• BMB Reports
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• 제53권12호
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• pp.611-621
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• 2020

Bacterial endoribonuclease toxins belong to a protein family that inhibits bacterial growth by degrading mRNA or rRNA sequences. The toxin genes are organized in pairs with its cognate antitoxins in the chromosome and thus the activities of the toxins are antagonized by antitoxin proteins or RNAs during active translation. In response to a variety of cellular stresses, the endoribonuclease toxins appear to be released from antitoxin molecules via proteolytic cleavage of antitoxin proteins or preferential degradation of antitoxin RNAs and cleave a diverse range of mRNA or rRNA sequences in a sequence-specific or codon-specific manner, resulting in various biological phenomena such as antibiotic tolerance and persister cell formation. Given that substrate specificity of each endoribonuclease toxin is determined by its structure and the composition of active site residues, we summarize the biology, structure, and substrate specificity of the updated bacterial endoribonuclease toxins.

• Animal Bioscience
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• 제34권3_spc호
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• pp.345-353
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• 2021

Phytobiotics, also known as phytochemicals or phytogenics, have a wide variety of biological activities and have recently emerged as alternatives to synthetic antibiotic growth promoters. Numerous studies have reported the growth-promoting effects of phytobiotics in chickens, but their precise mechanism of action is yet to be elucidated. Phytobiotics are traditionally known for their antioxidant activity. However, extensive investigations have shown that these compounds also have anti-inflammatory, antimicrobial, and transcription-modulating effects. Phytobiotics are non-nutritive constituents, and their bioavailability is low. Nonetheless, their beneficial effects have been observed in several tissues or organs. The health benefits of the ingestion of phytobiotics are attributed to their antioxidant activity. However, several studies have revealed that not all these benefits could be explained by the antioxidant effects alone. In this review, I focused on the bioavailability of phytobiotics and the possible mechanisms underlying their overall effects on intestinal barrier functions, inflammatory status, gut microbiota, systemic inflammation, and metabolism, rather than the specific effects of each compound. I also discuss the possible mechanisms by which phytobiotics contribute to growth promotion in chickens.

• Journal of Microbiology and Biotechnology
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• 제18권10호
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• pp.1621-1629
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• 2008

Harmful algal blooms (HABs), commonly called red tides, are caused by some toxic phytoplanktons, and have made massive economic losses as well as marine environmental disturbances. As an effective and environment-friendly strategy to control HAB outbreaks, biological methods using marine bacteria capable of killing the harmful algae or algicidal extracellular compounds from them have been given attention. A new member of the $\gamma$-Proteobacteria, Hahella chejuensis KCTC 2396, was originally isolated from the Korean seashore for its ability to secrete industrially useful polysaccharides, and was characterized to produce a red pigment. This pigment later was identified as an alkaloid compound, prodigiosin. During the past several decades, prodigiosin has been extensively studied for its medical potential as immunosuppressants and antitumor agents, owing to its antibiotic and cytotoxic activities. The lytic activity of this marvelous molecule against Cochlodinium polykrikoides cells at very low concentrations ($\sim$l ppb) was serendipitously detected, making H. chejuensis a strong candidate among the biological agents for HAB control. This review provides a brief overview of algicidal marine bacteria and their products, and describes in detail the algicidal characteristics, biosynthetic process, and genetic regulation of prodigiosin as a model among the compounds active against red-tide organisms from the biochemical and genetic viewpoints.

• Mycobiology
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• 제40권1호
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• pp.59-65
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• 2012

