• Journal of Species Research
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• 제12권spc2호
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• pp.23-32
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• 2023

During screening for indigenous prokaryotic species in Republic of Korea in 2021, a total of 21 bacterial strains assigned to the phylum Bacteroidota were isolated from a variety of environmental habitats including pine cone, seaweed, soil, sea sediment, brackish water and moss. Based on the 16S rRNA gene sequence similarity value of more than 98.7% and formation of a robust phylogenetic clade with the type strain of the closest bacterial species, it was found that the 21 strains belong to independent and recognized bacterial species. There has been no official report that the identified 21 species have been isolated in Republic of Korea up to date. Therefore, 16 species in six genera of two families in the order Flavobacteriales, two species in two genera of two families in the order Cytophagales, one species in one genus of one family in the order Chitinophagales and two species in one genus of one family in the order Sphingobacteriales are proposed as unrecorded species of the phylum Bacteroidota isolated in Republic of Korea. Their Gram reaction, colony and cell morphology, basic phenotypic characteristics, isolation source, taxonomic status, strain ID and other information are described in the species descriptions.

• 한국약용작물학회지
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• 제13권4호
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• pp.182-185
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• 2005

사람들의 생명연장과 각종 만성질환, 악성종양 등의 증가에 따른 우수한 항생제의 계속적인 개발로 많은 생명을 구할 수 있게 되었지만 반면 항생제를 지나치게 사용하여 이에 많은 부작용이 생기고 내성균도 많아지면서 중증감염이 증가되어 여러 가지의 새로운 문제점에 직면하게 되었다. 안전성이 있는 새로운 항균물질의 개발 목적으로 예비 검색 결과 선택된 독활을 추출하여 컬럼 크로마토그래피를 반복 수행한 결과 2종의 항균 효과를 보여주는 화합물을 분리하였다 이들 화합물은 물리 화학적 성질 및 분광학적 분석을 통하여 화합물 1은 mp가 $166{\sim}167^{\circ}C$인 백색침상, $C_{20}H_{30}O_2$의 분자식을 갖는 (-)-pimara-8(14), 15-dien-19-oic acid 즉, continentalic acld으로 동정하였으며, 화합물 2는 mp가 $164{\sim}165^{\circ}C$인 백색침상, $C_{29}H_{48}O$의 분자식을 갖는 $(24E)-stigmasta-5,\;22-dien-3{\beta}-ol$, 즉 stigmasterol으로 동정하였으며 항균효과를 측정한 결과 두 화합물 모두 유의성 있는 결과를 나타내었으며, 이 중 화합물 1인 continentalic acid이 더욱 우수한 활성을 나타내었다. 특히 그람 양성균인 S. aureus에서 MIC가 $7.8\;{\mu}g/ml$, E. faecalis에서는 MIC가 $12.5\;{\mu}g/ml$에서 비교적 강한 억제 효과를 보였으며, 화합물 2에서는 S. aureus에서 MIC가 $7.8\;{\mu}g/ml$, S. epidemidis에서는 MIC가 $12.5\;{\mu}g/ml$에서 억제 효과를 보여 주었으나 그람 음성균에서 $100\;{\mu}g/ml$ 이상으로 항균활성이 측정되지 않았다. 따라서 화합물 1과 화합물 2는 그람 양성균에 대한 새로운 항균제로 개발에 유용한 화합물이 될 것으로 기대된다.

• 대한약침학회지
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• 제20권2호
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• pp.119-126
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• 2017

Objectives: Semecarpus anacardium Linn. is a plant well-known for its antimicrobial, antidiabetic and anti-arthritic properties in the Ayurvedic and Siddha system of medicine. This has prompted the screening of this plant for antibacterial activity. The main aims of this study were to isolate compounds from the plant's seeds and to evaluate their antibacterial effects on clinical bacterial test strains. Methods: The n-butanolic concentrate of the seed extract was subjected to thin layer chromatography (TLC) and repeated silica gel column chromatography followed by elution with various solvents. The compound was identified based on observed spectral (IR, $^1H$ NMR, $^{13}C$ NMR and high-resolution mass spectrometry) data. The well diffusion method was employed to evaluate the antibacterial activities of the isolated acyclic isoprenoid compound (final concentration: $5-15{\mu}g/mL$) on four test bacterial strains, namely, Staphylococcus aureus (MTCC 96), Bacillus cereus (MTCC 430), Escherichia coli (MTCC 1689) and Acinetobacter baumannii (MTCC 9829). Results: Extensive spectroscopic studies showed the structure of the isolated compound to be an acyclic isoprenoid ($C_{21}H_{32}O$). Moreover, the isoprenoid showed a remarkable inhibition of bacterial growth at a concentration of $15{\mu}g/mL$ compared to the two other doses tested (5 and $10{\mu}g/mL$) and to tetracycline, a commercially available antibiotic that was used as a reference drug. Conclusion: The isolation of an antimicrobial compound from Semecarpus anacardium seeds validates the use of this plant in the treatment of infections. The isolated compound found to be active in this study could be useful for the development of new antimicrobial drugs.

