• 유기물자원화
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• 제18권2호
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• pp.76-83
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• 2010

당사는 중온/습식/이상 혐기성 소화공정인 HADS Pilot Plant를 이용하여 국내 음폐수에 대해 유기물 부하(OLR, Organic Loading Rate) 증량 방식을 달리하여 혐기성 소화 테스트를 진행하였다. 그 방식은 연속적이면서 빠르게 OLR을 증량시키는 급속 OLR 증량 운전과 단계적이면서 각 단계별로 적응기를 갖는 계단식 OLR 증량 운전 방식이었다. 그 결과 급속 OLR 증량 운전시에는 불안정한 VFA(Volatile Fatty Acid)/Alkalinity 비율을 보이다가 바이오가스 발생량이 급감하는 결과를 보여주었다. 반면, 계단식 OLR 증량 운전시에는 VFA/Alkalinity의 비율을 0.4이하로 유지하면서 혐기성 소화 운전을 실시한 결과 안정적인 혐기성소화 성능을 보였을 뿐만 아니라, $0.8Nm^3/kgVS_{rem}/d$의 바이오가스 회수 및 85%의 VS(Volatile Solid) 감량이 가능함을 확인하였다. 그리고 OLR 증량 운전 방식에 따라 완전히 다른 결과가 도출되어 각각의 혐기성 소화 운전시의 박테리아 및 메탄생성균 군집의 변화를 T-RFLP(Terminal-Restriction Fragment Length Polymorphism)를 통하여 분석하였다. 그 결과, 급속 OLR 증량 운전시와 계단식 OLR 증량 운전시의 미생물 군집이 달라져 있음을 확인하였고, 이에 따라 동일한 혐기성 소화 공정을 적용하여 음폐수에 대한 혐기성 소화 운전을 진행하였음에도 OLR 증량 운전 방식에 따라 미생물의 반응성 및 주변환경에 대한 내성이 달라질 수 있음을 알 수 있었다.

• 미생물학회지
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• 제46권2호
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• pp.169-176
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• 2010

회전접촉장치와 점감포기 생물반응조를 이용한 실험용 규모의 폐수처리 공정을 식품산업폐수를 유입수로 사용하여 5개월 동안 운전하였으며, 16S rRNA 유전자의 말단단편길이다형성(T-RFLP) 분석과 계통분류학적 분석방법으로 폐수처리 공정의 세균군집을 조사하였다. 유기물 외에 고농도의 질소와 인이 함유된 식품산업폐수를 적용하였음에도 불구하고, 안정화 기간 동안 화학적산소요구량, 총질소, 총인의 제거효율은 각각 98%, 93%, 95% 이상이었다. 가동 초기의 세균 군집과 안정화 이후의 세균군집은 뚜렷하게 구분되었으며, 안정화 기간 동안 가장 우점한 세균군집은 Bacteroidetes였다. 운전 기간중의 주요 세균 군집은 사상균으로 분류되는 Haliscomenobacter, Sphaerotilus, Candidate division TM7이었으나, 이들 사상균에 의한 슬러지 팽화 현상은 관찰할 수 없었다. Haliscomenobacter와 유연관계가 가까운 세균군집이 안정화 시기에 증가하여 최대 우점 군집이 되었다. 본 연구결과는 회전접촉장치와 점감포기 생물반응조를 이용한 폐수처리공정의 영양물질 제거에 사상균이 중요함을 제시한다.

• The Plant Pathology Journal
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• 제32권2호
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• pp.136-144
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• 2016

Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.161-161
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• 2017

Seed endophytes are very remarkable groups of bacteria for their unique abilities of being vertically transmitted and conserved. As plants attain hybrid vigor and heterosis in the process of crossbreeding, this might also lead to the changes in the community structure and diversity of plant endophytes in the hybrid plants ultimately affecting the endophytes of the seeds. It would be interesting to characterize how seed endophyte composition change over time. The objective of this study is to gain insights into the influence of natural crossbreeding and parental lineage in the seed bacterial endophytic communities of two pure inbred lines exploring contributions of the two most important sources of plant endophytes - colonization from external sources and vertical transmission via seeds. Total genomic DNA was isolated from rice seeds and bacterial DNA was selectively amplified by PCR. The diversity of endophytic bacteria was studied through Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis. Diversity between the original parents and the pure inbred line may show significant differences in terms of richness, evenness and diversity indices. Heat maps reveal astonishing contributions of both or either parents (IR29 ${\times}$ Pokkali and AT401 ${\times}$ IR31868) in the shaping of the bacterial seed endophytes of the hybrid, FL478 and IC32, respectively. Most of the T-RFs of the subsequent pure inbred line could be traced to any or both of the parents. Comparison of common and genotype-specific T-RFs of parents and their offspring reveals that majority of the T-RFs are shared suggesting higher transmission of bacterial communities common to both parents. The parents influence the bacterial community of their offspring. Unique T-RFs of the offspring also suggest external sources of colonization particularly as the seeds are cultivated in different ecogeographical locations. This study showed that host parental lines contributed greatly in the shaping of bacterial seed endophytes of their offspring. It also revealed transmission and potential conservation of core seed bacterial endophytes that generally become the dominant microbiota in the succeeding generations of plant hosts.

• 한국수소및신에너지학회논문집
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• 제17권4호
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• pp.379-388
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• 2006

Two mesophilic trickling bed bioreactors filled with two different types of media, hydrophilic- and hydrophobic-cubes, were designed and conducted for hydrogen production under the anaerobic fermentation of sucrose. Each bioreactor consisted of the column packed with polymeric cubes and inoculated with heat-treated sludge obtained from anaerobic digestion tank. A defined medium containing sucrose was fed by the different hydraulic retention time(HRT), and recycle rate. Hydrogen concentrations in gas-phase were constant, averaging 40% of biogas throughout the operation. Hydrogen production rate was increased till $10.5\;L{\cdot}h^{-1}{\cdot}L^{-1}$ of bioreactor when influent sucrose concentrations and recycle rates were varied. At the same time, the hydrogen production rate with hydrophobic media application was higher than its hydrophilic media application. No methane was detected when the reactor was under a normal operation. The major fermentation by-products in the liquid effluent of the both trickling biofilters were acetate, butyrate and lactate. In order to run in the long term operation of both reactor filled with hydrophilic and hydrophobic media, biofilm accumulation on hydrophilic media and biogas produced should be controlled through some process such as periodical backwashing or gas-purging. Four sample were collected from each reactor on the opposite hydrogen production rate, and their bacterial communities were compared by terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR products generated using bacterial 16s rRNA gene primers (8f and 926r). It was expressed a marked difference in bacterial communities of both reactors. The trickling bed bioreactor with hydrophobic media demonstrates the feasibility of the process to produce hydrogen gas. A likely application of this reactor technology can be hydrogen gas recovery from pre-treatment of high carbohydrate-containing wastewaters.