• Journal of Species Research
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• 제7권3호
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• pp.231-239
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• 2018

While screening indigenous prokaryotic species in Republic of Korea in 2017, a total of 17 bacterial strains assigned to the phylum Bacteroidetes were isolated from a variety of environmental habitats including water of fountain, tidal flat, plant root, soil, the gut of Russian grayling butterfly, ginseng field, seawater, lagoon and seashore sand. From the 16S rRNA gene sequence similarity of more than 98.7% and the formation of a robust phylogenetic clade with the closest species, it was found that the 17 strains belong to independent and recognized bacterial species. There has been no official report that the identified 17 species have been previously isolated in the Republic of Korea. Thus, 15 species in 10 genera of one family in the order Flavobacteriales, one species in one genus of one family in the order Cytophagales, and one species in one genus of one family in the order Sphingobacteriales are proposed as unrecorded species of the phylum Bacteroidetes found in the Republic of Korea. Gram reaction, colony and cell morphology, basic phenotypic characteristics, isolation source, taxonomic status, strain ID and other information are described in the species descriptions.

• Journal of Species Research
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• 제9권2호
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• pp.85-104
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• 2020

In 2019, after a comprehensive investigation of indigenous prokaryotic species in Korea, a total of 12 bacterial strains assigned to the phylum Proteobacteria were isolated from soil. With the high 16S rRNA gene sequence similarity (>98.8%) and formation of a robust phylogenetic clade with the closest species, it was determined that each strain belonged to independent, predefined bacterial species. This study identified two species in the family Burkholderiaceae, one species in the family Comamonadaceae, two species in the family Oxalobacteraceae, one species in the family Micrococcaceae, one species in the family Bradyrhizobiaceae, one species in the family Methylobacteriaceae, one species in the family Rhizobiaceae, one species in the family Rhodocyclaceae, and one species in the family Sphingomonadaceae. There is no official report about these 12 species in Korea, so are described as unreported bacterial species in Korea in this study. Gram reaction, basic biochemical characteristics, colony, and cell morphology are also described in the species description section.

• The Plant Pathology Journal
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• 제27권1호
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• pp.59-67
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• 2011

A bacterial strain CH-67 which exhibits antagonism towards several plant pathogenic fungi such as Botrytis cinerea, Fulvia fulva, Rhizoctonia solani, Sclerotinia sclerotiorum, Colletotrichum sp. and Phytophthora sp. was isolated from forest soil by a chitin-baiting method. This strain was identified as Burkholderia cepacia complex (Bcc) and belonging to genomovar IX (Burkholderia pyrrocinia) by colony morphology, biochemical traits and molecular method like 16S rRNA and recA gene analysis. This strain was used to develop a bio-fungicide for the control of tomato leaf mold caused by Fulvia fulva. Various formulations of B. pyrrocinia CH-67 were prepared using fermentation cultures of the bacterium in rice oil medium. The result of pot experiments led to selection of the wettable powder formulation CH67-C containing modified starch as the best formulation for the control of tomato leaf mold. CH67-C, at 100-fold dilution, showed a control value of 85% against tomato leaf mold. Its disease control efficacy was not significantly different from that of the chemical fungicide triflumidazole. B. pyrrocinia CH-67 was also effective in controlling damping-off caused by Rhizoctonia solani PY-1 in crisphead lettuce and tomato plants. CH67-C formulation was recognized as a cell-free formulation since B. pyrrocinia CH-67 was all lethal during formulation process. This study provides an effective biocontrol formulation of biofungicide using B. pyrrocinia CH-67 to control tomato leaf mold and damping-off crisphead lettuce and tomato.

