• Journal of Microbiology and Biotechnology
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• 제29권12호
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• pp.1916-1924
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• 2019

Outbreaks of staphylococcal food poisoning (SFP) causing serious human diseases and economic losses have been reported globally. Furthermore, the spread of Staphylococcus aureus with increased resistance to multiple antimicrobial agents has become a major concern in the food industries and medicine. Here, we isolated an endolysin LysSAP8, as one of the peptidoglycan hydrolases, derived from the bacteriophage SAP8 infecting S. aureus. This endolysin was tagged with a 6×His at the C-terminal of the target protein and purified using affinity chromatography. LysSAP8 demonstrated lytic activity against a broad spectrum of bacteria, which included a majority of the staphylococcal strains tested in this study as well as the methicillin-resistant S. aureus (MRSA); however, no such activity was observed against other gram-positive or gram-negative bacteria. Additionally, LysSAP8 could maintain bactericidal activity until 0.1 nM working concentration and after heat treatment at 37℃ for 30 min. The ability of LysSAP8 to lyse cells under varying conditions of temperature (4-43℃), pH (3-9), and NaCl concentrations (0-1,000 mM), and divalent metal ions (Ca²⁺, Co²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Hg²⁺, and Zn²⁺) was examined. At the optimized condition, LysSAP8 could disrupt approximately 3.46 log CFU/ml of the planktonic cells in their exponential phase of growth within 30 min. In this study, we have suggested that LysSAP8 could be a potent alternative as a biocontrol agent that can be used to combat MRSA.

• Journal of Microbiology and Biotechnology
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• 제25권9호
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• pp.1493-1501
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• 2015

A Bacillus species, EMD4, with strong antibacterial activity was isolated from ganjang (soy sauce) and identified as B. subtilis. B. subtilis EMD4 strongly inhibited the growth of B. cereus ATCC14579 and B. thuringiensis ATCC33679. The antibacterial activity was stable at pH 3-9 but inactive at pH 10 and above. The activity was fully retained after 15 min at 80℃ but reduced by 50% after 15 min at 90℃. The activity was completely destroyed by proteinase K and protease treatment, indicating its proteinaceous nature. The bacteriocin (BacEMD4) was partially purified from culture supernatant by ammonium sulfate precipitation, and Q-Sepharose and Sephadex G-50 column chromatographies. The specific activity was increased from 769.2 AU/mg protein to 8,347.8 AU/mg protein and the final yield was 12.6%. The size of BacEMD4 was determined to be 3.5 kDa by Tricine SDS-PAGE. The N-terminal amino acid sequence was similar with that of Subtilosin A. Nucleotide sequencing of the cloned gene confirmed that BacEMD4 was Subtilosin A. BacEMD4 showed bactericidal activity against B. cereus ATCC14579.

• 한국환경과학회지
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• 제5권2호
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• pp.179-185
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• 1996

본 연구는 생명을 위협하는 Vibrio vulnificus의 생존에 온도, 염분 pH 및 자외선과 같은 환경적 요인이 어떠한 영향을 미치는 가를 알아보기 위하여 수행하였다. 6일 동안 15에서 ${25\circ}C$의 온도범위에서 V.vulnificus의 수는 증가하였지만 이 범위외에서 V.vulnifivus의 생존수는 감소하였다. 1에서 ${10\circ}C$사이에서의 실험 결과, V.vulnificus 가 $10{\circ}C$이하에서는 생존수가 적었다. 한편 6일 동안 5에서 25ppt정도의 염분조건에서는 V.vulnificus수는 감소하였다. 최적의 pH 영역은 6.5에서 8.0이었고 이 영역밖에서는 V.vulnificus의 생존율은 낮았다. 15와 $25{\circ}C$에서 자외선은 V.vulificus에 대해 살균효과를 나타내어서 2시간 동안 자외선 처리후 V.vulnificus수가 약 10,00배 감소되었다. 이상과 같은 결과들은 환경적 요인이 V.vulnificus의 생존에 미치는 영향이 크다는 것을 보여주었다.

