• Membrane and Water Treatment
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• 제9권3호
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• pp.195-203
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• 2018

N-acetylcysteine (NAC) has been widely used as an initial mucolytic agent and is generally used as an antioxidant to help alleviate various inflammatory symptoms. NAC reduces bacterial extracellular polymeric substances (EPS) production, bacterial adhesion to the surface and strength of mature biofilm. The efficacy has been shown to inhibit proliferation of gram-positive and gram-negative bacteria. In membrane bioreactor (MBR) processes, which contain a variety of gram negative bacteria, biofilm formation has become a serious problem in stable operation. In this study, use of NAC as an inhibitor of biofilm contamination was investigated using the center for disease control (CDC) reactors with MBR sludge. Biomass reduction was confirmed with CLSM images of membrane surfaces by addition of NAC, which was more efficient as the concentration of NAC was increased to 1.5 mg/mL. NAC addition also showed decreases in EPS concentrations of the preformed biofilm, indicating that NAC was able to degrade EPS in the mature biofilm. NAC addition was also effective to inhibit biofilm formation by MBR sludge, which consisted of various microorganisms in consortia.

• 생명과학회지
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• 제31권1호
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• pp.100-108
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• 2021

구강에는 700여 종의 미생물이 부유성 세균(planktonic cells)으로 있거나 치아 표면에 부착하여 바이오필름(biofilms)을 형성하고 있으며 구강 바이오필름(oral biofilms)과 관련된 대표적인 구강질환에는 치아우식증과 치주질환이 있다. 구강 세균은 타액의 흐름, 숙주의 항균 단백질, 영양소의 가용성 및 pH 변화, 항생제, 방부제 등의 영향을 받고 있지만 바이오필름이 형성되면 바이오필름은 물리적으로 두꺼운 층을 이루고 있기 때문에 구강 세균은 이와 같은 구강 내부의 환경적 스트레스에 저항할 수 있을 뿐만 아니라 외부 물질의 침투가 어렵고 바이오필름 내 세포간 상호작용을 통해 유전자 변이가 일어나기 때문에 부유성 세균보다 항생제에 대한 저항성이 1,000배 정도 높다. 따라서 구강 세균의 바이오필름 형성을 억제하거나 제거하면 보다 효과적으로 세균 감염에 의한 구강질환을 예방하거나 치료할 수 있을 것이다. 특히 구강 바이오필름은 여러 세균이 모여서 바이오필름을 형성하는 특징을 가지고 있기 때문에 세포간 신호전달체계인 정족수 감지(quorum sensing)는 구강 바이오필름을 제어할 수 있는 목표점이 될 수 있다. 이외에도 구강세균의 알칼리 생성 기질인 아르기닌을 이용하여 구강 미생물의 분포를 건강한 치아와 유사한 환경으로 전환하거나 S. mutans의 glucosyltransferase 분비를 억제하여 비수용성의 글루칸 형성을 억제함으로써 바이오필름 형성을 억제하는 방법도 구강 바이오필름을 제어할 수 있는 목표점이 될 수 있다. 이처럼 구강 내 병원성 세균의 사멸을 유도하기 보다는 구강 세균의 바이오필름 형성을 억제하거나 제거하는 방법은 치아우식증을 비롯한 구강질환을 선택적으로 예방하거나 치료할 수 있는 새로운 전략이 될 것이다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권4호
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• pp.322-328
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• 2005

Acylhomoserine lactones (AHLs) are known to be the triggering molecules in the quorum sensing mechanism of many gram-negative bacteria. In order to detect AHL inhibitors that are potential biofilm inhibitors, a convenient and sensitive bioassay was developed based on the $\beta$-galactosidase activity ($\beta$-GAL) of a recombinant Agrobacterium tumefaciens strain. A series of commercially available AHLs were tested for inducing $\beta$-GAL at varying concentrations in agar-plate and liquid cultures of the reporter strain. All AHLs tested exhibited a concentration­dependent induction, and octanoyl homoserine lactone (OHL) showed the highest sensitivity with a detection limit of 0.1 nM in the liquid culture assay. When fimbrolide, a known quorum sensing inhibitor, was added, induction of $\beta$-GAL by OHL was repressed. The repression at a constant OHL concentration was dependent on the fimbrolide concentration with the detection limit below 1 ppm, indicating that this assay is a sensitive method for screening AHL inhibitors.

