• Environmental Engineering Research
• /
• 제20권1호
• /
• pp.51-57
• /
• 2015

As expected, the expression of denitrifying genes in a Typha wetland (relatively stagnant compared to other ponds), showing higher nitrogen removal efficiency in summer, was affected by temperature. The abundance and gene transcripts of nitrate reductase (narG), nitrite reductase (nirS), nitric oxide reductase (norB), and nitrous oxide reductase (nosZ) genes in seasonal sediment samples taken from the Acorus and Typha ponds of free surface flow constructed wetlands were investigated using quantitative polymerase chain reaction (Q-PCR) and quantitative reverse transcription PCR (Q-RT-PCR). Denitrifying gene copy numbers ($10^5-10^8$ genes $g^{-1}$ sediment) were found to be higher than transcript numbers-($10^3-10^7$ transcripts $g^{-1}$ sediment) of the Acorus and Typha ponds, in both seasons. Transcript numbers of the four functional genes were significantly higher for Typha sediments, in the warm than in the cold season, potentially indicating greater bacterial activity, during the relatively warm season than the cold season. In contrast, copy numbers and expression of denitrifying genes of Acorus did not provide a strong correlation between the different seasons.

• 상하수도학회지
• /
• 제26권4호
• /
• pp.591-598
• /
• 2012

Denitrification is an important biological mechanism in wastewater treatment process because this process is technically to remove nitrogen from water to air. There have been lots of study about denitrification engineering and molecular biological research about denitrifying bacteria, respectively. However, combination of these researches was unusual and rare. This study is about the correlation between quantity of denitrifying bacteria and denitrification potential, and consists of NUR batch test as analysis method of denitrification potential and quantitative molecular analysis for denitrifying bacteria. Three reactors (A/O, MLE and A/O of nitrogen deficiency) are operated to get activated sludge with various denitrification potential. All samples which were acquired from reactors were measured denitrification potential by NUR test and NUiR test. Also, Real-time PCR was conducted for quantification of denitrifying bacteria composition in activated sludge. The various denitrification potentials were measured in the reactors. The denitrifiaction potential was the highest in MLE process and the reactor of the nitrogen deficiency showed the lowest. Genomic DNA of activated sludge was obtained and consequently, real-time PCRuse the primer sets of nirK and nirS　were conducted to quantify genes involving denitrification reductase production. As the result of real-time PCR, nirK gene showed more significant influence on denitrification potential comapred with nirS gene.

• 미생물학회지
• /
• 제40권3호
• /
• pp.244-247
• /
• 2004

이산화탄소 농도의 증가가 습지토양의 탈질세균 군집구조에 미치는 영향을 살펴보기 위하여 자연농도 (370 ppm)와 고농도 (740 ppm)의 이산화탄소조건의 습지생태계를 조성하여 110일 이상 배양한 후 토양 내 미생물 군집구조의 변화양상을 관찰하였다. 미생물 군집군조 분석은 탈질과정에 관여하는 효소중하나인 nitrite reductase의 유전자인 nirS 유전자를 대상으로 polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) 분석기법을 이용하여 수행하였다. PCR 결과 모든 토양시료에서 nirS 유전자가 검출되었고, RFLP분석을 통해 자연농도의 이산화탄소조건에서 83개, 고농도 조건에서 95개의 phylotype을 획득하여 조성된 습지토양에서 탈질과정이 광범위하게 일어날 수 있음을 확인할 수 있었다. 두 경우 모두 두 종류 (type 1과 type 2)의 phylotype의 우점하고 있었고, 고농도 조건의 탈질세균 군집의 풍부도가 저농도 조건에 비해 더 높고, phylotype의 종류가 현저하게 변화되는 경향을 확인하였다. 본 연구결과는 습지토양의 탈질세균 군집이 매우 다양한 종류로 이루어져 있고, 이산화탄소의 증가에도 큰 영향을 받지 않는 상당히 안정적인 우점 개체군이 존재하고 있는 반면, 전체 phylotype의 약 60％는 이산화탄소 증가에 따라 민감하게 변화함을 보여주었다.

