• 대한환경공학회지
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• 제29권7호
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• pp.833-838
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• 2007

본 연구에서는 양전하를 띤 여재 입자에서 박테리아의 부착 및 이동에 관한 연구를 위하여 회분 및 칼럼실험을 수행하였다. 본 실험에 사용된 박테리아는 E. coli ATCC 11105(길이: 2.2 ${\mu}m$ 직경: 0.6 ${\mu}m$)이었고, 여재는 석영모래(입경분포: 0.5-2.0 mm, 평균 입경: 1.0 mm)와 철코팅 모래이었다. 회분실험결과에 의하면 철코팅 함량이 증가함에 따라, 박테리아의 부착량이 증가하는 것으로 나타났다. 철코팅 모래의 함량 0%(석영모래 100%)에서는 약 46% 정도의 박테리아가 부착되었고, 철코팅 모래의 함량 100%(석영모래 0%)에서는 약 97% 정도의 박테리아가 부착되었다. 칼럼실험결과 또한 철코팅 함량이 증가함에 따라, 박테리아의 부착량이 증가하는 것을 보여주고 있다. 철코팅 모래의 함량이 0에서 100%로 증가함에 따라 박테리아의 부착량이 8에서 94%로 증가하였다. 본 연구의 실험결과를 통해 양전하를 띤 여재 입자가 박테리아의 이동에 영향을 미칠 수 있음을 알 수 있다.

• The Plant Pathology Journal
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• 제29권4호
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• pp.374-385
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• 2013

Environmental stresses induce several plant pathogenic bacteria into a viable but nonculturable (VBNC) state, but the basis for VBNC is largely uncharacterized. We investigated the physiology and morphology of the copper-induced VBNC state in the plant pathogen Ralstonia solanacearum in liquid microcosm. Supplementation of $200{\mu}M$ copper sulfate to the liquid microcosm completely suppressed bacterial colony formation on culture media; however, LIVE/DEAD BacLight bacterial viability staining showed that the bacterial cells maintained viability, and that the viable cells contain higher level of DNA. Based on electron microscopic observations, the bacterial cells in the VBNC state were unchanged in size, but heavily aggregated and surrounded by an unknown extracellular material. Cellular ribosome contents, however, were less, resulting in a reduction of the total RNA in VBNC cells. Proteome comparison and reverse transcription PCR analysis showed that the Dps protein production was up-regulated at the transcriptional level and that 2 catalases/peroxidases were present at lower level in VBNC cells. Cell aggregation and elevated levels of Dps protein are typical oxidative stress responses. $H_2O_2$ levels also increased in VBNC cells, which could result if catalase/peroxidase levels are reduced. Some of phenotypic changes in VBNC cells of R. solanacearum could be an oxidative stress response due to $H_2O_2$ accumulation. This report is the first of the distinct phenotypic changes in cells of R. solanacearum in the VBNC state.

• Archives of Plastic Surgery
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• 제35권4호
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• pp.393-399
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• 2008

Purpose: Chronic infected wounds sustained over 4 weeks with exposed tendon or bone are difficult challenges to plastic surgeons. Vacuum assisted closure (VAC) device has been well used for the management of chronic wounds diminishing wound edema, reducing bacterial colonization, promoting formation of granulation tissue and local blood flow by negative pressure to wounds. But Commercial ready-made VAC device might have some difficulties to use because of its high expenses and heavy weight. So we modified traditional VAC device with silver dressing materials as topical therapeutic agents for control of superimposed bacterial wound infection such as MRSA, MRSE and peudomonas. Methods: We designed the modified VAC device using wall suction, 400 cc Hemovac and combined slow release silver dressing materials. We compared 5 consecutive patients' data treated by commercial ready-made VAC device(Group A) with 11 consecutive patients' data treated by modified VAC device combined with silver dressing materials(group B) from September 2004 to June 2007. Granulation tissue growth, wound discharge, wound culture and wound dressing expenses were compared between the two groups. Results: In comparison of results, no statistical differences were identified in reducing rate of wound size between group A and B. Wound discharge was significantly decreased in both groups. Modified VAC device with silver dressing materials showed advantages of convenience, cost effectiveness and bacterial reversion. Conclusion: In combination of modified VAC device and silver dressing materials, our results demonstrated the usefulness of managing chronic open wounds superimposed bacterial infection, cost effectiveness compared with traditional VAC device and improvement of patient mobility.