• Korean Journal of Geomatics
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• 제2권1호
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• pp.57-64
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• 2002

Measuring the depth of water is very important in ensuring the protection and safety of seaside. There are many difficulties in making the contour bathymetric map, and contour line due to the limitation of continuous measurement of water depth and collimation with the conventional measuring and positioning methods. But the real-time kinematic GPS (RTK GPS) positioning using a carrier phase enables us to decide a precise position without breaking a signal even under the condition of a moving environment. It is also possible to obtain an accurate depth of water in real time with a fathometer through the measuring of time delay between sending and receiving epochs. This research aims at investigation of accuracy potential of RTK GPS in combination with Echo Sounder(E/S) for the coastal mapping. Apart from this purpose, the accuracy of ambiguity resolution with the OTF(On the Fly) method was tested with respect to the initialization time. The result shows that the accuracy is better than 1cm with 5-minute initialization in the distance of 10km baseline. The seaside topography was measured by the RTK GPS only, on the other hand the seafloor topography was surveyed in combination of RTK GPS and E/S. Comparing to the volume of seaside measured by RTK GPS and digital topographical map, the difference of only 2 % was achieved. This indicates that the coastal mapping with RTK GPS is successfully conducted. In addition it is also demonstrated that the 3-dimensional perspective model resulted from the undersea topography measured by RTK GPS and E/S is very close to that from the digital map. Through this study, it was verified that RTK GPS is to be very useful method in the analysis of coastal morphology owing to its capability of getting the precise DTM for the using of harbor reclamation, dredging, and the estimation of soil movement in a river.

• 한국작물학회지
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• 제64권2호
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• pp.159-164
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• 2019

Weed control is a crucial practice not only in organic farming, but also in modern agriculture because it can lead to loss in crop yield. In general, weed is distributed in patches heterogeneously in the field. These patches vary in size, shape, and density. Thus, it would be efficient if chemicals are sprayed on these patches rather than spraying uniformly in the field, which can pollute the environment and be cost prohibitive. In this sense, weed detection could be beneficial for sustainable agriculture. Studies have been conducted to detect weed patches in the field using remote sensing technologies, which can be classified into a method using image segmentation based on morphology and a method with vegetative indices based on the wavelength of light. In this study, the latter methodology has been used to detect the weed patches. As a result, it was found that the vegetative indices were easier to operate as it did not need any sophisticated algorithm for differentiating weeds from crop and soil as compared to the former method. Consequently, we demonstrated that the current method of using vegetative index is accurate enough to detect weed patches, and will be useful for farmers to control weeds with minimal use of chemicals and in a more precise manner.

• Journal of Species Research
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• 제8권2호
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• pp.161-175
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• 2019

During a comprehensive investigation of indigenous prokaryotic species in Korea, a total of 46 bacterial strains assigned to the classes Alphaproteobacteria, Betaproteobacteria, Deltaproteobacteria, and Epsilonproteobacteria were isolated from a diversity of habitats including freshwater, seawater, brackish water, ginseng soil, plant roots, natural caves, and tidal flats. Based on their high 16S rRNA gene sequence similarities (>98.7%) and formation of strongly-supported phylogenetic clades with the closest type species, each strain was assigned to an independent, predefined bacterial species. Since there were no published or official reports regarding the isolation of these 46 species in Korea, here we report them as new species to Korea: 34 species in 14 families in the five orders of Alphaproteobacteria, 10 species in five families in the three orders of Betaproteobacteria, one species of Deltaproteobacteria and one species of Epsilonproteobacteria. Gram reaction, colony and cell morphology, basic biochemical characteristics, isolation source, and strain IDs are described in the species description section.

• ALGAE
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• 제37권1호
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• pp.1-14
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• 2022

Cyanobacteria are distributed worldwide, and many new cyanobacterial species are discovered in tropical region. The Nostoc-like genus Amazonocrinis has been separated from the genus Nostoc based on polyphasic methods. However, species diversity within this genus remains poorly understood systematically because only one species (Amazonocrinis nigriterrae) has been described. In this study, two novel strains (NUACC02 and NUACC03) were isolated from moist rice field soil in Thailand. These two strains were characterized using a polyphasic approach, based on morphology, 16S rRNA phylogenetic analysis, internal transcribed spacer secondary structure and ecology. Phylogenetic analyses based on 16S rRNA gene sequences confirmed that the two novel strains formed a monophyletic clade related to the genus Amazonocrinis and were distant from the type species A. nigriterrae. The 16S rRNA gene sequence similarity (<98.1%) between novel strains and all other closely related taxa including the Amazonocrinis members exceeded the cutoff for species delimitation in bacteriology, reinforcing the presence of a new Amazonocrinis species. Furthermore, the novel strains possessed unique phenotypic characteristics such as the presence of the sheath, necridia-like cells, larger cell dimension and akinete cell arrangement in long-chains and the singularity of D1-D1', Box-B, V2, and V3 secondary structures that distinguished them from other Amazonocrinis members. Considering all the results, we described our two strains as Amazonocrinis thailandica sp. nov. in accordance with the International Code of Nomenclature for Algae, Fungi and Plants.

