• 대한수의학회지
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• 제61권2호
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• pp.16.1-16.6
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• 2021

Pseudomonas aeruginosa is one of the most common pathogenic species associated with canine otitis externa (OE). Their resilience is achieved by forming a biofilm, which allows these bacteria to evade even the harshest of treatments. This study evaluated the in vitro synergistic efficacy of N-acetylcysteine (NAC) with different antimicrobial agents against P. aeruginosa isolated from dogs with OE to develop an effective treatment against P. aeruginosa. The antimicrobial activity was evaluated by the minimum inhibitory concentration test using the microdilution method. The efficacy of antibiofilm formation was evaluated using a crystal violet stain method. The treatment solutions included NAC alone, and in synergy with enrofloxacin, polymyxin B, and gentamicin. NAC alone exhibited antimicrobial and antibiofilm abilities. On the other hand, the combination of NAC and the antibiotics did not show any significant synergistic effects against P. aeruginosa.

• Journal of Microbiology and Biotechnology
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• 제31권1호
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• pp.115-122
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• 2021

Phenol-soluble modulins (PSMs) are responsible for regulating biofilm formation, persister cell formation, pmtR expression, host cell lysis, and anti-bacterial effects. To determine the effect of psm deletion on methicillin-resistant Staphylococcus aureus, we investigated psm deletion mutants including Δpsmα, Δpsmβ, and Δpsmαβ. These mutants exhibited increased β-lactam antibiotic resistance to ampicillin and oxacillin that was shown to be caused by increased N-acetylmannosamine kinase (nanK) mRNA expression, which regulates persister cell formation, leading to changes in the pattern of phospholipid fatty acids resulting in increased anteiso-C15:0, and increased membrane hydrophobicity with the deletion of PSMs. When synthetic PSMs were applied to Δpsmα and Δpsmβ mutants, treatment of Δpsmα with PSMα1-4 and Δpsmβ with PSMβ1-2 restored the sensitivity to oxacillin and slightly reduced the biofilm formation. Addition of a single fragment showed that α1, α2, α3, and β2 had an inhibiting effect on biofilms in Δpsmα; however, β1 showed an enhancing effect on biofilms in Δpsmβ. This study demonstrates a possible reason for the increased antibiotic resistance in psm mutants and the effect of PSMs on biofilm formation.

• Restorative Dentistry and Endodontics
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• 제46권2호
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• pp.20.1-20.11
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• 2021

Objectives: The aim of this study was to evaluate bacterial nanocellulose (BNC) membranes incorporated with antimicrobial agents regarding cytotoxicity in fibroblasts of the periodontal ligament (PDLF), antimicrobial activity, and inhibition of multispecies biofilm formation. Materials and Methods: The tested BNC membranes were BNC + 1% clindamycin (BNC/CLI); BNC + 0.12% chlorhexidine (BNC/CHX); BNC + nitric oxide (BNC/NO); and conventional BNC (BNC; control). After PDLF culture, the BNC membranes were positioned in the wells and maintained for 24 hours. Cell viability was then evaluated using the MTS calorimetric test. Antimicrobial activity against Enterococcus faecalis, Actinomyces naeslundii, and Streptococcus sanguinis (S. sanguinis) was evaluated using the agar diffusion test. To assess the antibiofilm activity, BNC membranes were exposed for 24 hours to the mixed culture. After sonicating the BNC membranes to remove the remaining biofilm and plating the suspension on agar, the number of colony-forming units (CFU)/mL was determined. Data were analyzed by 1-way analysis of variance and the Tukey, Kruskal-Wallis, and Dunn tests (α = 5%). Results: PDLF metabolic activity after contact with BNC/CHX, BNC/CLI, and BNC/NO was 35%, 61% and 97%, respectively, compared to BNC. BNC/NO showed biocompatibility similar to that of BNC (p = 0.78). BNC/CLI showed the largest inhibition halos, and was superior to the other BNC membranes against S. sanguinis (p < 0.05). The experimental BNC membranes inhibited biofilm formation, with about a 3-fold log CFU reduction compared to BNC (p < 0.05). Conclusions: BNC/NO showed excellent biocompatibility and inhibited multispecies biofilm formation, similarly to BNC/CLI and BNC/CHX.

• 대한약침학회지
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• 제26권4호
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• pp.307-318
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• 2023

