• 한국미생물·생명공학회지
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• 제48권4호
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• pp.539-546
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• 2020

A cellulolytic bacterial strain, S2-3, was isolated from sea water collected in Jeju island, Republic of Korea. The strain was aerobic and gram negative, and formed yellow colored colonies on marine agar medium. S2-3 cells were long rod-shaped, 0.5 × 0.25 ㎛ (width x length) in size, and did not have flagella. The optimal growth conditions for S2-3 were 30-35℃ and pH 6.5-7.0. Analysis of the 16S rRNA gene sequence of S2-3 revealed that it had the highest identity with those of Seonamhaeicola algicola Gy8 (97.08%), Hyunsoonleella udonensis JG48 (95.01%), and Aestuariibaculum scopimerae I-15 (94.86%). In phylogenetic analysis, S2-3 formed the same clade as S. algicola Gy8, implying that S2-3 belongs to the genus Seonamhaeicola. The major fatty acids (>10%) comprised C15:1 iso G (22.29%), C15:0 iso (17.71%), C17:0 iso 3OH (16.06%), and C15:0 iso 3OH (10.7%), resulting in quite different ratio of the component from those of S. algicola Gy8. Moreover, its biochemical characteristics, including acid production and enzyme activities, were different from those of S. algicola Gy8. Therefore, putting all these results together, we concluded S2-3 is distinct species from S. algicola Gy8, and thus named it Seonamhaeicola sp. S2-3. In liquid culture, S2-3 produced extracellular cellulases that can hydrolyze cellulose or cellooligosaccharides into cellobiose, which is a good enzyme resource that deserves further research.

• 상하수도학회지
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• 제35권1호
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• pp.63-69
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• 2021

Microalgae are primary producers of aquatic ecosystems, securing biodiversity and health of the ecosystem and contributing to reducing the impact of climate change through carbon dioxide fixation. Also, they are useful biomass that can be used as biological resources for producing valuable industrial products. However, harvesting process, which is the separation of microalgal biomass from mixed liquor, is an important bottleneck in use of valorization of microalgae as a bioresource accounting for 20 to 30% of the total production cost. This study investigates the applicability of sewage sludge-derived extracellular polymeric substance (EPS) as bioflucculant for harvesting microalgae. We compared the flocculation characteristics of microalgae using EPSs extracted from sewage sludge by three methods. The flocculation efficiency of microalgae is closely related to the carbohydrate and protein concentrations of EPS. Heat-extracted EPS contains the highest carbohydrate and protein concentrations and can be a best-suited bioflocculant for microalgae recovery with 87.2% flocculation efficiency. Injection of bioflocculant improved the flocculation efficiency of all three different algal strains, Chlorella Vulgaris, Chlamydomonas Asymmetrica, Scenedesmus sp., however the improvement was more significant when it was used for flocculation of Chlamydomonas Asymmetrica with flagella.

• The Plant Pathology Journal
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• 제37권6호
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• pp.580-595
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• 2021

Although late blight is an important disease in ecofriendly potato cultivation in Korea, it is highly dependent on the use of eco-friendly agricultural materials and the development of biological control technology is low. It is a necessary to develop an effective biocontrol agent to inactivate late blight in the field. AFB2-2 strain is a gram-positive with peritrichous flagella. It can utilize 20 types of carbon sources, like L-arabinose, and D-trehalose at 35℃. The optimal growth temperature of the strain is 37℃. It can survive at 20-50℃ in tryptic soy broth. The maximum salt concentration tolerated by AFB2-2 strain is 7.5% NaCl. AFB2-2 strain inhibited the mycelial growth of seven plant pathogens by an average inhibitory zone of 10.2 mm or more. Among the concentrations of AFB2-2, 10⁷ cfu/ml showed the highest control value of 85.7% in the greenhouse. Among the three concentrations of AFB2-2, the disease incidence and severity of potato late blight at 10⁷ cfu/ml was lowest at 0.07 and 6.7, respectively. The nucleotide sequences of AFB2-2 strain were searched in the NCBI GenBank; Bacillus siamensis strain KCTC 13613, Bacillus velezensis strain CR-502, and Bacillus amyloliquefaciens strain DSM7 were found to have a genetic similarity of 99.7%, 99.7%, and 99.5%, respectively. The AFB2-2 strain was found to harbor the biosynthetic genes for bacillomycin D, iturin, and surfactin. Obtained data recommended that the B. velezensis AFB2-2 strain could be considered as a promising biocontrol agent for P. infestans in the field.

