• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.697-706
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• 2018

Lactobacillus pentosus K1-23 was selected from among 25 lactic acid bacterial strains owing to its high inhibitory activity against several pathogenic bacteria, including Escherichia coli, Salmonella typhimurium, S. gallinarum, Staphylococcus aureus, Pseudomonas aeruginosa, Clostridium perfringens, and Listeria monocytogenes. Additionally, among 13 strains of Aureobasidium spp., A. pullulans NRRL 58012 was shown to produce the highest amount of ${\beta}$-glucan ($15.45{\pm}0.07%$) and was selected. Next, the optimal conditions for a solid-phase mixed culture with these two different microorganisms (one bacterium and one yeast) were determined. The optimal inoculum sizes for L. pentosus and A. pullulans were 1% and 5%, respectively. The appropriate inoculation time for L. pentosus K1-23 was 3 days after the inoculation of A. pullulans to initiate fermentation. The addition of 0.5% corn steep powder and 0.1% $FeSO_4$ to the basal medium resulted in the increased production of lactic acid bacterial cells and ${\beta}$-glucan. The following optimal conditions for solid-phase mixed culture were also statistically determined by using the response surface method: $37.84^{\circ}C$, pH 5.25, moisture content of 60.82%, and culture time of 6.08 days for L. pentosus; and $24.11^{\circ}C$, pH 5.65, moisture content of 60.08%, and culture time of 5.71 days for A. pullulans. Using the predicted optimal conditions, the experimental production values of L. pentosus cells and ${\beta}$-glucan were $3.15{\pm}0.10{\times}10^8CFU/g$ and $13.41{\pm}0.04%$, respectively. This mixed culture may function as a highly efficient antibiotic substitute based on the combined action of its anti-pathogenic bacterial and immune-enhancing activities.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.285-291
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• 2016

There has been an accelerating increase in water reuse due to growing world population, rapid urbanization, and increasing scarcity of water resources. However, it is well recognized that water reuse practice is associated with many human health and ecological risks due to numerous chemicals and pathogenic microorganisms. Especially, the potential transmission of infectious disease by hundreds of pathogenic viruses in wastewater is one of the most serious human health risks associated with water reuse. In this study, we determined the response of different bacteriophages representing various bacteriophage groups to chlorination in real wastewater in order to identify a more reliable bacteriophage indicator system for chlorination in wastewater. Different bacteriophages were spiked into secondary effluents from wastewater plants from three different geographic areas, and then subjected to various doses of free chlorine and contact time at $5^{\circ}C$ in a bench-scale batch disinfection system. The inactivation of ${\phi}X174$ was relatively rapid and reached ~4 log10 with a CT value of 5 mg/L*min. On the other hand, the inactivation of bacteriophage PRD1 and MS2 were much slower than the one for ${\phi}X174$ and only ~1 log10 inactivation was achieved by a CT value of 10 mg/L*min. Overall, the results of this study suggest that bacteriophage both MS2 and PRD1 could be a reliable indicator for human pathogenic viruses for chlorination in wastewater treatment processes and water reuse practice.

• Research in Plant Disease
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• v.25 no.2
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• pp.62-70
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• 2019

The global warming by increased $CO_2$ will effect of plant pathogenic microorganisms and resistance of host plants, and it is expected to affect host-pathogen interactions. This study used Capsicum annuum L. and Xanthomonas euvesicatoria, a pathogenic bacteria of pepper, to investigate interactions between hosts and pathogens in a complex environment with increasedcultivation temperature and drought stress. As a result, the bacterial spot disease of C. annuum L. caused by X. euvesicatoria was $35^{\circ}C$ higher than $25^{\circ}C$. In addition, the effect on water potential on bacterial spot disease was much greater water potential -150 kPa than -30 kPa. The disease progress and severity higher than water potential -30 kPa. This result will useful for understanding interaction with red pepper and X. euvesicatoria under the complex environment with increased cultivation temperature and in water potential -150 kPa drought stress in the future.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.73-80
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• 2023

Broad range of fatty acids were reported to show antimicrobial activities against broad range of microorganisms. However, possible changes of the antibacterial activity of a fatty acid based on structural variations are largely unknown. This study was focused on determination and comparison of the antimicrobial activities of the medium chain fatty acids, based on the position of carboxyl groups on either terminal end, against the representative food-pathogenic bacteria. Over all, mono-carboxyl medium chain fatty acids (MC-MCFA) presented stronger antimicrobial activities against the food-pathogenic bacteria tested including methicillin-resistant Staphylococcus aureus (MRSA) than di-carboxyl medium chain fatty acid (DC-MCFA). In addition, some of MC-MCFA and DC-MCFA showed high possibility to be used as a synergistic adjuvant for both the commercial β-lactam family antibiotics and aminoglycoside family antibiotics against MRSA.

