• 한국생명과학회:학술대회논문집
• /
• 한국생명과학회 2008년도 제49회 학술심포지움 및 국제학술대회
• /
• pp.73.2-73.2
• /
• 2008

• 한국미생물학회:학술대회논문집
• /
• 한국미생물학회 2000년도 International Meeting 2000
• /
• pp.9-12
• /
• 2000

• 미생물학회지
• /
• 제50권2호
• /
• pp.128-136
• /
• 2014

Acyl homoserine lactone (AHL) 분해효소인 lactonase는 높은 기질 특이성을 지니기 때문에 경제적이고 효율적인 쿼럼 저해 기술로 이용될 가능성을 지니고 있다. 본 연구에서는 Chromobacterium violaceum CV026과 Agrobacterium tumefaciens NTL4를 바이오센서로 이용하여 biofouling이 일어난 역삼투막 시료로부터 쿼럼 센싱과 관련된 생물막 형성을 억제하는 6종의 균주를 분리 연구하였다. 분리된 균주는 모두 Bacillus 속으로 동정되었으며, AHL 분자의 acyl 사슬 길이나 치환 종류에 상관 없이 쿼럼 저해활성을 보여주었다. 균주들은 Pseudomonas aeruginosa PAO1에 의한 생물막 형성을 46.7-58.3% 정도 감소시켰으며 이 때 저해물질은 열처리에 민감한 특성을 보여주었다. 분리 균주 중 RO1S-5를 이용하여 N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12 AHL)과 반응시킨 결과, 상응하는 acyl homoserine (3-oxo-C12-HS)이 생성되는 것을 LC-MS로 확인하여 쿼럼 저해가 lactonase 활성에 의한 것임을 규명하였다. AHL 물질에 대한 높은 특이성 등을 감안할 때 분리 균주 RO1S-5는 생물막 형성과 관련된 질병이나 산업공정 중 발생하는 biofouling을 해결하는데 유용하게 쓰일 수 있을 것으로 기대된다.

• Journal of Microbiology and Biotechnology
• /
• 제27권12호
• /
• pp.2104-2111
• /
• 2017

A new series comprising phenylacetyl-homoserine lactones (HSLs), caffeoyl-HSL and feruloyl-HSL, was biologically synthesized using an artificial de novo biosynthetic pathway. We developed an Escherichia coli system containing artificial biosynthetic pathways that yield phenylacetyl-HSLs from simple carbon sources. These artificial biosynthetic pathways contained the LuxI-type synthase gene (rpaI) in addition to caffeoyl-CoA and feruloyl-CoA biosynthetic genes, respectively. Finally, the yields for caffeoyl-HSL and feruloyl-HSL were $97.1{\pm}10.3$ and $65.2{\pm}5.7mg/l$, respectively, by tyrosine-overproducing E. coli with a $\text\tiny{L}$-methionine feeding strategy. In a quorum sensing (QS) competition assay, feruloyl-HSL and p-coumaroyl-HSL antagonized the QS receptor TraR in Agrobacterium tumefaciens NT1, whereas caffeoyl-HSL did not.

• 한국식물병리학회:학술대회논문집
• /
• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
• /
• pp.66.1-66
• /
• 2003

The aim of this study was to characterize the interactions of rice and Burkholderia glumae, a causal agent of bacterial grain rot of rice, at molecular levels using whole genomic sequences and to identify genes important for pathogenicity and symptom development. To do these, we sequenced whole genome of the bacterium and constructed cosmid clone profiles. We generated pools of mutants using various transposons and determined mutation sites by sequencing rescued plasmids. We focused on studying toxoflavin biosynthetic genes, quorum sensing regulation, and Hrp type III protein secretion systems. We found that two possible operons consisting of five genes are involved in toxoflavin biosynthesis and their expression is regulated by quorum sensing and LysR-type regulator, ToxR. We have isolated the nn PAI of B. glumae and characterized by mutational analyses. The hrp cluster resembled most the putative Type III secretion systems of B. pseudomallei, which is the causative agent of melioidosis, a serious disease of man and animals. The Hrp PAI core region showed high similarity to that of Ralstonia solanacearum and Xanthomonas campestris, however some aspects were dissimilar.

• Journal of Microbiology and Biotechnology
• /
• 제11권5호
• /
• pp.804-811
• /
• 2001

In many Gram-negative bacteria, autoinducers, such as N-acyl-L-homoserine lactone(acyl-HSL) and its derivative molecules, mediate the cell-density-dependnet expression of certain operons. The current study identified the autoinducers produced by Burkholderia cepacia G4, a trichloroethylene-degrading lagoon isolate, using TLC bioassays with Agrobacterium tumefaciens NT1(pDCI141E33) and Chromobacterium violaceum CVO26, and a GC-MS analysis. The ${R_f}\;and\;{R_t}$ values and mass spectra were compared with those of synthetic compounds. Based on the analyses, it was confirmed that G4 produces N-hexanoyl (C6)-, N-octanoyl (C8)-, N-decanoyl (C10)-, N-dodecanoyl (C12)-HSL, and an unknown active species. The integration of the GC peak areas exhibited a ratio of C8-HSL:C10-HSL:C12-HSL at 3:17:1 with C6-HSL and C10-HSL production at trace and micromolar levels, respectively, in the culture supernatants. Nutants partially defective in producing acyl-HSLs were also partially defective in the biosynthesis of an antibiotic substance. These results indicate that the autoinducer-dependent gene regulation in G4 is dissimilar to the clinical B. cepacia strains isolated from patients with cystic fibrosis.

