• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.150-156
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• 2000

Oligotrophic bacteria isolated from forest soil showed a specific community consisting of various taxonomic groups compared with those in other soil or aquatic habitats. Based on the cell shape, the isolates were divided into four groups: regular rod, curved/spiral rod, irregular rod, and prosthecate bacteria. The cellular fatty acids 60 oligotrophic isolates were analyzed. The 30 fatty acids which were identified or characterized are classified. At the dendrogram based on cellular fatty acid composition, four clusters(I-IV) were separated at a euclidian distance of about 50. Cluster 3 and 4-a strains were containing Q-8, these strains are accommodated in the Proteobacteria gamma and beta subdivision. The chemotaxonomic profiles of the cluster 4-a strains showed good agreement with those of the genus Burkholderia. Cluster 3 was characterized by the presence of branched-chain fatty acids, iso-C15:0, iso-C17:1, and iso-C17:0 as the major components. These chemotaxonomy suggested the close relationship of the isolates with Xathomonas/Sterotrophomonas group. Based on the 16S rDNA sequence analysis, the two representative strains(MH256 and MA828) of cluster 3 showed the close relation to genera, Xathomonas/Sterotrophomonas, but were not included in these genera. These strains were even further away from core Xanthomonas, and clearly were seen to branch outside the cluster formed by the Sterotrophomonas maltophilia. MH256 and MA828 16S rDNA sequence was different enough to put new genus on a separate branch. The isolates with Q-10 were also studied. They are corresponded to the two large groups in Proteobacteria alpha subdivision. One was incorporated in the genus Bradyrhizobium cluster, which also includes Agromonas, a genus for oligotrophic bacteria. The strains of the other group showed high similarity to the genus Agrobacterium.

• 한국균학회지
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• 제17권2호
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• pp.76-81
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• 1989

Fusarium oxysporum은 하나의 종내에 많은 formae speciales(분화종)과 races 등이 분화되어 있다. 그 중에서 10균주에 대하여 균사 내에서의 영양핵의 분열상을 찾아 Giemsa staining 용액으로 염색하여 그들의 염색체 수를 비교 관찰하였다. 균주에 따라 염색체 수에 차이가 있었으며 2균주(F. oxysporum f. sp. lycoperici, F. oxysporum Kangnung D2)는 n=4, 2균주(F. oxysporum S Sachun 3, F. oxysporum S Kohung 2)는 n=5, 5균주(F. oxysporum S Kohung 3, F. oxysporum CS Hongchun D16, F. oxysporum S Bosung 5, F. oxysporum S Sunchun 4, F. oxysporum S Haenam 4)는 n= 7개를 관찰할 수 있었고 Australia의 Sydney 대학에서 분양받은 F. oxysporum 14-39는 n=8개로 전체로 보아 4-8개의 염색체를 관찰할 수 있었다. 본인의 앞서 본문의 결과와 종합하여 고찰할 때 F. oxysporum의 기본염색체 수는 반수체가 4개로 추론되며 여기에서부터 여러가지 요인으로 인하여 diploidy, aneuploidy가 되어 다양한 염색체 수를 가진 것으로 사료된다.

• Journal of Microbiology and Biotechnology
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• 제23권3호
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• pp.289-296
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• 2013

Cryptomonads are unicellular, biflagellate algae. Generally, cryptomonad cells cannot be preserved well because of their fragile nature, and an improved methodology should be developed to identify cryptomonads from natural habitats. In this study, we tried using several cytological fixatives, including glutaraldehyde, formaldehyde, and their combinations to preserve field samples collected from various waters, and the currently used fixative, Lugol's solution was tested for comparison. Results showed that among the fixatives tested, glutaraldehyde preserved the samples best, and the optimal concentration of glutaraldehyde was 2%. The cell morphology was well preserved by glutaraldehyde. Cells kept their original color, volume, and shape, and important taxonomic features such as furrow/gullet complex, ejectosomes, as well as flagella could be observed clearly, whereas these organelles frequently disappeared in Lugol's solution preserved samples. The osmotic adjustments and buffers tested could not preserve cell density significantly higher. Statistical calculation showed the cell density in the samples preserved by 2% glutaraldehyde remained stable after 43 days of the fixation procedure. In addition, DNA was extracted from glutaraldehyde preserved samples by grinding with liquid nitrogen and the 18S rDNA sequence was amplified by PCR. The sequence was virtually identical to the reference sequence, and phylogenetic analyses showed very close relationship between it and sequences from the same organism. To sum up, the present study demonstrated that 2% unbuffered glutaraldehyde, without osmotic adjustments, can preserve cryptomonads cells for identification, in terms of both light microscopy and phylogenetic analyses based on DNA sequences.

