Effect of N-acyl homoserine lactones (AHLs) quorum sensing signal molecules on Enterococcus faecalis biofilm formation (original) (raw)
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Applied and Environmental Microbiology, 2019
Dental plaque is omnipresent in healthy oral cavities and part of our commensal microbial colonization. At the same time, dental plaque is the cause of the most common human diseases, caries and gum disease. Dental plaque consists of billions of microbes attached to the surface of your teeth. Communication among these microbes is pivotal for development of these complex communities yet poorly studied in dental plaque. In the present study, we show that a specific communication molecule induces changes within the community related to the development of gum disease. This finding suggests that interfering with microbial communication may represent an interesting novel strategy to prevent gum disease that should be further investigated.
Combating Biofilm and Quorum Sensing: A New Strategy to Fight Infections
Bacterial Biofilms [Working Title], 2019
Biofilms are structured aggregates of bacterial cells that are embedded in selfproduced extracellular polymeric substances. Various pathogens initiate a disease process by creating organized biofilms that enhance their ability to adhere, replicate to accumulate, and express their virulence potential. Quorum sensing, which refers to the bacterial cell-to-cell communication resulting from production and response to N-acyl homoserine lactone signal molecules, also plays an important role in virulence and biofilm formation. Attenuation of microorganisms' virulence such that they fail to adapt to the hosts' environment could be a new strategic fight against pathogens. Thus, agents or products that possess anti-biofilm formation and/or anti-quorum sensing activities could go a long way to manage microbial infections. The incidence of microbial resistance can be reduced by the use of antibiofilm formation and anti-quorum sensing agents.
Growth inhibition of adherent Pseudomonas aeruginosa by an N -butanoyl- l -homoserine lactone analog
Canadian Journal of Microbiology, 2010
The discovery of quorum sensing (QS) communication systems regulating bacterial virulence has afforded a novel opportunity for controlling infectious bacteria by interfering with QS. Pseudomonas aeruginosa is an example of an opportunistic human pathogen for which N-acyl homoserine lactone (AHL)-related compounds have been described as potent inhibitors of biofilm formation and virulence factors, given their similarity to the natural QS autoinducers (AHLs). Our purpose was to design potent analogs of N-butanoyl-L-homoserine lactone (C4-HSL) and to screen them for biological activity. Eleven original compounds characterized by the modification of the lactone moiety were screened for their ability to impair biofilm formation. Among them, compound 11 was able to modify the growth kinetics and to restrict the number of adherent cells when added from the early stages of biofilm formation (i.e., adhesion and microcolony formation) in a dose-dependent manner. To demonstrate antagonism with C4-HSL, we showed that the inhibition of biofilm formation by compound 11 was impaired when C4-HSL was added. Structure-activity relationships are discussed with respect to the results obtained.
Environmental Microbiology, 2000
A method is reported for the quantification of 3-oxoacyl homoserine lactones (3-oxo AHLs), a major class of quorum-sensing signals found in Gram-negative bacteria. It is based on the conversion of 3-oxo AHLs to their pentafluorobenzyloxime derivatives followed by gas chromatography–mass spectrometry (electron capture–negative ion). The method used [13C16]-N-3-oxo-dodecanoyl homoserine lactone ([13C16]-OdDHL) as the internal standard, and its validity was tested by spiking the supernatant and cell fractions with three levels of 3-oxo AHLs, i.e. 1, 10 and 100 ng per sample. These showed the method to be both sensitive (S/N ratio > 10:1 for 1 ng) and accurate. The assay was applied to the biofilm and effluent of a green fluorescent protein (GFP)-expressing strain of Pseudomonas aeruginosa (6294) culture grown in flow cells. Biofilm volume was determined for three replicate flow cells by confocal scanning laser microscopy. OdDHL was detected in the biofilm at 632 ± 381 µM and the effluent at 14 ± 3 nM. The biofilm concentration is the highest level so far reported for an AHL in a wild-type bacterial system. The next most abundant 3-oxo AHL in the biofilm and effluent was N-3-oxo-tetradecanoyl homoserine lactone (OtDHL) at 40 ± 15 µM and 1.5 ± 0.7 nM respectively. OtDHL is unreported for P. aeruginosa and has an activity equivalent to OdDHL in a lasR bioassay. Two other 3-oxo AHLs were detected at lower concentrations: N-3-oxo-decanoyl homoserine lactone (ODHL) in the biofilm (3 ± 2 µM) and effluent (1 ± 0.1 nM); and N-3-oxo-octanoyl homoserine lactone (OOHL) in the effluent (0.1 ± 0.1 nM).