• ALGAE
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• 제39권2호
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• pp.75-96
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• 2024

Rhodomonas (Cryptophyceae) and species assigned to this genus have undergone numerous taxonomic revisions. This also applies to R. marina studied here as it was originally assigned as a species of Cryptomonas and later considered a variation of R. baltica, the type species. Despite being described more than 130 years ago, R. marina still lacks a comprehensive characterization. Light and electron microscopy were employed to delineate a strain from western Greenland. The living cells were 18 ㎛ long and 9 ㎛ wide, elliptical in shape with a pointed to rounded posterior and truncated anterior in lateral view. Two sub-equal flagella emerged from a vestibulum, where also a furrow extended. In transmission electron microscopy, the furrow was associated with a tubular gullet and the pyrenoid embedded in a deeply lobed chloroplast. The chloroplast contained DNA in perforations and was surrounded by starch grains. A tubular nucleomorph was enclosed within the pyrenoid matrix. In scanning electron microscopy, the inner periplast consisted of rectangular plates with rounded edges and posteriorly these were replaced by a sheet-like structure. The water-soluble pigment was Crypto-Phycoerythrin type I (Cr-PE 545). A phylogenetic inference based on SSU rDNA confirmed the identity of strain S18 as a species of Rhodomonas as it clustered with congeners but also Rhinomonas, Storeatula, and Pyrenomonas. These genera formed a monophyletic clade separated from a diverse assemblage of other cryptophyte genera. To further explore the phylogeny of R. marina a concatenated phylogenetic analysis based on the SSU rDNA-ITS1-5.8S rDNA-ITS2-LSU rDNA region was performed but included only closely related species. The secondary structure of nuclear internal transcribed spacer 2 was predicted and compared to similar structures in related species. Using morphological and molecular signatures as diagnostic features the description of R. marina was emended.

• 한국미생물·생명공학회지
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• 제39권4호
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• pp.317-323
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• 2011

Amylase를 생산하는 능력을 갖고 있는 A-3 균주가 대한민국 대천 해변가의 바닷물로부터 분리되었다. A-3 균주는 1개의 polar flagella를 갖으며, Artificial Sea Water-Yeast extract-Peptone(ASW-YP) 한천배지 위에서 배양할 경우 $20-37^{\circ}C$에서 잘 자라지만, $15^{\circ}C$와 $40^{\circ}C$에서는 천천히 자라는 속성을 보였다. 또한 ASW-YP 액체배지를 사용하는 경우, pH 6-9 범위에서 잘 자라는 반면 pH 4-5, pH 10에서는 전혀 성장하지 못했다. 16S rRNA sequence 분석 결과, A-3 균주는 Pseudoalteromonas phenolica O-$BC30^T$, Pseudoalteromonas luteoviolacea $NCIMB1893^T$, Pseudoalteromonas rubra $ATCC29570^T$, Pseudoalteromonas byunsanensis $FR1199^T$와 각각 98.3, 97.86, 97.78, 97.25%의 similarity를 보였으며, 이를 기초로 한 phylogenetic tree 분석결과, P. phenolica O-$BC30^T$와 같은 clade를 형성하였다. 그러나, A-3 균주는 5% 이상의 NaCl 농도에서 전혀 성장하지 않고, D-glucose, D-mannose, D-maltose, Dmelibiose를 이용하지 못하며, lipase 활성(C-14)이 없는 등 많은 생리학적 특성이 P. phenolica O-$BC30^T$와는 상당히 달랐다. 이러한 생리학적 차이로부터 우리는 A-3 균주가 P. phenolica O-$BC30^T$와는 다른 종으로 판단하고, 이 균주를 Pseudoalteromonas sp. A-3로 명명하였다. Pseudoalteromonas sp. A-3는 배양시기 동안 계속해서 안정적으로 ${\alpha}$-amylase를 생산했으며, 총 amylase 활성은 pH 7과 $37^{\circ}C$에서 최대값을 보였다. 이 amylase 활성은 pH 10까지도 비교적 안정적이었으며, 이러한 alkali-tolerant amylase는 산업적으로도 유용성이 클 것으로 사료된다.