• Animal cells and systems
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• 제14권2호
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• pp.137-145
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• 2010

Four specimens of unknown Coilia sp. were collected for the first time from the Yellow Sea in 2008 and compared with Coilia mystus and Coilia nasus. Coilia sp. showed similar morphology to C. mystus and C. nasus, but differed in that its tail was considerably shorter. We conducted an analysis of the morphological and genetic characteristics in an effort to clarify the taxonomic position of Coilia sp. In counts and measurements, Coilia sp. were well distinguished from C. nasus by the number of scutes (42-44 in Coilia sp. vs. 40-45 in C. mystus vs. 45-55 in C. nasus), ratio of dorsal base length to head length (43.4-47.6 vs. 37.9-47.6 vs. 33.0-41.0), and eye length to head length (19.2-20.8 vs. 17.0-22.4 vs. 13.8-18.2). In caudal skeleton of Coilia sp., urostyle, hypural and epural bones were not observed; instead of them, caudal fin rays were supported by the last vertebra, neural and haemal spines' extension. The molecular phylogenetic relationship was analyzed using 414 base-pair 12S rRNA mitochondrial DNA sequences. The Kimura-2-parameter distance between Coilia sp. and C. mystus was 0.3%, but was 1.3% between Coilia sp. and C. nasus. Both the neighbor-joining tree and maximum-likelihood tree showed that Coilia sp. are closely clustered with C. mystus. Therefore, our results suggest that the Coilia sp. may be a deformed fish of C. mystus.

• 미생물학회지
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• 제25권4호
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• pp.318-327
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• 1987

북한강의 지류인 수동천 수층에서 세균 군집의 구성 맺 다양성을 통계학적으로 조사하였다. 4계절에 걸쳐 분리된 282개의1 균주를 계통분류한 결파, 진 정점에서 FLavob$\alpha$cten$\mu$m, Aero,pmas와 Enterobacterianae가 50% 이상으후 주종을 이루었다. 각 쟁점별로 분리된 세균들은 수리학적 분석을 행하여 각가 다른 형태학적, 생화학적 및 생리학적 특정을 나타내는 15-28개 집단으로 분류되어다. 각각의 수리학적 세균 집만은 계통분류에 의한 세균 집단(속병)들과 반드시 일치하지는 않았으며, 특히 독특한 당 분해능을 지닌 균주들은 수리학직 분석에 의하면 각각의 균주가 옥딩된 씌침-집만을 이음으로써 인관적인 관년상을 보이지 않았다. 80%의 유사도 수준에서 나위어진 각각의 집단을 하나의 종으로 하여 세균 다양성 지표(dlversity mdex:H)를 구한 결과, 2.37-3.149의 범위로 계산되어 조사 대상 지역은 밴영양-중영영 상태의 다양성을 갖는 세균 군집이 존재함이 밝혀졌다. 유기물질이나 세균 집단의 대량 유입 영향을 직접 받는 정선에서 세균 군집의 다양성 지표가 가장 높았으며 이러한 유입 현상이 전 수동천 생태계에서의 세균균집의 분포에 가장중요한 요인으로 작용함이 관찰되었다.

• ALGAE
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• 제28권2호
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• pp.173-183
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• 2013

Sodium hypochlorite (NaOCl) is widely used to disinfect seawater in power plant cooling systems in order to reduce biofouling, and in ballast water treatment systems to prevent transport of exotic marine species. While the toxicity of NaOCl is expected to increase by ongoing ocean acidification, and many experimental studies have shown how algal calcification, photosynthesis and growth respond to ocean acidification, no studies have investigated the relationship between NaOCl toxicity and increased $CO_2$. Therefore, we investigated whether the impacts of NaOCl on survival, chlorophyll a (Chl-a), and effective quantum yield in three marine phytoplankton belonging to different taxonomic classes are increased under high $CO_2$ levels. Our results show that all biological parameters of the three species decreased under increasing NaOCl concentration, but increasing $CO_2$ concentration alone (from 450 to 715 ${\mu}atm$) had no effect on any of these parameters in the organisms. However, due to the synergistic effects between NaOCl and $CO_2$, the survival and Chl-a content in two of the species, Thalassiosira eccentrica and Heterosigma akashiwo, were significantly reduced under high $CO_2$ when NaOCl was also elevated. The results show that combined exposure to high $CO_2$ and NaOCl results in increasing toxicity of NaOCl in some marine phytoplankton. Consequently, greater caution with use of NaOCl will be required, as its use is widespread in coastal waters.

• Parasites, Hosts and Diseases
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• 제59권2호
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• pp.139-148
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• 2021

This study was carried out to provide information on the taxonomic classification and analysis of mitochondrial genomes of Spirometra theileri. One strobila of S. theileri was collected from the intestine of an African leopard (Panthera pardus) in the Maswa Game Reserve, Tanzania. The complete mtDNA sequence of S. theileri was 13,685 bp encoding 36 genes including 12 protein genes, 22 tRNAs and 2 rRNAs with absence of atp8. Divergences of 12 protein-coding genes were as follow: 14.9% between S. theileri and S. erinaceieuropaei, 14.7% between S. theileri and S. decipiens, and 14.5% between S. theileri with S. ranarum. Divergences of 12 proteins of S. theileri and S. erinaceieuropaei ranged from 2.3% in cox1 to 15.7% in nad5, while S. theileri varied from S. decipiens and S. ranarum by 1.3% in cox1 to 15.7% in nad3. Phylogenetic relationship of S. theileri with eucestodes inferred using the maximum likelihood and Bayesian inferences exhibited identical tree topologies. A clade composed of S. decipiens and S. ranarum formed a sister species to S. erinaceieuropaei, and S. theileri formed a sister species to all species in this clade. Within the diphyllobothridean clade, Dibothriocephalus, Diphyllobothrium and Spirometra formed a monophyletic group, and sister genera were well supported.