• Journal of Microbiology and Biotechnology
• /
• 제24권6호
• /
• pp.843-853
• /
• 2014

In the context of artificial groundwater recharge, a reactive soil column at pilot-scale (4.5 m depth and 3 m in diameter) fed by treated wastewater was designed to evaluate soil filtration ability. Here, as a part of this project, the impact of treated wastewater filtration on soil bacterial communities and the soil's biological ability for wastewater treatment as well as the relevance of the use of multi-bioindicators were studied as a function of depth and time. Biomass; bacterial 16S rRNA gene diversity fingerprints; potential nitrifying, denitrifying, and sulfate-reducing activities; and functional gene (amo, nir, nar, and dsr) detection were analyzed to highlight the real and potential microbial activity and diversity within the soil column. These bioindicators show that topsoil (0 to 20 cm depth) was the more active and the more impacted by treated wastewater filtration. Nitrification was the main activity in the pilot. No sulfate-reducing activity or dsr genes were detected during the first 6 months of wastewater application. Denitrification was also absent, but genes of denitrifying bacteria were detected, suggesting that the denitrifying process may occur rapidly if adequate chemical conditions are favored within the soil column. Results also underline that a dry period (20 days without any wastewater supply) significantly impacted soil bacterial diversity, leading to a decrease of enzyme activities and biomass. Finally, our work shows that treated wastewater filtration leads to a modification of the bacterial genetic and functional structures in topsoil.

• 한국미생물·생명공학회지
• /
• 제48권1호
• /
• pp.72-78
• /
• 2020

The dynamics of nitrogen compounds and RNA-based functional genes were characterized in the nitrification-denitrification coupling process. For the removal of residual ammonium, intermittent aeration was introduced in the denitrification reactor. N₂O production was not observed in both reactors. In both reactors, the nitrifying genes (achaeal-amoA, bacterial-amoA and hor) and denitrifying genes (narG, nirK, norB and nosZ) had a copy number of 3.92 × 10²-7.25 × 10⁵ and 2.85 × 10²-3.06 × 10⁴ per ng of DNA, respectively. These results suggest that denitrification and nitrification reactions occur in both the nitrification and denitrification reactors, respectively. Therefore, the coupling process is a promising one for the conversion of ammonium to nitrogen without generating N₂O.

• Journal of Microbiology and Biotechnology
• /
• 제33권4호
• /
• pp.471-484
• /
• 2023

Compost is widely used as an organic additive to improve the bioremediation of diesel-contaminated soil. In this study, the effects of compost amendment on the remediation performance, functional genes, and bacterial community are evaluated during the bioremediation of diesel-contaminated soils with various ratios of compost (0-20%, w/w). The study reveals that the diesel removal efficiency, soil enzyme (dehydrogenase and urease) activity, soil CH₄ oxidation potential, and soil N₂O reduction potential have a positive correlation with the compost amendment (p < 0.05). The ratios of denitrifying genes (nosZI, cnorB and qnorB) to 16S rRNA genes each show a positive correlation with compost amendment, whereas the ratio of the CH₄-oxidizing gene (pmoA) to the 16S rRNA genes shows a negative correlation. Interestingly, the genera Acidibacter, Blastochloris, Erythrobacter, Hyphomicrobium, Marinobacter, Parvibaculum, Pseudoxanthomonas, and Terrimonas are strongly associated with diesel degradation, and have a strong positive correlation with soil CH₄ oxidation potential. Meanwhile, the genera Atopostipes, Bacillus, Halomonas, Oblitimonas, Pusillimonas, Truepera, and Wenahouziangella are found to be strongly associated with soil N₂O reduction potential. These results provide useful data for developing technologies that improve diesel removal efficiency while minimizing greenhouse gas emissions in the bioremediation process of diesel-contaminated soil.

