• 농업과학연구
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• 제44권2호
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• pp.181-187
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• 2017

The use of practical management factors to maximize pig health improvement cannot guarantee freedom from diseases. Moreover, because of health safety concerns, the use of antibiotics has been restricted in livestock, including pigs. Therefore, the swine industry has been looking for various alternatives to antibiotics to improve pig's health and performance. Clay is a dietary factor generally accepted for improving pig health. It is a naturally occurring material and is primarily composed of fine-grained minerals. It has a specific structure with polar attraction. Because of this structure, clay has the ability to lose or gain water reversibly. In addition, clay has beneficial physiological activities. First, clay has anti-diarrheic and antibacterial effects by penetrating the cell wall of bacteria or inhibiting their metabolism. Second, it can protect the intestinal tract by absorbing toxins, bacteria, or even viruses. When added to the diet, clay has also been known to bind some mycotoxins, which are toxic secondary metabolites produced by fungi, namely in cereal grains. Those beneficial effects of clay can improve pigs' health and performance by reducing pathogenic bacteria, especially pathogenic Escherichia coli, in the intestinal tract. Therefore, it is suggested that clay has a remarkable potential as an antibiotics alternative.

• Asian-Australasian Journal of Animal Sciences
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• 제6권3호
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• pp.441-445
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• 1993

Ten bacteriocin-producing Enterococcus faecium strains with urease activity ($1.10-6.2nkat.mL^{-1}$) were isolated from the rumen of 2-8 weeks old calves. All strains were resistant aginst disodium arsenate at a minimal inhibition concentration - MIC $5g.L^{-1}$ and mercury chloride ($MIC=10-20mg.L^{-1}$). Eight strains were resistant against silver nitrate ($MIC=40-50mg.L^{-1}$) and three against antibiotics used. The resistance against six antibiotics was found in A23 strain. Values of adherence index ranged from 5.02 to 20.4 enterococci adhered per one epithelial cell of rumen wall. All isolates produced bacteriocins which inhibited the growth at least of one of five indicator organisms. The EF1 strain with a good affinity to the epithelial cell ($15.2{\pm}1.2$) produced bacteriocin substance with antimicrobial activity against grampositive and gramnegative indicator bacteria.

• Current Research on Agriculture and Life Sciences
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• 제1권
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• pp.47-53
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• 1983

A strain of Alcaligenes sp. Isolated from the sludge of industrial area was found to uptake 24.1 mg lead/g dried cell during incubation in medium containing 100g/ml of lead. Analyses of cellular subfractions reveal that fractions of cell wall contain 88.6 percent of lead found associated with the cells and the remainder is found associated with the cytoplasmic fraction. Ultrastructural examination of the cells cultured in media containing 500 and 1000g/ml of lead showed no major irregularities between cells of the treated and untreated cultures.

• 한국미생물·생명공학회지
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• 제4권3호
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• pp.111-115
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• 1976

자연계에서 카드뮴 내성균을 142주 분리하여 그 중 1,500 ppm의 카드뮴 함유배지에서 가장 잘 증식하는 1주를 선발하여 Enterobater cloacae로 동정하였다. 본균은 배지중 카드뮴의 농도가 높아질수록 생장이 억제되었으며 0.5ppm의 카드뮴 함유 배지에서 최고 59%의 카드뮴을 균체내에 축적하였다. 카드뮴의 축적량은 균체의 건물양에 비례하여 균체 건물 1g당 7.8 mg이었으며 균체내 축적된 카드뮴은 60-70%가 세포벽획분에 존재하였다.

• 한국식품영양과학회지
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• 제34권5호
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• pp.581-585
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• 2005

