• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.3
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• pp.348-354
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• 2013

To investigate the effect of tagatose on the growth of intestinal bacteria, various species were cultivated individually on m-PYF medium containing tagatose as a carbon source. The tagatose inhibited the growth of intestinal harmful microorganisms such as Staphylococcus aureus subsp. aureus, Listeria monocytogenes, Vibrio parahaemolyticus, Salmonella Typhimurium, and Pseudomonas fluorescens. In the case of beneficial microorganisms found in the intestine, Lactobacillus casei grew effectively on m-PYF medium containing tagatose, while Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc citreum, and Lactobacillus acidophilus did not. To examine the effect of tagatose on fermentation by Lactobacillus casei, yogurt was prepared with tagatose as a carbon source. The resulting acid production stimulated a remarkable growth of lactic acid bacteria in the yogurt. After fermentation for 24 hours, the viable cell count and viscosity of yogurt were above 8.49 log CFU/mL and 1,266 cps, respectively. Moreover, sensory evaluations showed that the yogurt supplemented with tagatose was as acceptable as control yogurt prepared with glucose as a carbon source. The changes in pH, titratable acidity and lactic acid bacteria in yogurt prepared with tagatose did not show any significant changes during storage for 15 days at $4^{\circ}C$.

• Journal of Food Hygiene and Safety
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• v.21 no.3
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• pp.145-152
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• 2006

Efforts have been made to explore the possibility of using garlic as an antimicrobial therapeutic agent since garlic extract and its individual sulfur compounds show antimicrobial activities against all kinds of microorganisms including bacteria, molds, yeasts and protozoa. Staphylococcus aureus has been the most studied bacteria along with many other Gram positive and negative pathogenic bacteria, including species of the genera Clostridium, Mycobacterium, Escherichia, Klebsiella, Bacillus, Salmonella and Shigella. Candida albicans has been the most studied among the eukaryotic microorganisms. A pathogenic protozoa, Giardia intestinalis, was also tested. All the microorganisms tested was inhibited by garlic extract or its sulfur components. Garlic has been known to be growth inhibitory only when fresh garlic is crushed, since allicin-generating reaction is enzyme-catalyzed. Allicin is known to be growth inhibitory through a non-specific reaction with sulfhydryl groups of enzyme proteins that are crucial to the metabolism of microorganisms. Another plausible hypothesis is that allicin inhibits specific enzymes in certain biological processes, e.g. acetyl CoA synthetase in fatty acid synthesis in microorganisms. Allicin transforms into other compounds like ajoene and various sulfides which are also inhibitory to microorganisms, but not as potent as their mother compound. It is reported recently that garlic heated at cooking temperatures is growth inhibitory especially against yeasts, and that the growth inhibitory compound is allyl alcohol thermally generated from alliin in garlic.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.66-73
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• 2011

Bacterial density distributions of gut microbes in the digestive organs of Harmonia axyridis collected from three different sources (JK, CK, and CJ) were $6.0{\times}10^4$ CFU/gut under aerobic culture condition and $8.0{\times}10^6$ CFU/gut under anaerobic culture condition. Seven colony types were observed under aerobic condition and three types of similarity were detected under anaerobic condition. In total, 116 strains, including 34 strains under aerobic condition, were isolated from the digestive organs of H. axyridis. Based on the analysis of the 16S rRNA gene sequence, aerobic gut microbes were assigned to the Proteobacteria, Actinobacteria, Firmicutes, and Deinococcus-Thermus. A large number of isolates belonged to the genus Bacillus and Staphylococcus of the Firmicutes commonly found in H. axyridis from different sites. Anaerobic gut microbes were found to be similar according to colony morphological, phylogenetic analysis using ARDRA. Eighty-two anaerobic gut microbes were clustered into 17 different ARDRA types according to HaeIII. Representative anaerobic gut microbes in each ARDRA group were divided into five species of ${\gamma}$-Proteobacteria based on 16S rRNA gene sequence analysis; Hafnia alvei, Enterobacter ludwigii, Enterobacter kobei, Pseudomonas oryzihabitans and Pseudomonas koreensis. Phylogenetic analysis indicated that about 70% of the isolates belonged to ${\gamma}$-Proteobacteria, suggesting predominance of gut microbes.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.133-139
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• 2011

