• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.67-73
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• 2008

The potential of the exopolysaccharide (EPS) from a Serratia sp. strain Gsm01 as an antiviral agent against a yellow strain of Cucumber mosaic virus (CMV-Y) was evaluated in tobacco plants (Nicotiana tabacum cv. Xanthi-nc). The spray treatment of plants using an EPS preparation, 72h before CMV-Y inoculation, protected them against symptom appearance. Fifteen days after challenge inoculation with CMV-Y, 33.33% of plants showed mosaic symptoms in EPS-treated plants compared with 100% in the control plants. The EPS-treated plants, which showed mosaic symptoms, appeared three days later than the controls. The enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR) analyses of the leaves of the protected plants revealed that the EPS treatment affected virus accumulation in those plants. Analysis of phenylalanine ammonia lyase, peroxidase, and phenols in protected plants revealed enhanced accumulation of these substances. The pathogenesis-related (PR) genes expression represented by PR-lb was increased in EPS-treated plants. This is the first report of a systemic induction of protection triggered by EPS produced by Serratia sp. against CMV-Y.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권4호
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• pp.113-121
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• 2015

The contaminated soil at abandoned smelter areas present challenge for remediation, as the degraded materials are typically deficient in nutrients, and rich in toxic heavy metals and metalloids. Bioremediation technique is to isolate new strains of microorganisms and develop successful protocols for reducing metal toxicity with heavy metal tolerant species. The present study collected metal contaminated soil and characterized for pH and EC values, and heavy metal contents. The pH value was 5.80, representing slightly acidic soil, and EC value was 13.47 mS/m. ICP-AES analytical results showed that the collected soil samples were highly contaminated with various heavy metals and metalloids such as lead (183.0 mg/kg), copper (98.6 mg/kg), zinc (91.6 mg/kg), and arsenic (48.1 mg/kg), respectively. In this study, a bacterial strain, Bacillus cereus KM-15, capable of adsorbing the heavy metals was isolated from the contaminated soils by selective enrichment and characterized to apply for the bioremediation. The effects of heavy metal on the growth of the Bacillus cereus KM-15 was determined in liquid cultures. The results showed that 100 mg/L arsenic, lead, and zinc did not affect the growth of KM-15, while the bacterial growth was strongly inhibited by copper at the same concentration. Further, the ability of the bacteria to adsorb heavy metals was evaluated.

• Journal of Microbiology and Biotechnology
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• 제32권3호
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• pp.278-286
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• 2022

Live bacterial vector vaccines are one of the most promising vaccine types and have the advantages of low cost, flexibility, and good safety. Meanwhile, protein secretion systems have been reported as useful tools to facilitate the release of heterologous antigen proteins from bacterial vectors. The twin-arginine translocation (Tat) system is an important protein export system that transports fully folded proteins in a signal peptide-dependent manner. In this study, we constructed a live vector vaccine using an engineered commensal Escherichia coli strain in which amiA and amiC genes were deleted, resulting in a leaky outer membrane that allows the release of periplasmic proteins to the extracellular environment. The protective antigen proteins SLY, enolase, and Sbp against Streptococcus suis were targeted to the Tat pathway by fusing a Tat signal peptide. Our results showed that by exploiting the Tat pathway and the outer membrane-defective E. coli strain, the antigen proteins were successfully secreted. The strains secreting the antigen proteins were used to vaccinate mice. After S. suis challenge, the vaccinated group showed significantly higher survival and milder clinical symptoms compared with the vector group. Further analysis showed that the mice in the vaccinated group had lower burdens of bacteria load and slighter pathological changes. Our study reports a novel live bacterial vector vaccine that uses the Tat system and provides a new alternative for developing S. suis vaccine.

• 한국어병학회지
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• 제9권1호
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• pp.79-85
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• 1996

$\beta$-glucan의 투여가 세균감염증에 대한 저항성에 미치는 영향을 알아보기 위하여 복강주사 또는 침지에 의해 한국산 메기(Silurus asotus)에 투여하였다. 투여 농도는 어체중 100 g 당 200, 500, $1000{\mu}g$을 1회 또는 3일 간격으로 2회 복강주사하거나, $100{\mu}g$/ml의 $\beta$-glucan 부유액에 30분 또는 1시간 침지시켰다. $\beta$-glucan 투여 3일후에 Edwardsiella ictaluri와 Aeromonas hydrophila의 생균액($2{\times}106$ CFU/0.1 ml)을 복강주사한 다음 10일간 사육하면서 생존율을 조사하였다. 복강주사와 침지에 의한 투여결과 복장투여만이 생잔율을 높일 수 있었으며, 투여 농도에 있어 어체중 100 g당 $200\sim1000{\mu}g$의 범위에 있어서는 농도간에 차이가 없었다. 또한 투여회수는 1회 투여보다는 3일간격으로 2회 투여가 효과적이었으며, E. ictaluri보다는 A. hydrophila에 대한 저항성이 높은 것으로 나타나, 한국산 메기에 $\beta$-glucan을 복강투여함으로서 세균감염증의 초기단계에 있어 생잔율을 높일 수 있었다.