김치의 발효와 숙성 에 관여하는 2종의 유산균과 3종의 유제품으로부터 분리된 유산균을 Caco-2 세포 부착성과 $AFB_1$ 흡착능에 대해 비교 검토하여 보았다. 또한 유산균을 생균군, 열처리군, 강산처리군으로 나누어 유산균의 부착성 및 흡착력이 세포벽의 구조와 관련이 있다는 보고를 재확인하고자 하였다. L. plantarum KCTC 3099의 경우 Caco-2 세포 부착성이나 $AFB_1$ 흡착능이 높게 나타났으며 이것은 양성 대조군으로 사용된 L. rhamnosus GG와 유사한 수준을 나타내었다. 하지만 L. mesenteroides KCTC 3001은 Caco-2 부착성은 다소 높게 나타났으나 $AFB_1$ 흡착능은 낮게 나타났다. 이것은 Caco-2세포에 결합하는 부위와 $AFB_1$에 결합하는 부위가 일치하지는 않는다는 것을 암시하는 것으로 사료된다. 또한 유산균의 처리방법에 따라서도 다양한 차이를 보였는데 본 실험에서는 강산처리군의 경우 보다 효과적인 것으로 나타났으며 세포벽의 주된 구조인 peptidoglycan과 polysaccharides이 강산의 처리에 의해 결합이 파괴되면서 Caco2 세포 부착성이나 $AFB_1$ 흡착능의 상승에 영향을 미쳤으리라 여겨진다. 하지만 강산처리에 의한 세포벽의 변화는 비특이적으로 발생하기 때문에 동일한 형태로 모든 유산균에 적용 되기는 어려울 것이며 각 유산균종의 세포벽 구조와 특이 성분의 함량에 따라 다양하게 변화가 일어날 것으로 사료된다.

• Journal of Ginseng Research
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• 제24권3호
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• pp.107-112
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• 2000

적변삼 표피조직의 적갈색의 침적물은 강력한 산화제에 의해서만 산화(탈색)되는 chelation power가 매우 큰 화학결합을 형성하고 있었다. CLSM으로 관찰한 결과, 적변삼 조직의바깥쪽으로 두껍게 침적물이 형성되어 있음이 확인되었으며, 조직의 형광강도를 이용하여 두께를 측정한 결과 약 120rm의 침적물이 축적되어 있음이 확인되었다. 또한 Spectrum분석 결과 적변삼 표피의 물질은 건강삼의 표피조직과는 다른 functional group을 포함하는 것으로 확인되었다. 건강삼과 적변삼의 표피조직을 강산과 강염으로 가수분해 하여도 조직에 침적되어 있는 적색의 물질은 용출되지 않았다. 적변삼과 건강삼의 표피조직과 뿌리의 각 부위별 총 페놀성화합물의 함량을 측정한 결과, 건강삼의 표피조직에서 가장 높게 나타났다. 이러한 결과는 페놀성 물질이 적변물질의 원인이 된다는 보고와 차이가 있는 것으로 페놀성 물질은 적변현상 유발의 직접적인 원인물질이 아님이 확인되었다. 따라서 인삼의 적변물질은 인삼뿌리의 유기성분(세포벽 분해산물, 세포내용물, azodicarbonamide 등)과 철이온 복합체로 추론되며, 이물질에 대한 계속적인 추적을 진행하고 있다.

• The Korean Journal of Physiology and Pharmacology
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• 제13권1호
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• pp.39-47
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• 2009

Gaegurin 4(GGN 4), an antimicrobial peptide isolated from a Korean frog, is five times more potent against Gram-positive than Gram-negative bacteria, but has little hemolytic activity. To understand the mechanism of such cell selectivity, we examined GGN4-induced $K^+$ efflux from target cells, and membrane conductances in planar lipid bilayers. The $K^+$ efflux from Gram-positive M. luteus(2.5 ${\mu}g/ml$) was faster and larger than that from Gram-negative E. coli(75 ${\mu}g/ml$), while that from RBC was negligible even at higher concentration(100 ${\mu}g/ml$). GGN4 induced larger conductances in the planar bilayers which were formed with lipids extracted from Gram-positive B. subtilis than in those from E. coli(p<0.01), however, the effects of GGN4 were not selective in the bilayers formed with lipids from E. coli and red blood cells. Addition of an acidic phospholipid, phosphatidylserine to planar bilayers increased the GGN4-induced membrane conductance(p<0.05), but addition of phosphatidylcholine or cholesterol reduced it(p<0.05). Transmission electron microscopy revealed that GGN4 induced pore-like damages in M. luteus and dis-layering damages on the outer wall of E. coli. Taken together, the present results indicate that the selectivity of GGN4 toward Gram-positive over Gram-negative bacteria is due to negative surface charges, and interaction of GGN4 with outer walls. The selectivity toward bacteria over RBC is due to the presence of phosphatidylcholine and cholesterol, and the trans-bilayer lipid asymmetry in RBC. The results suggest that design of selective antimicrobial peptides should be based on the composition and topology of membrane lipids in the target cells.

