• Journal of Food Hygiene and Safety
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• v.38 no.5
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• pp.347-355
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• 2023

In this study, polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) were compared in terms of their ability to detect shiga-toxin-producing Escherichia coli (STEC). Various foods were artificially inoculated with STEC to evaluate the limit of detection (LOD), limit of quantification (LOQ), sensitivity, specificity, and efficiency of PCR and LAMP. The LODs were ≤10⁴ and ≤10³ CFU/mL for PCR and LAMP, respectively. The LOQs did not differ between PCR and LAMP. However, of the four considered food types, the sensitivities differed by a maximum of 11.1% for seasoned meat and by a minimum of 8.1% for ground beef. LAMP had higher sensitivity than that of PCR and 100% specificity for all four food types. Therefore, LAMP is a reliable molecular method for detecting STEC as comparable to PCR assay, and its specificity and sensitivity are superior to those of PCR, depending on the food type.

• Microbiology and Biotechnology Letters
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• v.51 no.4
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• pp.403-415
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• 2023

This study aimed to isolate and identify L-(+)-lactic acid-producing bacteria from tree barks collected in Thailand and evaluate the potential strain as probiotics. Twelve strains were isolated and characterized phenotypically and genotypically. The strains exhibited a rod-shaped morphology, high-temperature tolerance, and the ability to ferment different sugars into lactic acid. Based on 16S rRNA gene analysis, all strains were identified as belonging to Weizmannia coagulans. Among the isolated strains, BKMTCR2-2 demonstrated exceptional lactic acid production, with 96.41% optical purity, 2.33 g/l of lactic acid production, 1.44 g/g of lactic acid yield (per gram of glucose consumption), and 0.0049 g/l/h of lactic acid productivity. This strain also displayed a wide range of pH tolerance, suggesting suitability for the human gastrointestinal tract and potential probiotic applications. The whole-genome sequence of BKMTCR2-2 was assembled using a hybridization approach that combined long and short reads. The genomic analysis confirmed its identification as W. coagulans and safety assessments revealed its non-pathogenic attribute compared to type strains and commercial probiotic strains. Furthermore, this strain exhibited resilience to acidic and bile conditions, along with the presence of potential probiotic-related genes and metabolic capabilities. These findings suggest that BKMTCR2-2 holds promise as a safe and effective probiotic strain with significant lactic acid production capabilities.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.15-24
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• 2003

The purpose of this study is to investigate the sterilization effect of Er:YAG laser against the intraoral acid producing bacterium, S. mutans, by irradiating the culture solution containing S. mutans KCTC 3065 with Er:YAG laser having a $650{\mu}m$ diameter beam through the non-contact method. We obtained the following results after examining the temperature changes of the culture solution, numbers of bacterial colonies, and acid-producing ability and attaching ability on teeth by measuring the amount of extracellular polysaccharide produced by S. mutans. The number of bacterial colony was decreased in $10{\mu}l$ culture solution irradiated with laser in overall compared to the control solution. The number decreased as the irradiation intensity and pulse repetition rate were larger and as the exposure time was increased. However, it did not change significantly in $100{\mu}l$ culture solution compared to the control solution. Although the acid-producing ability of S. mutans was inhibited for a certain duration after laser irradiation in 10r1 bacterial culture solution, it did not change in $100{\mu}m$ solution compared with the control solution. The amount of extracellular polysaccharide synthesized by S. mutans was partially decreased through laser irradiation in $10{\mu}m$ culture solution but did not change in $100{\mu}m$ culture solution. Based on these findings, we concluded that Er:YAG laser has an sterilization effect on S. mutans in which we presume that the mechanism is through the heat effect rather than the mechanical effect from development of ultrasound.

• The Korean Journal of Food And Nutrition
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• v.33 no.2
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• pp.142-148
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• 2020

The purpose of this study was to investigate the prevalence, toxin gene profiles, and enterotoxin producing ability of Bacillus cereus isolated from environment-friendly vegetables and good agricultural practices (GAP) vegetables. A total of 49 vegetables including 40 environment-friendly vegetables and 9 GAP vegetables were tested. The Vitek 2 system was used to identify B. cereus and the PCR was used to detect 6 toxin genes, respectively. B. cereus was detected in 34 (69.3%) of 49 vegetables and the prevalence of B. cereus in GAP vegetables (44.4%) was lower than in the environment-friendly vegetables (75.0%). The detection rates of entFM, nheA, hblC, and cytK enterotoxin genes, respectively, among all isolates were 100%, 97.0%, 88.2%, and 73.5%, respectively. All of the isolates had at least one or more enterotoxin gene and 20 isolates (58.8%) had hemolysin BL enterotoxin producing ability. The risk of food poisoning from the environment-friendly vegetables and the GAP vegetables has been shown as constant. Thus, it is necessary to expand the supply of GAP vegetables showing lower B. cereus contamination than the environment-friendly vegetables. The characteristics of the environment-friendly vegetables and the GAP vegetables that must be consumed after cleaning should be disseminated to consumers regarding food poisoning prevention.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.254-259
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• 2016