Antagonistic microorganisms against $Rhizoctonia$ $solani$ were isolated and their antifungal activities were investigated. Two hundred sixteen bacterial isolates were isolated from various soil samples and 19 isolates were found to antagonize the selected plant pathogenic fungi with varying degrees. Among them, isolate C9 was selected as an antagonistic microorganism with potential for use in further studies. Treatment with the selected isolate C9 resulted in significantly reduced incidence of stem-segment colonization by $R.$ $solani$ AG2-2(IV) in Zoysia grass and enhanced growth of grass. Through its biochemical, physiological, and 16S rDNA characteristics, the selected bacterium was identified as $Bacillus$ $subtilis$ subsp. $subtilis$. Mannitol (1%) and soytone (1%) were found to be the best carbon and nitrogen sources, respectively, for use in antibiotic production. An antibiotic compound, designated as DG4, was separated and purified from ethyl acetate extract of the culture broth of isolate C9. On the basis of spectral data, including proton nuclear magneric resonance ($^1H$ NMR), carbon nuclear magneric resonance ($^{13}C$ NMR), and mass analyses, its chemical structure was established as a stereoisomer of acetylbutanediol. Application of the ethyl acetate extract of isolate C9 to several plant pathogens resulted in dose-dependent inhibition. Treatment with the purified compound (an isomer of acetylbuanediol) resulted in significantly inhibited growth of tested pathogens. The cell free culture supernatant of isolate C9 showed a chitinase effect on chitin medium. Results from the present study demonstrated the significant potential of the purified compound from isolate C9 for use as a biocontrol agent as well as a plant growth promoter with the ability to trigger induced systemic resistance of plants.

• 한국균학회지
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• 18권2호
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• pp.96-101
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• 1990

양송이 주요병해인 마이코곤병(M. perniciosa)의 생물적방제를 위한 항균성 미생물을 선발하기 위하여 실시한 시험 결과를 요약하면 다음과 같다. 1. 미생물의 분리는 Starch casein, Soybean meal, Oat meal 배지에서 균집락 형성과 균집락의 특성이 다른 배지 보다 빠르며, 다양한 미생물의 분리가 용이하였다. 2. 실내시험에서 사상균 91, 세균 342, 방사선균 556균주의 미생물을 분리 선발한 후 Oat meal 배지에서 대치배양하여 항균력이 높은 세균 12, 방사선균 71균주를 선발하였다. 3.실내에서 항균력이 있는 균주에 대해 실시한 1차 포장시험에서 5개 균주가 수량 및 항균력이 우수하였으며, 확인시험에서는 AJ-117, AJ-136, AK-139의3균주가 뚜렷한 항균력이 있었다.

• 미생물학회지
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• 제48권4호
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• pp.270-274
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• 2012

토양시료로부터 광범위한 항생작용을 보이는 방선균 3개 균주를 분리하여 그 특성을 조사하였다. 분리주의 16S rRNA 유전자 염기서열 비교 분석을 통해 3개 분리주는 모두 Streptomyces 속에 속하고, S. tanashiensis, S. nashivillensis 및 S. rubiginosohelvolus와 근연 관계에 있는 것으로 나타났으나 독립적인 계통을 형성하여 신종으로서의 가능성을 보여주었다. 항균활성 검정 결과 세 균주는 Bacillus subtilis, Staphylococcus aureus 등의 그람 양성세균, Salmonella typhi, Enterobacter cloacae, Serratia marcescens, Pseudomonas aeruginosa 등의 그람 음성 세균, 그리고 Candida tropicalis 및 Candida krusei 등의 진균류에 대해 각각 서로 다른 길항작용을 보였다. 또한 세 균주 간에는 생리학적 활성에도 차이가 나타나 각 균주가 서로 다른 항생물질을 분비할 가능성이 있음을 보여주었다.

• 대한한방내과학회지
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• 제34권3호
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• pp.278-288
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• 2013

Objectives : Methicillin-resistant Staphylococcus aureus (MRSA) has a cephalosporin and beta-lactam antibiotic-resistant strains. MRSA is one of the major pathogens causing hospital infection and the isolation ratio of MRSA has gradually increased. Consequently, increased resistance to antibiotics is causing serious problems in the world. Therefore, there is a need to develop alternative antimicrobial drugs for the treatment of infectious diseases. Methods : The antibacterial activities of Ipyo-san were evaluated against 2 strains of MRSA and 1 standard Methicillin-susceptible staphylococcus aureus (MSSA) strain by using the disc diffusion method, minimal inhibitory concentrations (MIC) assay, colorimetric assay using MTT test, checkerboard dilution test and time-kill assay performed under dark. Results : The MIC of Ipyo-san water extract against S. aureus strains ranged from 1000 to $2,000{\mu}g/ml$, so we confirmed that it had a strong antibacterial effect. Also, the combinations of Ipyo-san water extract and conventional antibiotics exhibited improved inhibition of MRSA with synergy effect. We suggest that Ipyo-san water extract against MRSA has antibacterial activity so it has potential as alternatives to antibiotic agents. For the combination test, we used Triton X-100 (TX) and DCCD for measurement of membrane permeability and inhibitor of ATPase. As a result, antimicrobial activity of Ipyo-san water extract was affected by the cell membrane. Conclusions : We suggest that the Ipyo-san water extract lead the treatment of bacterial infection to solve the resistance and remaining side-effect problems that are the major weak points of traditional antibiotics.

