• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.96-104
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• 2013

Staphylococcus aureus is a major human pathogen that produces a wide array of toxins, leading to a number of adverse symptoms. We examined 275 strains of Staphylococcus aureus isolated from various foods between 2006 and 2008 for antimicrobial susceptibility. At least 259 (94.2%) of the tested strains showed antibiotic resistant properties, and 106 (40.7%) of them showed multiple antibiotic resistance. Eleven of the tested strains were resistant to oxacillin and mec A-positive. Moreover, oxacillin-resistant strains were significantly more likely to be multi-drug resistant (p < 0.01). Of the 275 isolates tested, 24.4% were noted as being positive for slime production and 30.5% were positive for biofilm assay. Antibiotic resistance was not associated with a significantly higher prevalence of biofilm formation. Twenty strains were classified using the DiversiLab system. Most of the strains could be classified into 2 clusters and 4 unique types. All 10 mec A-positive strains (cluster I) were grouped together into the same sub-cluster. Cluster II (6 strains) was not found to be resistant to oxacillin in this study. Although the prevalence of methicillin-resistant S. aureus in food is currently low, the risk of its transmission through the food chain cannot be disregarded.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.88-95
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• 2013

Candida biofilms are self-organized microbial communities growing on the surfaces of host tissues and medical devices. These biofilms have been displaying increasing resistance against conventional antifungal agents. The roots of Scutellaria baicalensis have been widely used for medicinal purpose throughout East Asia. The aim of the present study was to evaluate the effect of S. baicalensis aqueous extract upon the preformed biofilms of 10 clinical C. albicans isolates, and assess the mechanism of the antibiofilm activity. Its effect on preformed biofilm was judged using an XTT reduction assay and the metabolic activity of all tested strains were reduced ($57.7{\pm}17.3$%) at MIC values. The S. baicalenis extract inhibited (1, 3)-${\beta}$-D-glucan synthase activity. The effect of S. baicalensis on the morphology of C. albicans was related to the changes in growth caused by inhibiting glucan synthesis; most cells were round and swollen, and cell walls were densely stained or ruptured. The anticandidal activity was fungicidal, and the extract also arrested C. albicans cells at $G_0/G_1$. The data suggest that S. baicalensis has multiple fatal effects on target fungi, which ultimately result in cell wall disruption and killing by inhibiting (1, 3)-${\beta}$-D-glucan synthesis. Therefore, S. baicalensis holds great promise for use in treating and eliminating biofilm-associated Candida infections.

• Microbiology and Biotechnology Letters
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• v.41 no.3
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• pp.350-357
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• 2013

Lichens are symbiotic organisms composed of fungi, algae, or cyanobacteria which are able to survive in extreme environmental conditions ranging from deserts to polar areas. Some lichen symbionts produce a wide range of secondary metabolites that have many biological activities such as antibacterial, antifungal, antiviral, antitumor, antioxidant and anti-inflammatory etc. Among the symbionts of lichens, of the bacterial communities of lichen symbionts little is known. In this study, we isolated 4 microbial species from the Arctic lichen Stereocaulon spp. and evaluated their antioxidant properties using 1,1-diphenyl-2-picryl-hydrazyl assay as well as 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulphonic acid) assay. Total phenolic contents and total flavonoid contents were also measured. A potent radical scavenging activity was detected in a number of the lichen extracts. Among the 4 species tested in this study, the ethyl acetate extract of Bosea vestrisii 36546(T) exhibited the strongest free radical scavenging activity, with an inhibition rate of 86.8% in DPPH and 75.2% in ABTS assays. Overall, these results suggest that lichen-bacteria could be a potential source of natural antioxidants.