• Journal of Microbiology and Biotechnology
• /
• 제20권12호
• /
• pp.1624-1629
• /
• 2010

Bacterial cell-to-cell communication, termed quorum sensing (QS), leads to coordinated group behavior in a cell-density-dependent fashion and controls a variety of physiological processes including virulence gene expression. The repressor of the lsr operon, LsrR, is the only known regulator of LuxS/AI-2-mediated QS in Salmonella. Although lack of lsrR did not result in noticeable differences in Salmonella survival, the down-regulation of QS as a result of lsrR overexpression decreased Salmonella survival within macrophages. We found that impaired growth of Salmonella overexpressing lsrR within macrophages was due largely to its hypersensitivity to NADPH-dependent oxidative stress. This, in turn, was a result of decreased expression of genes involved in the oxidative stress response, such as sodA, sodCI, and sodCII, when lsrR was overexpressed. These results suggest that down-regulation of QS by excess LsrR can lower Salmonella virulence by hampering Salmonella evasion from oxidative killing within macrophages.

• International Journal of Oral Biology
• /
• 제46권3호
• /
• pp.111-118
• /
• 2021

Periodontitis and periimplantitis are caused as a result of dental biofilm formation. This biofilm is composed of multiple species of pathogens. Therefore, controlling biofilm formation is critical for disease prevention. To inhibit biofilm formation, sugars can be used to interrupt lectin-involving interactions between bacteria or between bacteria and a host. In this study, we evaluated the effect of D-Arabinose on biofilm formation of putative periodontal pathogens as well as the quorum sensing activity and whole protein profiles of the pathogens. Crystal violet staining, confocal laser scanning microscopy, and scanning electron microscopy revealed that D-Arabinose inhibited biofilm formation of Porphyromonas gingivalis, Fusobacterium nucleatum, and Tannerella forsythia. D-Arabinose also significantly inhibited the activity of autoinducer 2 of F. nucleatum and the expression of representative bacterial virulence genes. Furthermore, D-Arabinose treatment altered the expression of some bacterial proteins. These results demonstrate that D-Arabinose can be used as an antibiofilm agent for the prevention of periodontal infections.

• 한국미생물·생명공학회지
• /
• 제50권1호
• /
• pp.1-14
• /
• 2022

Bacteria communicate with each other through an intricate communication mechanism known as quorum sensing (QS). QS regulates different behavioral aspects in bacteria, such as biofilm formation, sporulation, virulence gene expression, antibiotic production, and bioluminescence. Several different chemical signals and signal detection systems play vital roles in promoting highly efficient intra- and interspecies communication. Gram-negative bacteria coordinate gene regulation through the production of acyl homoserine lactones (AHLs). Gram-positive bacteria do not code for AHL production, while some gram-negative bacteria have an incomplete AHL-QS system. Despite this fact, these microbes can detect AHLs owing to the presence of LuxR solo receptors. Various studies have reported the role of AHLs in interspecies signaling. Moreover, as bacteria live in a polymicrobial community, the production of extracellular compounds to compete for resources is imperative. Thus, AHL-mediated signaling and inhibition are considered to affect virulence in bacteria. In the current review, we focus on the synthesis and regulation mechanisms of AHLs and highlight their role in interspecies bacterial signaling. Exploring interspecies bacterial signaling will further help us understand host-pathogen interactions, thereby contributing to the development of therapeutic strategies intended to target chronic polymicrobial infections.

• 한국멀티미디어학회논문지
• /
• 제24권8호
• /
• pp.1101-1113
• /
• 2021

The rapid growth of sense-and-respond applications and the emerging cloud computing model present a new challenge: providing publish/subscribe middleware as a scalable and elastic cloud service. The publish/subscribe interaction model is a promising solution for scalable data dissemination over wide-area networks. In addition, there have been some work on the publish/subscribe messaging paradigm that guarantees reliability and availability in the face of node and link failures. These publish/subscribe systems are commonly used in information-centric networks and edge-fog-cloud infrastructures for IoT. The IoT has an edge-fog cloud infrastructure to efficiently process massive amounts of sensing data collected from the surrounding environment. In this paper. we propose a quorum-based hierarchical fault-tolerant publish/subscribe systems (QHFPS) to enable reliable delivery of messages in the presence of link and node failures. The QHFPS efficiently distributes IoT messages to the publish/subscribe brokers in fog overlay layers on the basis of proposing extended stepped grid (xS-grid) quorum for providing tolerance when faced with node failures and network partitions. We evaluate the performance of QHFPS in three aspects: number of transmitted Pub/Sub messages, average subscription delay, and subscritpion delivery rate with an analytical model.