• 미생물학회지
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• 제16권4호
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• pp.161-169
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• 1978

Escherichiae-like organisms were isolated from rectal specimens of 56 children who were either in preschool age or in elementary school. The isolated strains were subjected to tests to screen enteropathogens producing heat-labile enterotoxin and susceptibility test to various antibiotics by disc diffusion method on agar plates. Production of heat-labile enterotoxin by the strains was assyed in the sensitive and reproducible cultured adrenal tumor cell system. The assay was sterodogenesis of the cell in the presence of heat-labile enterotoxin. Among 56 strains, gave positive reaction in the test of toxin production. This meant that about 10% of the children population objected to the study harbored the toxigenic strain of enteropathogenes. Some of these toxigenic strains were resistant to the antibiotics employed in the test. This study suggested that considerable population in Korea may harbor entertoxigenic E. coli as a part of intestinal normal flora. The toxigenic strains which are resistant to antibiotics may bring issue of public health in the future.

• Food Science and Biotechnology
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• 제15권4호
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• pp.499-505
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• 2006

Clostridium botulinum spores are widely distributed in nature. Type A and proteolytic type B bacteria produce heat-resistant spores that are primarily involved in most of the food-borne botulism outbreaks associated with low-acid canned foods. Food-borne botulism results from the consumption of food in which C. botulinum has grown and produced neurotoxin. Growth and toxin production of type A and proteolytic type B in canned foods can be prevented by the use of thermal sterilization alone or in combination with salt and nitrite. The hazardousness of C. botulinum in low-acid canned foods can also be reduced by preventing post-process contamination and introducing hazard analysis and critical control point (HACCP) practices during production. Effectiveness of non-thermal technologies such as high pressure processing with elevated process temperatures on inactivation of spores of C. botulinum will be discussed.

• Journal of Microbiology and Biotechnology
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• 제30권7호
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• pp.1037-1043
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• 2020

Actinobacillus pleuropneumoniae (APP) is a causative agent of porcine pleuropneumonia. Therefore, the development of an effective vaccine for APP is necessary. Here, we optimized the culture medium and conditions to enhance the production yields of Apx toxins in APP serotype 1, 2, and 5 cultures. The use of Mycoplasma Broth Base (PPLO) medium improved both the quantity and quality of the harvested Apx toxins compared with Columbia Broth medium. Calcium chloride (CaCl₂) was first demonstrated as a stimulation factor for the production of Apx toxins in APP serotype 2 cultures. Cultivation of APP serotype 2 in PPLO medium supplemented with 10 ㎍/ml of nicotinamide adenine dinucleotide (NAD) and 20 mM CaCl₂ yielded the highest levels of Apx toxins. These findings suggest that the optimization of the culture medium and conditions increases the concentration of Apx toxins in the supernatants of APP serotype 1, 2, and 5 cultures and may be applied for the development of vaccines against APP infection.

• 대한미생물학회지
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• 제20권1호
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• pp.55-63
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• 1985

Phosphate, ammonia, glucosamine, glucose, pyruvate, succinate, fumarate, malate and acetate were examined for their ability to control the heat-stable enterotoxin (ST) production in succinate salts medium or in M9 medium. The results obtained were summerized as follows. 1. When the initial phosphate concentration was adjusted to 1.0mM, ST production was decreased to 80u/ml or less. But when the initial phosphate concentration was adjusted to 64mM or 100mM, enterotoxin production was 320u/ml. 2. When the initial ammonia concentration in the medium was adjusted to 1.0mM, no ST production and cell growth were observed. But when ammonia concentration was adjusted to 10mM, 19mM, 38mM or 76mM, enterotoxin production was 320u/ml. 3. Among carbon sources, glucosamine, glucose, pyruvate, succinate, fumarate, malate and acetate, acetate supported the highest specific production (928 unit/O.D.) of heat-stable enterotoxin. From this results, we could assume that heat-stable enterotoxin production is controlled by stringent control mechanism. 4. When the pH of the succinate salts medium was kept between 6.2 to 6.5, no heat-stable enterotoxin production was observed, but when the pH of the medium was kept between pH 6.2 to 6.5, 267 unit/O.D. of heat-stable enterotoxin was produced. 5. Glucose inhibited the heat-stable enterotoxin production and the mechanism was assumed due to its capacity to lower the pH of the medium during catabolysis and its high metabolic energy.