Objectives: Bacterial biofilm is regarded as a significant threat to the production of safe food and the arise of antibiotic-resistant bacteria. The objective of this investigation is to evaluate the quorum sensing inhibitory effect of Nepeta curviflora methanolic extract. Methods: The effectiveness of the leaves at sub-inhibitory concentrations of 2.5, 1.25, and 0.6 mg/mL on the virulence factors and biofilm formation of P. aeruginosa was evaluated. The effect of N. curviflora methanolic extract on the virulence factors of P. aeruginosa, including pyocyanin, rhamnolipid, protease, and chitinase, was evaluated. Other tests including the crystal violet assay, scanning electron microscopy (SEM), swarming motility, aggregation ability, hydrophobicity and exopolysaccharide production were conducted to assess the effect of the extract on the formation of biofilm. Insight into the mode of antiquorum sensing action was evaluated by examining the effect of the extract on the activity of N-Acyl homoserine lactone (AHL) and the expression of pslA and pelA genes. Results: The results showed a significant attenuation in the production of pyocyanin and rhamnolipid and in the activities of protease and chitinase enzymes at 2.5 and 1.25 mg/mL. In addition, N. curviflora methanolic extract significantly inhibited the formation of P. aeruginosa biofilm by decreasing aggregation, hydrophobicity, and swarming motility as well as the production of exopolysaccharide (EPS). A significant reduction in AHL secretion and pslA gene expression was observed, indicating that the extract inhibited quorum sensing by disrupting the quorum-sensing systems. The quorum-sensing inhibitory effect of N. curviflora extract appears to be attributed to the presence of kaempferol, quercetin, salicylic acid, rutin, and rosmarinic acid, as indicated by LCMS analysis. Conclusion: The results of the present study provide insight into the potential of developing anti-quorum sensing agents using the extract and the identified compounds to treat infections resulting from quorum sensing-mediated bacterial pathogenesis.

• 생명과학회지
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• 제20권3호
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• pp.321-325
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• 2010

구강에 상주하는 미생물 중, Streptococcus mutans는 충치 및 치주염의 원인인 치아플라그를 형성하는데 중요한 역할을 한다. Phytochemical은 식물에서 추출된 화학성분으로서, 사람의 건강에 유익한 영양물질로서 많은 연구들이 진행되어왔다. 본 연구는 이 phytochemical이 중요 구강미생물인 S. mutans에 대한 효과를 살펴보았다. 최근에 Thomson seedless raisin에서 여러 phytochemicals가 추출되었는데, 그 중 oleanolic acid (OA)와 5-(hydroxymethyl)-2-furfural (HF)의 임상적으로 중요한 여러 미생물에 대한 항균활성효과를 확인한 결과, OA가 그람음성균들에게는 항균활성효과가 나타나지 않았고, 그람양성균들에만 항균활성효과를 보였다. 그러나, HF의 경우에는 모든 균주에 대해 항균활성을 나타내지 않았다. 또한, OA는 S. mutans 균주의 표면부착과 생균막의 형성을 저해하기도 하였다. 따라서, 이 연구결과들은 OA가 치아에 존재하는 S. mutans의 생육 및 여러 생리적 특성들을 저해하므로 항플라그제나 항충치약으로서의 활용가능성을 확인할 수 있었다.

• 한국미생물·생명공학회지
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• 제32권1호
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• pp.1-10
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• 2004

Many bacteria monitor their population density and control the expression of specialized gene sets in response to bacterial cell density based on a mechanism referred to as quorum sensing. In all cases, quorum sensing involves the production and detection of extracellular signaling molecules, auto inducers, as which Gram-negative and Gram-positive bacteria use most prevalently acylated homoserine lactones and processed oligo-peptides, respectively. Through quorum-sensing communication circuits, bacteria regulate a diverse array of physiological functions, including virulence, symbiosis, competence, conjugation, antibiotic production, motility, sporulation, and biofilm formation. Many pathogens have evolved quorum-sensing mechanisms to mount population-density-dependent attacks to over-whelm the defense responses of plants, animals, and humans. Since these AHL-mediated signaling mechanisms are widespread and highly conserved in many pathogenic bacteria, the disruption of quorum-sensing system might be an attractive target for novel anti-infective therapy. To control AHL-mediated pathogenicity, several promising strategies to disrupt bacterial quorum sensing have been reported, and several chemicals and enzymes have been also investigated for years. These studies indicate that anti-quorum sensing strategies could be developed as possible alternatives of antibiotics.

• 대한소아치과학회지
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• 제42권4호
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• pp.302-311
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• 2015

본 연구는 Planktonic growth inhibition test와 CDC Biofilm Reactor를 사용한 Biofilm assay를 통해 S-PRG filler를 함유하는 치면열구전색제의 S. mutans에 대한 항미생물 효과를 기존의 치면열구전색제와 비교하고자 하였다. S-PRG 필러를 함유하는 치면열구전색제인 BeautiSealant, 불소를 방출하는 치면열구전색제인 Clinpro$^{TM}$ sealant, 불소 미방출 치면열구전색제인 Concise$^{TM}$ sealant를 실험군으로 선정하였다. 성장억제평가를 위해 치면열구전색제를 사용하지 않은 군을 음성 대조군으로 설정하였으며, 3개의 실험군 모두 대조군보다 유의할 정도로 낮은 집락 형성 단위를 보였고, Clinpro$^{TM}$ sealant가 BeautiSealant와 Concise$^{TM}$ sealant보다 유의할 정도로 낮은 집락 형성 단위를 보였다. BeautiSealant와 Concise$^{TM}$ sealant 군간에는 유의한 차이가 관찰되지 않았다. 바이오 필름 평가에서도 Clinpro$^{TM}$ sealant군이 BeautiSealant와 Concise$^{TM}$ sealant군들에 비해 유의할 정도로 낮은 집락 형성을 보였으며, BeautiSealant와 Concise$^{TM}$ sealant 군간에 유의한 차이는 관찰되지 않았다. 본 연구 결과 S-PRG filler를 포함하는 치면열구전색제인 BeautiSealant는 기존의 불소방출 치면열구전색제에 비하여 낮은 항미생물 효과와 높은 바이오 필름 형성능을 보였다.