• Journal of Environmental Health Sciences
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• v.50 no.2
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• pp.102-112
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• 2024

Background: Despite the rise in the number of domestic indoor climbing gyms, there is a lack of specific hygiene standards and research on the holds installed in them. Holds can act as vectors for microbial transmission through the hands, posing a risk of infectious diseases, especially with damaged skin. Objectives: The aim of this study is to investigate the contamination level and species of microorganisms on holds according to the management methods practiced in indoor climbing gyms and identify effective strategies for reducing microbial contamination. Methods: We investigated factors that may influence microbial contamination of holds, including hold management methods, user information, and hygiene management at three climbing gyms in Seoul. A total of 72 holds were sampled, 18 for each management method of brushing, high-pressure washing, and ethanol disinfection. Samples were cultured on LB and blood agar at 37℃ for 48 hours to calculate CFUs. PCR assay targeting 16S rRNA was carried out to identify microorganisms. Dunn-Bonferroni was employed to see the microbial reduction effect of the management method and the difference in microbial contamination by management method and climbing gym. Results: As a result of microbial identification, microorganisms such as Bacillus, Staphylococcus, and Micrococcus, which were derived from various environments such as skin and soil, were discovered on the surface of the climbing hold. Among the discovered microorganisms, some species had potential pathogenic properties that could cause food poisoning, gastrointestinal disease, bacteremia, and sepsis. All hold management methods were effective in reducing microorganisms (p<0.05), with ethanol disinfection being the most effective (p<0.001). Conclusions: Our results indicate that there are potential pathogens on holds that demand thorough management for microbial prevention. Proposed methods include regular brushing and ethanol disinfection in addition to high-pressure washing with long cycles, which are the existing forms of hold management. Further studies on shoe management are advised to curb soil-derived microorganisms.

• Food Science of Animal Resources
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• v.32 no.6
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• pp.763-768
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• 2012

This study has been performed to measure the prevalence and microbial flora on chicken slaughtering as well as the processing process from the months of October to November. Whole-chicken rinsing technique was used in order to analyze the incidence of microorganisms on chicken carcass at the stage before chilling (after evisceration), after chilling and after cutting. The swab technique was used on processing the processed samples, such as working plates and cutting knives. Brine and cooling water from four cooling tubs were taken from each processing processes and were used as samples. Furthermore, the matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) for whole cell fingerprinting in combination with a dedicated bioinformatic software tool was used to identify the isolated microorganisms. Of the tested samples and processes, brine ($4.50{\pm}0.64$ Log CFU/mL) and chicken carcass before chilling ($4.15{\pm}0.46$ Log CFU/mL) showed the highest population of microorganisms; the predominant microbial flora of them were Moellerella wisconsensis (54.84%), a member of the Enterobacteriaceae family, and Escherichia coli (60.36%), respectively. However, the predominant microbial flora of cut carcass was changed to Staphylococcus aureus (27.32%), which is a kind of pathogenic microorganism that can cause a food-borne illness. Therefore, the slaughtering and processing procedure of chicken are needed to be controlled more hygienically.

