• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.2
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• pp.237-243
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• 2020

Listeria sp. is one of the pathogenic bacteria causes the infection listeriosis, through mainly raw food such as fishery food, dairy food and vegetables. Listeria sp. is a Gram-positive, non-spore-forming, motile, and facultative anaerobic bacterium. Because of the tolerance of Listeria sp. to low temperature and high salt concentration, it is very difficult to prevent them contaminated in the food, which do not require heating, especially, such as raw fishery products. So prevention and removal of bacterial contamination at the food manufacturing stage is the best method. In this study, therefore, several natural products including Psidium guajava and Geranium thunbergii were screened to investigate the antibacterial activity against Listeria sp., with expectation of fewer side effects and fewer resistance problems. Significant effects of two extracts were confirmed by well diffusion assay, MIC assay, and growth inhibition assay. P. guajava and G. thunbergii showed MIC values at 64-256 ㎍/mL meaning strong antibacterial activities against 6 kind of Listeria sp. tested. And the growth of Listeria sp. in the liquid media was actually inhibited by the addition of these two extracts.

• The Korean Journal of Pesticide Science
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• v.13 no.4
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• pp.275-282
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• 2009

The effect of two plant growth-promoting rhizobacteria (PGPR) on plant growth and systemic protection against soft rot disease and stem rot disease of canola (Brassica napus), caused by Erwinia carotovora and Sclerotinia sclerotiorum was investigated in a laboratory and a greenhouse. Selected PGPR strains C4 and D8 were treated to canola seeds by soaking. Strains C4 and D8 significantly not only increased plant height and root length about 74% and 40.3% and also reduced disease severity of soft rot disease by 80% by C4 and D8 respectively, compared to the control. Especially strain C4 showed antifungal activity against 6 fungal pathogens, S. sclerotiorum, Rhizoctonia solani, Botrytis cinerea, Fusarium oxysporum, Phytophthora capsici and Colletotrichum acutatum. In greenhouse experiment, the seed treatment of both of them increased plant height, leaf width and leaf length of canola plant to 19.5% and 24.9%, 11.3% and 15.3%, and 14.1% and 20.7% by C4 and D8, respectively, and reduced disease severity of S. sclerotiorium. These results indicate that these two PGPR strains can decrease disease severity and increased plant growth under greenhouse condition. Therefore, these two bacteria have a potential in controlling Sclerotinia stem rot of canola. These strains have to investigate under field condition to determine their role of antibiosis, induced systemic resistance and plant growth promotion on canola.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.667-673
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• 2017

This study was carried out to verify the antimicrobial effect of Graviola leaves against pathogenic bacteria for the purpose of developing an antibacterial material. The extraction conditions of graviola leaves were $60^{\circ}C$, $80^{\circ}C$ and $98^{\circ}C$, and graviloa leaves werewater extracted at $60^{\circ}C$, $80^{\circ}C$ and $98^{\circ}C$.The extraction yields and extraction conditions were determined. The antimicrobial activity against S. epidermidis, S. aureus and E. coli TOP10 was evaluated by agar diffusion method. The extraction yields were 3.02%, 14.73% and 20.76% at $60^{\circ}C$, $80^{\circ}C$ and $98^{\circ}C$, respectively. The antimicrobial activity against S. epidermidis, S. aureus and E. coli TOP10 was found in S. epidermidis.In the samples extracted at $98^{\circ}C$, a clear zone of 13 mm was observed at 200 mg/mL and of 20 mm at 500 mg/mL. The MIC was 100 mg/mL. The higher the extraction temperature and concentration, the better was the growth inhibition effect. As a result, the natural antimicrobial activity contained in natural materials can solve the problem of resistance to antibiotics. It is considered that antimicrobial activity against S. epidermidis in skin is highly applicable to basic cosmetics and cosmetic materials.

