• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1238-1243
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• 2009

The susceptibilities of major enterohemorrhagic Escherichia coli (EHEC) strains to antimicrobial agents and the cytotoxicity of these agents were examined using a total of 38 strains of E. coli O26, O111, and O157, which are the major serogroups of EHEC. Among the 38 strains, 35, 36, and 36 were susceptible to amikacin, imipenem, and norfloxacin, respectively. These antimicrobial agents were further examined to determine their cytotoxicity on Vero cells as well as their effect on the release of Shiga toxins along with trimethoprim/sulfamethoxazole. Each of the E. coli O26, O111, and O157 strains containing both the stx1 and stx2 genes were grown in the absence or presence of these agents at 1/4 minimal inhibitory concentration for 6 h, 12 h, and 18 h. At the concentrations used in this study, none of the agents significantly altered cell count compared with the control group. The level of cytotoxicity in the imipenem group was lower at 12 hand 18 h than their respective controls. In contrast, the level of cytotoxicity in cultures treated with trimethoprim/sulfamethoxazole, norfloxacin, and amikacin was increased. The strains were also examined for the release of Shiga toxins 1 and 2 following treatment with the agents, which were measured by the reversed passive latex agglutination (RPLA) method. The RPLA assay showed a suppression of release of Shiga toxin 2 in the strain cultures containing imipenem. These results indicate that imipenem may be a safe and effective agent for inhibition of these bacteria, which has clinical implications for the treatment of EHEC infections.

• Journal of Applied Biological Chemistry
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• 제61권1호
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• pp.69-73
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• 2018

표고버섯(Lentinus edodes)은 원목이나 톱밥배지를 사용하여 재배한다. 이 배지에 푸른곰팡이(Trichoderma)가 감염되면 표고버섯의 생장을 크게 억제한다. 버섯은 신선식품이기 때문에 푸른곰팡이를 방제하기 위한 항생제와 화학약품의 사용은 허용되지 않는다. Pseudomonas tolaasii에 의해 분비되는 펩티드 독소인 톨라신과 톨라신 유사체들은 항진균 활성을 가져 푸른곰팡이병 방제에 성공적이었다. 푸른곰팡이 Trichoderma harzianum H1에 톨라신 펩티드를 처리하였을 때 곰팡이의 성장은 효과적으로 억제되었고, 실제 톱밥배지에서 균주 배양액을 푸른곰팡이 균사에 분사하였을 때, 균사 성장은 완벽하게 억제되었다. 특히, P. tolaasii 6264와 HK11 균주의 배양 추출액을 혼합하여 처리하였을 때에 항진균 활성이 크게 증가하였다. 따라서 이러한 균주들과 펩티드 독소들은 푸른곰팡이의 성장을 억제할 수 있고, 표고버섯 재배에서 푸른곰팡이병을 방제하기 위한 좋은 후보가 될 수 있다.

• The Plant Pathology Journal
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• 제33권3호
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• pp.229-237
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• 2017

Rye (Secale cereale L.) serves as an alternative host of Pyrenophora tritici-repentis (PTR) the cause of tan spot on wheat. Rye is cultivated as a forage or cover crop and overlaps with a significant portion of wheat acreage in the U.S. northern Great Plains; however, it is not known whether the rye crop influences the evolution of PTR races. We evaluated a global collection of 211 rye accessions against tan spot and assessed the diversity in PTR population on rye in South Dakota. All the rye genotypes were inoculated with PTR races 1 and 5, and infiltrated with Ptr ToxA and Ptr ToxB, at seedling stage. We observed 21% of the genotypes exhibited susceptibility to race 1, whereas, 39% were susceptible to race 5. All 211 accessions were insensitive to both the Ptr toxins. It indicates that though rye exhibits diversity in reaction to tan spot, it lacks Ptr ToxA and ToxB sensitivity genes. This suggests that unknown toxins or other factors can lead to PTR establishment in rye. We characterized the race structure of 103 PTR isolates recovered from rye in South Dakota. Only 22% of the isolates amplified Ptr ToxA gene and were identified as race 1 based on their phenotypic reaction on the differential set. The remaining 80 isolates were noted to be race 4. Our results show that races 1 and 4 are prevalent on rye in South Dakota with a higher frequency of race 4, suggesting a minimal role of rye in the disease epidemiology.

