Lee J.M.,Pukyong National University |
Kim Y.-R.,CBR Defense Research Institute |
Kim J.K.,Pukyong National University |
Jeong G.-T.,Pukyong National University |
And 2 more authors.
Bioprocess and Biosystems Engineering | Year: 2015
The β-glucosidase gene, bglC, was cloned from Bacillus sp. SJ-10 isolated from the squid jeotgal. Recombinant BglC protein overexpression was induced in Escherichia coli. The optimal pH and temperature of the enzyme, using p-nitrophenyl-β-d-glucopyranoside (pNPβGlc) as a substrate, were pH 6 and 40 °C, respectively. Enzymatic activity increased by 3.3- and 3.5-fold in the presence of 15 % NaCl and KCl, respectively. Furthermore, enzyme thermostability improved in the presence of NaCl or KCl. At 45 °C in the presence of salts, the enzyme was stable for 2 h and maintained 80 % activity. In the absence of salts, BglC completely lost activity after 110 min at 45 °C. Comparison of the kinetic parameters at various salt concentrations revealed that BglC had approximately 1.5- and 1.2-fold higher affinity and hydrolyzed pNPβGlc 1.9- and 2.1-fold faster in the presence of 15 % NaCl and KCl, respectively. Additionally, the Gibb’s free energy for denaturation was higher in the presence of 15 % salt than in the absence of salt at 45 and 50 °C. Since enzymatic activity and thermostability were enhanced under high salinity conditions, BglC is an ideal salt-tolerant enzyme for further research and industrial applications. © 2015 Springer-Verlag Berlin Heidelberg
Lee J.-B.,Korea Consumer Agency |
Lee J.-B.,Dongguk University |
Kim M.K.,Dongguk University |
Kim B.-K.,Korea Consumer Agency |
And 2 more authors.
International Journal of Food Science and Technology | Year: 2016
In this study, the levels of polychlorinated biphenyls (PCBs), heavy metals and omega-3 polyunsaturated fatty acids (docosahexaenoic acid; DHA and eicosapentaenoic acid; EPA), as well as chemical indices including acid and peroxide values were determined among twenty-four commercially available functional fish oil supplements. The sum of indicator PCB congeners (congeners 28, 52, 101, 118, 138, 153 and 180) was below the limit of quantification of 0.043 mg kg−1. Metallic compounds (Cd, Pb, Hg and As) were not detected in all fish oil supplement samples. The relative percentages of EPA and DHA in fish oil supplements ranged from 25% to 80%. The acid values ranged from 0.1 to 1.4 mg KOH per g oil, and peroxide values ranged from 2.7 to 28.8 meq per kg oil. All fish oil supplement samples tested in current study met the safety standard for fish oil supplements set by Korean government as well as International standard. © 2016 Institute of Food Science and Technology
Cho K.,Korean University of Science and Technology |
Cho K.,Korea Basic Science Institute |
Kim K.-N.,Korea Basic Science Institute |
Lim N.-L.,Korea Basic Science Institute |
And 8 more authors.
Biomass and Bioenergy | Year: 2015
We investigated the effects of inositols, which are well-known plant growth-promoting agents, on the growth of the oceanic microalga Dunaliella salina. Of the four inositol derivatives tested (myo-inositol, scyllo-inositol, d-chiro-inositol, and l-chiro-inositol), myo-inositol (MI) showed the greatest growth-promoting effect in a concentration-dependent manner. The yield of biomass from the alga cultured with 500mgL-1 of MI was 1.48-times that of the control culture. No significant effect of MI on the total carotenoid content was observed, but neutral lipid content was significantly increased, 1.34-times greater than the control. MI also influenced the fatty acid methyl ester composition, with the levels of linoleic, linolenic, and linolelaidic acids significantly higher than those of the control culture. To the best of our knowledge, this is the first demonstration that MI promotes the growth of a marine microalga. Our results suggest that MI has potential for enhancing the efficiency of biofuel production by D. salina through growth promotion and increasing lipid productivity. © 2014 Elsevier Ltd.
Kim J.M.,Seoul National University |
Hong J.,Korea Consumer Agency |
Bae W.,Seoul National University |
Bae W.,Standard Diagnostics Inc. |
And 4 more authors.
