• Journal of Microbiology and Biotechnology
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• v.21 no.2
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• pp.187-191
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• 2011

Microbial fuel cells (MFCs) were successfully enriched using sludge contaminated with Cr(VI) and their characteristics were investigated. After enrichment, the charge of the final 10 peaks was 0.51 C ${\pm}$ 1.16%, and the anodic electrode was found to be covered with a biofilm. The enriched MFCs removed 93% of 5 mg/l Cr(VI) and 61% of 25 mg/l Cr(VI). 16S rDNA DGGE profiles from the anodic electrode indicated that ${\beta}$-Proteobacteria, Actinobacteria, and Acinetobacter sp. dominated. This study is the first to report that electrochemically active and Cr(VI)-reducing bacteria could be enriched in the anode compartment of MFCs using Cr(VI)-containing sludge and demonstrates the Cr(VI) removal capability of such MFCs.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1407-1429
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• 2007

The Burkholderia genus consists of over 40 Gram-negative, ${\beta}$-proteobacteria species that occupy remarkably diverse ecological niches. This genus contains species pathogenic to human, animals, and plants, as well as species involved in promoting plant growth and biodegradation of pollutants. This is largely explained by the extraordinary versatility of Burkholderia, as reflected by the remarkable diversity of extracellular products released by these bacteria. We exhaustively surveyed the extracellular enzymes, siderophores, toxins, antimicrobials, and other secondary metabolites produced by the members of this very diverse genus. Available information on regulation, especially quorum sensing mechanisms, and secretion is highlighted.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06c
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• pp.265-267
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• 2006

사용목적(Purpose)은 최근 개인 프라이버시 보호와 관련하여 데이타 수집과 수집 후 보안관리에 있어서 중요한 요소로 사용되고 있다. W3C(World Wide Web Consortium)는 데이타 제공자가 자신이 방문한 웹 사이트에 개인정보를 제공하는 것을 통제할 수 있도록 하는 표준을 제시하였다. 그러나 데이타 수집 후 유통과정에서 개인정보에 대한 보안관리에 대한 언급이 없다. 현재 히포크라테스 데이타베이스(Hippocratic Databases), 사용목적기반 접근제어(Purpose Based Access Control)등은 W3C의 데이타 수집 메커니즘을 따르고 있으며, 데이타 수집 후 보안관리에 대하여 사용목적 관리와 접근제어 기법을 사용하여 관리를 하고 있으나 사용목적에 대한 표현과 사용목적 관리의 미흡함으로 인하여 그에 따르는 개인정보의 프라이버시 보호에 있어서 효과적인 해결책을 제시하지 못하고 있다. 본 논문은 사용목적의 표현력을 향상시키면서. 사용목적의 효과적인 관리기법을 제시한다. 또한 개인의 프라이버시 보호를 위한 방법으로 사용목적의 분류화를 통해 최소권한의 원칙을 따르는 접근제어 기법을 제시한다. 본 논문에서는 사용목적을 상속적, 시간적 그리고 독립적 구조로 분류화하였으며, 이렇게 분류화된 사용목적에 대한 각기 다른 관리기법을 제시한다. 또한 접근제어의 유연성을 위해 RBAC의 역할계층 구조를 사용하였으며, 일의 최소 단위인 태스크(task)의 최소권한을 얻기 위한 조건으로 몇몇 특성의 사용목적을 사용하여 만족할 경우 태스크를 처리하기 위한 기존 모델보다 향상된 최소사용권한을 제공하는 기법을 제시한다. Interference Contrast)에 의한 내부구조 관찰이 최종 동정기준이 되어야할 것으로 나타났다.cillus로 구성되었다. 한편, DAL세균군(42균주)은 high G+C 및 low G+C gram positive 계통군 이외에도 proteobacteria -subdivision에 속하는 Afipia와 Ralstonia, proteobacteria -subdivision에 속하는 Variovorax, proteobacteria $\beta$-subdivision에 속하는Pseudomonas로 구성되어 계통학적으로 다양한 세균임이 확인되었다. 40%까지 대체가 가능하였으며, 아울러 높은 라이신 부산물의 대체 수준에 있어서 사료효율과 단백질 전환효율을 고려한다면 아미노산 첨가(라이신과 아르지닌)와 중화 효과에 좋은 결과가 있을 것으로 사료된다.의한 적정 양성수용밀도는 각고 5~6cm 크기의 경우 10~15개체가 적합하였다. 수증별 성장은 15~20 m 수층에서 빨랐으며, 성장촉진과 폐사를 줄이기 위해서는 고수온이 지속되는 7~10월에는 20~30m수층으로 채롱을 내려 양성하고 그 외 시기에는 15 m층 내외가 좋은 것으로 나타났다. 상품으로 출하 가능한 크기 인 각고 10 cm이상, 전중량 140 g 내외로 성장시 키기까지는 채묘후 22개월이 소요되었고, 출하시기는 전중량 증가가 최대에 이르는 3월에서 4월 중순이 경제적일 것으로 판단된다.er 90 % of good relative dynamic modulus of elasticity due to fineness of formation caused by the

