• 한국식품위생안전성학회지
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• 제18권2호
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• pp.79-86
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• 2003

대부분의 식중독은 단체 급식으로부터 발생하는 경우가 많으며, 특히 위생상태와 연관되어 식중독을 야기 시키는 병인 물질 중 포도상 구균은 많은 부분을 차지하고 있다 따라서 본 연구에서는 서부경남지역의 5개 초등학교 급식시설에서 총 98개의 샘플 중 A 급식소의 식수, D 급식소의 손, E 급식소의 냉장고와 앞치마에서 4개의 포도상 구균을 분리하였다. 분리된 균주들은 1개의 메티실린 저항성 혈장응고 효소 음성 황색포도상구균(Methicilline Resistant Coagulase Negative Staphylococcus aureus； MRCPS)과 3개의 메치실린 민감성 혈장응고효소 양성 황색포도상구균 (Methicilline sensitive Coagulase positive Staphylococcus aureus； MSCPS)으로 구분되었다. 한편 포도상 구균은 내열성 내독소로서, 이 중 가장 문제가 되는 내독소 B(enterotoxin B)를 검색하기 위한 PCR을 실시한 결과, A 장소의 식수, D 장소의 손, E 장소의 냉장고와 앞치마에서 분리된 균주로부터 477bp의 생성물을 갖는 sob gene을 확인할 수 있었다. 이들 분리된 황색포도상구균에 대한 항생제 민감성 실험에서는 ampicillin과 penicillin에 대하여 전체적으로 저항성을 가졌으며, 특히 A 식수에서 분리된 균주는 옥사실린 저항성(oxacilline resistant)균주로 나타나 MRSA(methicilline resistant staphylococcus aureus)균주로 확인되었다.

• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.417-428
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• 2017

Diseases caused by foodborne or waterborne pathogens are emerging. Many pathogens can enter into the viable but nonculturable (VBNC) state, which is a survival strategy when exposed to harsh environmental stresses. Pathogens in the VBNC state have the ability to evade conventional microbiological detection methods, posing a significant and potential health risk. Therefore, controlling VBNC bacteria in food processing and the environment is of great importance. As the typical one of the gram-negatives, Escherichia coli (E. coli) is a widespread foodborne and waterborne pathogenic bacterium and is able to enter into a VBNC state in extreme conditions (similar to the other gram-negative bacteria), including inducing factors and resuscitation stimulus. VBNC E. coli has the ability to recover both culturability and pathogenicity, which may bring potential health risk. This review describes the concrete factors (nonthermal treatment, chemical agents, and environmental factors) that induce E. coli into the VBNC state, the condition or stimulus required for resuscitation of VBNC E. coli, and the methods for detecting VBNC E. coli. Furthermore, the mechanism of genes and proteins involved in the VBNC E. coli is also discussed in this review.

• Applied Biological Chemistry
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• 제42권4호
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• pp.271-276
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• 1999

새로운 천연물 농약 또는 생산군주를 개발하기 위하여 Streptomyces 속의 여러 균주를 대상으로 항진균 물질을 탐색하여 항진균 물질 생산 균주 Streptomyces hygroscopicus MJM1004를 선발하였다. 항진균 물질의 생산을 위한 발효 배지를 선정하기 위하여 여러 탄소원, 질소원과 무기원을 대상으로 균체 생장 정도와 항진균 물질의 생산성을 조사하였으며, 생산 배지는 2% soybean meal, 1% glucose, 2% starch, 0.3% $CaCO_3$, 0.05% $MgSO_4{\cdot}7H_2O$, 0.05% $K_2HPO_4$를 조성으로 하였다. S. hygroscopicus MJM1004 균주의 균체에서 추출된 항진균 물질은 Candida albicans와 여러 식물 병원성 곰팡이들에 대하여 광범위한 저해 효과를 나타내었다. S. hygroscopicus MJM1004 균체로부터 분리된 항진균 물질, SH-1004를 핵자기공명법($^1H,\;^{13}C$, DQF COSY, HMQC 및 HMBC)을 통하여 분석한 결과 azalomycin F complex 임을 확인할 수 있었다. Positive FAB mass spectrum을 통하여 SH-1004는 azalomycin F4a와 F5a가 1.8 : 1의 비율로 혼합된 물질임을 확인하였다.