• Food Science and Preservation
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• v.16 no.2
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• pp.286-291
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• 2009

Microorganisms in seafood cooking drips were counted and identified. Total viable cell counts were 6.40 and 3.10 log CFU/g in cooking drips of Hizikia fusiformis and Thunnus thynnus, respectively. However, microbial populations fell with increased irradiation doses. In H. fusiformis cooking drips, a 5-log reduction in total aerobic bacteria was obtained by irradiation with 5 kGy. In T. thynnus cooking drips, however, contaminating microorganisms were more resistant to gamma irradiation and only a 1-log reduction was seen. DNA sequence analysis showed that the principal contaminating microorganisms in H. fusiformis and T. thynnus cooking drips were Lactobacillus and Bacillus species, respectively. Therefore, the high irradiation resistance of T. thynnus cooking drips microbes may result from spore formation by Bacillus species.

• Korean journal of applied entomology
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• v.56 no.1
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• pp.19-28
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• 2017

Polydnaviruses (PDVs) are a group of double-stranded DNA viruses symbiotic to some endoparasitoid wasps. Cotesia plutellae bracovirus (CpBV) is a PDV symbiotic to an endoparasitoid wasp, C. plutellae, parasitizing young larvae of Plutella xylostella. An early expressed gene, CpBV-ELP1, plays an important role in the parasitism by suppressing host cellular immunity by its cytotoxic activity against hemocytes. This study aimed to test its oral toxicity against insect pest by expressing it in a recombinant tobacco plant. A recombinant CpBV-ELP1 protein was produced using a baculovirus expression system and secreted to cell culture medium. The cell cultured media were used to purify CpBV-ELP1 by a sequential array of purification steps: ammonium sulfate fractionation, size exclusion chromatography, and ion exchange chromatography. Purified rCpBV-ELP1 exhibited a significant cytotoxicity against Spodoptera exigua hemocytes. CpBV-ELP1 was highly toxic to the fifth instar larvae of S. exigua by injection to hemocoel. It also showed a significant oral toxicity to fifth instar larvae of S. exigua by a leaf-dipping assay. CpBV-ELP1 was cloned into pBI121 vector under CaMV 35S promoter with opaline synthase terminator. Resulting recombinant vector (pBI121-ELP1) was used to transform Agrobacterium tumefaciens LBA4404. The recombinant bacteria were then used to induce callus of a tobacco (Nicotiana tabacum Xanthi) leaves and subsequent generation (T1) plants were selected. T1 generation tobacco plants expressing CpBV-ELP1 gave significant insecticidal activities against S. exigua larvae. These results suggest that CpBV-ELP1 gene can be used to control insect pests by constructing transgenic crops.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.1
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• pp.12-19
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• 2016

The probiotic effects of kimchi lactic acid bacteria (LAB), Lactobacillus plantarum (Lab. plantarum) and Leuconostoc mesenteroides (Leu. mesenteroides), were studied. Lab. plantarum KCCM 11352P (LPpnu) and Leu. mesenteroides KCCM 11353P (LMpnu) were isolated from kimchi and were the predominant LAB. We compared their probiotic effects with Lactobacillus rhamnosus GG (LRgg), a well-known probiotic LAB. LPpnu showed better probiotic activities than LRgg. LMpnu also exhibited almost equal activities as LRgg. These two kimchi LAB strains exhibited resistance to gastric and bile acid, adhesion to intestines, and thermal stability. In particular, LPpnu showed excellent probiotic properties. In addition, LPpnu showed greater antioxidant activity by scavenging DPPH radicals or hydroxyl radicals than LMpnu or LRgg. LPpnu also inhibited growth of HT-29 human colon cancer cells by inducing apoptosis, increasing Bax and suppressing Bcl-2 expression compared to LMpnu or LRgg. Taken together, LPpnu and LMpnu could be used as probiotics, and LPpnu exhibited the most beneficial probiotic activities with anti-oxidant and anti-cancer properties.