• 한국축산식품학회지
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• 제42권1호
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• pp.84-97
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• 2022

We evaluated the anti-biofilm formation and anti-inflammatory activity of Hovenia monofloral honey (HMH) against Enterococcus faecalis. Co-culture of HMH with E. faecalis attenuated the biofilm formation of E. faecalis on a polystyrene surface. In addition, HMH effectively eradicated the established E. faecalis biofilm. HMH significantly attenuated E. faecalis growth but did not affect the production of extracellular polymeric substances on E. faecalis, indicating that reduction of E. faecalis biofilm is a result of HMH-mediated killing of E. faecalis. Furthermore, we found that HMH can effectively attenuate E. faecalis-induced expression of a proinflammatory interleukin-8 (IL- 8) in HT-29 cells. Interestingly, treatment of HMH significantly attenuated the E. faecalis-mediated expression of Toll-like receptor-2 (TLR-2) and its adaptor molecules, myeloid differentiation primary response 88 (MyD88), in HT-29 cells. In addition, E. faecalis-induced mitogen-activated protein kinases (MAPKs) phosphorylation was significantly attenuated by HMH administration. Furthermore, HMH-mediated antiinflammatory efficacy (0.2 mg/mL of HMHs) had an equal extent of inhibitory efficacy as 5 μM of MyD88 inhibitor to attenuate E. faecalis-mediated IL-8 expression in HT-29 cells. These results suggest that HMH could effectively inhibit E. faecalis-mediated gastrointestinal inflammation through regulating the TLR-2/MyD88/MAPKs signaling pathways. Collectively, our data suggest that HMH could be developed as a potential natural agent to control E. faecalis-mediated biofilm formation and inflammation.

• Journal of Microbiology and Biotechnology
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• 제27권6호
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• pp.1078-1089
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• 2017

Biofilm formation of Staphylococcus aureus is one of its mechanisms of drug resistance. Anti-biofilm screening of 106 compounds from marine-derived fungi displayed that 12 compounds inhibited S. aureus biofilm formation by >50% at the concentration of $100{\mu}g/ml$, and only secalonic acid D (SAD) and B inhibited by >90% at $6.25{\mu}g/ml$ without inhibiting cell growth after 24-h incubation. Meanwhile, it was found that the double bond between C-1 and C-10 of citrinin derivatives and the C-C connection position of two chromone monomers may be important for their anti-biofilm activities. Moreover, SAD slightly facilitated biofilm eradication and influenced its architecture. Furthermore, SAD slowed the cell growth rate in the preceding 18-h incubation and differentially regulated transcriptional expression of several genes, such as agr, isaA, icaA, and icaD, associated with biofilm formation in planktonic and biofilm cells, which may be the reason for the anti-biofilm activity of SAD. Finally, SAD acted synergistically against S. aureus growth and biofilm formation with other antibiotics. These findings indicated that various natural products from marine-derived fungi, such as SAD, could be used as a potential biofilm inhibitor against S. aureus.