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1055-1064
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• 2006

Extremely slow growing anammox(anaerobic ammonium oxidation) bacteria were cultivated using a combination of UASB(Upflow Anaerobic Sludge Blanket) reactor seeded with anaerobic granular sludge and carbon-fiber cultivating reactor. After 180 days of continuous cultivation, average nitrogen removal rate showed 0.54 kg $N/m^3-day$ when 0.6 kg $N/m^3-day$ of nitrogen loading was applied. The black granule was changed to brown and red granule as continuous operation, and the red granule was highly dependant on the high anammox activity. Microbial community structure of red granule in the UASB reactor was analyzed by molecular methods such as gene cloning, phylogenetic tree analysis, and FISH(Fluorescence In Situ Hybridization) method. As a result of gene cloning and phylogenetic tree analysis, 5 kinds of phylum were found to be Planctomycetes, Proteobacteria, Acidobacteria, Chlorobi and Chloroflexi. 13 clones were matched to anammox bacteria among 51 clones in the red anammox granule. In-silico test which used cloning information and FISH probe of the AMX368 was conducted to detect the presence of anammox bacteria in the red anammox granule. As a result of in-silico test only one clone was exactly matched to AMX368 but 11 clones was mutated one base among 18 bases representing all 12 clones are anammox bacteria. A filamentous Chloroflexi might be related to the granulation of anammox bacteria. As a result of FISH analysis, anammox bacteria was abundant in the red anammox granule.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.172-178
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• 2006

The dynamics of bacterial populations belonging to $\alpha\;\beta\;\gamma-subclass$ proteobacteria, Cytophaga-Flavobacterium (CF) group and sulfate reducing bacteria (SRB) in water column of the middle reaches of Nakdong River depending on sediment harvesting were analyzed by fluorescent in situ hybridization (FISH) at sediment harvesting site (near the Seongju bridge) and non-sediment harvesting site (near the Gumi bridge). In addition, some physico-chemical parameters such as temperature, pH, $chi-\alpha$ and electrical conductivity were measured. Regarding the number of total cell counts, cells stained by DAPI, there were no substantial quantitative differences between both sites, but those fluctuation at sediment Harvesting site was greater. And also the ratios of CFgroup and SRB to total cell counts tend to increase at sediment harvesting site with higher $chl-\alpha$, maybe due to the resuspension of sediment into water column. But the total proportion of all determined bacterial populations to total cell counts were greater at non-sediment harvesting site, compared with those at sediment harvesting site. Since the detectibility of bacteria by FISH depends on their metabolic activity, those lower proportion at the sediment harvesting site implies that sediment harvesting may lead to malfunction of those bacteria respect to nutrient recycling and subsequently negative effects on microbial food web.

• Korean Journal of Microbiology
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• v.40 no.4
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• pp.307-312
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• 2004

Diversity of the bacterial communities and the relation between community structure and components of waste­water were analyzed by 16S rRNA-based molecular techniques. Clone libraries of the 16S rDNAs from the sludges were constructed by PCR and cloning. The 1,151 clones from a sludge sample of sewage treatment plant were clustered into 699 RFLP phylotypes and the 1,228 clones from the wastewater disposal plant of chemical industry were clustered into 300 RFLP phylotypes. Shannon-Weiner diversity indices of two sampling sites were 8.7 and 6.1, indicating that the bacterial community structure of sewage treatment plant was more diverse than that of wastewater disposal plant of chemical industry. Forty clones belonging to predominant RFLP types were selected and sequenced. Seventy percent (28 clones) of the sequenced clones were related to the uncultured bacteria in public databases. The ${\beta}-Proteobacteria$ dominated in the bacterial communities of investigated two sludge samples. 16S rDNA sequences of the sewage treatment plant were similar to those of other activated sludges, while the bacterial community in wastewater disposal plant of chemical industry rep­resented the strains identified from high-temperature, anaerobic, hydrocarbon-rich, and sulfur-rich environ­ments. This result suggested that bacterial communities depended upon the components of wastewater.

• Korean Journal of Microbiology
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• v.43 no.3
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• pp.201-209
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• 2007

The CFDA (6-carboxyfluorescein diacetate) direct viable count method and plate count (PC) method using conventional nutrient broth (NB) medium and $10^{-2}$ diluted NB (DNB) medium were applied to samples collected from Mt. Yongdoo In Andong, in an effect to determine the number of living bacteria pine mushroom forest soil. The number of living bacteria determined via plate count in NB medium comprised $5{\sim}8%$ of the CFDA direct viable count, and the bacteria in the DNB medium comprised $40{\sim}47%$. This result indicated that viable but nonculturable (VBNC) bacteria existed in the pine mushroom forest soil at a high percentage. The phylogenetic characteristics of the VBNC bacterial populations in the samples of pine mushroom (Tricholoma matsutake) forest soil were analyzed via the direct extraction of DNA and 16S rDNA-ARDRA. The 115 clones from pine mushroom forest soil were clustered into 31 different RFLP phylotypes by ARDRA. Based on the 16S rDNA sequences, the 31 ARDRA clusters were classified into 6 phylogenetic groups: ${\alpha}-,\;{\beta}-,\;{\gamma}-Proteobacteria$, Acidobacteria, Actinobacteria and Firmicutes. Among these bacterial populations, approximately 85% were classified as members of phylum Acidobacteria. The Acidobacteria phylum was shown to exist abundantly in the pine mushroom forest soil.