In this study, we determined the changes in microbial numbers in solar salts according to the manufacturing process and storage duration. The salt samples were harvested from salt farms in Shinan (area 2) and Yeonggwang (area 1). They were serially diluted ten-fold and then placed on 4 kinds of cultivable media (mannitol salt agar, eosin methylene blue, plate count agar, and trypticase soy agar). After incubation, we obtained 62 halophilic isolates from the salt samples. Coliform and general bacteria were not detected in all salt samples. By 16S rRNA sequencing analysis, we found 12 kinds of halophilic bacteria belonging to the genera Halobacillus, Halomonas, Bacillus, Idiomarina, Marinobacter, Pseudoalteromonas, Vibrio, Salinivibrio, Virgibacillus, Alteromonas, Staphylococcus and some un-known stains. In our study, we discovered two novel species that have a 16S rDNA sequence similarity below 97%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.7
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• pp.1026-1034
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• 2016

To develop a natural antimicrobial agent, we investigated the antimicrobial activities of 13 species of edible herbal plant extracts against major Gram-positive foodborne bacteria. Among the 13 screened edible herbal plants, Caesalpinia sappan L. showed the highest antimicrobial activity. In the paper disc agar diffusion assay, Caesalpinia sappan L. extracts had strong antibacterial activities against most Gram-positive bacteria but did not have antibacterial activities against most Gram-negative bacteria. Minimum inhibitory concentrations of the ethanol extract were 0.06 mg/mL against Clostridium difficile and Listeria monocytogenes and 0.03 mg/mL against Staphylococcus aureus. Their inhibitory activities were not reduced by heat treatment or pH adjustment against C. difficile, L. monocytogenes, and S. aureus. Antimicrobial activities were higher in ethanol extract than in distilled water extract. These results support the potential use of Caesalpinia sappan L. ethanol extract as an antimicrobial agent or functional food components against Gram-positive bacteria.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.3
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• pp.214-220
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• 2020

Handwashing with soap is an important practice to reduce the transmission of potentially pathogenic microorganisms, but liquid soaps with refillable dispensers are prone to extrinsic bacterial contamination. This study investigated the bacterial contamination of liquid soaps in 58 public restrooms in six buildings. The bacteria were identified by a biochemical test and MALDI-TOF mass spectrophotometry. The antimicrobial susceptibility was determined using the Vitek II system. Of the 58 restrooms examined, 27(46.55%) were using a refill dispenser, of which 25(92.59%) were contaminated with bacteria. The bacteria recovered from the soaps ranged from 1.6×10³ to 2.7×10⁵ CFU/mL. Serratia liquefaciens (12), Achromobacter xylosoxidans (9), S. marcescens (4), Staphylococcus pastueri (1), and Achromobacter spanius (1) were isolated. Except for one A. xylosoxidans, bacteria of the same species isolated in the same building showed a unique resistance pattern. In conclusion, handwashing with contaminated soap may play a role in the transmission of bacteria in public health settings. Therefore, it is necessary to limit the use of refillable liquid soaps in the restrooms of hospitals used by patients with reduced immunity.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.4
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• pp.366-372
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• 2012

The aim of this study was to compare two commercial root canal medicaments, ProRoot MTA (Dentsply Tulsa, USA) and OrthoMTA (Bio MTA, Korea), by assessing the antimicrobial effects on three selected species commonly found in root canals of infected teeth, namely Enterococcus faecalis, Fusobacterium nucleatum and Staphylococcus epidermidis. Colonies of these bacteria were treated with varied concentrations of ProRoot MTA or OrthoMTA over different lengths of time. The results are as follows : 50, 25 and 12.5 mg/mL of ProRoot MTA or OrthoMTA did not completely inhibit the growth of E. faecalis, but a decreased growth rate was evident in comparison to the control (p < 0.05). 50 mg/mL of both materials successfully eliminated F. nucleatum during the first 24 hours. Regrowth of microbes after 24 hours, however, indicated a diminished effect of ProRoot MTA whereas OrthoMTA showed its continuously sustained antimicrobial actions (p < 0.05). 50 mg/mL of ProRoot MTA and 50, 25 mg/mL of OrthoMTA exerted their full antibacterial actions against S. epidermidis during the first 24 hours. Although the regrowth of colony was observed after 24 hours, the rate of growth was significantly decreased, approximating a complete inhibition (p < 0.05). The present study revealed that OrthoMTA, recently developed in Korea, had antimicrobial activity higher than ProRoot MTA.