• Journal of Microbiology and Biotechnology
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• 제24권7호
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• pp.888-897
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• 2014

A bacterial community analysis of the gut of Tenebrio molitor larvae was performed using pyrosequencing of the 16S rRNA gene. A predominance of genus Spiroplasma species in phylum Tenericutes was observed in the gut samples, but there was variation found in the community composition between T. molitor individuals. The gut bacteria community structure was not significantly affected by the presence of antibiotics or by the exposure of T. molitor larvae to a highly diverse soil bacteria community. A negative relationship was identified between bacterial diversity and ampicillin concentration; however, no negative relationship was identified with the addition of kanamycin. Ampicillin treatment resulted in a reduction in the bacterial community size, estimated using the 16S rRNA gene copy number. A detailed phylogenetic analysis indicated that the Spiroplasma-associated sequences originating from the T. molitor larvae were distinct from previously identified Spiroplasma type species, implying the presence of novel Spiroplasma species. Some Spiroplasma species are known to be insect pathogens; however, the T. molitor larvae did not experience any harmful effects arising from the presence of Spiroplasma species, indicating that Spiroplasma in the gut of T. molitor larvae do not act as a pathogen to the host. A comparison with the bacterial communities found in other insects (Apis and Solenopsis) showed that the Spiroplasma species found in this study were specific to T. molitor.

• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.46.1-46.10
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• 2018

Objectives: This study was to evaluate the antibacterial effect of different instrumentation and irrigation techniques using confocal laser scanning microscopy (CLSM) after root canal inoculation with Enterococcus faecalis (E. faecalis). Materials and Methods: Mesiobuccal and mesiolingual canals of extracted mandibular molars were apically enlarged up to a size 25 hand K-file, then autoclaved and inoculated with E. faecalis. The samples were randomly divided into 4 main groups according to the system of instrumentation and irrigation: an XP-endo Shaper (XPS) combined with conventional irrigation (XPS/C) or an XP-endo Finisher (XPF) (XPS/XPF), and iRaCe combined with conventional irrigation (iRaCe/C) or combined with an XPF (iRaCe/XPF). A middle-third sample was taken from each group, and then the bacterial reduction was evaluated using CLSM at a depth of $50{\mu}m$ inside the dentinal tubules. The ratio of red fluorescence (dead cells) to green-and-red fluorescence (live and dead cells) represented the percentage of bacterial reduction. The data were then statistically analyzed using the Kruskal-Wallis test for comparisons across the groups and the Dunn test was used for pairwise comparisons. Results: The instrumentation and irrigation techniques had a significant effect on bacterial reduction (p < 0.05). The iRaCe/XPF group showed the strongest effect, followed by the XPS/XPF and XPS/C group, while the iRaCe/C group had the weakest effect. Conclusions: Combining iRaCe with XPF improved its bacterial reduction effect, while combining XPS with XPF did not yield a significant improvement in its ability to reduce bacteria at a depth of $50{\mu}m$ in the dentinal tubules.