• Nutrition Research and Practice
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• 제6권3호
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• pp.187-194
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• 2012

In this study, the antibacterial effect was evaluated to determine the benefits of high speed drying (HSD) and far-infrared radiation drying (FIR) compared to the freeze drying (FD) method. Citrus press-cakes (CPCs) are released as a by-product in the citrus processing industry. Previous studies have shown that the HSD and FIR drying methods are much more economical for drying time and mass drying than those of FD, even though FD is the most qualified drying method. The disk diffusion assay was conducted, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined with methanol extracts of the dried CPCs against 11 fish and five food-related pathogenic bacteria. The disk diffusion results indicated that the CPCs dried by HSD, FIR, and FD prevented growth of all tested bacteria almost identically. The MIC and MBC results showed a range from 0.5-8.0 mg/mL and 1.0-16.0 mg/mL respectively. Scanning electron microscopy indicated that the extracts changed the morphology of the bacteria cell wall, leading to destruction. These results suggest that CPCs dried by HSD and FIR showed strong antibacterial activity against pathogenic bacteria and are more useful drying methods than that of the classic FD method in CPCs utilization.

• 미생물학회지
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• 제23권4호
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• pp.265-270
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• 1985

Brevibacterium flavum과 Corllnebac ter ium glutamicum세포로부터의 원형질쳐l 형성과정, 형성된 원형질체의 미세구조, 이들 원형질체간의 융합 및 세포벽 재생을 투과전자현미경을 사용하여 관찰하였다. 원형질쳐1의 형성과 정은 특이하게 관찰되었다. 즉, penicillin G와 lysozyme의 작용을 받아 세포벽의 한 부위가 파괴되어 생긴 細孔응 통하여 원형질이 빠져나가 구형의 원형질체를 형성하였닥 융합과정에서는 원형질체들이 서로 접촉하여 접촉부꾀 를 형성하고 이어서 이 부위의 셰포막이 얼부 소실되며 양 원형질쳐1간에 내부의 울질들이 이동하였다 융합 원 행질체들은 비융합 원형질체에 비하여 세포벽의 재생이 다소 더디게 일어나는 것으로 관찰되었으며, 융합 원형질 쳐l들이 비융합 원형질체들 보다 그 크기가 월등히 컸다.

• Journal of Microbiology and Biotechnology
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• 제19권9호
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• pp.932-945
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• 2009

Several species of Gram-positive bacteria have cell wall peptidoglycan (syn. murein) in which not all of the sugar moieties are N-acetylated. This has recently been shown to be a secondary effect, caused by the action of a peptidoglycan N-acetylglucosamine deacetylase. We have found that the opportunistic pathogen Listeria monocytogenes is unusual in having three enzymes with such activity, two of which remain in the cytoplasm. Here, we examine the enzyme (PgdA) that crosses the cytoplasmic membrane and is localized in the cell wall. We purified a hexa-His-tagged form of PgdA to study its activity and constructed a mutant devoid of functional Lmo0415 (PgdA) protein. L. monocytogenes PgdA protein exhibited peptidoglycan N-acetylglucosamine deacetylase activity with natural substrates (peptidoglycan) from both L. monocytogenes and Escherichia coli as well as the peptidoglycan sugar chain component N-acetylglucosamine, but not with N-acetylmuramic acid. As was reported recently [6], inactivation of the structural gene was not lethal for L. monocytogenes nor did it affect growth rate or morphology of the cells. However, the pgdA mutant was more prone to autolysis induced by such agents as Triton X-100 and EDTA, and is more susceptible to the cationic antimicrobial peptides (CAMP) lysozyme and mutanolysin, using either peptidoglycan muramidases or autolysis-inducing agents. The pgdA mutant was also slightly more susceptible than the wild-type strain to the action of certain beta-lactam antibiotics. Our results indicate that protein PgdA plays a protective physiological role for listerial cells.