• 농약과학회지
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• 제18권3호
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• pp.181-190
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• 2014

곤충병원세균인 Bacillus thuringiensis (비티)는 포자 형성과 더불어 살충성 Cry 독소단백질을 생산한다. Cry 독소단백질은 대상 곤충의 중장에 위치한 수용체와 특이적으로 결합하며 살충작용을 발휘하기에 비티의 적용해 충범위가 비교적 좁다. 본 연구는 비티의 적용해충범위와 살충력을 증가시키기 위한 일환으로 실시되었다. 서로 다른 네 가지 비티 균주에서 분리된 Cry 독소단백질은 각각 좁은 적용해충범위를 나타냈다. 이들 Cry 독소단백질을 혼합한 결과 적용범위가 현격하게 증가했다. 벡큘로바이러스가 비티의 적용범위를 증가시키는 지 알아보기 위해 Cry1Ac 또는 Cry1Ca 독소단백질을 각각 발현시키는 재조합바이러스로 검정한 결과 벡큘로바이러스는 Cry 독소단백질의 적용범위를 증가시키는 데 유효하지 않았다. Xenorhabdus nematophila (Xn) 세균 배양액은 조사된 모든 곤충의 세포성 면역을 억제하고 Cry 독소단백질의 살충력을 증가시켰다. 이 Xn 세균배양액을 혼합 Cry 독소단백질에 추가한 결과 적용해충범위와 살충력을 모두 증가시켰다.

• Nutrition Research and Practice
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• 제16권4호
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• pp.464-475
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• 2022

BACKGROUND/OBJECTIVES: Increased levels of uremic toxins and decreased antioxidant capacity have a significant impact on the progression of chronic kidney disease (CKD). However, it remains unclear whether they interact with each other to mediate the damage of kidney function. The purpose of this study was to investigate whether uremic toxins (i.e., homocysteine and indoxyl sulfate [IS]), as well as glutathione-dependent antioxidant enzyme activities are dependently or independently associated with kidney function during different stages of CKD patients. SUBJECTS/METHODS: One hundred thirty-two patients diagnosed with CKD at stages 1 to 5 participated in this cross-sectional study. RESULTS: Patients who had reached an advanced CKD stage experienced an increase in plasma uremic toxin levels, along with decreased glutathione peroxidase (GSH-Px) activity. Plasma homocysteine, cysteine, and IS concentrations were all positively associated with each other, but negatively correlated to GSH-Px activity levels after adjusting for potential confounders in all CKD patients. Although plasma homocysteine, cysteine, IS, and GSH-Px levels were significantly associated with kidney function, only plasma IS levels still had a significant association with kidney function after these parameters were simultaneously adjusted. In addition, plasma IS could interact with GSH-Px activity to be associated with kidney function. CONCLUSIONS: IS plays a more dominant role than homocysteine and GSH-Px activity in relation to kidney function.

• 한국수산과학회지
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• 제28권3호
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• pp.364-372
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• 1995