• 한국미생물·생명공학회지
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• 제3권2호
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• pp.69-72
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• 1975

어유에 대하여 독작용을 나타내는 본 물질의 항생작용, succinic dehydrogenase 활성에 대한 조해작용 및 가토의 혈구에 미치는 영향 등에 대한 실험결과는 Candida japonica에서 $GI_{50}$ (세포생육의 50% 조해농도)이 7.5ug/ml, C. utilis에서 10.2ug/ml, Cryptococcus neoformans 6.4ug/ml 등으로서 극히 일부의 균에서만 항균작용이 인정되었으나 전반적으로 균에 대한 항생작용이 인정되지 않았다. 또 Cyprinus carpio L.의 각 조직에 대한 succinic dehydrogenas 활성조해능을 측정한 결과 비교적 전 장기조직에서 그 활성을 조해하였으며 특히 아가미 조직에 대한 조해현상은 흥미있는 일이다. 또 가토의 혈액에 leukopenia및 leukocytosis 현상의 여부 등을 알고저 본 물질을 유맥주사후 혈구변화도를 검토해 보았으나 별로 영향을 나타내지 않았으며 neutropenia 및 Iymphopenia 현상도 일어나지 않았다.

• 한국미생물·생명공학회지
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• 제21권1호
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• pp.41-46
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• 1993

순수분리된 2,000여 주의 혐기성 세균으로부터 선발된 stain KH-431은 bacteria 및 fungi에 대하여 재현성있는 항균활성을 보이는 물질을 생산하였다. Strain KH-431은 그 형태 및 생리, 생화학적 특성으로 미루어 보아 Clostridium fallax의 근연종으로 동정되었다. strain KH-431의 항생물질 생산을 위한 최적 배양조건에 대해 고찰한 결과 PY배지를 기초배지로 사용하고 sorbitol, yeast extract, d-biotin 그리고 $CaCl_2$를 영양원으로 첨가하였을 때가 양호한 것으로 나타났다. 배지초기 pH 및 배양온도 배양시간에 대한 최적조건은 각각 pH7과 $30^{\circ}C$, 108시간으로 나타났다.20$\ell$ 의 배양액으로부터 solvent extraction, silica gel column chromatography를 거쳐 얻은 sample을 재결정한 결과 KG-431B는 순수한 결정상태로 얻어졌으나 KG-431A의 완전정제에는 많은 문제점이 뒤따른 바 현재 다른 정제방법의 도입을 고려중에 있다.

• 한국동물위생학회지
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• 제33권2호
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• pp.177-183
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• 2010

This study was conducted to investigate the antibiotic effects of bee venom (Apis mellifera) on the growth performance and blood characteristics in broiler chicken. 1-day-old broiler chicks were randomly divided into 3 groups with 3 replicates of 5,000 birds each. The treatments were control without antibiotic and bee venom, 0.5ppm or 1ppm bee venom. The final body weight and body weight gain were significantly higher in bee venom than control (P<0.05). The feed conversion ratio in all treated groups were significantly improved as compared to that of control (P<0.05). No significant differences among the groups were observed in the contents of total cholesterol, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total protein, albumin and globulin in blood serum. The white blood cell, red blood cell, heterophil, lymphocyte, and stress indicator (heterophil:lymphocyte rate) were not significantly different among the groups. The superoxide dismutase-like activities in the groups that were water containing bee venom were significantly increased compared to those in the control group (P<0.05). It has been suggested that bee venom promotes the growth of broilers without any negative effect when added in broiler water.