• Journal of Life Science
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• v.29 no.11
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• pp.1294-1303
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• 2019

Perchlorate is an anionic pollutant that is very soluble and stable in water. It has been detected not only in soil/ground water but also in surface water, drinking water, food, fish, and crops. Perchlorate inhibits iodine uptake by the thyroid gland and reduces production of thyroid hormones that are primarily responsible for regulation of metabolism. Although various technologies have been developed to remove perchlorate from the environment, biodegradation is the method of choice since it is economical and environmentally friendly. However there is limited information on perchlorate biodegradation in salt environment such as salt water. Therefore this paper reviews biodegradation of perchlorate in salt water and related microorganisms. Most biodegradation research has employed heterotrophic perchlorate removal using organic compounds such as acetate as electron donors. Biodegradation research has focused on perchlorate removal from spent brine generated by ion exchange technology that is primarily employed to clean up perchlorate-contaminated ground water. Continuous removal of perchlorate at up to 10% NaCl was shown when bioreactors were inoculated with enriched salt-tolerant perchlorate-reducing bacteria. However the reactors did not show long-term stable removal of perchlorate. Microorganisms belonging to ${\beta}$- and ${\gamma}$-Proteobacteria were dominant in bioreactors used to remove perchlorate from salt water. This review will help our understanding of perchlorate removal from salt water to develop a decent biotechnology for the process.

• Proceedings of the Microbiological Society of Korea Conference
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• 2001.11a
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• pp.157-163
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• 2001

Mycolic acid-containing gram-positive bacteria, so called nocardioform actinomycetes, have become a great interest to environmental microbiologists due to their metabolic versatility, multidegradative capacity and potential for bioremediation of priority pollutants. For example, Rhodococcus rhodochrous N75 was able to metabolize 4-methy1catechol via a modified $\beta$-ketoadipate pathway whereby 4-methylmuconolactone methyl isomerase catalyzes the conversion of 4-methylmuconolactone to 3-methylmuconolactone in order to circumvent the accumulation of the 'dead-end' metabolite, 4-methylmuconolactone. R. rhodochrous N75 has also shown the ability to transform a range of alkyl-substituted catechols to the corresponding muconolactones. A novel 3-methylmuconolactone-CoAsynthetase was found to be involved in the degradation of 3-methylmuconolactone, which is not mediated in a manner analogous to the classical $\beta$-ketoadipate pathway but activated by the addition of CoA prior to hydrolysis of lactone ring, suggesting that the degradative pathway for methylaromatic compounds by gram-positive bacteria diverges from that of proteobacteria. Mycobacterium sp. Strain PYR-l isolated from oil-contaminated soil was capable of mineralizing various polyaromatic hydrocarbons (PAHs), such as naphthalene, phenanthrene, pyrene, fluoranthrene, 1-nitropyrene, and 6-nitrochrysene. The pathways for degradation of PAHs by this organism have been elucidated through the isolation and characterization of chemical intermediates. 2-D gel electrophoresis of PAH-induced proteins enabled the cloning of the dioxygenase system containing a dehydrogenase, the dioxygenase small ($\beta$)-subunit, and the dioxygenase large ($\alpha$)-subunit. Phylogenetic analysis showed that the large a subunit did not cluster with most of the known sequences except for three newly described a subunits of dioxygenases from Rhodococcus spp. and Nocardioides spp. 2-D gel analysis also showed that catalase-peroxidase, which was induced with pyrene, plays a role in the PAH metabolism. The survival and performance of these bacteria raised the possibility that they can be excellent candidates for bioremediation purposes.

• Korean Journal of Microbiology
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• v.36 no.4
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• pp.292-298
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• 2000

For scrutinizing the changes of aggregated bacteria in Lake Paldang, the FISH method was applied by using the rhodamine labeled probes, and total bacteria, chloropyll a concentrations and nutrients concentrations were measured. The aggregates were collected with sediment traps. The T-N, T-P, chlorophyll a concentrations of aggregates were higher 5-15 times, 81-140 and 49-66 times than water samples, respectively. Also, the bacterial numbers of aggregates were 200 times higher than those of water smaples. The ratios of each groups of water sample were 2.1-7.4% for $\alpha$-group, 4.5-8.3% for $\beta$-group, 2.1-7.4% for $\gamma$-group, 2.1-6.1% for Cytophaga-Flavobacterium group and 0.1-2.5% for 'other'group, respectively. While, in aggregates, the ratios of $\alpha$-, $\beta$-, $\gamma$- and Cytophaga-Flavobacterium groups were very small and most abundant group was 'other' bacteria. With these results, the aggregated bacteria in Lake Paldang had a particular group composition of bacteria.