Background: N-Acyl homoserine lactone (AHL) is found to be the main component of quorum sensing (QS) in Gram-negative bacteria and plays an important role in biofilm formation. Little information is available regarding the role of AHL in biofilm formation in Escherichia coli (E. coli). The purpose of this investigation was to biochemically detect and characterize AHL activity in biofilm-forming uropathogenic E. coli (UPEC) isolated from urine samples of the patients with urinary tract infections (UTIs) in Kerman, Iran. Methods: Thirty-five UPEC isolates were obtained from urine samples of the patients with UTIs referred to the Afzalipoor hospital. The isolates were identified by biochemical tests. Biofilm analyses of all the isolates were performed using the microtiter plate method at OD 490nm. N-Acyl homoserine lactone was separated from cell mass supernatants by liquid-liquid extraction (LLE) and analyzed by a colorimetric method. N-Acyl homoserine lactone functional groups were identified by Fourier Transform-Infrared Spectroscopy (FT-IR). Results: The biofilm formation assay identified 10 (28.57%) isolates with strong, 16 (45.71%) with moderate, and 9 (25.71%) with weak biofilm activities. The UPEC isolates with strong and weak biofilm activities were subjected to AHL analyses. It was found that isolates with the highest AHL activities also exhibited strong adherence to microplate wells (P≤0.05). Two E. coli isolates with the highest AHL activities were selected for FT-IR spectroscopy. Peaks at 1764.33, 1377.99, and 1242.90 cm -1 correspond to the C=O bond of the lactone ring, and the N=H and C-O bonds of the acyl chain, respectively. Conclusion: We found that many UPEC isolates exhibited strong biofilm formation. The control of this property by AHL may contribute to the pathogenesis of the organism in UTI's.
Methods in molecular biology (Clifton, N.J.), 2010
Widespread antibiotic resistance is a major incentive for the investigation of novel ways to treat or prevent infections. Much effort has been put into the discovery of peptides in nature accompanied by manipulation of natural peptides to improve activity and decrease toxicity. The ever increasing knowledge about bacteria and the discovery of quorum sensing have presented itself as another mechanism to disrupt the infection process. We have shown that the natural quorum sensing (QS) peptide, competence-stimulating peptide (CSP), used by the caries causing bacteria Streptococcus mutans when used in higher than normally present concentrations can actually contribute to cell death in S. mutans. Using an analogue of this quorum sensing peptide (KBI-3221), we have shown it to be beneficial at decreasing biofilm of various Streptococcus species. This chapter looks at a number of assay methods to test the inhibitory effects of quorum sensing peptides and their analogues on the growth and b...
Journal of Scientific Research in Science, 2018
The present study included collecting of 125 clinical bacterial isolates from different sources such as pus, sputum, nasal polyps, urine and blood. The collected bacterial isolates were preliminary identified by biochemical tests as 44 Pseudomonas spp., 35 Klebsiella spp., 18 E. coli, 17 Acinetobacter spp., 8 Proteus spp. and 3 Enterobacter spp., The test for biofilm formation in these isolates was carried out by using three different methods that finally resulted in 27 positive biofilm forming isolates. Production of quorum sensing signal molecules (acyl homoserine lactone) was detected in 20 isolates using gas chromatography mass spectrum (GC/MS); These isolates were 3 Pseudomonas spp., 6 Klebsiella spp., 8 E. coli and 3 Enterobacter spp., The anti-biofilm activity of some plant extracts was carried out using tube method. It showed that Syzygium aromaticum was the most effective one and inhibited biofilm formation in all isolates followed by Allium sativum. Syzygium aromaticum extract also inhibited quorum sensing production in the selected 20 bacterial isolates. From the above results, Syzygium aromaticum extract was recommended to be used as an active antibacterial agent against multidrug resistant bacteria due to its ability to inhibit biofilm formation and quorum sensing signal production. Finally, the most potent bacterial isolates were genetically identified by 16S rRNA gene sequencing.