• 한국치위생학회지
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• 제18권5호
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• pp.843-852
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• 2018

Objectives: The study aimed to isolate the abundant bacteria in dental caries in children and to investigate the bacterial species involved in addition to those that have been previously reported. Methods: The specimens were collected from the supragingival plaques of each dental caries area, pit and fissure caries, deep dentinal caries, smooth surface caries, and dental caries, and from healthy subjects in the control group. Bacteria were cultured from these specimens, DNA was extracted from the isolated bacteria, and the 16S rRNA gene sequences were analyzed and identified. Results: Based on the results of the 16S rRNA gene sequence analysis for the 90 strains of dominant bacteria from the 45 specimens, 5, 7, 8, 7, and 13 species were identified from the supragingival plaques from healthy teeth, pit and fissure caries, deep dentinal caries, smooth surface caries, and dental caries, respectively. In healthy teeth, Actinomyces naeslundii dominated. Corynebacterium durum, Ralstonia pickettii, and Streptococcus intermedius showed equal distribution. The dominant bacterial species in dental caries, S. sanguinis, showed the greatest difference in prevalence in pit and fissure caries. In deep dentinal caries, S. mutans and Lactobacillus rhamnosus were dominant; in smooth surface caries, S. mutans and S. sanguinis were dominant; and in the supragingival plaques of dental caries, S. sanguinis and S. mutans were dominant. Conclusions: The bacterial species isolated from dental caries encompassed four phyla, eight genera, and 22 species. In addition, the SS1-2 strain, belonging to the genus Neisseria, was identified as a new species from among the isolated strains.

• 상하수도학회지
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• 제22권2호
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• pp.205-212
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• 2008

This study aimed to investigate the biofilm formation, bacterial regrowth, and bacterial community structure in the granular-activated carbon (GAC) filter adsorbers (FAs) used in water treatment plants. In 2005 and 2006, raw water, settled water, GAC FA by depth, and filtered water were collected twice a year from water treatment plants (WTPs) B and S. The number of heterotrophic bacteria, including mesophilic and psychrophilic bacteria, in such collected waters was investigated along with the total number of coliforms therein. Heterotrophic bacteria were detected in most samples, mainly at the surface layers of the GAC FAs, and fewer such bacteria were found in the lower and bottom layers. An increase in the bacterial number, however, was observed in the samples from various depths of the GAC FAs in WTPs B and S compared with the surface layers. An increase in the bacterial number was also detected in the filtered water. This may indicate that there is a regrowth of the bacteria in the GAC FA. Considering, however, that heterotrophic bacteria were not found in the filtered water, it can be deduced that most bacteria are removed in the chlorination process. Coliforms were detected at the surface layer of the GAC FAs, but their regrowth was not observed. MicroLog systems were used to identify the bacteria community distribution. Eight genera and 14 species, including Pseudomonas spp., were detected in WTP B, and 8 genera and 9 species, including Aeromonas spp., in WTP S. Further studies are required to elucidate their role in the biofilms in water treatment processes.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.95.2-96
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• 2003

In order to develop a new microbial fungicide for the control of vegetable diseases using endophytic bacteria, a total of 260 bacterial strains were isolated from fresh tissues of 5 plant species. After they were cultured in broth media, their antifungal activities were screened by in vivo bioassays against Botrytis cinerea(tomato gray mold), Pythium ultimum(cucumber damping-off), Phytopkhora infestans(tomato late blight), Colletotrichum orbiculare(cucumber anthracnose), and Blumeria graminis f. sp. hordei(barley powdery mildew). As the results of screening, 38 bacterial strains showed potent antifungal activities against at least one of 5 plant pathogens. A bacterial strain EB072 displayed potent disease control activities against 3 plant diseases. Among the bacterial strains with a potent antifungal activity against cucunlber anthracnose, three bacterial strains, EB054, EB151 and EB215, also displayed a potent in vitro antifungal activity against C. acutatum, a fungal agent causing pepper anthracnose. A bacterial strain EB215 obtained from roots of cucumber was identified as Burkholderia cepacia based on its physiological and biochemical characteristics and 165 rRNA gene sequence. An antifungal substance was isolated from the liquid cultures of B. cepacia EB215 strain by ethyl acetate partitioning, repeated silica gel column chromatography, and invitro bioassay, Its structural determination is in progress by various instrumental analyses.