• Journal of Microbiology
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• 제43권4호
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• pp.337-344
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• 2005

Although pneumococcus is one of the most frequently encountered opportunistic pathogen in the world, the mechanisms responsible for its infectiveness have not yet been fully understood. In this paper, we have attempted to characterize the effects of pneumococcal transformation on the pathogenesis of the organism. We constructed three transformation-deficient pneumococcal strains, which were designated as Nos. 1d, 2d, and 22d. The construction of these altered strains was achieved via the insertion of the inactivated gene, comE, to strains 1, 2 and 22. We then conducted a comparison between the virulence of the transformation-deficient strains and that of the wild-type strains, via an evaluation of the ability of each strain to adhere to endothelial cells, and also assessed psaA mRNA expression, and the survival of hosts after bacterial challenge. Compared to what was observed with the wild-type strains, our results indicated that the ability of all of the transformation-deficient strains to adhere to the ECV304 cells had been significantly reduced (p < 0.05), the expression of psaA mRNA was reduced significantly (p < 0.05) in strains 2d and 22d, and the median survival time of mice infected with strains Id and 2d was increased significantly after intraperitoneal bacterial challenge (p < 0.05). The results of our study also clearly indicated that transformation exerts significant effects on the virulence characteristics of S. pneumoniae, although the degree to which this effect is noted appears to depend primarily on the genetic background of the bacteria.

• BMB Reports
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• 제39권1호
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• pp.26-36
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• 2006

Differential Display PCR technique (DD-PCR) was used for the analysis of altered gene expression in hemocytes of Vibrio harveyi-infected Penaeus monodon. Forty-four combinations of arbitrary and oligo(dT) primers were used to screen for differentially expressed genes. A total of 79 differentially expressed bands could be identified from 33 primer combinations. These included 48 bands (61%) whose expression level increased and 31 bands (39%) decreased after V. harveyi challenge. Subsequently, forty-eight differential display fragments were successfully reamplified and cloned. A total of 267 clones were randomly selected and sequenced. The sequence analysis showed that 85 (31%) out of 267 clones were matched with sequences in the GenBank database which represented 24 different genes with known functions. Among the known genes, glucose transporter 1, interferon-related developmental regulator 1, lysozyme, profilin, SERPINB3, were selected for further confirmation of their differentially expression patterns by real-time PCR. The results showed increasing in expression level of the selected genes in shrimp hemocytes after microbial challenge suggesting the involvement of such genes in bacterial response in shrimp. The anti-lipopolysaccharide factor type 3 (ALFPm3) gene, previously reported in P. monodon (Supungul et al., 2002) was found among the up-regulated genes but diversity due to amino acid changes was observed. Increase in ALFPm3 transcripts upon V. harveyi injection is in accordance with that found in the previous study.

• 수산해양교육연구
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• 제25권6호
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• pp.1285-1293
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• 2013

This study was conducted to investigate the effects of dietary inclusion of various additives Solid sulfur, fucoidan, and glucan on growth performance and immune responses in Juvenile olive flounder paralichthys olivaceus. Six experimental diets supplemented with : no additives (CON); 0.5 and 1.0% solid sulfur (S); 0.2 and 0.4% fucoidan (F); 0.1% glucan (G) of these additives diet on a dry-matter basis. Fish averaging $8.2{\pm}0.17g$ were fed one of six experimental diets in triplicate groups for 6 weeks. By the end of the feeding trial, weight gain, feed efficiency, specific growth rate, protein efficiency ratio, hepatosomatic index and condition factor of fish fed diet CON were significantly lower then those of fish fed the all additives diets (P < 0.05). In challenge test, fish were infected by intraperitonel injection of 0.1 ml bacterial suspension with Edwardsiella tarda per fish after the feeding trial. As a result fish fed All additive diet showed a lower cumulative mortality then did fish fed CON diet throughout the challenge test. In conclusion, these results indicated that solid sulfur, fucoidan and glucan enhanced the growth, feed efficiency and non-specific immune activity of juvenile flounder and protect the fish against microbial infections.