Acinetobacter sp. B-W producing siderophore, 2, 3-dihydroxybenzoic acid (DHB) was analyzed for plasmid content. Strain B-W harbored plasmid of 20 kb in size. Growth at $43^{\circ}C$ was effective in producing mutant cured of plasmid of strain B-W. This mutant lost the ability to produce 2, 3-DHB. Formation of siderophore halos on the chrome azurol S (CAS) agar medium was not detected by cured strain B-W. pHs of supernatants of wild type strain B-W and cured mutant grown in glucose and $MnSO_4$ containing medium at $28^{\circ}C$ for 3 days were 4.5 and 8.5, respectively. Antibiotic resistance against ampicillin, actinomycin D, bacitracin, lincomycin, and vancomycin was lost in cured mutant. Plasmid curing of strain B-W resulted in drastic reduction of minimal inhibitory concentration (MIC) of several antibiotics. E. coli $DH5{\alpha}$ was transformed with plasmid isolated from strain B-W. The transformant E. coli $DH5{\alpha}$ harbored a plasmid of the same molecular size as that of the donor plasmid. Transformant E. coli $DH5{\alpha}$ produced 2, 3-DHB and contained antibiotic resistant ability. Thus a single plasmid of 20 kb seemed to be involved in 2, 3-DHB production. Genes encoding resistance to antibiotics were also supposed to be located on this plasmid.

• Journal of The Korean Society of Grassland and Forage Science
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• v.29 no.2
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• pp.137-152
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• 2009

Present experiment was conducted at the field of Gyeongnam Agricultural Research and Extension Services in Jinju city for two continuous cropping seasons to develop several adaptable and valuable year-round forage-producing system for elevating self-sufficiency and dollar-saving by reduced importing of crude forage. Twenty cropping systems were tested in experiment using whole crop barley (WCB), oat, rye, Italian ryegrass (IRG), and triticale in winter season and com, sorghum, sorghum ${\times}$ sudangrass hybrid, and oat in summer time. Sorghum ${\times}$ sudangrass hybrid showed highest fresh forage yield among experimented summer season crops, and followed com. Com produced the most dry matter yield, and followed sorghum${\times}$sudangrass hybrid, sorghum and oat in order. There was no significant effect of former winter crops on fresh and dry matter production succeeding summer time crops. Among winter season forage crops tested, oat showed the highest fresh and dry matter when clipped on mid-May, and followed triticale, IRG, rye and WCB. Winter-time cultivated crops showed no clear effect on the growth and forage (fresh and dry matter) producing ability of following summer crops. There was the most protein content in oat plant among summer season planted crops, and in sorghum for acid detergent fiber (ADF) and in sorghum ${\times}$ sudangrass hybrid for neutral detergent fiber (NDF), respectively. While, com showed highest value of relative feed value (RFV) and total digestive nutrients (TDN) among those crops. Among winter crops, the highest crude protein was in oat plant showing no significant differences of ADF and NDF, while, relatively higher value of RFV was recognized with rye and triticale. Also, triticale contained more TDN as compare to other forage crops. The cropping combinations such as com followed by (fb) rye and maize fb triticale were regarded as promising systems having higher dry matter producing ability among tested combinations. Considering TDN producing potential, the combinations with sorghum ${\times}$ sudangrass hybrid fb triticale andlor rye were would be suitable ones, coincidently. There was a tendency which elevating pH, electric conductivity (EC) and organic matter (OM) contents in soil after experiment comparing to before planting. More crude protein content in plant was shown at mid-May clipping as compared to the forage at April cut in all winter season grown crops. ADF and NDF contents were increased by delayed clipping showing decreased tendency of RFV and TDN in plant. In conclusion, many cropping systems would be available using above mentioned forage crops according to farmer's conditions and scale, etc.

• Journal of The Korean Association For Science Education
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• v.42 no.4
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• pp.397-415
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• 2022

As the global warming problem becomes serious, the need for carbon cycle education in school is increasing. Adopting systems thinking ability is needed to understand the carbon cycle systematically. Furthermore, under the rapid change of environment, society, and economy, systems thinking ability is being emphasized as it can strengthen the competencies of students who will be leading the future society. The purposes of this study are as follows: first, is developing the systems thinking instrument for the carbon cycle and the rubric for analysis of systems thinking instrument. The second is analyzing the systems thinking ability of students using the developed instrument and rubric. In order to perform this study, previous studies related to the carbon cycle and systems thinking education were analyzed. Based on the analysis results, the systems thinking instrument for the carbon cycle and rubric were developed. The systems thinking ability was analyzed by implementing the developed instrument and rubric to 172 high school and university students. The results of this study are as follows: first, the systems thinking instrument for the carbon cycle was developed, and a rubric utilization guide was constructed. The instrument and rubric were modified through pilot study for middle school students producing expert opinion in relation to systems thinking and carbon cycle. Second, the systems thinking ability of students was analyzed. Consequently, students had systems thinking ability fully at a low level, such as identifying the variables related to the carbon cycle. However, it was shown that they lacked the systems thinking ability at a high level, such as time delay and feedback processes. The importance of the carbon cycle has been increasing since the global warming is the most pressing issue and significant environmental problem facing us today. Application of the systems thinking ability can contribute to understanding these complex problems and finding fundamental solutions.