• Asian-Australasian Journal of Animal Sciences
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• 제32권1호
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• pp.82-91
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• 2019

Objective: This experiment was conducted to compare the structure and composition of ruminal microorganisms in goats with high and low neutral detergent fibre (NDF) digestibility. Methods: Nineteen crossbred goats were used as experimental animals and fed the same total mixed rations during the 30-day pre-treatment and 6-day digestion trialperiods. All faeces were collected during the digestion period for measuring the NDF digestibility. Then, high and the low NDF digestibility individuals were chosen for the high NDF digestibility group (HFD) and low NDF digestibility group (LFD), respectively. Rumen contents were collected for total microbial DNA extraction. The V4 region of the bacterial 16S rRNA gene was amplified using universal primers of bacteria and sequenced using high-throughput sequencer. The sequences were mainly analysed by QIIME 1.8.0. Results: A total of 18,694 operational taxonomic units were obtained, within 81.98% belonged to bacteria, 6.64% belonged to archaea and 11.38% was unassigned microorganisms. Bacteroidetes, Firmicutes, and Proteobacteria were the predominant microbial phyla in both groups. At the genus level, the relative abundance of fifteen microorganisms were significantly higher (p<0.05) and six microorganisms were extremely significantly higher (p<0.01) in LFD than HFD. Overall, 176 core shared genera were identified in the two groups. The relative abundance of 2 phyla, 5 classes, 10 orders, 13 families and 15 genera had a negative correlation with NDF digestibility, but only the relative abundance of Pyramidobacter had a positive correlation with NDF digestibility. Conclusion: There were substantial differences in NDF digestibility among the individual goats, and the NDF digestibility had significant correlation with the relative abundance of some ruminal microorganisms.

• The Plant Pathology Journal
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• 제38권6호
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• pp.583-592
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• 2022

Root-knot nematode disease is a widespread and catastrophic disease of tobacco. However, little is known about the relationship between rhizosphere bacterial community and root-knot nematode disease. This study used 16S rRNA gene sequencing and PICRUSt to assess bacterial community structure and function changes in rhizosphere soil from Meloidogyne incognita-infected tobacco plants. We studied the rhizosphere bacterial community structure of M. incognita-infected and uninfected tobacco plants through a paired comparison design in two regions of tobacco planting area, Yuxi and Jiuxiang of Yunnan Province, southwest China. According to the findings, M. incognita infection can alter the bacterial population in the soil. Uninfested soil has more operational taxonomic unit numbers and richness than infested soil. Principal Coordinate Analysis revealed clear separations between bacterial communities from infested and uninfested soil, indicating that different infection conditions resulted in significantly different bacterial community structures in soils. Firmicutes was prevalent in infested soil, but Chloroflexi and Acidobacteria were prevalent in uninfested soil. Sphingomonas, Streptomyces, and Bradyrhizobium were the dominant bacteria genera, and their abundance were higher in infested soil. By PICRUSt analysis, some metabolism-related functions and signal transduction functions of the rhizosphere bacterial community in the M. incognita infection-tobacco plants had a higher relative abundance than those uninfected. As a result, rhizosphere soils from tobacco plants infected with M. incognita showed considerable bacterial community structure and function alterations.

• 한국균학회지
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• 제30권2호
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• pp.78-85
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• 2002

저장배에서 분리한 15그룹 3종을 KCTC, KCCM, 충남대에서 분양받은 16균주를 대상으로 상호 유연관계를 분석하고자 배양적 특성을 관찰하고 RAPD 검정에 의한 진단 가능성을 검토하였다. 병원균의 배양특성을 조사한 결과 배지상 생육형태, 색, 속도 등에 있어서 균주간 차이를 보였으며 배양적 특성과 RAPD에 의한 유연관계 분석 결과를 비교 분석하기 위하여 배에서 분리한 15개 균주와 16개 표준 균주의 종간 다형성을 관찰하였다. RAPD을 이용하여 유전적 다양성을 분석하기 위하여 5개의 URP primer를 이용하여 genomic DNA를 증폭시킨 결과 $0.1{\sim}2.0kb$ 크기의 총 744개 band들이 증폭되었다. cluster 분석결과 전체 유사도는 47.7%로 31 균주들은 4개의 genomic DNA RAPD 집단으로 분류되었다. 배에서 분리한 P. expansum 균주간에는 87.4% 이상의 상동성을 보였고, P. solitum 균주간에는 97.5%, P. crustosum 균주 간에는 95.1% 이상의 상동성을 보였다. 배에서 분리된 동일한 종내에서는 배양적 특성에 의한 동정결과와 RAPD에 의한 분석결과와 일치하였다.