• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
• /
• pp.133-137
• /
• 2004

Tetrachloroethylene(PCE) dechlorination was investigated in an anaerobic enrichment culture from landfill soil. Anaerobic PCE dechlorinating microorganisms could convert 150mg/L of PCE via trichloroethylene(TCE) to cir-1,2-dichloroethylene(CDCE) within 2 days at the optimum temperature of 30 to 35$^{\circ}C$. The enrichment culture could dechlorinate TCE but did not degrade other chlorinated aliphatic compounds, such as cDCE, trans-1,2-dichloroethylene, 1,1-dichloroethylene, 1,1-dichloroethane, 1,2-dichloro- ethane, and 1,1,1-trichloroethane during 5 days incubation. Several isolates from the enrichment culture did not show dechlorinating activity of PCE. Microbial analysis of the dechlorinating enrichment culture by using Polymerase chain reaction-Denaturing gradient gel electrophoresis (PCR-DGGE) method showed that at least three microorganisms were related to the anaerobic PCE dechlorination in the enrichment

• Journal of Microbiology and Biotechnology
• /
• 제19권7호
• /
• pp.651-657
• /
• 2009

Shifts in the activity and diversity of microbes involved in aliphatic and aromatic hydrocarbon degradation in contaminated soil were investigated. Subsurface soil was collected from a gas station that had been abandoned since 1995 owing to ground subsidence. The total petroleum hydrocarbon content of the sample was approximately 2,100 mg/kg, and that of the soil below a gas pump was over 23,000 mg/kg. Enrichment cultures were grown in mineral medium that contained hexadecane (H) or naphthalene (N) at a concentration of 200 mg/l. In the Henrichment culture, a real-time PCR assay revealed that the 16S rRNA gene copy number increased from $1.2{\times}10^5$to $8.6{\times}10^6$with no lag phase, representing an approximately 70-fold increase. In the N-enrichment culture, the 16S rRNA copy number increased about 13-fold after 48 h, from $6.3{\times}10^4$to $8.3{\times}10^5$. Microbial communities in the enrichment cultures were studied by denaturing gradient gel electrophoresis and by analysis of 16S rRNA gene libraries. Before the addition of hydrocarbons, the gas station soil contained primarily Alpha- and Gammaproteobacteria. During growth in the H-enrichment culture, the contribution of Bacteriodetes to the microbial community increased significantly. On the other hand, during N-enrichment, the Betaproteobacteria population increased conspicuously. These results suggest that specific phylotypes of bacteria were associated with the degradation of each hydrocarbon.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
• /
• pp.332-336
• /
• 2004

An anaerobic PCE(tetrachloroethylene) dechlorinating bacterial culture from a landfill soil was enriched and characterized. The enrichment culture could dechlorinate 60$\mu$mol/$m\ell$ of PCE during a month of incubation and cis-DCE(cis-dichloroethylene) was observed as a main product of PCE dechlorination. Microbial analysis of the dechlorinating enrichment culture by rising PCR-DGGE (Polymerase chain reaction-Denaturing gradient gel electrophoresis) method showed that at least three microorganisms were related to the anaerobic PCE dechlorination.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제9권2호
• /
• pp.41-47
• /
• 2004

This research in the degradation of polychlorinated biphenyls(PCB) has focussed on the use of experimental enrichment cultures to obtain PCB-deading communities and identification of PCB-degrading bacteria accor야ng to pure culture. During 180 days, enrichment culture was performed to obtain PCB-degrading bacteria and initial concentration was injected 1.6 ppm,0.7 ppm, respectively. After 180 days of enrichment culture, PCBs was removed 80-87% and 57-71%. Biodegradation of PCBs was studied according to dominated PCB-degrading bacteria. Biodegraddation of PCBs was 80% in initial concentration of PCBs for 20days, enrichment cultured PCB-degrading bacteria was isolated by pure culture and it was verified to Pseudoxanthomonas sp.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2003년도 추계학술발표회
• /
• pp.136-139
• /
• 2003