• Journal of Microbiology and Biotechnology
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• 제25권8호
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• pp.1390-1400
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• 2015

Quorum sensing is a process of cell-to-cell communication in which bacteria produce autoinducers as signaling molecules to sense cell density and coordinate gene expression. In the present study, a LuxI-type synthase, AnoI, and a LuxR-type regulator, AnoR, were identified in Acinetobacter nosocomialis, an important nosocomial pathogen, by sequence analysis of the bacterial genome. We found that N-(3-hydroxy-dodecanoyl)- _L -homoserine lactone (OH-dDHL) is a quorum-sensing signal in A. nosocomialis. The anoI gene deletion was responsible for the impairment in the production of OH-dDHL. The expression of anoI was almost abolished in the anoR mutant. These results indicate that AnoI is essential for the production of OH-dDHL in A. nosocomialis, and its expression is positively regulated by AnoR. Moreover, the anoR mutant exhibited deficiency in biofilm formation. In particular, motility of the anoR mutant was consistently and significantly abolished compared with that of the wild type. The deficiency in the biofilm formation and motility of the anoR mutant was significantly restored by a functional anoR, indicating that AnoR plays important roles in the biofilm formation and motility. Furthermore, the present study showed that virstatin exerts its effects on the reduction of biofilm formation and motility by inhibiting the expression of anoR. Consequently, the combined results suggest that AnoIR is a quorum-sensing system that plays important roles in the biofilm formation and motility of A. nosocomialis, and virstatin is an inhibitor of the expression of anoR.

• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1426-1432
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• 2018

Staphylococcus aureus causes a broad variety of diseases. The spread of multidrug-resistant S. aureus highlights the need to develop new ways to combat S. aureus infections. Sortase A (SrtA) can anchor proteins containing LPXTG binding motifs to the bacteria surface and plays a key role in S. aureus infections, making it a promising antivirulence target. In the present study, we used a SrtA activity inhibition assay to discover that isovitexin, a Chinese herbal product, can inhibit SrtA activity with an $IC_{50}$ of $28.98{\mu}g/ml$. Using a fibrinogen-binding assay and a biofilm formation assay, we indirectly proved the SrtA inhibitory activity of isovitexin. Additionally, isovitexin treatment decreased the amount of staphylococcal protein A (SpA) on the surface of the cells. These data suggest that isovitexin has the potential to be an anti-infective drug against S. aureus via the inhibition of sortase activity.

• 한국미생물·생명공학회지
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• 제39권1호
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• pp.29-36
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• 2011

그람음성 간균인 녹농균(Pseudomonas aeruginosa)은 비뇨기, 각막, 호흡기, 화상부위 등에 광범위하게 감염하는 기회감염성 병원균으로, 병원성의 발현에 세균의 세포밀도 인식 기전인 쿼럼 센싱(quorum sensing)이 매우 중요하게 관여한다. 사전 연구에서 녹농균 감염력을 제어하기 위한 방법으로 쿼럼 센싱의 주 신호물질인 N-3-oxododecanoyl-HSL(3OC12-HSL)의 분자 구조가 변형된 물질들을 합성하여 쿼럼 센싱 억제물질로 사용하고자 하였으며, 그 중 두 개의 물질들(5b, 5f)이 대장균을 이용한 스크리닝을 통해 녹농균의 주요 쿼럼 센싱 수용체 단백질인 LasR의 활성을 억제할 수 있음을 확인하였었다. 본 연구에서는 이 물질들의 효과를 보다 면밀히 분석하기 위하여 실제 녹농균에서 이 물질들이 쿼럼 센싱과 병독성을 억제할 수 있는지 분석해 보았다. 대장균을 이용한 리포터 분석에서와는 달리, 5b와 5f 모두 녹농균에서 직접 처리하였을 때는 LasR의 활성에 영향을 주지 못하였다. 대신 이 물질들은 녹농균의 또다른 쿼럼 센싱 수용체 단백질인 QscR의 활성에 선택적으로 영향을 주었다. 흥미롭게도 이 물질들의 효과는 대장균에서 얻어진 결과와는 달랐으며 다소 복잡하였다. 두 물질 모두 낮은 농도 범위(<10 ${\mu}m$)에서 QscR의 활성을 증가시켰으며, 높은 농도의 5f(${\approx}$1 mM)는 QscR을 강하게 억제하였다. 두 물질 모두 중요한 병독인자인 프로테아제 활성에는 영향을 주지 않으면서도, 만성감염을 매개하는데 중요한 생물막의 형성은 의미있게 감소시켰다. 특히 5f는 생물막의 성숙단계 보다는 녹농균 세포의 초기 부착을 억제하였다. 이러한 결과들을 바탕으로, 5f의 경우 독성의 증가 없이 생물막 형성을 억제할 수 있는 물질로 응용이 가능하다고 제안한다.

