• Clinical and Experimental Pediatrics
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• 제64권11호
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• pp.543-551
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• 2021

The human microbiome, which consists of a collective cluster of commensal, symbiotic, and pathogenic microorganisms living in the human body, plays a key role in host health and immunity. The human nasal cavity harbors commensal bacteria that suppress the colonization of opportunistic pathogens. However, dysbiosis of the nasal microbial community is associated with many diseases, such as acute respiratory infections including otitis media, sinusitis and bronchitis and allergic respiratory diseases including asthma. The nasopharyngeal acquisition of pneumococcus, which exists as a pathobiont in the nasal cavity, is the initial step in virtually all pneumococcal diseases. Although the factors influencing nasal colonization and elimination are not fully understood, the adhesion of opportunistic pathogens to nasopharyngeal mucosa receptors and the eliciting of immune responses in the host are implicated in addition to bacterial microbiota properties and colonization resistance dynamics. Probiotics or synbiotic interventions may show promising and effective roles in the adjunctive treatment of dysbiosis; however, more studies are needed to characterize how these interventions can be applied in clinical practice in the future.

• 한국미생물·생명공학회지
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• 제38권1호
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• pp.105-111
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• 2010

소목은 전통적으로 타박상, 염증 등의 질병치료를 위해 민간의학에서 오래 동안 사용되어 온 한약재야다. 소목의 섬재로부터 항균효과를 조사하기 위하여 MeOH 추출에 의한 hexane, $CHCl_3$, EtOAc, n-BuOH, MeOH 및 $H_2O$ 분획을 얻었다. 분획 시료 중 3.94%의 가장 높은 수율의 EtOAc 분획이 조사된 인채 병원성 세균에 대해 가장 강한 항균활성 나타냈다. 또한 EtOAc 분획의 항균활성은 Gram (-) 균주 보다 Gram (+) 균주에 더 효과적이며, Gram (-) 균주에 대해서는 세균에 따른 항균활성의 차이를 보였다. EtOAc 분획은 silica gel adsorption column chromatography 및 Sephadex LH-20을 이용하여 분리하였으며 수득한 주요 성분은 채결정을 통하여 얻어진 단일물질을 HPLC를 이용하여 순도를 측정하였다. 300g의 C. sappan으로부터 3.94%의 EtOAc 분획을 얻었으며 EtOAc분획물은 분석한 결과 10 mg에는 1.67 mg의 brazilin을 포함하였다. 분리된 활성울질은 짧은 황색 결정의 단일 화합물로 MS에 의해 분자량이 285로 나타났으며, $^1H$-NMR, $^{13}C$-NMR에 의한 구조분석으로 brazilin($C_{16}H_{14}O_5$을 동정하였다. 이 같은 결과는 소목의 MeOH 추출에 의한 EtOAc 분획에 존재하는 brazilin이 S. aureus와 같은 인체 병원성 Gram (+) 균주에 대한 생약치료제로 활용이 가능할 것을 시사한다.

• Journal of Microbiology and Biotechnology
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• 제19권2호
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• pp.204-207
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• 2009

We investigated novel antibacterial and synergistic activities of isocryptomerin isolated from Selaginella tamariscina. Isocryptomerin showed potent antibacterial activity against Gram-positive and Gram-negative bacterial strains including clinical isolates of antibiotic-resistant species such as methicillin-resistant Staphylococcus aureus(MRSA). Additionally, we further investigated the synergistic activity of isocryptomerin with a conventional antibiotic against MRSA. The result indicated that isocryptomerin had considerable synergistic activity in combination with cefotaxime. In summary, the present study suggests that isocryptomerin may have potential as a novel therapeutic agent for treatment of infectious diseases by not only human pathogenic bacteria but also multidrug-resistant bacteria.

• International Journal of Oral Biology
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• 제35권4호
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• pp.203-207
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• 2010

A number of bacterial species coexist in oral cavities as a biofilm rather than a planktonic arrangement. By forming an oral biofilm with quorum sensing properties, microorganisms can develop a higher pathogenic potential and stronger resistance to the host immune system and antibiotics. Hence, the inhibition of biofilm formation has become a major research issue for the future prevention and treatment of oral diseases. In this study, we investigated the effects of pentose on biofilm formation and phenotypic changes using wild type oral bacteria obtained from healthy human saliva. D-ribose and D-arabinose were found to inhibit biofilm formation, but have no effects on the growth of each oral bacterium tested. Pentoses may thus be good candidate biofilm inhibitors without growth-inhibition activity and be employed for the future prevention or treatment of oral diseases.

