• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1717-1723
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• 2010

The integrated fixed-film activated sludge (IFAS) system is a variation of the activated sludge wastewater treatment process, in which hybrid suspended and attached biomass is used to treat wastewater. Although the function and performance of the IFAS system are well studied, little is known about its microbial community structure. In this study, the composition and diversity of the bacterial community of suspended and attached biomass samples were investigated in a full-scale IFAS system using a high-throughput pyrosequencing technology. Distinct bacterial community compositions were examined for each sample and appeared to be important for its features different from conventional activated sludge processes. The abundant bacterial groups were Betaproteobacteria (59.3%), Gammaproteobacteria (8.1%), Bacteroidetes (5.2%), Alphaproteobacteria (3.9%), and Actinobacteria (3.2%) in the suspended sample, whereas Actinobacteria (14.6%), Firmicutes (13.6%), Bacteroidetes (11.6%), Betaproteobacteria (9.9%), Gammaproteobacteria (9.25%), and Alphaproteobacteria (7.4%) were major bacterial groups in the attached sample. Regarding the diversity, totals of 3,034 and 1,451 operational taxonomic units were identified at the 3% cutoff for the suspended and attached samples, respectively. Rank abundance and community analyses demonstrated that most of the diversity was originated from rare species in the samples. Taken together, the information obtained in this study will be a base for further studies relating to the microbial community structure and function of the IFAS system.

• Journal of Microbiology and Biotechnology
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• 제24권3호
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• pp.313-323
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• 2014

Significant alteration in the microbial community can occur across reclamation areas suffering subsidence from mining. A reclamation site undergoing fertilization practices and an adjacent coal-excavated subsidence site (sites A and B, respectively) were examined to characterize the bacterial diversity using 454 high-throughput 16S rDNA sequencing. The dominant taxonomic groups in both the sites were Proteobacteria, Acidobacteria, Bacteroidetes, Betaproteobacteria, Actinobacteria, Gammaproteobacteria, Alphaproteobacteria, Deltaproteobacteria, Chloroflexi, and Firmicutes. However, the bacterial communities' abundance, diversity, and composition differed significantly between the sites. Site A presented higher bacterial diversity and more complex community structures than site B. The majority of sequences related to Proteobacteria, Gemmatimonadetes, Chloroflexi, Nitrospirae, Firmicutes, Betaproteobacteria, Deltaproteobacteria, and Anaerolineae were from site A; whereas those related to Actinobacteria, Planctomycetes, Bacteroidetes, Verrucomicrobia, Gammaproteobacteria, Nitriliruptoria, Alphaproteobacteria, and Phycisphaerae originated from site B. The distribution of some bacterial groups and subgroups in the two sites correlated with soil properties and vegetation due to reclamation practice. Site A exhibited enriched bacterial community, soil organic matter (SOM), and total nitrogen (TN), suggesting the presence of relatively diverse microorganisms. SOM and TN were important factors shaping the underlying microbial communities. Furthermore, the specific plant functional group (legumes) was also an important factor influencing soil microbial community composition. Thus, the effectiveness of 454 pyrosequencing in analyzing soil bacterial diversity was validated and an association between land ecological system restoration, mostly mediated by microbial communities, and an improvement in soil properties in coal-mining reclamation areas was suggested.

• Ocean Science Journal
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• 제40권3호
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• pp.145-153
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• 2005

Variation in the microbial biomass and community structure found in sediment of heavily polluted bays and the adjacent unpolluted areas were examined using phospholipid fatty acid analysis. Total microbial biomass and microbial community structure were responding to environmental determinants, sediment grain size, depth of sediment, and pollution due to petroleum hydrocarbons. The marker fatty acids of microeukaryotes and prokaryotes - aerobic, anaerobic, and sulfate-reducing bacteria - were detected in sediments of the areas studied. Analysis of the fatty acid profiles revealed wide variations in the community structure in sediments, depending on the extent of pollution, sediment depth, and sediment grain size. The abundance of specific bacterial fatty acids points to the dominance of prokaryotic organisms, whose composition differed among the stations. Fatty acid distributions in sediments suggest the high contribution of aerobic bacteria. Sediments of polluted sites were significantly enriched with anaerobic bacteria in comparison with clean areas. The contribution of this bacterial group increased with the depth of sediments. Anaerobic bacteria were predominantly present in muddy sediments, as evidenced from the fatty acid profiles. Relatively high concentrations of marker fatty acids of sulfate-reducing bacteria were associated with organic pollution in this site. Specific fatty acids of microeukaryotes were more abundant in surface sediments than in deeper sediment layers. Among the microeukaryotes, diatoms were an important component. Significant amounts of bacterial biomass, the predominance of bacterial biomarker fatty acids with abundance of anaerobic and sulfate-reducing bacteria are indicative of a prokaryotic consortium responsive to organic pollution.