• Journal of Periodontal and Implant Science
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• 제46권2호
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• pp.84-95
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• 2016

Purpose: The objective of this study was to investigate the effect of a dietary flavonoid, kaempferol, which has been shown to possess antiallergic, anti-inflammatory, anticarcinogenic, and antioxidant activities on the periodontium by histomorphometric analysis and on gingival tissue matrix metalloproteinase-1 (MMP-1), MMP-8, and tissue inhibitor of metalloproteinase-2 (TIMP-2) by biochemical analysis of rats after experimental periodontitis induction. Methods: Sixty Wistar rats were randomly divided into six groups of ten rats each, and silk ligatures were placed around the cervical area of the mandibular first molars for 15 days, except in the healthy control rats. In the experimental periodontitis groups, systemic kaempferol (10 mg/kg/2d) and saline were administered by oral gavage at two different periods (with and without the presence of dental biofilm) to all rats except for the ten non-medicated rats. Alveolar bone area, alveolar bone level, and attachment level were determined by histomorphometric analysis, and gingival tissue levels of MMP-1, MMP-8, and TIMP-2 were detected by biochemical analysis. Results: Significantly greater bone area and significantly less alveolar bone and attachment loss were observed in the kaempferol application groups compared to the control groups (P<0.05). In addition, gingival tissue MMP-1 and -8 levels were significantly lower in the kaempferol application groups compared to the control groups and the periodontitis group (P<0.001). There were no statistically significant differences in TIMP-2 levels between the kaempferol and saline application groups (P>0.05). Conclusions: Kaempferol application may be useful in decreasing alveolar bone resorption, attachment loss, and MMP-1 and -8 production in experimental periodontitis.

• Archives of Plastic Surgery
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• 제42권1호
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• pp.59-67
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• 2015

Background Negative-pressure wound therapy (NPWT) induces angiogenesis and collagen synthesis to promote tissue healing. Although acetic acid soaks normalize alkali wound conditions to raise tissue oxygen saturation and deconstruct the biofilms of chronic wounds, frequent dressing changes are required. Methods Combined use of NPWT and acetic acid irrigation was assessed in the treatment of chronic wounds, instilling acetic acid solution (1%) beneath polyurethane membranes twice daily for three weeks under continuous pressure (125 mm Hg). Clinical photographs, pH levels, cultures, and debrided fragments of wounds were obtained pre- and posttreatment. Tissue immunostaining (CD31, Ki-67, and CD45) and reverse transcription-polymerase chain reaction (vascular endothelial growth factor [VEGF], vascular endothelial growth factor receptor [VEGFR]; procollagen; hypoxia-inducible factor 1 alpha [HIF-1-alpha]; matrix metalloproteinase [MMP]-1,-3,-9; and tissue inhibitor of metalloproteinase [TIMP]) were also performed. Results Wound sizes tended to diminish with the combined therapy, accompanied by drops in wound pH (weakly acidic or neutral) and less evidence of infection. CD31 and Ki-67 immunostaining increased (P<0.05) post-treatment, as did the levels of VEGFR, procollagen, and MMP-1 (P<0.05), whereas the VEGF, HIF-1-alpha, and MMP-9/TIMP levels declined (P<0.05). Conclusions By combining acetic acid irrigation with negative-pressure dressings, both the pH and the size of chronic wounds can be reduced and infections be controlled. This approach may enhance angiogenesis and collagen synthesis in wounds, restoring the extracellular matrix.