• 한국식품위생안전성학회지
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• 제28권2호
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• pp.138-145
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• 2013

어린이집 유아들이 공용으로 사용하는 수건의 미생물 오염도와 분리된 식중독 미생물의 장독소 유전자 및 장독소 생산 특성을 분석하여 어린이집 유아 사용 수건의 위생안전성을 확보하고자 어린이가 손 씻은 후 공용으로 사용하는 수건 22개 (사용 전 7개, 사용 중 15개)를 연구대상으로 하였다. 일반세균수는 평균 6.2 log CFU/100 $cm^2$로 검출되었고 진균수는 평균 4.1 log CFU/100 $cm^2$로 검출되었으며 대장균군은 사용 전 수건의 경우 7건 중 4건 (57.1%), 사용 중인 수건의 경우 15건 모두에서 (100%) 검출되었다. 어린이 사용 수건의 미생물 오염도가 높게 나타나 수건의 위생적인 살균 세탁 및 상대습도가 낮은 곳에 보관하는 등의 보관 방법 개선이 필요한 것으로 판단되었다. Salmonella spp.의 경우 실험에 사용된 모든 수건에서 검출되지 않았으나, Staph. aureus는 22건 중 5건 (22.7%), B. cereus는 11건 (50.0%)에서 검출되어 B. cereus 오염이 가장 심각한 것으로 나타났다. Staph. aureus 장독소 유전자와 독소 단백질은 모두 불검출 되었으나 분리 동정된 11균주의 B. cereus 장독소 유전자 실험 결과 hblC, hblD, hblA 유전자가 각각 72.7, 72.7, 54.5% 검출되고 nheA, nheB, nheC 유전자가 각각 81.8, 72.7, 54.5% 검출되었으며 cytK, entFM 장독소 유전자는 각각 45.5, 90.0% 검출되었다. B. cereus 장독소 실험결과 HBL 장독소는 11균주 중 8균주 (72.7%), NHE 장독소는 5균주 (45.5%) 검출되었고 HBL과 NHE 장독소 중 하나 이상을 생산하는 B. cereus 균주는 10균주 (90.9%)로 나타났다. 수건에 오염된 B. cereus 균주의 교차오염에 따른 식중독 위험성이 상존하는 것으로 나타나 개인별 수건 또는 종이 타올 사용을 고려하여야 할 것으로 판단되었다.

• 한국수산과학회지
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• 제52권3호
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• pp.241-246
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• 2019

To understand the characteristics of paralytic shellfish poisoning in a major production area of the bay scallop Argopecten irradians in Korea, the seasonal variation and anatomical distribution of paralytic shellfish toxin (PST) were determined in bay scallops collected from the Gyeongnam coast of Korea from March to May 2018. PST levels in bay scallops in the survey area showed remarkable seasonal variation. PST was first detected at a level of 0.42 mg/kg on April 2, 2018, and the highest toxin level (3.15 mg/kg) was recorded on April 12. Among the tissues of bay scallops, the highest proportion of PST was found in the viscera ($54.9%{\pm}17.8%$), followed by the adductor ($22.8%{\pm}10.9%$), gonads ($8.9%{\pm}4.6%$), gills ($7.1%{\pm}3.7%$), and mantle ($6.3%{\pm}.8%$). In addition, with higher PST levels in the whole tissues of bay scallops, the proportion of PST in the viscera increased, whereas those in the mantle, gill, and gonad tissues decreased. In a high-toxicity group with more than 2.0 mg/kg PST in the whole tissues, the proportion of PST in the viscera was $71.8%{\pm}6.7%$.

• 대한수의학회지
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• 제39권2호
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• pp.301-310
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• 1999

Anthrax caused by Bacillus anthracis is one of the most important zoonotic diseases. The bacterium produces several virulence factors. Of the factors, protective antigen (PA) of tripatite toxin has been identified as a central component in the pathogenesis of anthrax. However, precise roles of PA and other cellular components in the reaction with the target cells remain to be elucidated, especially in the initial stage of the disease. Three B anthracis antigens were prepared for investigation; PA, sonicated cellular antigens (S-Ag) and formalin-inactivaed whole cell antigens (W-Ag). PA was purified from culture supernatant of the bacterium using FPLC system with MonoQ. S-Ag and W-Ag were prepared by sonication and formalin inactivation of the cultured cells, respectively. Purity of the antigens was confirmed by SDS-PAGE and Western blot analysis. The roles of these antigens in the production of inflammatory mediators such as NO, IL-6 and $TNF{\alpha}$ from mouse peritoneal macrophages were investigated. PA alone did not induce the production of the inflammatory mediators while the other antigens, S-Ag and W-Ag, did in a dose and time dependent manner. These results suggested that in addition to major virulence factors, other cellular antigens are also involved in the initial stage of the disease by the induction of inflammatory mediators.