• 한국동물위생학회지
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• 제32권1호
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• pp.77-82
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• 2009

Salmonella (S.) Typhimurium infection in pigs is a major source of human foodborne salmonellosis. Recently, the swine industry in Korea has been suffered from salmonellosis causing severe economic loss to farms. Organic acids have antibacterial activity which prevents bacteria from multiplying by reducing the pH in the gastrointestinal tract. The aim of the present study is to evaluate whether $Salstop^{(R)}$ mixed with organic acids is able to have influence on growth performance and whether it prevents against S. Typhimurium in weaning pigs. Four experimental treatments were examined: general diet added with 0.3% of $Salstop^{(R)}$ after S. Typhimurium ($1.0{\times}10^{10}CFU/ml$) challenge, group A; commercial feed after Salmonella ($1.0{\times}10^{10}CFU/ml$) challenge, group B; commercial feed and $Salstop^{(R)}$, group C; commercial feed, Group D. At the end of the study, no significant differences in daily body weight gain and feed intake were observed between groups treated with $Salstop^{(R)}$ and groups treated without, whereas feed conversion ratio (FCR) tended to be improved in groups treated with $Salstop^{(R)}$ between days 1 to 14. Serological and microbiological evolution of the infection were examined by ELISA and microbiological culture from serums and fecal samples, respectively. In groups that challenged by S. Typhimuriums, the group without $Salstop^{(R)}$ showed higher prevalence and bacterial shedding compared to the groups treated with $Salstop^{(R)}$. Our results suggest that the administration of $Salstop^{(R)}$ could be used to promote feed efficiency and to reduce the prevalence of salmonellosis in weaners.

• Journal of Microbiology and Biotechnology
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• 제29권3호
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• pp.489-499
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• 2019

Subunit vaccines are safer and more stable than live vaccines although they have the disadvantage of eliciting poor immune response. To develop a subunit vaccine, an effective delivery system targeting the key elements of the protective immune response is a prerequisite. In this study, oxidized carbon nanospheres (OCNs) were used as a subunit vaccine delivery system and tuberculosis (TB) was chosen as a model disease. TB is among the deadliest infectious diseases worldwide and an effective vaccine is urgently needed. The ability of OCNs to deliver recombinant Mycobacterium tuberculosis (Mtb) proteins, Ag85B and HspX, into bone marrow derived macrophages (BMDMs) and dendritic cells (BMDCs) was investigated. For immunization, OCNs were mixed with the two TB antigens as well as the adjuvant monophosphoryl lipid A (MPL). The protective efficacy was analyzed in vaccinated mice by aerosol Mtb challenge with a virulent strain of Mtb and the bacterial burdens were measured. The results showed that OCNs are highly effective in delivering Mtb proteins into the cytosol of BMDMs and BMDCs. Upon immunization, this vaccine formula induced robust Th1 immune response characterized by cytokine profiles from restimulated splenocytes and specific antibody titer. More importantly, enhanced cytotoxic $CD8^+$ T cell activation was observed. However, it did not reduce the bacteria burden in the lung and spleen from the aerosol Mtb challenge. Taken together, OCNs are highly effective in delivering subunit protein vaccine and induce robust Th1 and $CD8^+$ T cell response. This vaccine delivery system is suitable for application in settings where cell-mediated immune response is needed.

• 식물병연구
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• 제17권3호
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• pp.302-310
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• 2011

Elsinoe fawcettii는 현재 감귤 산업의 경제 가치를 떨어뜨리며, 감귤 더뎅이병을 일으키는 원인중 하나로 일반적으로 살균제를 이용하여 방제가 이루어지고 있다. 하지만 안전한 농산물에 대한 관심이 증대되면서 생물학적인 방제에 대한 연구가 많이 요구되고 있다. 이에 미생물 방제에 대한 연구로서 제주에서 분리한 식물근권세균 215개 중 Elsinoe fawcettii에 의해 발병되는 감귤 더뎅이병균의 항균 효과와 병원균 발병 억제효과가 나타나는지 조사하였다. 그 중 in vitro 실험에서 더뎅이병균에 저지원을 형성하며 항균 효과를 나타내는 근권세균은 THJ 609-3, MRL 408-3, TRH 423-3이었다. 또한 이들 식물근권세균을 선처리하고 병원균을 접종한 결과 감귤 더뎅이병 억제효과가 있었다. 근권세균에 의한 병억제 기작을 알아보기 위해 형광현미경을 이용하여 조사한 결과 선발된 식물근권 세균이 병원균의 포자수를 감소시켰으며 병원균 발아율도 접종 1일 후에 감소되었다. 식물근권세균 rDNA의 Internal Transcript Spaces(ITS)을 분석을 통해 동정한 결과 THJ 609-3은 Pseudomonas pudia로 동정되었으며, MRL 408-3과 TRH 423-3은 Burkholderia gladioli로 동정되었다. 본 연구는 생물적 방제로 감귤 더뎅이병균을 방제할 수 있는 친환경적 미생물제제로 유용하게 이용할 수 있는 가치가 있다고 생각된다.