• 한국임상수의학회지
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• 제34권4호
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• pp.261-267
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• 2017

The aim of this study was to investigate the antibacterial properties of chitosan silver nanocomposites (CAgNCs) using pathogenic Vibrio ichthyoenteri as a bacterial model. Results of agar disc diffusion and turbidimetric assays showed that CAgNCs could inhibit the growth of V. ichthyoenteri in concentration dependent manner. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CAgNCs were 75 and $125{\mu}g/mL$, respectively. Furthermore, CAgNCs treatment induced the reactive oxygen species (ROS) level in V. ichthyoenteri cells in concentration and time dependent manner, suggesting that it generates oxidative stress, leading to bacterial cell death. The field emission scanning electron microscope (FE-SEM) images of CAgNCs treated V. ichthyoenteri exhibited strong cell membrane damage than un-treated control bacteria. MTT assay results showed the highest cell viability (22%) at $75{\mu}g/mL$ of CAgNCs treated bacteria samples. The results from this study suggest that CAgNCs is a potential antibacterial agent to control fish pathogenic bacteria.

• 멤브레인
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• 제30권5호
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• pp.293-306
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• 2020

물 부족을 포함한 기후 변화의 해로운 결과는 효과적인 정수에 대한 관심을 가져왔다. 또한, 수질 오염 수준이 높아지고 환경 파괴 수준이 심해지면서 오염 물질을 제거하려는 방안들이 요구되고 있다. 물을 정화하기 위해 반투막을 통한 삼투압 절차들을 사용할 수 있으며, 최근 연구에 따르면 탄소 양자점(CQD), 그래핀 양자점(GQD) 및 산화 그래핀 양자점(GOQD)을 포함한 나노입자를 복합 박막(TFC)에 합체하면 유사한 수준의 염 거부율을 유지하면서 물흐름을 증가시킬 수 있다. 이러한 효과 외의 여러 가지 효과가 있지만 그 중에서도 친수성을 높이고, 살균 성질을 보이고, 방오 특성으로 인해 박테리아 및 기타 미생물의 축적을 방지하면서 막의 효과가 감소하는 것을 막는 것을 보여준다. 이 보고서는 양자점이 합체된 정수용 복합 막에서 양자점의 제조 과정, 응용, 기능성, 성질 및 역할을 논의한다.

• 대한수의학회지
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• 제56권2호
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• pp.103-108
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• 2016

Salmonellosis is a major bacterial zoonosis that causes self-limited enteritis in animals and foodborne disease and typhoid fever in humans. Recently, multi-drug-resistant strains of Salmonella spp. have increased and caused more serious problems in public health. The present study investigated the antibacterial effects of egg-white lysozyme (EWL) against Salmonella (S.) Typhimurium and the therapeutic effects of EWL for murine salmonellosis. Evaluation of the antibacterial effects of EWL against S. Typhimurium revealed a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of EWL of 6.25 and $300{\mu}g/mL$, respectively. In the bacterial growth inhibition test, EWL at 300 (p < 0.05) and $600{\mu}g/mL$ (p < 0.01) significantly inhibited the growth of S. Typhimurium at 4 h post-incubation. EWL administration at MIC (LYS-1), MBC (LYS-2) and $2{\times}MBC$ (LYS-3) for 14 days resulted in mortality of mice infected with S. Typhimurium of 70, 40 and 10%, respectively, while that of control mice (CON) was 90%. Counts of S. Typhimurium in murine spleens were significantly lower in LYS-2 and LYS-3 than CON (p < 0.05). The results of this study indicate that EWL has the potential for treatment of ICR mice infected with S. Typhimurium.

• Journal of Ginseng Research
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• 제41권2호
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• pp.180-187
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• 2017

Background: The incidence of halitosis has a prevalence of 22-50% throughout the world and is generally caused by anaerobic oral microorganisms, such as Fusobacterium nucleatum, Clostridium perfringens, and Porphyromonas gingivalis. Previous investigations on the structure-activity relationships of ginsenosides have led to contrasting results. Particularly, the antibacterial activity of less polar ginsenosides against halitosis-related bacteria has not been reported. Methods: Crude saponins extracted from the Panax quinquefolius leaf-stem (AGS) were treated at $130^{\circ}C$ for 3 h to obtain heat-transformed saponins (HTS). Five ginsenoside-enriched fractions (HTS-1, HTS-2, HTS-3, HTS-4, and HTS-5) and less polar ginsenosides were separated by HP-20 resin absorption and HPLC, and the antimicrobial activity and mechanism were investigated. Results: HPLC with diode-array detection analysis revealed that heat treatment induced an extensive conversion of polar ginsenosides (-Rg1/Re, -Rc, -Rb2, and -Rd) to less polar compounds (-Rg2, -Rg3, -Rg6, -F4, -Rg5, and -Rk1). The antimicrobial assays showed that HTS, HTS-3, and HTS-4 were effective at inhibiting the growth of F. nucleatum, C. perfringens, and P. gingivalis. Ginsenosides-Rg5 showed the best antimicrobial activity against the three bacteria, with the lowest values of minimum inhibitory concentration and minimum bactericidal concentration. One major reason for this result is that less polar ginsenosides can more easily damage membrane integrity. Conclusion: The results indicated that the less polar ginsenoside-enriched fraction from heat transformation can be used as an antibacterial agent to control halitosis.