• Applied Biological Chemistry
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• v.50 no.1
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• pp.23-28
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• 2007

Auxin-producing antagonistic bacterium K11, which can inhibit Phytophtora capsici, was isolated from a local red-pepper field soil in Gyeong-buk. In order to check for additional PGPR(plant growth promoting rhizobacterium) functions of the strain K11, we confirmed siderophore and cellulase productions by CAS (chrome azurol S) blue agar and CMC plate with congo red, respectively. The strain K11 was identified as Bacillus licheniformis with 98% similarity on 16s rDNA comparison and Biolog analyses. B. licheniformis K11 promoted mung bean adventitious root induction and enhanced root growth of mung bean (160%), pea (150%), and Chinese cabbage (130%), Also, B. licheniformis K11 was able to effectively suppress (63%) P. capsici causing red-pepper blight in the pot in vivo test. Therefore, we could select a triple-functional PGPR which has auxin, siderophore, and cellulase producing ability for effective crops production in organic farming.

• The Journal of Fisheries Business Administration
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• v.5 no.1
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• pp.9-42
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• 1974

Korea is a peninsular country surrounded by seas on three sides, and the fishing industry has carried out the service of suppling to the people with important anima protein. The distribution of fishery products has very complicated structures, because the production is in charge of small producers scattering along the coast all over the country, while consumpstion is made by separate homes in areas away from producing district. The relation between these two factors the structures make very complicated. The most typical and special structures of fishery distridution are distinguished in two, that is, one is landing market, the other is inland market. Landing markets have been monopolized by fishermen's cooperatives, providing with landing facilities and building sites. Fish markets played not only an important role in the landing, but distribution and price determination of catches by auction or tender. Inland markets are two types of wholesale market in consuming center, one is the terminal market for urban consumers, the other type is the local market for rural consumers. Fundamental functions of landing markets are gathering, assessment, and distribution functions. Gathering function is in charge of wholesaler in fishery cooperative. Gathering amounts are equal to gathering capacity of wholesaler and transact ability of licensed dealers as shown below model. Gathering amount=f.gathering capacity(=pre price.landing facility.account of wholesaler.distance of fishing ground.conveniency purchasing.home port)=fㆍ transact ability of licensed dealers≒f.population or port, and table 1 indicates these relationship. Assessment and distribution functions are in charge of licensed dealers in consumption side. Assessment function should bring the value in production activity through the auction between the cooperative seller and the licensed dealer as buyer. For fair trade transaction in auction, the free competition is supposed to be a prerequisite among the licensed dealers. The ideal condition for free competition is sameness in the scale of buying amount by licensed delaers, but it is almost impossible to attain its goal in actual marketing.

• Food Science of Animal Resources
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• v.33 no.5
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• pp.595-602
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• 2013

As a major inhibitory neurotransmitter of the central nervous system in animals, ${\gamma}$-aminobutyric acid (GABA) has several physiological functions, such as anti-hypertensive, diuretic, tranquilizer and anti-stress effects in human. In order to determine strains with high GABA producing ability and glutamate decarboxylase (GAD) activity, 273 bacteria were isolated from various types of Kimchi. Strain K255 contained $386.37{\mu}g/mL$ of GABA in MRS broth containing 1% MSG, $600.63{\mu}g/mL$ of GABA in MRS broth containing 2% MSG and $821.24{\mu}g/mL$ of GABA in MRS broth containing 3% MSG. It showed that K255 had the highest GABA production ability compared to other commercial lactic acid bacteria. K255 was identified as Lactobacillus plantarum based on its API carbohydrate fermentation pattern and 16S rDNA sequence. K255 was investigated for its physiological characteristics. The optimum growth temperature of K255 was $37^{\circ}C$and cultures took 13 h to reach the pH 4.4. K255 showed more sensitive to bacitracin in a comparison of fifteen different antibiotics, and showed most resistance to kanamycin and vancomycin. Moreover, it was comparatively tolerant to bile juice and acid and displayed resistance to Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus, with rates of 30.8%, 29.7%, and 23.4% respectively. These results demonstrate that K255 could be an excellent strain for the production of functional products.