• Journal of Microbiology and Biotechnology
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• 제33권7호
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• pp.857-863
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• 2023

Pathogenic bacteria that colonize the human intestinal tract have evolved strategies to overcome acidic conditions when they pass through the gastrointestinal tract. Amino acid-mediated acid resistance systems are effective survival strategies in a stomach that is full of amino acid substrate. The amino acid antiporter, amino acid decarboxylase, and ClC chloride antiporter are all engaged in these systems, and each one plays a role in protecting against or adapting to the acidic environment. The ClC chloride antiporter, a member of the ClC channel family, eliminates negatively charged intracellular chloride ions to avoid inner membrane hyperpolarization as an electrical shunt of the acid resistance system. In this review, we will discuss the structure and function of the prokaryotic ClC chloride antiporter of amino acid-mediated acid resistance system.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권2호
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• pp.61-75
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• 2022

This study evaluated the potential threat of agricultural and human activities to groundwater in the Noseong stream watershed, a typical agricultural area, through hydrogeochemical characteristics and microbial community analyses. The groundwater in the study area was Ca-SO₄ and Ca-HCO₃ types alluvial aquifer mainly used for agricultural and living purposes, and contained high levels of NO₃^- and Cl^- ions generated from anthropogenic sources such as fertilizer, livestock wastewater, and domestic sewage. Proteobacteria was most abundant in all samples with an average of 46.1% while Actinobacteria, Bacteroidetes, and Cyanobacteria were dominant on an occasional basis. The prevalence of aerobic bacteria such as the genus Mycobacterium, Flavobacterium, and Sphingomonas suggests that groundwater was well connected with the surface layer. The potential pathogen Mycobacterium was detected in most samples, and other pathogenic bacteria were also widely distributed, indicating the vulnerability to contamination. Therefore, an integrated management system is required to secure the sustainable use of groundwater in agricultural areas with high groundwater dependence.

• Journal of Microbiology and Biotechnology
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• 제34권2호
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• pp.314-329
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• 2024

Fifteen cyclic dipeptides (CDPs) containing proline, one cyclo(Phe-Ala) without proline, and a non-peptidyl ᴅⳑ-3-phenyllactic acid were previously identified in the culture filtrates of Lactobacillus plantarum LBP-K10, an isolate from kimchi. In this study, we used Japanese quail (Coturnix japonica) eggs to examine the effects of probiotic supplementation on the antimicrobial CDPs extracted from quail eggs (QE). Eggshell-free QE were obtained from two distinct groups of quails. The first group (K10N) comprised eggs from unsupplemented quails. The second group (K10S) comprised eggs from quails supplemented with Lb. plantarum LBP-K10. The QE samples were extracted using methylene chloride through a liquid-liquid extraction process. The resulting extract was fractionated into 16 parts using semi-preparative high-performance liquid chromatography. Two fractions, Q6 and Q9, were isolated from K10S and identified as cis-cyclo(ⳑ-Ser-ⳑ-Pro) and cis-cyclo(ⳑ-Leu-ⳑ-Pro). The Q9 fraction, containing cis-cyclo(ⳑ-Leu-ⳑ-Pro), has shown significant inhibitory properties against the proliferation of highly pathogenic multidrug-resistant bacteria, as well as human-specific and phytopathogenic fungi. Some of the ten combinations between the remaining fourteen unidentified fractions and two fractions, Q6 and Q9, containing cis-cyclo(ⳑ-Ser-ⳑ-Pro) and cis-cyclo(ⳑ-Leu-ⳑ-Pro) respectively, demonstrated a significant increase in activity against multidrug-resistant bacteria only when combined with Q9. The activity was 7.17 times higher compared to a single cis-cyclo(ⳑ-Leu-ⳑ-Pro). This study presents new findings on the efficacy of proline-containing CDPs in avian eggs. These CDPs provide antimicrobial properties when specific probiotics are supplemented.