• 생명과학회지
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• 제29권6호
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• pp.712-723
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• 2019

화학적으로 합성된 물질들이 주로 구강 위생 제품에 사용된다. 그러나 이러한 화학 물질을 장기간 사용 시, 내성 발생이나 알레르기, 치아변색과 같은 부작용이 발생할 수 있다. 이런 문제를 해결하기 위해 식물로부터 유래된 항균 물질의 사용과 이러한 항균 물질들의 탐색을 위한 노력이 계속 진행되고 있다. 본 연구를 통해 Streptococcus mutans의 성장과 생물막 형성을 저해하는 해외 자생식물을 탐색하고자 하였다. 본 실험에는 총 300종의 해외 자생식물 추출물이 사용되었으며, 그 중 Chesneya nubigena (D. Don) Ali 추출물이 S. mutans에 대한 비교적 높은 항균활성을 나타내는 것으로 확인되었다(clear zone, 9 mm; MBC, 1.5 mg/ml). 또한, 19종의 식물추출물이 농도에 비례적으로 S. mutans의 생물막 형성량을 최소 6배 이상 감소시키는 것을 확인하였다. 특히, C. nubigena (D. Don) Ali 추출물은 1.25 mg/ml의 낮은 농도에서부터 효과적으로 생물막 형성을 억제하는 것으로 관찰하였다. 본 연구를 통하여 C. nubigena (D. Don) Ali 추출물이 S. mutans의 생육 성장과 생물막 형성 저해 효과를 나타내었으며, 이를 통해 본 식물추출물이 충치 예방과 치료에 효과가 있는 항균 대체재 개발의 후보 소재로써 평가된다.

• 생명과학회지
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• 제26권12호
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• pp.1487-1497
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• 2016

정족수 인식 체계라 불리는 세균들의 세포간 의사교환 전략은 다양한 유전자의 발현조절을 통해, 생물막 성숙, 세포 외 고분자물질의 생산, 병원성 발현 및 항생제 생산 등과 같은 다양한 표현형을 조절하는 세균의 다세포성 행동 양식을 제어한다. 다수의 연구에 의하면 많은 종류의 그람 (Gram)음성 세균들이 정족수 인식체계에 필요한 신호전달 물질로 acyl-homoserine lactones (AHLs)를 사용하고 있으며, 이들은 생물막 형성에 중요한 인자로 작용함을 시사하였다. 이러한 정족수 인식체계에 의한 생물막의 형성은 물이 존재하는 모든 표면환경에서 불필요한 바오매스 축적이라는 심각한 기술적, 경제적 문제를 초래하고 있다. 최근 정족수 인체 체계를 교란하는 다수의 물질들이 다양한 미생물로부터 발견되어, 그들의 정족수 인식 체계와 관련된 주요 기능과 기작들이 밝혀지고 있다. 이러한 정족수 제어 물질들은 최근 다양한 산업에서 발생하는 생물 부착현상들을 제어할 수 있는, 환경 친화적이며 세균의 항생제 다재 내성을 완화 시킬 수 있는 새로운 방법으로 대두되고 있다. 따라서 본 논문은 세균의 정족수 인식 체계와 관련된 최근 정보, 정족수 인식 신호를 제어할 수 있는 정족수 제어 효소와 이러한 기술을 이용한 생물 부착 저해 방법 등을 논의하고자 한다.

• 생약학회지
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• 제52권1호
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• pp.41-48
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• 2021

This research was conducted to investigate the antibacterial and anti-inflammatory effects of MeOH Ex. of Salvia miltiorrhiza (MESM) against oral pathogenic bacteria. Minimum inhibitory concentration (MIC), removal effect of biofilm produced by Streptococcus mutans, effect of gene expression of proinflammatory cytokines and effect of production of proinflammatory cytokine of MESM were tested. MESM showed moderated antibacterial activity against oral pathogenic bacteria. About 89±8% of biofilms produced by S. mutans were removed by MESM at a concentration of 1 mg/mL. Gene expression of IL-1β and TNF-α induced by Porphyromonas gingivalis were 8~9 folds reduced by MESM. Gene expression of IL-8 induced by Fusobacterium nucelatum were 12 folds reduced by MESM. Production of IL-1β, TNF-α and IL-8 were significantly suppressed by MESM. Conclusively, MESM showed potent antibacterial and anti-inflammatory effect against oral pathogenic bacteria.