• 환경생물
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• 제32권3호
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• pp.168-175
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• 2014

본 연구는 2012년 3월 저수온기 동해연안의 10개 정점에서 식물플랑크톤의 군집구조를 세포의 크기에 따라 구분하여 조사하였다. 식물플랑크톤의 총 개체수는 $3.4{\times}10^6{\sim}7.6{\times}10^6cells\;L^{-1}$, 탄소량은 $0.0^8{\times}10^8{\sim}6.3{\times}10^8pg\;L^{-1}$로 나타났다. 개체수를 기반으로 생물량을 보았을 때, 극미소플랑크톤의 비율이 미세 미소 플랑크톤보다 높았다. 그러나 탄소량을 기반으로 하는 생물량을 보았을 때, 극미소플랑크톤은 세포 크기가 작아 기여도가 미미하였고, Coscinodiscus속과 같이 크기가 큰 종들은 기여도가 높았다. 이와 같이 식물플랑크톤의 생물량을 정확하게 파악하기 위해서는 다양한 관점으로 여러 항목을 조사할 필요성이 있는 것으로 나타났다. 식물플랑크톤의 군집 구조를 확인한 결과, 총 10개 정점 중에 8 정점에서 극미소플랑크톤이 우점하였다. 또한 8개 정점에서 미소플랑크톤의 개체수가 미세플랑크톤보다 높은 비율을 나타냈다. 미세 미소플랑크톤 중에서는 규조류의 비율이 95% 이상이었다. 극미소플랑크톤의 군집구조를 살펴보면, 5가지의 형태학적 특성이 다른 군집이 확인되었으며, 7개 정점에서 S type이 가장 우점한 것으로 나타났다. 본 연구를 통해 확인된 극미소플랑크톤이 차지하는 생태학적 기여도가 커 이들에 대한 연구가 꾸준히 수행되어야 하며, 이를 위하여 그들의 분류학적 체계 구축과 생리학적 특성 연구가 선행되어야 할 것으로 판단된다. 이와 같은 연구를 기반으로 향후, 변화하고 있는 동해연안에서 생물 군집 변화 현상을 규명할 수 있을 것이다.

• Journal of Plant Biotechnology
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• 제32권4호
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• pp.233-241
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• 2005

Plants have considerable advantages for the production of antigenic proteins because they provide an inexpensive source of protein and an easy administration of vaccine. Since a publication describing edible plant vaccine of HBsAg in 1992, a number of laboratories around the world have studied the use of plants as the bioreactor to produce antigenic proteins of human or animal pathogens. Over the last ten years, these works have been mainly focused on three major strategies for the production of antigenic proteins in plants: stable genetic transformation of either the nuclear or plastid genome, or transient expression in plants using viral vectors. As many antigenic proteins have been expressed in tobacco, also several laboratories have succeeded to express genes encoding antigenic proteins in other crop plants: potato, tomato, maize, carrot, soybean and spinach. At present many works for the production of edible plant vaccine against bacteria-mediated diseases have mostly performed the studies of enterotoxins and adhesion proteins. Also the development of new-type antigens (pili, flagella, surface protein, other enterotoxin and exotoxin etc.) is required for various targets and more efficacy to immunize against microorganism pathogens. Many works mostly studied in experimental animals had good results, and phase I clinical trial of LTB clearly indicated its immunogenic ability. On the other hand, edible plant vaccines have still problems remained to be solved. In addition to the accumulation of sufficient antigen in plants, human health, environment and agriculture regulation should be proven. Also oral tolerance, the physiological response to food antigens and commensal flora is the induction of a state of specific immunological unresponsiveness, needs to be addressed before plant-derived vaccine becomes a therapeutic option.

