• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.218-226
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• 2016

Helicobacter pylori primarily colonizes the human stomach. Infection by this bacterium is associated with various gastric diseases, including inflammation, peptic ulcer, and gastric cancer. Although there are antibiotic regimens for the eradication of H. pylori, the resistance of this species against antibiotics has been continuously increasing. The natural compound plumbagin has been reported as an antimicrobial and anticancer molecule. In this study, we analyzed the inhibitory effect of plumbagin on H. pylori strain ATCC 49503 as well as the expression of various molecules associated with H. pylori growth or virulence by immunoblotting and reverse transcription polymerase chain reaction (RT-PCR) analyses. We demonstrated the minimal inhibitory concentration of plumbagin on H. pylori through the agar dilution and broth dilution methods. Furthermore, we investigated the effect of plumbagin treatment on the expression of the RNA polymerase subunits and various virulence factors of H. pylori. Plumbagin treatment decreased the expression of RNA polymerase subunit alpha (rpoA), which is closely associated with bacterial survival. Moreover, the mRNA and protein levels of the major CagA and VacA toxins were decreased in plumbagintreated H. pylori cells. Likewise, the expression levels of urease subunit alpha (ureA) and an adhesin (alpA) were decreased by plumbagin treatment. Collectively, these results suggest that plumbagin may inhibit the growth, colonization, and pathogenesis of H. pylori by the mechanism demonstrated in this study.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.273-283
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• 1999

When microorganism is injected into porous medium such as soils, biomass is retained in the pore. Soil pore size and shape are varied from the initial condition as a result of biofilm formation which makes hydraulic conductivity reduced and friction rate between soil aggregates increased. In this research, hydraulic conductivity reduction was measured after microorganism are inoculated and cultured with synthetic substrate and nutrient. In addition, this research evaluated the applicability of biomass-soil mixture to the field condition as an alternative cover material in landfill by measuring hydraulic conductivity change after repetitive freeze-thaw cycles. Hydraulic conductivity of silty soil decreased by approximately 1/50 after biomass inoculation and cultivation. Biofilm attached on soil aggregates is resistant to acidic or basic condition. After repetitive freeze-thaw cycles, however, hydraulic conductivity increase implies that biomass clogging can be impaired.

• Research in Plant Disease
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• v.23 no.1
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• pp.42-48
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• 2017

Chlorella is one of the microorganisms which can live autotrophically by their own photosynthesis. It was previously revealed that pre-treatment of Chlorella fusca caused a suppression of appressorium formation on the cucumber leaves after inoculation with Colletothrichum orbiculare. In this study, the ultrastructures of C. orbiculare on the cucumber leaves pretreated with C. fusca were observed using both scanning electron microscope (SEM) and transmission electron microscope (TEM). The SEM images revealed that most fungal conidia and hyphae were attached with lots of C. fusca cells. Also, the conidia could germinate but not form appressorium, which is necessary to penetrate into host tissue. These observations suggested that C. fusca adjoined to the fungus may play a role in suppression of the appressorium formation. On the other hand, the observations of TEM showed no remarkable cytological differences on the ultrastructures of the intracellular hyphae between in the pre-treated and untreated leaves. It seemed that the fungus could grow in the pre-treated plant tissues as in the untreated one. Based on these observations, it is suggested that the suppression of appressorium on the leaf surfaces by the C. fusca cells may be a main cause of the reduction of the anthracnose disease.

• Journal of Animal Science and Technology
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• v.49 no.5
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• pp.647-656
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• 2007

In order to investigate the effects of supplemental ionic surfactants in in vitro ruminal fermentation, N-Lauroylsarcosine sodium salt(N-LSS) and sodium dodecyl sulfate(SDS) for negative(－) ionic surfactant, and hexadecylpyridinium chloride monohydrate(HPCM) and hexadecyltrimethyl ammonium bromide(HTAB) for positive (+) ionic surfactant were supplemented by 0.05% and 0.1% into the Dehority’s artificial medium containing rice straw(1mm) as a substrate. In vitro DM digestibility, the growth of rumen mixed microbes, pH, cumulative gas production and SEM(Scanning Electron Microscopy) observation of microbial attachment on rice straw particle were investigated through the experiment composing 9 treatments (two supplemental levels of two positive ionic(+) surfactant, two supplemental levels of two negative(－) ionic surfactant) including the control. The sample collection was at 6, 12, 24, 48 and 72 h post fermentation with 3 replications per treatments. DM digestibility in treatments supplemented (+) or (－) surfactants almost stopped afterward 12 h fermentation, in vitro DM digestibility at 72 h post fermentation in the ionic surfactants was at half level of that of the control(P<0.05). Accumulative gas production in in vitro was less(P<0.05) with addition of ionic surfactants compared to the control. The amount of rumen mixed microbes recovered from in vitro incubation fluid pleateaued at 12 h post fermentation for the positive (+) ionic surfactants, but steadily increased as fermentation time elapsed for the control. Rumen microbial growth rate was significantly(P<0.05) low in the negative(－) ionic surfactant compared to the control. pH of the incubation fluid was ranged from 6.02 to 7.20, and was the highest in the negative(－) ionic surfactants, and was the lowest in the control(P<0.05). In SEM observation, rumen microbial population attached on rice straw particle was less with addition of ionic surfactants than the control. In conclusion we could not found any positive effects of negative- and positive- charged surfactants on rumunal fermentation characteristics and rumen microbial growth rates.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.2
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• pp.93-101
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• 1999