• 한국수산과학회지
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• 제48권2호
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• pp.244-248
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• 2015

We explored the efficiency of natural antibacterial agents used to enhance the self-life and sensory properties of shucked and packed Pacific oyster Crassostrea gigas, which are in high demanded. First, we screened natural resources exhibiting antibacterial activity against food spoilage and pathogenic bacteria. Of theses, ignited oyster shell powder (IOS) and the natural food preservative, lactic acid bacteria fermented powder (LBF), were selected for further study considering the efficacy, mass production, and cost. The addition of 0.1% IOS (W/V) and 0.5% LBF (W/V) to shucked and packed oyster optimally extended the shelf-life without affecting the sensory evaluation. The results obtained in this study will provide a clue to enhance self-life in raw oyster products.

• Parasites, Hosts and Diseases
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• 제49권4호
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• pp.341-347
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• 2011

Acanthamoeba infection is difficult to treat because of the resistance property of Acanthamoeba cyst against the host immune system, diverse antibiotics, and therapeutic agents. To identify encystation mediating factors of Acanthamoeba, we compared the transcription profile between cysts and trophozoites using microarray analysis. The DNA chip was composed of 12,544 genes based on expressed sequence tag (EST) from an Acanthamoeba ESTs database (DB) constructed in our laboratory, genetic information of Acanthamoeba from TBest DB, and all of Acanthamoeba related genes registered in the NCBI. Microarray analysis indicated that 701 genes showed higher expression than 2 folds in cysts than in trophozoites, and 859 genes were less expressed in cysts than in trophozoites. The results of real-time PCR analysis of randomly selected 9 genes of which expression was increased during cyst formation were coincided well with the microarray results. Eukaryotic orthologous groups (KOG) analysis showed an increment in T article (signal transduction mechanisms) and O article (posttranslational modification, protein turnover, and chaperones) whereas significant decrement of C article (energy production and conversion) during cyst formation. Especially, cystein proteinases showed high expression changes (282 folds) with significant increases in real-time PCR, suggesting a pivotal role of this proteinase in the cyst formation of Acanthamoeba. The present study provides important clues for the identification and characterization of encystation mediating factors of Acanthamoeba.

• The Plant Pathology Journal
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• 제32권3호
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• pp.182-189
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• 2016

Together with the Fusarium graminearum species complex, F. culmorum is a major member of the causal agents of Fusarium head blight on cereals such as wheat, barley and corn. It causes significant yield and quality losses and results in the contamination of grain with mycotoxins that are harmful to humans and animals. In Korea, F. culmorum is listed as a quarantine fungal species since it has yet to be found in the country. In this paper, we report that two isolates (J1 and J2) of F. culmorum were collected from the air at a rice paddy field in Korea. Species identification was confirmed by phylogenetic analysis using multilocus sequence data derived from five genes encoding translation elongation factor, histone H3, phosphate permease, a reductase, and an ammonia ligase and by morphological comparison with reference strains. Both diagnostic PCR and chemical analysis confirmed that these F. culmorum isolates had the capacity to produce nivalenol, the trichothecene mycotoxin, in rice substrate. In addition, both isolates were pathogenic on wheat heads and corn stalks. This is the first report on the occurrence of F. culmorum in Korea.

• 한국식품영양학회지
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• 제22권3호
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• pp.367-376
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• 2009

This study aimed to determine the antioxidant and antibacterial effects of solvent extracts from Scutellaria baicalensis. The S. baicalensis was successively extracted with 5 kinds of solvents. The obtained samples were as follows; hexan fraction (IPK-1), chloroform fraction(IPK-2), ethyl acetate fraction(IPK-3), butanol fraction(IPK-4), and water fraction(IPK-5). These extracts were determined to process antibacterial effects using a paper disc method against 18 species of human pathogenic bacteria, antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl(DPPH) method and inhibiting ability of linoleic acid autoxidation. Extracts of S. baicalensis has shown selective antibacterial effects on various strains of bacteria. Ethyl acetate fraction(IPK-3) showed the highest antimicrobial activity against selective bacteria, such as Staphylococcus aureus 285, S. aureus 503. In antioxidant activity test, free radical scavenger activity of IPK-3 fraction was 92% compared with BHA at the same concentration, while lipid peroxidation inhibition was 48%. These results suggest that IPK-3 fraction of S. baicalensis could be suitable in development of antimicrobial and antioxidant agents.