1993년 진해만 일원의 마비성패독 발생의 원인규명을 위한 모니터링의 일환으로 원인생물의 독생산과 성분조성을 조사하기 위하여 양식장 인근해역의 저서 휴면포자를 발아시켜 분리한 무균주의 독성분을 분석하였다. 분리된 전체주중에서 수정리산 (St. 1) 5주, 욱곡리산 (St. 2) 3주 및 대곡리산 (St. 4) 11주의 독조성 및 독함량을 비교하였을 때, 각 지점별 평균 독량은 약 54-70 fmol/cell 높은 량을 나타내었고, 동일 휴면포자의 clone 분리주 뿐만 아니라 전체 분리주에서 개체별 독함량의 차이가 크게 나타났다. 독조성은 C1/C2 (epiGTX8/GTX8), GTX1/GTX4 및 neoSTX가 주요 구성성분을 이루었고, GTX2/GTX3, GTX5, C4, dcSTX 및 STX성분은 미량 또는 산발적으로 출현하였다. 주요 성분중에서 neoSTX는 $5-54mol\%$로 변동이 컸으나, 전체 분리주의 절반은 출현을 보이지 않아 이 지역에서 조성이 다른 개체군의 출현이 시사되었다 한편, 상대적으로 독성이 강한 GTX1-4 및 neoSTX와 같은 Carbamate군의 성분이 세 정점에서 각각 $57\%,\;54\%$ 및 $67\%$의 높은 평균치를 나타내어 이 지역에서의 높은 독화율과 독화 가능성의 잠재력이 큰 것으로 시사되었다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2018년도 춘계학술대회 및 임시총회
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• pp.13-13
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• 2018

Alternaria is a ubiquitous fungal genus, widely distributed in the environment and a range of different habitats. It includes both plant pathogenic and saprophytic species, which can affect crops in the field or cause post-harvest spoilage of plant fruits and kernels. Numerous Alternaria species cause damage to agricultural products including cereal grains, fruits and vegetables, and are responsible for severe economic losses worldwide. Most Alternaria species have the ability to produce a variety of secondary metabolites, which may play important roles in plant pathology as well as food quality and safety. Alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA), tentoxin (TEN) and altenuene (ALT) are considered the main Alternaria compounds thought to pose a risk to human health. However, food-borne Alternaria species are able to produce many additional metabolites, whose toxicity has been tested incompletely or not tested at all. Both alternariols are mutagenic and their presence in cereal grain has been associated with high levels of human esophageal cancer in China. TeA exerts cytotoxic and phytotoxic properties, and is acutely toxic in different animal species, causing hemorrhages in several organs. The possible involvement of TA in the etiology of onyalai, a human hematological disorder occurring in Africa, has been suggested. Altertoxins (ALXs) have been found to be more potent mutagens and acutely toxic to mice than AOH and AME. Other metabolites, such as TEN, are reported to be phytotoxins, and their toxicity on animals has not been demonstrated up to now. Vegetable foods infected by Alternaria rot are obviously not suitable for consumption. Thus, whole fresh fruits are not believed to contribute significantly with Alternaria toxins to human exposure. However, processed vegetable products may introduce considerable amounts of these toxins to the human diet if decayed or moldy fruit is not removed before processing. The taxonomy of the genus is not well defined yet, which makes it difficult to establish an accurate relationship between the contaminant species and their associated mycotoxins. Great efforts have been made to organize taxa into subgeneric taxonomic levels, especially for the small-spored, food associated species, which are closely related and constitute the most relevant food pathogens from this genus. Several crops of agricultural value are susceptible to infection by different Alternaria species and can contribute to the entry of Alternaria mycotoxins in the food chain. The distribution of Alternaria species was studied in different commodities grown in Argentina. These food populations were characterized through a polyphasic approach, with special interest in their secondary metabolite profiles, to understand their full chemical potential. Alternaria species associated with tomato, bell pepper, blueberry, apples and wheat cultivated in Argentina showed a surprisingly high metabolomic and mycotoxigenic potential. The natural occurrence of Alternaria toxins in these foods was also investigated. The results here presented will provide background for discussion on regulations for Alternaria toxins in foods.