• Asian-Australasian Journal of Animal Sciences
• /
• 제26권11호
• /
• pp.1651-1658
• /
• 2013

Nitrate contamination in ground and surface water is an increasingly serious environmental problem and only a few bacterial strains have been identified that have the ability to remove nitrogen pollutants from wastewater under thermophilic conditions. We therefore isolated thermophilic facultative bacterial strains from wood chips that had been composted with swine manure under aerated high temperature conditions so as to identify strains with denitrifying ability. Nine different colonies were screened and 3 long rod-shaped bacterial strains designated as SG-01, SG-02, and SG-03 were selected. The strain SG-01 could be differentiated from SG-02 and SG-03 on the basis of the method that it used for sugar utilization. The 16S rRNA genes of this strain also had high sequence similarity with Geobacillus thermodenitrificans $465^T$ (99.6%). The optimal growth temperatures ($55^{\circ}C$), pH values (pH 7.0), and NaCl concentrations (1%) required for the growth of strain SG-01 were established. This strain reduced 1.18 mM nitrate and 1.45 mM nitrite in LB broth after 48 h of incubation. These results suggest that the G. thermodenitrificans SG-01 strain may be useful in the removal of nitrates and nitrites from wastewater generated as a result of livestock farming.

• 미생물학회지
• /
• 제53권1호
• /
• pp.58-60
• /
• 2017

Halioglobus sp. RR3-57는 해수순환여과양식시스템의 생물여과조에서 순수분리되었으며, PacBio RS II 서열분석법을 이용하여 전체 유전체 서열이 해독되었다. 그 결과 길이 4,847,776 bp, G+C함량 57.5%인 염색체와 155,799 bp, 53.2%인 플라스미드로 구성된 유전체 서열을 획득하였다. 유전체 분석결과 탈질작용에 관련된 18개의 유전자와 불완전한 프로파지(prophage)로 추정되는 유전자서열이 확인되었다.

• 대한환경공학회지
• /
• 제28권7호
• /
• pp.752-756
• /
• 2006

최근 수계의 총질소(T-N) 규제가 강화되면서 기존 BAF 공정의 개선을 위해 독립적인 무산소조가 추가로 도입되었다. 본 연구에 사용된 공정은 유기물과 질산화 중심으로 개발 된 기술인 $Biobead^{(R)}$공법으로 상용화된 상향류의 BAF공정의 하나이다. 독립적인 무산소조의 도입의 타당성을 검토하기 위해 분자생물학적 방법의 하나인 PCR-DGGE기법이 수행되었다. 두 가지 type의 nitrite reductase genes를 통해 진행되었는데, nirS로 암호화된 cytocrome $cd_1$ nitrite reductase gene과 nirK로 암호화된 Cu를 함유한 nitrite reductase gene이다. 이러한 탈질 기능유전자를 이용하여 PCR-DGGE를 통해 탈질 목적으로 순화된 독립적인 무산소조의 탈질미생물의 군집을 해석하였다. PCR 증폭결과, 탈질을 수행하는 무산소조 내에서는 nirS와 nirK유전자 가운데 nirS유전자만 검출되었고, DGGE 분석결과, 최초 식종원으로 이용된 활성슬러지에서는 상대적으로 많은 band들이 검출되는 반면, 무산소조 내에서는 운전일수와 nitrate 부하량이 증가할수록 단일 band로 우점화 하는 경향을 나타내었다. DGGE band에 대한 염기서열 분석결과, 식종 슬러지의 경우 다양한 uncultured bacteria가 나타났으나, nitrate 제거율이 높은 안정화된 무산소조에서는 alcaligenes faecalis 등 특정 탈질미생물이 우점화 되는 것으로 확인되었다. 결론적으로 이러한 탈질미생물 군집특성을 가지는 무산소조의 도입은 96%이상의 안정적인 탈질을 가능하게 하였으며, BAF 공정 개선을 위한 독립적인 무산소조의 도입은 적절한 것으로 판단되었다.