• Journal of Dairy Science and Biotechnology
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• 제34권2호
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• pp.75-82
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• 2016

Members of the genus Bifidobacterium are prevalent in the human colon and represent up to 90% of all bacteria in fecal samples of breast-fed infants, and 3~5% of adult fecal microbiota. Bifidobacteria produce organic acids, thus reducing the colon pH to a level inhibitory for pathogenic bacteria. They can also detoxify a number of toxic compounds and adhere to the colon mucosa, thus preventing the adherence of pathogens and induction of colon cancer. Recently, we identified a novel Bifidobacterium longum subsp. longum strain, KACC 91563, in a fecal sample of a Korean neonate, and demonstrated its functional properties. We showed that B. longum KACC 91563 alleviates food allergy through mast cell suppression and produces antioxidative and antihypertensive peptides by casein hydrolysis. Dairy products are considered as an ideal food system for the delivery of probiotic cultures to the human gastrointestinal tract. Cheese affords protection to probiotic microbes during gastric transit due to its relatively high pH, more solid consistency, higher fat content, and higher buffering capacity. Incorporation of B. longum KACC 91563 into cheese making is currently under study.

• The Plant Pathology Journal
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• 제33권2호
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• pp.148-162
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• 2017

As a step towards discovering novel pathogenesis-related proteins, we performed a genome scale computational identification and characterization of secreted and transmembrane (TM) proteins, which are mainly responsible for bacteria-host interactions and interactions with other bacteria, in the genomes of six representative Burkholderia species. The species comprised plant pathogens (B. glumae BGR1, B. gladioli BSR3), human pathogens (B. pseudomallei K96243, B. cepacia LO6), and plant-growth promoting endophytes (Burkholderia sp. KJ006, B. phytofirmans PsJN). The proportions of putative classically secreted proteins (CSPs) and TM proteins among the species were relatively high, up to approximately 20%. Lower proportions of putative type 3 non-classically secreted proteins (T3NCSPs) (~10%) and unclassified non-classically secreted proteins (NCSPs) (~5%) were observed. The numbers of TM proteins among the three clusters (plant pathogens, human pathogens, and endophytes) were different, while the distribution of these proteins according to the number of TM domains was conserved in which TM proteins possessing 1, 2, 4, or 12 TM domains were the dominant groups in all species. In addition, we observed conservation in the protein size distribution of the secreted protein groups among the species. There were species-specific differences in the functional characteristics of these proteins in the various groups of CSPs, T3NCSPs, and unclassified NCSPs. Furthermore, we assigned the complete sets of the conserved and unique NCSP candidates of the collected Burkholderia species using sequence similarity searching. This study could provide new insights into the relationship among plant-pathogenic, humanpathogenic, and endophytic bacteria.

• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1413-1425
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• 2018

Shiga toxins (Stxs) are the main virulence factors expressed by the pathogenic Stx-producing bacteria, namely, Shigella dysenteriae serotype 1 and certain Escherichia coli strains. These bacteria cause widespread outbreaks of bloody diarrhea (hemorrhagic colitis) that in severe cases can progress to life-threatening systemic complications, including hemolytic uremic syndrome (HUS) characterized by the acute onset of microangiopathic hemolytic anemia and kidney dysfunction. Shiga toxicosis has a distinct pathogenesis and animal models of Stx-associated HUS have allowed us to investigate this. Since these models will also be useful for developing effective countermeasures to Stx-associated HUS, it is important to have clinically relevant animal models of this disease. Multiple studies over the last few decades have shown that mice injected with purified Stxs develop some of the pathophysiological features seen in HUS patients infected with the Stx-producing bacteria. These features are also efficiently recapitulated in a non-human primate model (baboons). In addition, rats, calves, chicks, piglets, and rabbits have been used as models to study symptoms of HUS that are characteristic of each animal. These models have been very useful for testing hypotheses about how Stx induces HUS and its neurological sequelae. In this review, we describe in detail the current knowledge about the most well-studied in vivo models of Stx-induced HUS; namely, those in mice, piglets, non-human primates, and rabbits. The aim of this review is to show how each human clinical outcome-mimicking animal model can serve as an experimental tool to promote our understanding of Stx-induced pathogenesis.