• 한국식품위생안전성학회지
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• 제29권2호
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• pp.85-91
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• 2014

Deoxynivalenol (DON) and related trichothecene mycotoxins are extensively distributed in the cereal-based food and feed stuffs worldwide. Recent climate changes and global grain trade increased chance of exposure to more DON and related toxic metabolites in poorly managed production systems. Monitoring the biological and environmental exposures to the toxins are crucial in protecting human and animals from toxicities of the hazardous contaminants in food or feeds. Exposure biomarkers including urine DON itself are prone to shift to less harmful metabolites by intestinal microbiota and liver metabolic enzymes. De-epoxyfication of DON by gut microbes such as Eubacterium strain BBSH 797 and Eubacterium sp. DSM 11798 leads to more fecal secretion of DOM-1. By contrast, most of plant-derived DON-glucoside is also easily catabolized to free DON by gut microbes, which produces more burden to body. Phase 2 hepatic metabolism also contributes to the glucuronidation of DON, which can be useful urine biomarkers. However, chemical modification could be very typical depending on the anthropologic or genetic background, luminal bacteria, and hepatic metabolic enzyme susceptibility to the toxins in the diet. After toxin exposure, effect biomarkers are also important in estimating the linkage and mechanisms of foodborne diseases in human and animal population. Most prominent adverse effects are demonstrated in the DON-induced immunological and behavioral disorders. For instance, acutely elevated interleukin-8 from insulted gut exposed to dietaty DON is a dominant clinical biomarker in human and animals. Moreover, subchronic exposure to the toxins is associated with high levels of serum IgA, a biological mediator of IgA nephritis. In particular, anorexia monitoring using mouse models are recently developed to monitor the biological activities of DON-induced feed refusal. It is also mechanistically linked to alteration of serotoin and peptide YY, which are promising biomarkers of neurological disorders by the toxins. As animal-alternative biomonitoring, huamn enterocyte-based assay has been developed and more realistic gut mimetic models would be useful in monitoring the effect biomarkers in resposne to toxic contaminants in the future investigations.

• 분석과학
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• 제28권3호
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• pp.168-174
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• 2015

남조류 독소인 마이크로시스틴은 여름철 우리나라 여러 호수들에 존재하여 물고기와 가축 그리고 인간에게 강한 독성을 나타내는 독소이다. 본 논문에서는 이러한 수중 남조류 독소, 마이크로시스틴을 정량분석하는 두가지 방법, 즉 고성능 액체크로마토그래피(HPLC) 분석법과 최근 우리 실험실에서 개발한 스트립분석법의 비교를 시도하였다. 두 분석법의 측정가능농도범위가 많이 달라 HPLC 법으로 먼저 측정한 후 시료를 물로 희석시켜 스트립분석법에 적용하였다. 서로 다른 농도의 마이크로시스틴을 함유한 7가지 물시료들을 사용하여 HPLC분석법과 스트립 분석법으로 남조류 독소 총량을 측정하였다. 그 결과 두 분석법의 정량측정결과가 매우 잘 일치하는 것을 볼 수 있었다. 두 분석법의 상관분석 결과 r 값은 0.99998 이었으며 통계적인 유의성을 나타내는 p 값은 0.00001 이었다.

• Mycobiology
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• 제43권2호
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• pp.93-106
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• 2015

Alternaria species are common saprophytes or pathogens of a wide range of plants pre- and post-harvest. This review considers the relative importance of Alternaria species, their ecology, competitiveness, production of mycotoxins and the prevalence of the predominant mycotoxins in different food products. The available toxicity data on these toxins and the potential future impacts of Alternaria species and their toxicity in food products pre- and post-harvest are discussed. The growth of Alternaria species is influenced by interacting abiotic factors, especially water activity ($a_w$), temperature and pH. The boundary conditions which allow growth and toxin production have been identified in relation to different matrices including cereal grain, sorghum, cottonseed, tomato, and soya beans. The competitiveness of Alternaria species is related to their water stress tolerance, hydrolytic enzyme production and ability to produce mycotoxins. The relationship between A. tenuissima and other phyllosphere fungi has been examined and the relative competitiveness determined using both an Index of Dominance ($I_D$) and the Niche Overlap Index (NOI) based on carbon-utilisation patterns. The toxicology of some of the Alternaria mycotoxins have been studied; however, some data are still lacking. The isolation of Alternaria toxins in different food products including processed products is reviewed. The future implications of Alternaria colonization/infection and the role of their mycotoxins in food production chains pre- and post-harvest are discussed.