• Geomechanics and Engineering
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• 제17권5호
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• pp.485-496
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• 2019

Sealing of leakage in waterfront or water-retaining structures is one of the major issues in geotechnical engineering practices. With demands for biological methods as sustainable ground improvement techniques, bioclogging, defined as the reduction in hydraulic conductivity of soils caused by microbial activities, has been considered as an alternative to the chemical grout techniques for its economic advantages and eco-friendliness of microbial by-products. This study investigated the feasibility of bioaugmentation and biostimulation methods to induce fermentation-based bioclogging effect in coarse sands. In the bioaugmentation experiments, effects of various parameters and conditions, including grain size, pH, and biogenic gas generation, on hydraulic conductivity reduction were examined through a series of column experiments while Leuconostoc mesenteroides, which produce an insoluble biopolymer called dextran, was used as the model bacteria. The column test results demonstrate that the accumulation of bacterial biopolymer can readily reduce the hydraulic conductivity by three-to-four orders of magnitudes or by 99.9-99.99% in well-controlled environments. In the biostimulation experiments, two inoculums of indigenous soil bacteria sampled from waterfront embankments were prepared and their bioclogging efficiency was examined. With one inoculum containing species capable of fermentation and biopolymer production, the hydraulic conductivity reduction by two orders of magnitude was achieved, however, no clogging was found with the other inoculum. This implies that presence of indigenous species capable of biopolymer production and their population, if any, play a key role in causing bioclogging, because of competition with other indigenous bacteria. The presented results provide fundamental insights into the bacterial biopolymer formation mechanism, its effect on soil permeability, and potential of engineering bacterial clogging in subsurface.

• The Plant Pathology Journal
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• 제37권2호
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• pp.137-151
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• 2021

The present study describes the bacterial blight of walnut, caused by Xanthomonas arboricola pv. juglandis (Xaj) in the northern Gyeongbuk province, Korea. Disease symptoms that appear very similar to anthracnose symptoms were observed in walnut trees in June 2016. Pathogens were isolated from disease infected leaves, fruits, shoots, bud, flower bud of walnut, and cultured onto yeast dextrose carbonate agar plates. Isolated bacteria with bacterial blight symptoms were characterized for their nutrient utilization profiles using Biolog GN2 and Vitek 2. In addition, isolates were subjected to physiological, biochemical, and morphological characterizations. Furthermore, isolates were identified using 16S rDNA sequence analysis, and multi-locus sequence analysis using atpD, dnaK, efp, and rpoD. To confirm pathogenicity, leaves, fruits, and stems of 3-year-old walnut plants were inoculated with bacterial pathogen suspensions as a foliar spray. One week after inoculation, the gray spots on leaves and yellow halos around the spots were developed. Fruits and stems showed browning symptoms. The pathogen Xaj was re-isolated from all symptomatic tissues to fulfill Koch's postulates, while symptoms were not appeared on control plants. On the other hand, the symptoms were very similar to the symptoms of anthracnose caused by Colletotrichum gloeosporioides. When walnut plants were inoculated with combined pathogens of Xaj and C. gloeosporioides, disease symptoms were greater in comparison with when inoculated alone. Xaj population size was more in the month of April than March due to their dormancy in March, and sensitive to antibiotics such as oxytetracycline and streptomycin, while resistant to copper sulfate.

• The Plant Pathology Journal
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• 제38권3호
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• pp.239-247
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• 2022

Bacterial wilt caused by the pathogen Ralstonia solanacearum is a devastating disease of potato crops. Harmonizing immunity to pathogens and crop yield is a balance between productive, economic, and environmental interests. In this work, the agronomic performance of two events of potato cultivar INIA Iporá expressing the Arabidopsis thaliana EFR gene (Iporá EFR 3 and Iporá EFR 12) previously selected for their high resistance to bacterial wilt was evaluated under pathogen-free conditions. During two cultivation cycles, the evaluated phenotypic characteristics were emergence, beginning of flowering, vigor, growth, leaf morphology, yield, number and size of tubers, analyzed under biosecurity standards. The phenotypic characteristics evaluated did not show differences, except in the morphology of the leaf with a more globose appearance and a shortening of the rachis in the transformation events with respect to untransformed Iporá. The Iporá EFR 3 genotype showed a ~40% yield decrease in reference to untransformed Iporá in the two trials, while Iporá EFR 12 did not differ statistically from untransformed Iporá. Iporá EFR 12 shows performance stability in the absence of the pathogen, compared to the untransformed control, positioning it as an interesting candidate for regions where the presence of the pathogen is endemic and bacterial wilt has a high economic impact.