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1122-1132
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• 2018

In this study, we attempted to find new and efficient microbial enzymes for producing rare sugars. A ribose-5-phosphate isomerase B (OsRpiB) was cloned, overexpressed, and preliminarily purified successfully from a newly screened Ochrobactrum sp. CSL1, which could catalyze the isomerization reaction of rare sugars. A study of its substrate specificity showed that the cloned isomerase (OsRpiB) could effectively catalyze the conversion of $\text\tiny{L}$-rhamnose to $\text\tiny{L}$-rhamnulose, which was unconventional for RpiB. The optimal reaction conditions ($50^{\circ}C$, pH 8.0, and 1 mM $Ca^{2+}$) were obtained to maximize the potential of OsRpiB in preparing $\text\tiny{L}$-rhamnulose. The catalytic properties of OsRpiB, including $K_m$, $k_{cat}$, and catalytic efficiency ($k_{cat}/K_m$), were determined as 43.47 mM, $129.4sec^{-1}$, and 2.98 mM/sec. The highest conversion rate of $\text\tiny{L}$-rhamnose under the optimized conditions by OsRpiB could reach 26% after 4.5 h. To the best of our knowledge, this is the first successful attempt of the novel biotransformation of $\text\tiny{L}$-rhamnose to $\text\tiny{L}$-rhamnulose by OsRpiB biocatalysis.

• Journal of Animal Science and Technology
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• v.54 no.1
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• pp.59-63
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• 2012

Bovine serum contains various nutrients and growth factors that can be potentially used in biological experiments, drug manufacturing process and food industry. However, almost all the bovine blood has been wasted during slaughter process in Korea, thus there is a high demand for alternative uses of the wasted sera. In order to produce high quality and safe sera, it is necessary to screen zoonotic pathogens as well as other microbial contaminants to prevent any downstream contamination. The present research has been undertaken to assess biological safety of Hanwoo sera by determining microbiological contamination during slaughtering and handling processes. Serological tests have been performed to detect bacteria, mycoplasma and virus contamination in total of 52 Hanwoo sera. No sera were found to be contaminated with mycoplasma or virus, but only two sera were found to be contaminated with Bacillus thuringiensis. The present result shows that Hanwoo sera obtained from slaughtering process are biologically safe and have potentials to be developed as a biological reagent. Moreover, the methods employed in our study may provide basic standard for microbiological screening methods once wasted Hanwoo sera gain industrial values.

• Journal of Plant Biotechnology
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• v.29 no.4
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• pp.287-293
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• 2002

We are trying to develop a transgenic carrot with aims of production and delivery of oral vaccine against microbial enteropathogen using a K88ac pilin gene. A K88ac antigen (pilin) gene was isolated by PCR from the K88ac genomic DNA. The pilin gene was constructed in pGA748 and introduced via Agrobacterium tumefaciens to the explants of carrot hypocotyl and then 494 transgenic lines were established. The amounts of the K88ac antigen produced in each of the cell lines were determined by western and two elite cell lines (M1-17, Y14-1) were selected based on higher levels of expression of the antigens as well as rate of cell growth and efficiency of embryogenesis. In order to test an immunization induced by oral administration of the transgenic carrot, serum of the mice fed with the carrot vaccine were tested in ELISA. It tumed out that the mice fed with 3 g of transgenic carrot showed a similar level of antibody compared to those applied with 10 $\mu\textrm{g}$ of the purified recombinant pilin protein. Besides, various clinical responses were measured after challenging with ETEC K88ac strain to the piglets experiencing an oral immunization with the transgenic carrot. The piglets fed with carrot vaccine showed a lower level of diarrhea in fecal score compared to those fed with non-transgenic carrot. A higher level of increase in weight of the piglets fed with the transgenic carrot vaccine was observed comparing to those fed with non-transgenic carrot as control.