A simple experimental method was used in an attempt to realize the elevation of the fishing ability of purse seine in the sea area of Cheju Island, the changes of seine volume and tension in the purseline during pursing. Experiments carried out on the six types simplified reduced model seines which were made of knotless nettings. The nettings were woven in different leg length 4.3, 5.0, 5.5, 6.0, 6.6 and 7.7mm of polyester 28 tex two threads two-ply twine, and each of the seines were named I, II, III, IV, V and Ⅵ seine. Dimension of seine models were 450cm for corkline and 85cmfor seine depth, each seines rigged up 160g of float for a floatline and 50g (underwater weight) of lead for a leadline. These model purse seines were made of the scale of 1/200 of its full scale, a 120 ton in the near sea of Cheju Island. Designing and testing for the model purse seines were based on the Tauti's law. Experiments were measured in the observation channel of a flume tank at the static conditions set up shooting and pursing equipments. Motion of purse seine during purse line was recorded by the two sets video camera for VTR which were placed in top and front of the model seine. The reading coordinate of seine volume carried out by the video digitization system, disk data for the purseline tension. An analysis were performed on the changes seine volume and tension in the purseline during pursing. The results obtained were as follows: 1. The seine volume during pursing was largest for Ⅵ seine with smallest d/l followed by V, IV, III, II and I seines, and tension in the purseline was small. 2. Seine volume during pursing can be expressed by the following equation; CVt=l-EXP[｛2.79 (d/l）＋0.35｝t-33.37 (d/l) ＋ 0.57] Where CVt is volume ratio, d is twine diameter, l is leg length and t is pursing time (sec). 3. Tension in the purse line during pursing can be expressed by the following equation; T= 1- EXP ｛0.57t ＋ 13.36 (d/l)+2.97｝ Where T is tension (kg) in the purseline during pursing.

• Korean journal of applied entomology
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• v.50 no.2
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• pp.107-113
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• 2011

Benzylideneacetone (BZA) is a compound derived from culture broth of an entomopathogenic bacterium, Xenorhabdus nematophila (Xn). Its immunosuppressive activity is caused by its inhibitory activity against eicosanoid biosynthesis. This BZA is being developed as an additive to enhance control efficacy of other commercial microbial insecticides. This study was focused on the enhancement of the immunosuppressive activity of BZA by generating its chemical derivatives toward decrease of its hydrophobicity. Two hydroxylated BZA and one sugar-conjugated BZA were chemically synthesized. All derivatives had the inhibitory activities of BZA against phospholipase $A_2$ ($PLA_2$) and phenoloxidase (PO) of the diamondback moth, Plutella xylostella, but BZA was the most potent. Mixtures of any BZA derivative with Bacillus thuringiensis (Bt) significantly increased pathogenicity of Bt. BZA also inhibited colony growth of four plant pathogenic fungi. However, BZA derivatives (especially the sugar-conjugated BZA) lost the antifungal activity. These results indicated that BZA and its derivatives inhibited catalytic activities of two immune-associated enzymes ($PLA_2$ and PO) of P. xylostella and enhanced Bt pathogenicity. We suggest its use to control plant pathogenic fungi.

• Korean journal of food and cookery science
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• v.24 no.6
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• pp.912-918
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• 2008

This study was conducted to evaluate the quality characteristics of Backsulgies prepared using different ratios (0, 10, 20, 30, 40%) of trehalose after 4 days of storage. As the concentration of trehalose increased, the moisture content of the Backsulgies decreased. Furthermore, increased levels of trehalose, resulted in significantly lower L and b values. However, the a values did not differ significantly in response to the addition of trehalose. The total cell counts of Backsulgies also decreased as the level of trehalose increased, which indicates that microorganisms were inhibited by its addition. Furthermore, the hardness of the Backsulgies decreased as the level of trehalose increased, whereas the hardness of the Backsulgies increased as the storage time was extended. Finally, the sensory evaluations revealed that the chewiness and hardness of Backsulgies decreased as the level of trehalose increased.