• 미생물학회지
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• 제40권3호
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• pp.189-198
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• 2004

강화도 장화리 갯벌 퇴적물 내의 두 층(0-1cm, 6-7cm 깊이)에 서식하는 미생물 군집구조 및 다양성을 비교하기 위해 16S rDNA의 서열에 기초한 말단제한절편 다형성(terminal-restriction fragment length polymorphism ; T-RFLP)분석과 클론의 염기서열 분석을 실시하였다. 제한 효소HhaI을 이용한 T-RFLP분석 결과표층(0-1cm)에서는 다양한 크기(($60{\pm}2$) bp-($667{\pm}2$)bp)의 말단제한절편(T-RF)들이 고른 분포로 나타났으며, 저층(6-7 cm)에서는 ($60{\pm}2$)bp와 ($93{\pm}2$) bp의 T-RF가 우세하게 나타나 표층에 비해 미생물 군집구조가 단순한 것으로 조사되었다. 총 172개의 클론의 16S rDNA부분 염기서열 분석 결과 98% 유사도 수준에서 98%의 클론이 GenBank에 등록된 염기서열 중 배양된 어떤 미생물과도 일치하지 않는 것으로 조사되었으며, 이 중 148개의 클론(86%)이 서로 다른 계통형(phylotype)으로 분류되어 다양한 미생물이 서식하고 있음을 알 수 있었다. 대부분의 클론들은 $\alpha$-, $\gamma$, $\delta$-Proteobacteria, Acidobacteria/Holophaga 그리고 green nonsulfur bacteria 그룹 내에 속하였고, 이 중 Proteobacteria 그룹이 표층에서는 전체의 69%, 저층에서는 46%의 높은 비율을 차지하였다. 또한 황원소의 산화와 환원에 관련된 $\gamma$-Proteobacteria와 $\delta$-Proteobacteria 그룹이 각각 21.5%와 15.7%로 우세하게 나타나 갯벌의 미생물 군집 구조가 혐기성 환경에서의 황환원에 의해 생성된 황의 거동과 밀접한 연관이 있음을 시사하였다.

• 미생물학회지
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• 제37권1호
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• pp.72-79
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• 2001

폐수 처리장의 방류수에 페놀을 첨가한 후 terminal restriction fragment length polymorphism (T-RFLP) 방법을 이용하여 세균군집의 구조와 변화를 조사하였다. 시료로부터 얻은 16S rRNA gene은 eubacterial primer로 증폭하였으며, 한 primer는 5'말단에 biotin을 부착하였다. 증폭된 product는 HaeIII와 AluI으로 각각 절단하였고, 절단된 단편 중에서 terminal restriction fragment (T-RF)를 streptavidin paramagnetic particle을 이용하여 분리하였다. 분리된 T-RF는 전기영동과 silver staining을 통하여 확인하였다. 본 실험의 유용성을 검증하기 위하여 표준 균주 10 균주를 대상으로 실험하였고, 균주마다 특징적인 T-RF를 가지는 것과 그 크기가 Ribosomal database project (RDP) 자료로부터 계산된 결과와 일치하는 것을 확인할 수 있었다. 한편, 대조군으로 사용된 페놀을 첨가하지 않은 방류수 시료에서는 Acinetobacter, Bacillus, Pseudomonas 속 등이 우점종을 차지하고 있었고, 페놀 (최종농도 250mg.$l^{-1}$)을 첨가한 방류수 시료에서는 Acinetobacter, Comamonas, Cytophaga, Pseudomonas 속 등이 우점종을 차지함을 알 수 있었다. Gel에서 분리한 Acinetobacter와 Cytophaga에 해당되는 T-RF는 재증폭 및 염기 서열 분석이 가능하였는데, database의 염기서열과 비교한 결과 Acinetobacter junii와 유연관계가 가깝다는 것을 확인하였다.