• Journal of Bio-Environment Control
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• v.25 no.1
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• pp.49-56
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• 2016

This study was conducted to develop the disinfection system using electric shock for recycled nutrient solution in recycling soilless culture. Stainless steel (SUS 316) was found as the most appropriate electrode material for electrical disinfection system from the view of high electrical conductivity, low electric resistance, and low price. There were no changes in nutritional elements when the electric shock passed through the nutrient solution by stainless steel electrode. The amount of electric current increased with width than thickness of the electrode. The farther the distance between the electrodes was increased the time to reach out the aimed amount of current. The electric shock was applied to Ralstonia solanacearum and Fusarium oxysporum as representative bacteria and also fungi. Any of those pathogens were killed with the percentage of higher than 97% in the condition of 15VDC or 24VDC.

• Journal of Plant Biotechnology
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• v.45 no.3
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• pp.155-170
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• 2018

In this paper, mechanisms of gene editing technologies including ZFN, TALENS and CRISPR were briefly discussed with mutual advantages and disadvantages. Classification criteria of gene edited, site-directed mutagenesis (SDN) crops for regulatory purpose were also discussed. The number of studies using CRISPR technology was high and studies conducted on Arabidopsis thaliana and rice were highest, followed by tobacco, tomato, wheat, and corn. It has been applied to a variety of plants such as other grain crops, flower crops, vegetable crops, and fruit trees. The number of studies focused on practical application or commercialization in the future were also increasing yearly, and the scope of studies also expanded to include research on metabolic engineering for mass production of useful proteins or substances, development of disease resistant crops against viruses, bacteria, and fungi, abiotic environmental stressresistant crops, and increased yields. In addition to this, it was revealed that application range is becoming more diversified, including the development of parthenocarpic tomatoes, hybrid rice lines using male sterility and increased shattering resistance Brassica napus. It was also revealed that the number of CRISPR gene edited crops permitted by the USDA(APHIS) increases yearly, to be released in the international seed market soon.

• Korean Journal of Food Science and Technology
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• v.38 no.5
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• pp.659-667
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• 2006

In order to standardize the manufacturing processes of Hahyangju, a traditional Korean liquor, 29 yeast strains were isolated from traditional Nuruk. Strain N8 exhibited a particularly strong resistance to sugar. Strains HA2, HA3 and HA4 grew successfully in medium containing 10% ethanol. In comparison with the growth exhibited by these strains when grown in a yeast malt extract medium, the ethanol production rates for the three strains were 10.8%, 10.45%, and 10%, respectively in a yeast malt extract medium containing 25% glucose. Based on these results, HA3 was the strain selected for use in the manufacturing processes of Hahyangju and it was identified as a Saccharomyces cerevisiae strain with 97% ITS sequence similarity. The use of Saccharomyces cerevisiae HA3 causcd a decrease in the lactic acid content, acidity and growth of lactic acid bacteria in the fermentation mash. Following thc addition of Saccharomyces cerevisiae HA3 to the manufacturing process of Hahyangju, the second fermentation mash showed a 22% increase in the alcohol production rate associated with traditional fermentation; however, the amino acidity, pH and reducing sugar content showed little change. Sensory evaluation of Hahyangju fermented with S. cerevisiae HA3 also showed better scores than Hahyangju mashed by the traditional method.

• Journal of Environmental Health Sciences
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• v.37 no.4
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• pp.279-288
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• 2011

Objectives: This study investigated the levels and components of floor-settled dust in two elementary schools located at different sites (one near the Shihwa industrial complex and the other in a rural area) in order to evaluate the amounts of trace metal elements (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) and microorganisms. Methods: Over twenty settled-dust samples were collected from the two elementary schools. Trace metal elements were extracted from the dust using hydrochloric acid and nitric acid, and the amounts were measured by ICP-OES. Microbiological analysis was performed by bacterial culturing using R2A medium and denaturing gradient gel electrophoresis (DGGE). Results: The results showed that the amounts of three metal elements (Cr, Pb, and Zn) were significantly different between the schools (${\alpha}$=0.05, p<0.04). In addition, microbial communities in each school were highly correlated with one another. Among the identified microorganisms, a number of potentially opportunistic microorganisms, including antibiotic-resistant bacteria such as Acinetobacter baumannii, were found. Conclusions: This study will provide preliminary data for assessing levels and types of chemical and microbiological agents in elementary schools and for further evaluating human health risks associated with the agents.