• Journal of Food Hygiene and Safety
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• v.32 no.6
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• pp.500-506
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• 2017

Kimchi cabbage is one of the four major vegetable crops in Korea. The total annual production of kimchi cabbage, the main material of kimchi, was 20,559 tons in 2015. Kimchi cabbage is one of the majer crops produced by farmers which accounts for about 80% of the total leaf vegetable production in Korea. As the consumption of environmental-friendly agricultural products increases, food safety is one of the major public health concerns. We analyzed the biological hazards of kimchi cabbage produced by two types of cultivation methos such as organic farming and conventional farming using various culture media and microscopy. A total of 432 samples were analysed for presence of sanitary indicator microorganisms (aerobic plate count, coliform count, yeast & mold) and food-borne pathogens (Staphylococcus aureus, environmental Listeria, Bacillus cereus). The population of sanitary indicating microorganisms and food borne pathogens was under 5 Log CFU/g in all tested samples. The results of total microorganism numbers of leaf surface showed a positive correlation to those of soil samples. Additionally, we examined chemical factors such as pesticide residues and heavy metals in soil samples. All tested samples did not shown contamination levels higher than the standard limit.

• Journal of Animal Science and Technology
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• v.65 no.1
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• pp.225-243
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• 2023

Large amounts of additives are used during meat product processing to maintain product quality and shelf life. With the growing interest in healthy foods, natural plant-based additives are being used as alternatives to synthetic additives. In this study, six types of natural extracts with excellent antibacterial activity were selected, and their antibacterial and antioxidant activities against four types of pathogens were evaluated in various combinations. In addition, the pH, color, amount of thiobarbituric acid reactive substances (TBARS), and growth of pathogenic microorganisms were analyzed during the storage of sausages treated with various combinations of these extracts. The natural extract mixtures exhibited different antibacterial activities, depending on the combination. Compared to grapefruit seed extract, a mixture of natural extracts extracted with ethanol (M4) reduced the Escherichia coli content by more than 99.9% after 8 days of storage and slowed the growth of Listeria monocytogenes and Salmonella spp. by more than 80% after 14 days. Compared to untreated (NC) and grapefruit extract (PC)-treated sausages, sausages treated with the natural extract mixtures showed a significant decrease in CIE L^* and an increase in CIE a^* and CIE b^* (p < 0.05). The pH value was significantly lower in sausages containing natural extract mixtures than in the NC and PC sausages (p < 0.05). The natural plant extract mixtures significantly prevented lipid oxidation (p < 0.05). In summary, different types of natural extract mixtures have a synergistic effect when used together, suggesting that natural preservatives can generally inhibit the growth of microorganisms and oxidation of processed meat.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.501-506
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• 2004

Microflora and contamination process of Saengshik products were investigated to ensure microbial safety of Saengshik. Food-borne pathogenic bacteria, such as Staphylococcus aureus, Bacillus cereus, and Clostridium perfringens detected mainly from grains were not removed by washing with tap water and freeze-drying. Contaminations of food-borne pathogenic bacteria occurred through raw material powder processed at other factories and during actual product manufacturing process, because detection rates of final products were higher than those of raw materials. Concentration of food-borne pathogenic bacteria increased with advancing of process after first pulverization. Dusts of powder and powder attached to machine were good media for air-borne microorganisms and caused to increase of food-borne pathogenic bacteria during process. Improvement of manufacturing process and sanitary control of machines arc necessary to ensure microbial safety of Saengshik.

• The Korean Journal of Mycology
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• v.37 no.1
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• pp.96-103
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• 2009

For the control of pathogenic microorganisms, Bacillus spp. were isolated from diseased pepper fruits in Korea. Among them, Bacillus sp. IUB158-03 showed high inhibitory effect on mycelial growth and spore germination of C. gloeosporioides and Botrytis cinerea. The strain was identified as B. amyloliquefaciens IUB158-03 based on its physiological, biochemical characteristics and Microlog analysis. The highest level of antifungal substances by B. amyloliquefaciens IUB158-03 were obtained when the bacterium was cultured in medium containing 2% soluble starch, 3% yeast extract, 0.5% tryptone, 0.5% $NH_4H_2PO_4$, and 1% NaCl (pH 6.0) at $25^{\circ}C$ for 72 hrs. The antifungal substances were purified by butanol extraction, silica gel column chromatography, preparative thin layer chromatography, and high performance liquid chromatography. The purified antifungal substance was confirmed $R_f$ 0.27 by TLC. This substance exhibited antifungal activity against Fusarium solani, Rhizoctonia solani, Botrytis cineria, Alternata alternaria of plant pathogenic fungi and Trichophyton mentagrophytes, Epidermophyton floccosum, Cryptococcus neoformans of human pathogenic fungi.