• 한국수산과학회지
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• 제47권1호
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• pp.45-51
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• 2014

Scuticociliates are regarded as serious pathogens in marine aquaculture worldwide. In Korea, they cause mass-mortalities in fish such as the commercially important olive flounder Paralichthys olivaceus. In particular, mixed infections of scuticociliates with pathogenic bacteria have been commonly reported. During efforts to identify natural marine-algae derived products that possess anti-bacterial and anti-scuticociliate properties, we found that an 80% methanolic extract of the red alga Polysiphonia morrowii Harvey exhibits both anti-scuticociliate activity against Miamiensis avidus, which is a major causative agent of scuticociliatosis, and anti-bacterial activities against fish pathogenic bacteria. Activity-guided fractionation and isolation of the 80% methanolic extract of P. morrowii yielded three bromophenols, which were identified as 3-bromo-4,5-dihydroxybenzyl methyl ether (1), 3-bromo-4,5-dihydroxybenzaldehyde (2) and urceolatol (3) based on spectroscopic analyses. 3-bromo-4,5-dihydroxybenzyl methyl ether (1) showed the highest anti-bacterial and anti-scuticociliate activities, with a minimal inhibitory concentration (MIC) of $62.5{\mu}g/mL$ (against Vibrio anguillarum) and minimal lethal concentration (MLC) of 62.5 ppm (in seawater). Investigations of the anti-bacterial and anti-scuticociliate activities of seventeen bromophenol derivatives, including the three isolated natural bromophenols, showed that the existence of an electron donating group or atom with a non-covalent electron pair at $C_4$ of the 2-bromophenol structure may be important in anti-scuticociliate activity. These findings suggest that the extract and bromophenol derivatives of P. morrowii may provide useful alternatives in aquaculture anti-scuticociliate therapies.

• Journal of Species Research
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• 제7권1호
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• pp.13-23
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• 2018

In 2016, as a part of the research program 'Survey of Korean Indigenous Species', diverse environmental samples were collected from various sources of freshwater, seawater, soil, wetland, reclaimed land, sand, pine forest, plant root, ginseng field, solar saltern, and caves. Thousands of bacterial strains were isolated from the diverse samples and identified based on 16S rRNA gene sequence analyses. The present study, as a phylogenetic subset of the primary research program, reports 24 unrecorded bacterial species in Korea that belong to the orders Rhizobiales and Sphingomonadales in the class Alphaproteobacteria. Based on the high 16S rRNA gene sequence similarities (>98.8%) and formation of a robust phylogenetic clade with the closest type species, it was determined that each strain belonged to each independent and predefined bacterial species. There is no official report that these 24 bacterial species have been described in Korea; therefore, 10 species of nine genera in the order Rhizobiales and 14 species of seven genera in the order Sphingomonadales are described for unreported alphaproteobacterial species in Korea. Gram reaction, colony and cell morphology, biochemical properties, and isolation sources are also provided in the species description section.

• 한국미생물·생명공학회지
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• 제17권5호
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• pp.429-435
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• 1989

A bacterial strain of Brevibaterium sp. CH1 was isolated and used to produce an enzyme (nitrile hydratase) necessary for earring out the bioconversion of acrylonitrile to acrylamide. The culture and reaction conditions, and medium optimization were studied for the strain. The conversion yield was nearly 100％ with a trace amount of acrylic acid produced. The strain showed strong activity of nitrile hydratase toward acrylonitrile and extremely low activity of the amidase toward acrylamide. We sought optimum culture conditions for the formation of nitrile hydratase by Brevibacterium sp. CH1. The effects of temperature and pH on the activity of free and immobilized tells were investigated. The nitrite hydratase of Brevibacterium sp. CH1 acted not only on various aliphatic nitrites such as acrylonitrile, propionitrile and acetonitrile, but also on aromatic nitrile as nicotinonitrile.

• 한국미생물·생명공학회지
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• 제16권5호
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• pp.421-426
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• 1988

한강의 지천으로부터 채취한 시료에서 29종의 아닐린 분해 균주를 분리선발하였다. 분리 균주중 10, 균주에 대하여 동정 시험하여 본 결과 9균주는 Pseudomonas 속이었고 한 균주는 Acinetobacter 속이었다. 전체 29균주중 plasmid를 갖고 있는 균주는 모두 5종이었으며 이들 5균주중 4균주는 meta 경로를 통하여 아닐린을 분해 이용하였고 나머지 한 균주는 ortho 경로를 통하여 아닐린을 분해하였다. meta 경로 이용 균주의 하나인 Pseudomonas acidovorans 4A1은 230kb 크기의 plasmid를 갖고 있었으며, 접합실험과 curing 실험을 통하여 이 plasmid에 아닐린 분해 유전 정보가 수록되었을 가능성을 확인할 수 있었다.