• The Plant Pathology Journal
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• 제19권3호
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• pp.129-132
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• 2003

Fusarium wilt of cucumber caused by Fusarium oxy-sporum f. sp. cucumerinum is a serious vascular disease worldwide. Biological control of Fusarium wilt in several crops has been accomplished by introducing non-pathogenic Fusarium sup. and other biocontrol agents in soil or in infection courts. In this study, quantitative models were used to determine the biocontrol efficacy of inundatively applied antagonist formulations and the length of their effectiveness in controlling Fusarium wilt of cucumber. Quantitative model of the form [Y=L (1${-exp}^{-kx}$)] best described the relationship between disease incidence (Y, %) and inoculum density (X) of isolates F51 and F55. Isolate F51 was selected as a more virulent isolate based on the extent of its effectiveness in causing the wilt disease. The degree of disease control (Xi/X) obtained with the density of the biocontrol agent (Z), was described by the model [Xi/X=A (1${-exp}^{-cz}$)]. The zeolite-based antagonist formulation amended with chitosan (ZAC) was better at lower rates of application and peaked at around 5 g/ kg of the potting medium, whereas the peat-based antagonist formulation (PA) peaked at around 10 g/kg of the potting medium. ZAC formulation provided significantly better suppression of Fusarium wilt as described by the curvilinear relationship of the type Y= a+bX+c$X^2$, where Y represents percent disease incidence and X represents sustaining effect of the biocontrol agent.

• The Plant Pathology Journal
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• 제28권1호
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• pp.68-74
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• 2012

Biocontrol microbes have mainly been screened among large collections of microorganisms $via.$ nutrient-rich $in$ $vitro$ assays to identify novel and effective isolates. However, thus far, isolates from only a few genera, mainly spore-forming bacilli, have been commercially developed. In order to isolate field-effective biocontrol microbes, we screened for more than 200 oligotrophic bacterial strains, isolated from rhizospheres of various soil samples in Korea, which induced systemic resistance against the soft-rot disease caused by $Pectobacterium$ $carotovorum$ SCC1; we subsequently conducted in $planta$ bioassay screening. Two oligotrophic bacterial strains were selected for induced systemic disease resistance against the $Tobacco$ $Mosaic$ $Virus$ and the gray mold disease caused by $Botrytis$ $cinerea$. The oligotrophic bacterial strains were identified as $Pseudomonas$ $manteilii$ B001 and $Bacillus$ $cereus$ C003 by biochemical analysis and the phylogenetic analysis of the 16S rRNA sequence. These bacterial strains did not exhibit any antifungal activities against plant pathogenic fungi but evidenced several other beneficial biocontrol traits, including phosphate solubilization and gelatin utilization. Collectively, our results indicate that the isolated oligotrophic bacterial strains possessing induced systemic disease resistance could provide useful tools as effective biopesticides and might be successfully used as cost-effective and preventive biocontrol agents in the field.

• The Plant Pathology Journal
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• 제28권1호
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• pp.20-31
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• 2012

Endophytic bacterial communities of tidal flat plants antagonistic to oomycete plant pathogens were studied by the isolation of 256 root colonizing endophytic bacteria from surface-disinfected root tissues of six plants ($Rosa$ $rugosa$, $Suaeda$ $maritima$, $Vitex$ $rotundifolia$, $Carex$ $scabrifolia$, $Glehnia$ $littoralis$ and $Elymus$ $mollis$) growing in a tidal flat area of Namhae Island, Korea. To understand the antagonistic potential, an $in$ $vitro$ antagonistic assay was performed to characterize and identify strains that were antagonistic to the oomycete plant pathogens $Phytophthora$ $capsici$ and $Pythium$ $ultimum$ from the total population. Nine percent of the total number of isolated bacteria exhibited in vitro inhibitory activity against target plant pathogenic oomycetes. Taxonomic and phylogenetic placement of the antagonistic bacteria was investigated by analysis of the 16S rRNA gene sequences. The sequence analysis classified the antagonistic strains into four major classes of the domain bacteria ($Firmicutes$, ${\alpha}-Proteobacteria$, ${\gamma}-Proteobacteria$ and $Actinomycetes$) and 10 different genera. Further production of secondary metabolites, hydrolytic enzymes and plant growth promoting traits were determined for the putative new species of antagonistic endophytic bacteria. These new strains could not be identified as known species of ${\alpha}-Proteobacteria$, and so may represent novel bacterial taxa. The unexpected high antagonistic bacterial diversity associated with the tidal flat plants may be indicative of their importance in tidal flat plants as a promising source of novel antimicrobial compounds and biocontrol agents.