• Journal of Ecology and Environment
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• 제47권3호
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• pp.118-133
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• 2023

Background: Free-living amoebae (FLA) are widely distributed in freshwater, seawater, soil, and extreme environments, and play a critical role as feeders on diverse preys in the ecosystem. Also, some FLA can become opportunistic pathogens in animals including humans. The taxa Amoebozoa and Heterolobosea are important amoeboid groups associated with human pathogens. However, the identification and habitat of amoebae belonging to Amoebozoa and Heterolobosea remain poorly reported in the Republic of Korea. This study highlights the first record for identification and source of four amoebae including putative pathogens in the Republic of Korea. Results: In the present study, four previously reported FLA were isolated from freshwaters in Sangju Gonggeomji Reservoir (strain GO001), one of the largest reservoirs during the Joseon Dynasty period, and along the Nakdong River, the largest river in the Republic of Korea (strains NR5-2, NR12-1, and NR14-1) for the first time. Microscopic observations and 18S rDNA phylogenetic trees revealed the four isolated strains to be Acanthamoeba polyphaga (strains NR5-2 and NR12-1), Tetramitus waccamawensis (strain GO001), and Naegleria australiensis (strain NR14-1). Strains NR5-2 and NR12-1 might be the same species and belonged to the morphological Group 2 and the T4 genotype of Acanthamoeba. Strain GO001 formed a clade with T. waccamawensis in 18S rDNA phylogeny, and showed morphological characteristics similar to previously recorded strains, although the species' flagellate form was not observed. Strain NR14-1 had the typical morphology of Naegleria and formed a strongly supported clade with previously recorded strains of N. australiensis in phylogenetic analysis of 18S rDNA sequences. Conclusions: On the bases of morphological and molecular analyses, four strains of FLA were newly observed and classified in the Republic of Korea. Three strains belonging to the two species (A. polyphaga and N. australiensis) isolated from the Nakdong River have the potential to act as opportunistic pathogens that can cause fatal diseases (i.e. granulomatous amoebic encephalitis, Acanthamoeba Keratitis, and meningoencephalitis) in animals including humans. The Nakdong River in the Republic of Korea may provide a habitat for potentially pathogenic amoebae, but additional research is required to confirm the true pathogenicity of these FLA now known in the Republic of Korea.

• 한국잡초학회지
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• 제14권1호
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• pp.62-70
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• 1994