Journal of Food Protection | Year: 2010
The antibiotic resistance patterns and prevalence of the transferable tet(O) plasmid were investigated in Campylobacter jejuni and Campylobacter coli isolates from raw chicken, pork, and humans with clinical campylobacteriosis. A total of 180 C. jejuni and C. coli isolates were identified, and the prevalence rates of C. jejuni and C. coli in raw chicken samples were 83% (83 of 100) and 73% (73 of 100), respectively. Twelve percent (6 of 50) and 10% (5 of 50) of pork samples were contaminated with C. jejuni and C. coli, respectively. Disk diffusion susceptibility testing revealed that the most frequently detected resistance was to tetracycline (92.2%), followed by nalidixic acid (75.6%), ciprofloxacin (65.0%), azithromycin (41.5%), ampicillin (33.3%), and streptomycin (26.1 %). Of the C, jejuni and C, coli isolates, 65.7% (n = 109) contained plasmids carrying the tet(O) gene. Six C. jejuni isolates and two C. coli isolates with high-level resistance to tetracycline (MIC = 256 ug/ml) harbored the tet(O) plasmid, which is transferable to other C. jejuni and C. coli isolates. These results demonstrate the presence of an interspecies transferable plasmid containing the tet(O) gene and a high prevalence of antibiotic resistance in Korean Campylobacter isolates and provide an understanding of the antibiotic resistance distribution among Campylobacter species in Korea. Copyright © International Association for Food Protection.
Kwon K.H.,Seoul National University |
Kwon K.H.,Animal and Plant Quarantine Agency |
Hwang S.Y.,Seoul National University |
Hwang S.Y.,Seegene Institute of Life Science |
And 4 more authors.
Journal of Food Safety | Year: 2014
Rapid, quantitative and sensitive detection methods are essential for prevention and risk assessment of food poisoning. In this study, we developed quantitative real-time immuno-polymerase chain reaction (qRT-iPCR), a highly sensitive and efficient method for detection of staphylococcal enterotoxin H (SEH). The qRT-iPCR is based on antigen-antibody recognition, similar to the traditional enzyme-linked immunosorbent assay (ELISA). However, unlike ELISA, the method relies on DNA probes and RT-PCR for detection rather than on a chromogenic reaction. We produced recombinant SEs and monoclonal antibodies for SEH. Then, coupled RT-PCR using DNA probes was applied. This qRT-iPCR showed a lower limit of detection (LOD) than traditional ELISA did. In the sandwich format, qRT-iPCR system could detect approximately 4.5pg/mL of SEH. Our qRT-iPCR system simplified the detection and quantification of SEH and accelerated the process compared with traditional ELISA. To our knowledge, this is the most sensitive technique for detection of SEH reported to date. © 2014 Wiley Periodicals, Inc.
Lee J.-H.,Konkuk University |
Song K.-Y.,Konkuk University |
Hyeon J.-Y.,Konkuk University |
Hwang I.-G.,South Korea National institute of Food and Drug Safety Evaluation |
And 4 more authors.
Korean Journal for Food Science of Animal Resources | Year: 2010
Staphylococcus aureus is one of the major pathogens that can cause staphylococcal infection and food poisoning. In this study, we compared conventional culture methods and real-time PCR for detection of S. aureus in artificially inoculated milk, sausage, raw pork, and vegetable salad. The performance of a coagulase test for confirming S. aureus was also compared with a colony PCR test. Bulk food samples (500 g each) were artificially inoculated with S. aureus and divided into 20 samples (25 g or mL each). All samples were added to tryptic soy broth (225 mL/sample) with 10% NaCl and incubated at 37°C for 24 h. After the enrichment, broth cultures were streaked onto Baird-Parker (BP) agar with egg yolk tellulite, and incubated at 37°C for 24 h. In addition, 1 mL of broth cultures was collected to perform real-time PCR. Two suspicious colonies from the BP agar were picked up and plated on nutrient agar and incubated at 37°C for 24 h followed, by a coagu-lase confirmation test and a colony PCR analysis. There were no statistical differences between culture methods and realtime PCR in food samples with low background microflora, such as milk and sausage. However, a significant statistical difference was found between the culture methods and real-time PCR for raw pork and vegetable salad. Furthermore, the colony PCR test of the presumptive colonies on BP agar for confirming S. aureus is more accurate and efficient than the coagulase test for unprocessed foods.