population of the microorganisms in the air, the photocatalyst PC-1 added to the suspensions of Pseudomonas putida, Phytophthora capsici, and Salmonella typhimurium obviously inhibited the microbial growth under the artificial light. The photocatalyst PC-1 showed a bactericidal activity against Salmonella typhimurium spread on the nutrient broth agar medium. These results suggest that the photosensitizers/photocatalysis under the light can remove some air pollutants and hence they can be used to reduce the exposure of the workers in the horticultural facilities and/or the public in the environment to the harmful pollutants.