각(各) 재배양식별(栽培樣式別)로 벼와 피의 생육특성(生育特性) 및 각부형태적(各部形態的) 진전(進展)의 변화(變化)를 알아보기 위하여 파종(播種) 및 이앙후(移秧後)(DAS/T) 1, 2, 3, 5, 7, 10, 15, 20일째에 식물체(植物體)를 굴취(堀取)하여 조사(調査)하였으며, 조사내용별(調査內容別) 결과(結果)는 다음과 같다. 1) 벼와 피의 발아(發芽) 및 입묘양상(立苗樣相)의 차이(差異) 가. 벼는 발아시(發芽時) 초엽과 유근 모두 같은 배반(胚盤)에서 출현(出現)하는데 반해 피는 그와 반대방향(反對方向)에서 출현(出現)하였다. 나. 재배양식(栽培樣式)간의 벼 입묘양상(立苗樣相)은 건답직파(乾沓直播)의 경우 지상부(地上部) 및 지하부생육(地下部生育)이 균형적(均衡的)이었으나 담수직파(湛水直派)는 지하부(地下部) 위주(爲主)의 생육(生育)이 이루어졌고 표면(表面)벼보다 토중(土中)벼의 입묘(立苗가) 더 좋았다. 2) 벼와 피의 생육특성(生育特性) 차이(差異) 가. 초기생육(初期生育)을 통한 벼와 피간의 초장차이(草長差異)는 담수직파(湛水直播)보다는 건답직파(乾沓直播)에서 더 컸고 같은 직파(直播)에서도 피가 표면(表面)벼나 토중(土中)벼보다 컸으며 이앙재배(移秧栽培)에서는 벼가 피보다 지속적으로 우위성을 유지하였다. 나. 근장(根長)은 모든 재배양식(載培樣式)에서 피가 벼보다 컸으며 벼와 피간의 근장(根長) 차이(差異)는 담수(湛水)보다 건답(乾沓)에서, 이앙(移秧)보다 직파(直播)벼에서 유의적(有意的)으로 컸다. 다. 地上部重(지상부중)은 직파(直播)의 경우 건답(乾沓짧)피가 가장 컸으며 벼와 피간(間)의 지상부(地上部) 생육중(生體重) 차이(差異)는 담수(湛水) 보다 건답(乾沓에)에서, 표면(表面)벼보다는 토중(土中)벼가, 그리고 벼보다 피가 컸으나 이앙조건(移秧條件)에서는 이앙(移秧)벼가 피보다 우위에 있었다. 라. 지상부(地下部) 생체중(生體重)은 직파(直播)의 여러 양식간(樣式間)에 차이(差異)를 보이지 않았으나 파종후(播種後) 10일(日) 이후부터 피가 벼를 능가하는 경향이었고 이앙재배(移秧栽培)에서는 벼가 피보다 지속적으로 우위에 있었다. 마. 중경장(中莖長)은 피만이 형성되었고 건답(乾沓)보다는 담수(湛水)에서, 파종(播種)깊이가 클수록 더 컸다. 바. 엽령(葉齡)은 직파재배(直播載培)에서 피가 벼보다 크고, 벼와 피간의 엽령(葉齡) 차이(差異)는 담수(湛水)보다는 건답(乾沓)에서 약간 더 컸으며 이앙재배(移秧我培)에서는 벼가 피보다 컸다. 사. 엽면적지수(葉面積指數)는 벼와 피간의 차이(差異)가 담수직파(湛水直播)보다는 건답직파(乾沓直播)에서 월등히 컸으며 이앙조건(移秧條件)에서 벼가 유의적으로 컸다. 아. 엽록소함량(葉綠素含量)은 각 재배양식(我培樣式)에서 피가 유의적으로 높았으며 담수직파(湛水直播)보다는 이앙(移秧)벼에서, 이앙(移秧)벼보다는 간답직파(乾畓直播)에서 높았다.

• 공업화학
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• 제21권1호
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• pp.52-57
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• 2010

중금속 이온이나 방사성 양이온을 처리하는 공정으로서 화학약품에 의한 침전법이나 일반 이온교환법을 가장 보편적으로 활용하고 있으나, 이 공정들은 약품의 과다 투여, 유효 금속의 폐기, 고형 폐기물에 의한 2차적인 토양 오염 유발 등과 같은 문제점을 가지고 있다. 이에 따라 최근 들어 선진국을 중심으로 전해환원 전착반응과 이온교환 반응을 결합시킨 전기화학적 이온교환법을 대체 신기술로 개발하고자 많은 관심과 연구가 집중되고 있다. 본 연구에서는 전기화학적 이온교환체 중의 하나인 nickel hexacyanoferrate (NiHCNFe)의 최적 제조조건을 규명하기 위해, 기지금속인 니켈판 표면에 화학적 방법과 전기화학적 방법으로 NiHCNFe 막을 생성하였으며, NiHCNFe의 구조 형태와 조성을 각각 SEM과 EDS 분석을 통하여 조사하였다. 또한 NiHCNFe 막이 생성된 니켈판을 운전전극으로 설치한 단일 평행평판 이온교환 전극반응기에서 산화-환원 전위를 연속적으로 순환시켜 순환전위곡선을 측정하고 피크 전류의 변화 거동을 조사하였다. 본 연구의 실험 결과에 의하면, 화학적으로 제조한 NiHCNFe가 전기화학적으로 제조한 경우보다 우수함을 알 수 있었고, 특히 118 h 화학반응시킨 NiHCNFe 이온교환체의 조밀도, 밀착성, 내구력이 가장 우수하게 나타났다.