• ALGAE
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• 제28권3호
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• pp.213-231
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• 2013

Amphidinium massartii Biecheler is an epiphytic and toxic dinoflagellate. Prior to the present study, A. massartii has been reported in the waters off the Mediterranean, Australian, USA, and Canadian coasts. We isolated Amphidinium cells from the coastal waters of Jeju Island, Korea and their morphology and rDNA sequences indicated that they were A. massartii. Herein, we report for the first time the occurrence of A. massartii in the waters of the temperate region in the northwestern Pacific Ocean. The large subunit (LSU) rDNA sequences of the Korean strains were 0.7% different from those of an Australian strain of A. massartii CS-259, the closest species, but were 4.1-5.8% different from those of the other Australian strains and the USA strains of A. massartii and from those of Amphidinium sp. HG115 that was isolated from subtropical Okinawan waters. In phylogenetic trees based on LSU, internal transcribed spacer, small subunit rDNA, and cytochrome b sequences, the Korean strains belonged to the A. massartii clade, which was clearly divergent from the A. carterae clade. The morphology of the Korean A. massartii strains was similar to that of the originally described French strain and recently described Australian strain. However, we report for the first time here that scales were observed on the surface of the flagella. In conclusion, the Korean A. massartii strains have unique rDNA sequences, even though they have a very similar morphology to that of previously reported strains. This report extends the known range of this dinoflagellate to the temperate waters of the northwestern Pacific Ocean.

• Journal of Microbiology and Biotechnology
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• 제30권4호
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• pp.505-514
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• 2020

The symbiotic nature of the relationship between algae and marine bacteria is well-studied among the complex microbial interactions. The mutual profit between algae and bacteria occurs via nutrient and vitamin exchange. It is necessary to analyze the genome sequence of a bacterium to predict its symbiotic relationships. In this study, the genome of a marine bacterium, Pseudoruegeria sp. M32A2M, isolated from the south-eastern isles (GeoJe-Do) of South Korea, was sequenced and analyzed. A draft genome (91 scaffolds) of 5.5 Mb with a DNA G+C content of 62.4% was obtained. In total, 5,101 features were identified from gene annotation, and 4,927 genes were assigned to functional proteins. We also identified transcription core proteins, RNA polymerase subunits, and sigma factors. In addition, full flagella-related gene clusters involving the flagellar body, motor, regulator, and other accessory compartments were detected even though the genus Pseudoruegeria is known to comprise non-motile bacteria. Examination of annotated KEGG pathways revealed that Pseudoruegeria sp. M32A2M has the metabolic pathways for all seven vitamin Bs, including thiamin (vitamin B1), biotin (vitamin B7), and cobalamin (vitamin B12), which are necessary for symbiosis with vitamin B auxotroph algae. We also identified gene clusters for seven secondary metabolites including ectoine, homoserine lactone, beta-lactone, terpene, lasso peptide, bacteriocin, and non-ribosomal proteins.

• 한국미생물·생명공학회지
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• 제45권2호
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• pp.168-177
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• 2017

Strain A28-5는대한민국 제주도 연안의 해수샘플로부터 고체배지내 xylan과 agar를 분해하는 균주로 분리되었다. Strain A28-5는그람 음성균으로 한 개의 polar flagella로 운동성을 갖는 $Na^+$ 이온 요구성 균주로 분석되었다. 또한 ampilcillin과 thiostreptone 등의 항생제에 내성을 보였다. Genome 내 G+C content는 43.96%이고, Menaquinone-7 (MK-7)을 predominant quinone으로 함유하고 있었다. Strain A28-5의 세포벽을 구성하는 주요 지방산은 $C_{16:1}$ ${\omega}7c/iso-C_{15:0}$ 2-OH (23.32%), $C_{16:0}$ (21.83%), $C_{18:1}$ ${\omega}7c$ (17.98%)였다. strain A28-5의 16S rRNA gene sequence는 Catenovulum agarivorans YM01와 가장 높은 상동성(98.94%)을 보였으며, Neighbor-Joining phylogenetic tree 제작을 통해서 Catenovulum agarivorans YM01와 가장 높은 근연관계를 보이는 것을 증명하였다. Catenovulum agarivorans YM01과의 DNA-DNA hybridization 분석을 통하여 A28-5을 Catenovulum 속의 신종으로 분류하여Catenovulum jejuensis A28-5로 명명하였다. 이 균주의 액체배양으로부터 준비된 두 종류의 조효소를 이용한 xylan 또는 agarose와의 효소반응액을 Thin layer chromatography로 분석하여 각각 tetramer와 hexamer의 xylooligosaccharides와 (neo)agarooligosacchardes가 생산되는 것을 확인하였다.