• Journal of Plant Biotechnology
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• v.39 no.4
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• pp.300-304
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• 2012

In order to research changes of asparagine content according to stage after harvest to storage, it was analysed asparagine content of potato tuber and potato sprout. The results of the asparagine content in potato cultivars after harvest ranked in cv. Superior, cv. Gahwang, cv. Atlantic and cv. Goun in descending order. The content of asparagine in potato was approximately 1300 mg/100g (D.W.) The changes the asparagine content according to storage condition and the difference of asparagine between tuber and sprout can be summarized as follows. In the asparagine content of potato cultivars, Little variation in the content was observed while potato tubers were stored at $4^{\circ}C$. However, after 3 months of storage at $10^{\circ}C$, the content increased by 9.7%, indicating that the content increases as the storage temperature and period increases. The content of asparagine also increased during sprouting of potato tubers. In the sprout, the proximal region contained 21% higher content of asparagines than the distal region, which suggests that the sprout develops with the increasing of the content of asparagines.

• Korean Journal of Food Science and Technology
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• v.50 no.2
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• pp.165-171
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• 2018

Atmospheric-pressure plasma (APP) was applied to determine quality characteristics of brown rice (BR) and white rice (WR) of Samkwang and Palbangmi. APP (250 W, 15 kHz, ambient air) was generated and dielectric barrier discharge was applied for 0, 10, and 20 min for 2 weeks at 4 and $25^{\circ}C$. The growth of total aerobic bacteria and mold increased depending on the storage. Water content of BR and WR decreased by storage temperature and periods. No viable counts were detected for molds by APP-treated 20 min at $4^{\circ}C$. Changes in protein and damaged starch contents in plasma were not observed. Amylose contents were not changed, but WR (Palbangmi) showed a tendency to increase. The results show that APP improved the microbial quality of BR and WR of Samkwang and Palbangmi, although further studies should be conducted to determine change in quality by APP.

• Journal of Life Science
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• v.15 no.2 s.69
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• pp.267-272
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• 2005

The objective of this study is to suggest the potentialities of nanoliposome composed of ceramide as an anti-irritant against various irritants used in cosmetics. Ceramides are major structural components of the epidermal permeability barrier, which is known to play an essential part in human physiology by not only preventing the loss of water from the body but also protecting the body from external physical, chemical, and microbial insults. According to the results, better effects on reinforcement of skin barrier function and anti-irritation were obtained with nanoliposome composed of ceramide than with dispersed ceramide. And, we performed in vitro skin penetration test using horizontal Franz diffusion cells with skin membrane prepared from hairless mouse to evaluate the influence of nanoliposome composed of ceramide on the skin penetration of lactic acid in formulations. From the results, we found that the anti-irritation effects of nanoliposome containing ceramide were due to reduced penetration rate of irritants. Conclusively, we could develop a new anti-irritation system and apply this nanoliposome composed of ceramide to the final cosmetic products successfully.

• Food Science of Animal Resources
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• v.28 no.2
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• pp.165-170
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• 2008

In this study, the physicochemical, microbial, and sensory properties of law-fat hamburger patties during storage for 25 days at $7{\pm}1^{\circ}C$ were investigated. The law-fat hamburger patties were manufactured by three different packing methods (control: added with 10% lard regular-fat patty, T1: added with 10% lard and organic vegetable of regular-fat patty, T2: added with 3% olive oil of vegetability low-fat patty, T3: added with 3% lard of low-fat patty). The pH of all treated samples increased as the storage time increased, and then decreased after 15 days of storage. The low-fat hamburger patty added with organic olive oil (T2) showed significantly higher pH (p<0.05) compared with other treatments (T1 and T3). The TBARS values of the all treated samples tended to increase after 5 days of storage, and then significant quality loss was observed after 15 days of storage period for the control (T1). However, the samples of the vegitability low-fat patty added organic olive oil had longer shelf-life than the control. The total bacterial counts were 7 log CFU/g after 15 days and 20 days of storage for the control and treatments, respectively. The results of this study showed that the storage period of the treatments was slightly extended compared with the control. Low-fat hamburger patties showed no differences for overall acceptability between control and other patties.