• 한국기후변화학회지
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• 제5권3호
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• pp.249-256
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• 2014

Permafrost is frozen soil below $0^{\circ}C$ for two or more years. Surface of permafrost is called as active layer that seasonally thaws during the summer. Although the thawing of permafrost may deepen the active layer and consequently increase the microbial activity, the microbial community structure in this habitat has not yet been well described. In this study, we presented bacterial and archaeal diversity in the active layer soil from Resolute, Canada using pyrosequencing analysis. The soil sample was collected from the surface of the marsh covered with moss and Carex. A total of 7,796 bacterial reads for 40 phyla and 245 archaeal reads for 4 phyla were collected, reflecting the high diversity of bacteria. Predominant bacterial groups were Proteobacteria (37.7%) and Bacteroidetes (30.0%) in this study. Major groups in Archaea were Euryarchaeota (51.4%) and Thaumarchaeota (46.1%). Both methane producing archaea and consuming bacteria were detected in this study. Although it might be difficult to characterize microbial community with only one sample, it could be used for the basis of assessing the relative importance of the specific groups with a high resolution on the bacterial and archaeal community in this habitat.

• 미생물학회지
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• 제36권2호
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• pp.136-141
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• 2000

소양호에서 수온, 엽록소$\alpha$, pH 그리고 DOC의 농도가 세균군집에 미치는 영향을 파악하였다. 이 연구에서는 fluorescent in situ hybridization(FISH) 방법을 사용하기 1998년 4월부터 5월까지 세균군집구조를 조사하였고 이 시기 환경요인과 세균군집간의 상관성 분석을 실시하기 위해 수온, 엽록체$\alpha$, pH, DOC의 측정도 함께 수행하였다. 또한 환경요인과 세균군집간의 상관성 분석을 실시하기 위해 통계프로그램(SPSS)을 이용하였다. 그 결과 소양호에서 DOC, 엽록체$\alpha$, pH와 온도가 다중선형희귀직선상 설명가능정도가 약 43~58%정도로 나타났으며, 세균군집변화의 약 50%정도가 본 조사 이외의 환경요인에 영향을 받은 것으로 나타났다. $\alpha$-group은 DOC가 증가할수록 감소하여 DOC와 음의 상관관계를 보였고 , ${\gamma}$-group은 엽록소 $\alpha$농도와 음의 상관관계를 나타내었다. $\beta$-Cytophaga-Flavobacterium group 의 경우 수온과 뚜렷한 양의 상관성이 있는 것으로 나타났다. 또한 $\alpha$-group과 Cytophaga-Flavobacterium group은 pH와 양의 상관관계를 보였다. 이처럼 소양호의 세균군집은 계절에 따른 여러 가지 수 환경요인의 변화에 의해 다양하게 변화하였다.

• Journal of Microbiology and Biotechnology
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• 제29권7호
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• pp.1014-1021
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• 2019

In the bacterial community, unicellular organisms act together as a multicellular being. Bacteria interact within the community and programmed cell death (PCD) in prokaryotes is a sort of altruistic action that enables the whole population to thrive. Genetically, encoded cell death pathways are triggered by DNA damage or nutrient starvation. Given the environmental and bacterial diversity, different PCD mechanisms are operated. Still, their biochemical and physiological aspects remain unrevealed. There are three main pathways; thymineless death, apoptosis-like death, and toxin-antitoxin systems. The discovery of PCD in bacteria has revealed the possibility of developing new antibiotics. In this review, the molecular and physiological characteristics of the three types of PCD and their development potential as antibacterial agents are addressed.