• Applied Biological Chemistry
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• 제33권2호
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• pp.169-173
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• 1990

곡류 등에 오염되어 황색 독소성분인 skyrin을 생합성하는 Penicillium islandicum 배지에 grapefruit 종자로부터 추출한 천연유기 복합물인 DF-100을 처리하여 곰팡이 생육 및 skyrin 생성을 저해하는 효과를 볼 수 있었다. DF-100 500ppm 농도로 Penicillium islandicum의 생육을 91% 저해하였고 750ppm 농도에서 곰팡이 생육을 완전히 저해하였으며 500ppm농도로 skyrin생성을 완전히 저해하였다. skyrin 생합성경로를 고려할 때 DF-100은 낮은 농도에서 emodinanthrone으로부터 emodin을 거쳐 skyrin으로 전환되는 효소 반응계와 skyrinanthrone으로 진행하는 반응단계를 저해하는 것으로 밝혀 졌다.

• 한국식물병리학회지
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• 제14권2호
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• pp.177-183
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• 1998

A DNA fragment which is involved in tolassin production was cloned to obtain a molecular marker of Pseudomonas tolaasii, a casual agent of bacterial brown blotch disease of oyster mushroom (Pleurotus ostreatus). Tolaasin is a lipodepsipeptide toxin and known as a primary disease determinant of the P. tolaasii. It is responsible for formation of white line in agar when P. tolaasii were cultured against white line reacting organisms (WLROs). White line negative mutants (WL-) were generated by conjugation between rifampicin resistant strain of P. tolaasii and E. coli carrying suicidal plasmid pSUP2021 : : Tn5. The ability of tolaasin production of the WL- mutants was examined by hemolysis test, pathogenicity test, and high pressure liquid chromatography (HPLC) analysis of culture filtrate. All of the WL- mutants were lost the ability of tolaasin production (Tol-). Genomic library of the Tol- mutant was constructed in pLAFR3 and the cosmid clone containing Tn5 was selected. DNA fragment fro franking region of Tn5 was cloned from the plasmid and used as a probe in Southern blot. DNA-DNA hybridization with the probe to total DNA from group of bacteria ecologically similar to P. tolaasii including WLORs, fluorescent Pseudomonads isolated from oyster mushroom, P. agarici, P. gingeri, and some of other species of Psedomonas showed that some of the tested bacteria do not have any hybridized band and others have bands sowing RFLP. The cloned DNA fragment or its nucleotide sequence will be useful in detection and identification of the P. tolaasii.

• BMB Reports
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• 제57권2호
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• pp.86-91
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• 2024

The fatty acids content of castor (Ricinus communis L.) seed oil is 80-90% ricinoleic acid, which is a hydroxy fatty acid (HFA). The structures and functional groups of HFAs are different from those of common fatty acids and are useful for various industrial applications. However, castor seeds contain the toxin ricin and an allergenic protein, which limit their cultivation. Accordingly, many researchers are conducting studies to enhance the production of HFAs in Arabidopsis thaliana, a model plant for oil crops. Oleate 12-hydroxylase from castor (RcFAH12), which synthesizes HFA (18:1-OH), was transformed into an Arabidopsis fae1 mutant, resulting in the CL37 line producing a maximum of 17% HFA content. In addition, castor phospholipid:diacylglycerol acyltransferase 1-2 (RcPDAT1-2), which catalyzes the production of triacylglycerol by transferring HFA from phosphatidylcholine to diacylglycerol, was transformed into the CL37 line to develop a P327 line that produces 25% HFA. In this study, we investigated changes in HFA content when endogenous Arabidopsis PDAT1 (AtPDAT1) of the P327 line was edited using the CRISPR/Cas9 technique. The successful mutation resulted in three independent lines with different mutation patterns, which were transmitted until the T4 generation. Fatty acid analysis of the seeds showed that HFA content decreased in all three mutant lines. These findings indicate that AtPDAT1 as well as RcPDAT1-2 in the P327 line are involved in transferring and increasing HFAs to triacylglycerol.