The combined effect of bioaugmentation of dechlorinating bacterial cultures and addition of iron powder (Fe$^{0}$ ) on reductive dechlorination of tetrachloroethylene (PCE) and other chlorinated ethylenes in a artificially contaminated soil slurry (60$\mu$mo1es PCE/kg soil) were tested. Two different anaerobic bacterial cultures, a pure bacterial culture of Desulfitobacterium sp. strain Y-51 capable of dechlorinating PCE to cis-1, 2-dechloroethylene (cis-DCE) and the other enrichment culture PE-1 capable of dechlorinating PCE completely to ethylene, were used for the bioaugmentation test. Both treatments introduced with the strain Y-51 and PE-1 culture (3mg dry cell weight/kg soil) showed conversion of PCE to cis-DCE within 40 days. The treatments added with Fe$^{0}$ (0.1 -1.0 %(w/w)) alone to the soil slurry resulted in extended PCE dechlorination to ethylene and ethane and the, dechlorination rate depended on the amount of Fe$^{0}$ added. The combined use of the bacterial cultures with Fe$^{0}$ (0.1-1.0%) showed the higher PCE dechlorination rate than the separated application and the pattern of PCE dechlorination and end-product formation was different from those of the separated application. These results suggested that the combined application of Fe$^{0}$ and the bactrial culture, specially the complete dechlorinating enrichment culture such as PE-1 culture, would be practically effective for remediation of PCE contaminated soil.

• Journal of Microbiology and Biotechnology
• /
• 제23권11호
• /
• pp.1617-1626
• /
• 2013

The Bacterial community structure and its complexity of the enrichment culture during the isolation and screening of imidacloprid-degrading strain were studied using denaturating gradient gel electrophoresis analysis. The dominant bacteria in the original tea rhizosphere soil were uncultured bacteria, Rhizobium sp., Sinorhizobium, Ochrobactrum sp., Alcaligenes, Bacillus sp., Bacterium, Klebsiella sp., and Ensifer adhaerens. The bacterial community structure was altered extensively and its complexity reduced during the enrichment process, and four culturable bacteria, Ochrobactrum sp., Rhizobium sp., Geobacillus stearothermophilus, and Alcaligenes faecalis, remained in the final enrichment. Only one indigenous strain, BCL-1, with imidacloprid-degrading potential, was isolated from the sixth enrichment culture. This isolate was a gram-negative rod-shaped bacterium and identified as the genus Ochrobactrum based on its morphological, physiological, and biochemical properties and its 16S rRNA gene sequence. The degradation test showed that approximately 67.67% of the imidacloprid (50 mg/l) was degraded within 48 h by strain BCL-1. The optimum conditions for degradation were a pH of 8 and $30^{\circ}C$. The simulation of imidacloprid bioremediation by strain BCL-1 in soil demonstrated that the best performance in situ (tea soil) resulted in the degradation of 92.44% of the imidacloprid (100 mg/g) within 20 days, which was better than those observed in the ex situ simulations that were 64.66% (cabbage soil), 41.15% (potato soil), and 54.15% (tomato soil).

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제9권3호
• /
• pp.49-55
• /
• 2004

염화에틸렌 화합물에 오염된 토양으로부터 고농도 (150mg/L)의 PCE를 cis-DCE까지 탈염소화하는 혼합미생물 농화 배양계 LYF-1을 구축하였다. LYF-1은 효모추출물, 펩톤, 포름산, 아세트산, 락트산, 피루브산, 시트르산, 석신산, 글루코오스, 수크로오스, 에탄올 등을 전자공여체로 이용하여 PCE를 탈염소화할 수 있었다. 한편, PCE를 대신할 수 있는 전자 수용체에 의한 PCE 탈염소화에 미치는 영향을 살펴본 결과, NO$_3$$^{-}$와 NO$_2$$^{-}$는 PCE의 탈염소화반응을 완전히 저해하였으나, S$_2$O$_3$$^{-2}$ , SO$_3$$^{-2}$ 및 SO$_4$$^{-2}$ 는 PCE의 탈염소화반응에 그다지 큰 영향을 미치지 않았다. LYF-1 혼합미생물을 혐기성 고정생물막 반응기내의 세라믹 메디아에 부착하고, PCE의 유입부하율 변화에 따른 처리 효율을 조사한 결과, PCE의 부하율 0.13-0.78 $\mu$moles/L/hr의 범위 내에서 99% 이상의 PCE 탈염소화 효율을 보였으며, PCE 탈염소화 반응의 최종산물은 cis-DCE이었다.