• 한국식품과학회지
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• 제22권1호
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• pp.26-32
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• 1990

김치발효 지표로서 미생물군집의 특성을 밝히고자 하였다. 군집크기는 Gram염색법에 의한 현미경직접계수에 의하여 측정하였다. 실온$(15^{\circ}C)$에서 김치발효는 Gram양성균군집, 효모군집 그리고 Gram음성균군집이 순서적으로 천이되었다. Gram양성균군집은 김치를 발효시키는 유산균으로 구성되어 있다. 효모군집의 발달은 김치의 악취를 내는 원인이 되며, Gram음성균군집은 악취와 더불어 김치의 연화작용에 관계된다는 사실이 특정적이었다. 그리고, 외관상의 Gram음성균군은 Gram양성균군집 내의 개체군의 노화와 사멸을 평가하는데 이용될 수 있었다. 특히 저온$(5^{\circ}C)$ 김치발효에서는 효모군집과 Gram 음성균군집이 발달되지 않고 Gram양성균군집만이 발달됨을 알았다. 이 사실로부터 숙성된 김치는 Gram양성균군집에 의하여 만들어짐을 의미한다. 따라서 미생물군집의 발달과 크기는 김치발효의 지표로 이용될 수 있고, 또한 김치숙성도를 수십분 내에 예측하는데 중요한 방법이 될 수 있다.

• Asian-Australasian Journal of Animal Sciences
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• 제32권1호
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• pp.92-102
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• 2019

Objective: To investigate changes in rumen fermentation characteristics and bacterial community by a sudden change to a high concentrate diet (HC) in Korean domestic ruminants. Methods: Major Korean domestic ruminants (each of four Hanwoo cows; $545.5{\pm}33.6kg$, Holstein cows; $516.3{\pm}42.7kg$, and Korean native goats; $19.1{\pm}1.4kg$) were used in this experiment. They were housed individually and were fed ad libitum with a same TMR (800 g/kg timothy hay and 200 g/kg concentrate mix) twice daily. After two-week feeding, only the concentrate mix was offered for one week in order to induce rapid rumen acidosis. The rumen fluid was collected from each animals twice (on week 2 and week 3) at 2 h after morning feeding using an oral stomach tube. Each collected rumen fluid was analyzed for pH, volatile fatty acid (VFA), and $NH_3-N$. In addition, differences in microbial community among ruminant species and between normal and an acidosis condition were assessed using two culture-independent 16S polymerase chain reaction (PCR)-based techniques (terminal restriction fragment length polymorphism and quantitative real-time PCR). Results: The HC decreased ruminal pH and altered relative concentrations of ruminal VFA (p<0.01). Total VFA concentration increased in Holstein cows only (p<0.01). Terminal restriction fragment length polymorphism and real-time quantitative PCR analysis using culture-independent 16S PCR-based techniques, revealed rumen bacterial diversity differed by species but not by HC (p<0.01); bacterial diversity was higher in Korean native goats than that in Holstein cows. HC changed the relative populations of rumen bacterial species. Specifically, the abundance of Fibrobacter succinogenes was decreased while Lactobacillus spp. and Megasphaera elsdenii were increased (p<0.01). Conclusion: The HC altered the relative populations, but not diversity, of the ruminal bacterial community, which differed by ruminant species.

• Journal of Microbiology and Biotechnology
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• 제17권4호
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• pp.560-570
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• 2007

The effective and accurate assessment of the total microbial community diversity is one of the primary challenges in modem microbial ecology, especially for the detection and characterization of unculturable populations and populations with a low abundance. Accordingly, this study was undertaken to investigate the diversity of the microbial community during the biodegradation of cis- and trans-dichloroethenes in soil and wastewater enrichment cultures. Community profiling using PCR targeting the l6S rRNA gene and denaturing gradient gel electrophoresis (PCR-DGGE) revealed an alteration in the bacterial community profiles with time. Exposure to cis- and trans-dichloroethenes led to the disappearance of certain genospecies that were initially observed in the untreated samples. A cluster analysis of the bacterial DGGE community profiles at various sampling times during the degradation process indicated that the community profile became stable after day 10 of the enrichment. DNA sequencing and phylogenetic analysis of selected DGGE bands revealed that the genera Acinetobacter, Pseudomonas, Bacillus, Comamonas, and Arthrobacter, plus several other important uncultured bacterial phylotypes, dominated the enrichment cultures. Thus, the identified dominant phylotypes may play an important role in the degradation of cis- and trans-dichloroethenes.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.227.2-227.2
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• 2003

In the situation of high bacterial resistance to antibiotics in Korea, to assess diffusion of methicillin-resistant Staphylococcus aureus (MRSA) and levels of bacterial resistance to antibiotics in community, we monitored antibiotic resistance of S. aureus isolates from healthy volunteers of community. (omitted)