• Journal of the Mineralogical Society of Korea
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• v.28 no.3
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• pp.209-220
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• 2015

The aim of this study was leaching valuable metal ions from mine waste rocks which were abandoned mine site using indigenous aerobic bacteria. In order to tolerate the the indigenous aerobic bacteria to the heavy metal ions they were repeatedly adapted in $CuSO_4{\cdot}5H_2O$ environment. As the repeated generation-adaptation progressed, the pH values of the growth-medium were gradually decreased. During bio-leaching experiments with indigenous aerobic bacteria raised in a heavy metal ion environment for 42 days, the pH of the leaching solution was decreased while increasing the adaptation period. The indigeous bacteria were much more active on the surface of Younhwa waste rocks which contained relatively few the chalcopyrite and Cu content than the Goseong mine waste rocks, and also the amount of Cu and Fe ions were leached more in the Younhwa sample(leaching rate of 92.79% and 55.88%, respectively) than the Goseong sample(leaching rate of 66.77% and 21.83%, respectively). Accordingly, it is confirmed that valuable metal ions can be leached from the mine waste rocks, if any indigenous bacteria which inhabits a mine environment site for a long time with heavy metal ions can be used, and these bacteria can be progressively adapted in the growth-solutions containing the target heavy metals.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.165-171
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• 2006

ERM proteins transfer the methyl group to $A_{2058}$ in 23S rRNA to confer the resistance to MLS (macrolide-lincosamide-streptogramin B) antibiotics on microorganism ranging from antibiotic producers to pathogens. To define the functional role of peptide segment encompassing amino acid residues 1 to 25 in NTER (N-terminal end region) of ErmSF, one of the ERM proteins, DNA fragment encoding mutant protein deprived of that peptide was cloned and overexpressed in E. coli to obtain a purified soluble form protein to the apparent homogeneity in the yield of 12.65 mg per liter of culture. The in vitro activity of mutant protein was found to be 85% compared to wild type ErmSF, suggesting that this peptide interact with substrate to affect the enzyme activity. This diminished activity of mutant protein caused the delayed expression of antibiotic resistance in vivo, that at fIrst cells expressing mutant protein showed the retarded growth due to the antibiotic action but with time cells inhibited by antibiotic gradually recovered the viability to exert the resistance to the same extent as those with wild type protein.

• Journal of Periodontal and Implant Science
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• v.37 no.sup2
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• pp.339-351
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• 2007

Cytolethal distending toxin(CDT)은 세포 주기 중 G2에서 M 기로의 전환을 막아 세포의 증식을 억제할 수 있는 세균 단백 독소의 일종이다. 구강 미생물 중 유일하게 Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans)만이 이 CDT를 생성 할 수 있는 것으로 알려져 있다. A. actinomycetemcomitans는 localized aggressive periodontitis (LAP)의 원인균으로 여겨지며 비 운동성의 그람 음성 구간균이고 $37^{\circ}C$, 5% $CO_2$ 하에 성장이 왕성하다. A. actinomycetemcomitans의 CDT는 3개의 인접한 유전자인 cdtA, cdtB, cdtC에 의해 형성 되며 각각의 유전자에 대한 단백질의 기능은 아직 완전히 밝혀지지 않았다. 현재까지 연구에 의하면 cdtA는 CDT의 세포부착과 관련이 있는 것으로 여겨지며 이 유전자의 기능 이상 시 CDT의 독성 효과가 현저히 감소한다고 알려져 있다. 따라서 본 연구는 A. actinomycetemcomitans의 cdtA 유전자를 클로닝, 단백질 발현하여 향후 치주질환의 발병 과정에서 CdtA의 역할을 규명하고 질환의 예방 및 치료법에 도움을 주고자 하였다. A. actinomycetemcomitans Y4균주를 cdtA 유전자 클로닝을 위해 사용하였다. A. actinomycetemcomitans의 genomic DNA는 genomic DNA 추출 kit를 사용하여 분리하고 cdtA에 특이적인 primer를 이용하여 PCR을 통해 cdtA 유전자를 증폭하였다. 증폭된 cdtA 유전자를 T-vector에 클로닝 하였으며, 클로닝 된 cdtA 유전자는 단백질 발현을 위해 pRSET Avector에 서브클로닝 한 후 발현 균주인 BL21(DE3)를 이용하여 발현시켰다. 발현 후 Ni-NTA AP conjugate를 이용한 Western blot을 통해 pRSET-CDTA를 확인하였다.