• Korean Journal of Microbiology
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• v.43 no.3
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• pp.193-200
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• 2007

Indoor airborne bacterial and fungal concentrations were examined at classrooms and corridors of 3 elementary schools in Ulsan. Airborne microorganisms were collected with an impaction-type air sampler using plate count agar and dichloran rose bengal chloramphenicol agar. During the semester, concentrations of bacteria ranged $168{\sim}3,887 MPN/m^3$ at classrooms and $168{\sim}6,339 MPN/m^3$ at corridors, while those of fungi ranged $34{\sim}389 MPN/m^3$ at classrooms and $91{\sim}507 MPN/m^3$ at corridors. The bacterial concentrations showed larger variations between situations and schools compared to those of fungi. When airborne bacteria were isolated and identified, 84% were observed as Gram-positive, and Micrococcus spp. was the most abundant group with 61% of tested isolates, followed by genus Staphylococcus with 10%. The Micrococcus spp. isolates, of which 75% were identified as M. luteus, appeared to be from human origins. The protective pigments and substantial cell wall of Micrococcus may provide selective advantage for their survival in the air. We also isolated and identified 15 genera of filamentous fungi. The most common culturable fungi were Cladosporium, Aspergillus and Penicillium, and these 3 genera were 69% of fungal isolates. Genus Stachybotrys, of which S. chartarum is a well known producer of many potent mycotoxins, was also detected from one of the schools. further systematic studies are necessary with an emphasis on species identification and mycotoxin production of isolated fungal genera, including Aspergillus, Penicillium, and Stachybotrys.

• Journal of Food Hygiene and Safety
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• v.33 no.5
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• pp.399-403
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• 2018

In this study, safety investigations on harmful microorganisms and mycotoxins were conducted on honeybee drone pupae as a new food material, which is rich in nutrients and capable of being mass produced in apiaries. The honeybee drone pupae produced in apiaries were collected from three different regions in Korea and frozen immediately. Subsequently, the samples were subjected to freeze-drying. According to the Korean Food Code test method, coliforms, Salmonella species, Staphylococcus aureus, and enterohemorrhagic Escherichia coli were not detected in 280 honeybee drone pupas. In addition, mycotoxins, aflatoxin $B_1$, ochratoxin A, deoxynivalenol, and zearalenone were not detected. Therefore, it is proposed that the honeybee drone pupae collected from the beehives and immediately frozen as safe from harmful microorganisms and mycotoxins and can be used as a food material.

• Journal of Life Science
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• v.11 no.5
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• pp.483-488
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• 2001

The antimicrobial substance produced by Pseudomonas aeruginosa KLP-2 strain was purified and identified. The substance was identified as a pyocyanine by the fast atom bombardment mass(FAB-MS). In physic-chemical properties, the pyocyanine was dark blue needles, and was soluble in various organic solvents such as chlorogorm, methanol, ethanol and ethyl acetae. The pyocyanine possessed a ultraviolet absorbance spectrum in methanol, 0.1 M HCl, and chlorogorm. The maximum absorption peak of the pyocyanine showed at 318 mm in methanol. The molecular formula of the pyocyanine was determined to the $C_{13}$ H$_{10}$ N$_{2}$O and protonate molecular ion species (M+H)$^{+}$ was observed at m/z 211 by FAB-MS. The pyocyanine showed antimicrobial against Bacillus cereus, Bacillus subtilis, Micrococcus luteus, Rodococcus equi, Staphylococcus aureus, Streptococcus faecalis, E. col, Legionella pneumophila, Shigella flexneri Shigella boydii, shgella sonnei, NAG Vibrio cholerae, Vibrio parahaemolyticus, Vibro vulnificus, Yersinia enterocolitica, and Saccharomyces cerevisiae. However, Salmonella spp. Shigela dysenteriae, 3 strains of Pseudomonas aeruginosa, Klebsiela pneumoniae, and Aspergillus niger were resistant to the pyocyanine. The pyocyanine showed the highest antimicrobial activity aganist Legionella pneumophila based on the size of inhibition zone by the disk contained 0.5 $\mu\textrm{g}$ of the pyocyanine.e.