• 한국임상수의학회지
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• 제25권5호
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• pp.346-354
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• 2008

The combined effects of EDTA-Tris and eighteen antimicrobial agents have been evaluated in eight clinically isolated methicillin-resistant bacteria (Staphylococcus aureus, Escherichia coli, Streptococcus uberis and Streptococcus agalactiae) from bovine mastitis. The antimicrobial activity was evaluated by measuring the minimal bactericidal concentration (MBC) for the antibiotics alone or in combination with EDTA-Tris in Mueller-Hilton broth and milk. Combined use of EDTA-Tris and antibiotics potentiated or antagonized activity of antibiotics against mastitic pathogens. Milk increased the antibiotic potency of erythromycin and spiramycin on S. aureus. Culture in milk changed patterns of EDTA-Tris combinational effects compared with that in standard Mueller-Hilton broth. Combined with EDTA-Tris in milk, synergic effects were observed in colistin, dihydrostreptomycin, kanamycin, erythromycin, gentamycin, oxytetracycline, streptomycin to E. coli, Str. uberis, and Str. agalactiae. However, significant antagonistic effects of milk on antibiotic susceptibility in combination with EDTA-Tris were noted in neomycin, streptomycin, penicillin, roxithromycin, and amoxicillin. This study indicates that combination therapy of EDTA-Tris with antibiotics in bovine mastitis should be used with caution because of the possible antagonistic effects of antibiotic combination with EDTA-Tris on mastitic pathogens. In addition, antibiotic susceptibility test in combination with EDTA-Tris in milk culture condition can be benefit in search of effective treatment regimen for some antibiotic-resistant bacteria of mastitis.

• International Journal of Oral Biology
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• 제38권3호
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• pp.127-134
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• 2013

Xylitol is a sugar alcohol with a variety of functions including bactericidal and anticariogenic effects. However, the cellular mechanisms underlying the role of xylitol in bone metabolism are not yet clarified. In our present study, we exploited the physiological role of xylitol on osteoclast differentiation in a co-culture system of osteoblastic and RAW 264.7 cells. Xylitol treatment of these co-cultures reduced the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells induced by 10 nM $1{\alpha},25(OH)_2D_3$ in a dose-dependent manner. A cell viability test revealed no marked cellular damage by up to 100 mM of xylitol. Exposure of osteoblastic cells to xylitol decreased RANKL, but not OPG, mRNA expression in the presence of $10^{-8}M$ $1{\alpha},25(OH)_2D_3$ in a dose-dependent manner. Furthermore, bone resorption activity, assessed on bone slices in the coculture system, was found to be dramatically decreased with increasing xylitol concentrations. RANKL and OPG proteins were assayed by ELISA and the soluble RANKL (sRANKL) concentration was decreased with an increased xylitol concentration. In contrast, OPG was unaltered by any xylitol concentration in this assay. These results indicate that xylitol inhibits $1{\alpha},25(OH)_2D_3$-induced osteoclastogenesis by reducing the sRANKL/OPG expression ratio in osteoblastic cells.

• 한국식품영양과학회지
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• 제25권5호
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• pp.804-809
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• 1996

식품위생 관련 미생물 8종에 대한 방사선 단독 및 가열처리와의 병용처리에 의한 살균효과를 조사한 결과, 방사선 단독처리시는 공시균주들의 D$_{10}$ 값은 0.14~0.48 kGy로 나타났으며 그 중 Escherichia coli가 0.14 kGy로 감수성이 가장 높았다. 불활성화 계수는 2~3 kGy 조사시 4.54~21.43으로 나타났다. 가열 단독 처리시에는 D(min) 값이 $50\pm1^{\circ}C에서$ 는 10~40분, $60\pm1^{\circ}C에서는$ 5~15분 정도로 나타났다. 가열과 방사선과의 병용처리시는 D$_{10}$ 값이 0.04~0.31 kGy의 범위로 나타났고 불활성화 계수도 2~3 kGy 조사시 에는 6.45~75로 나타났다. 이상의 결과, 가열과 방사선의 병용처리는 균주들의 방사선 감수성을 현저하게 상승시킴을 알 수 있었다.있었다.