• 생명과학회지
• /
• 제27권4호
• /
• pp.435-441
• /
• 2017

퍼클로레이트($ClO_4^-$)는 토양, 지하수, 그리고 지표수의 신규 오염물질이다. 원소 황을 전자공여체로 이용하여 퍼클로레이트를 분해하는 농화배양에 존재하는 세균 군집에 대한 정보는 이전 연구를 통해 밝혀졌다. 본 연구에서는 정량 및 정성적인 분자기법으로 이 농화배양 내 고세균 군집을 조사하였다. 농화배양 내의 16S rRNA 유전자 copy수를 실시간 정량 PCR로 조사한 결과 고세균의 이 유전자 copy수는 세균의 1.5%를 나타냈다. 그래서 이 농화배양 환경에서 적응하는 고세균의 수가 적어 세균이 우점하는 것으로 나타났다. DGGE 밴드패턴을 통해 농화배양과 식종균으로 이용한 활성슬러지의 고세균 군집조성이 다르다는 것을 알 수 있었다. 농화배양의 가장 우세한 DGGE 밴드는 Methanococci와 연관되는 것으로 나타났다. 향후 이 우점 고세균 개체군의 대사적 역할이 규명되면 퍼클로레이트를 제거하는 농화배양 내 존재하는 미생물 군집을 이해하는데 도움이 될 것이다.

• 한국환경과학회지
• /
• 제21권8호
• /
• pp.989-996
• /
• 2012

Nitrate contamination of water environments can create serious problems such as eutrophication of rivers. Conventional biological processes for nitrate removal by heterotrophic denitrification often need additional organic substrates as carbon sources and electron donors. We tried to accelerate biological denitrification by using bioelectrochemical reactor (BER) in which electrode works as an electron donor. Denitrification activity of 8 environmental samples from various sediments, soils, groundwaters, and sludges were tested to establish an efficient enrichment culture for BER. The established enrichment culture from a soil sample showed stable denitrification activity without any nitrite accumulation. Microbial community analysis by using PCR-DGGE method revealed that dominant denitrifiers in the enrichment culture were Pantoea sp., Cronobacter sakazakii, and Castellaniella defragrans. Denitrification rate ($0.08kg/m^3{\cdot}day$) of the enrichment culture in BER with electrode poised at -0.5 V (vs Ag/AgCl) was higher than that ($2.1{\times}10^{-2}kg/m^3{\cdot}day$) of BER without any poised potential. This results suggested that biological denitrification would be improved by supplying potential throughout electrode in BER. Further research using BER without any organic substrate addition is needed to apply this system for bioremediation of water and wastewater contaminated by nitrate.

• Journal of Microbiology and Biotechnology
• /
• 제18권4호
• /
• pp.711-717
• /
• 2008

To speed up the conversion of rice straw into feeds in a low-temperature region, a start culture used for ensiling rice straw at low temperature was selected by continuous enrichment cultivation. During the selection, the microbial source for enrichment was rice straw and soil from two places in Northeast China. Lab-scale rice straw fermentation at $10^{\circ}C$ verified, compared with the commercial inoculant, that the selected start culture lowered the pH of the fermented rice straw more rapidly and produced more lactic acid. The results from denatured gradient gel eletrophoresis showed that the selected start culture could colonize into the rice straw fermentation system. To analyze the composition of the culture, a 16S rRNA gene clone library was constructed. Sequencing results showed that the culture mainly consisted of two bacterial species. One (A) belonged to Lactobacillus and another (B) belonged to Leuconostoc. To make clear the roles of composition microbes in the fermented system, quantitative PCR was used. For species A, the DNA mass increased continuously until sixteen days of the fermentation, which occupied 65%. For species B, the DNA mass amounted to 5.5% at six days of the fermentation, which was the maximum relative value during the fermentation. To the authors' best knowledge, this is the first report on ensiling rice straw with a selected starter at low temperature and investigation of the fermented characteristics.