Background:N-Acyl homoserine lactone (AHL) is found to be the main component of quorum sensing (QS) in Gram-negative bacteria and plays an important role in biofilm formation. Little information is available regarding the role of AHL in biofilm formation in Escherichia coli (E. coli). The purpose of this investigation was to biochemically detect and characterize AHL activity in biofilm-forming uropathogenic E. coli (UPEC) isolated from urine samples of the patients with urinary tract infections (UTIs) in Kerman, Iran. Methods: Thirty-five UPEC isolates were obtained from urine samples of the patients with UTIs referred to the Afzalipoor hospital. The isolates were identified by biochemical tests. Biofilm analyses of all the isolates were performed using the microtiter plate method at OD 490nm. N-Acyl homoserine lactone was separated from cell mass supernatants by liquid-liquid extraction (LLE) and analyzed by a colorimetric method. N-Acyl homoserine lactone functional groups were identified by Fourier Transform-Infrared Spectroscopy (FT-IR). Results: The biofilm formation assay identified 10 (28.57%) isolates with strong, 16 (45.71%) with moderate, and 9 (25.71%) with weak biofilm activities. The UPEC isolates with strong and weak biofilm activities were subjected to AHL analyses. It was found that isolates with the highest AHL activities also exhibited strong adherence to microplate wells (P≤0.05). Two E. coli isolates with the highest AHL activities were selected for FT-IR spectroscopy. Peaks at 1764.33, 1377.99, and 1242.90 cm-1 correspond to the C=O bond of the lactone ring, and the N=H and C-O bonds of the acyl chain, respectively. Conclusion:We found that many UPEC isolates exhibited strong biofilm formation. The control of this property by AHL may contribute to the pathogenesis of the organism in UTI’s.
A chemosensor to recognize N-acyl homoserine lactone in bacterial biofilm
Sensors and Actuators B: Chemical, 2018
A simple, sensitive, and rapid assay has been developed for detection of N-acyl homoserine lactone (HSL) autoinducers involved in bacterial quorum sensing (QS) by a new coumarin appended rhodamine derivative (RNC) ensembled with Cu 2+. RNC-Cu 2+ conjugate shows "turn on" fluorescence while binding with HSLs. The interaction of ensemble with HSL is found to be 1:1 stoichiometry on the basis of absorption and fluorescence titrations with the detection limit of 2.4 M at neutral pH. NMR, IR titrations and DFT calculations were performed in order to demonstrate the sensing mechanism and the electronic properties of the receptor-donor complex. The present chemosensor improves upon any previous biosensor-based approaches to selectively quantitate HSL, both in cell-free and in whole-cell assay system.
Bacterial biofilms: role of quorum sensing and quorum quenching
Journal of Experimental Biology and Agricultural Sciences
Bacterial biofilms provide an adjustable strategy to manage themselves in the existing conditions. Biofilms of pathogenic bacteria act as a reservoir for various device and non-device related diseases which are tough to cure. Exposure to a high dose of antibiotics is not an appropriate solution to this problem as high antibiotic concentrations lead to the generation of Multi-drug resistant strains as well as affect the human body. So, it is needed to bypass the use of antibiotics to prevent bacterial biofilms. In this context, Quorum Sensing (QS) may be a potential target since biofilm formation is regulated by QS. N-acyl homoserine lactones (N-AHL) act as predominant QS signal molecules in Gram-negative bacteria. Counteraction of the QS-regulated activities using quorum quenching may be an alternative way to combat biofilm formation in bacteria. Quorum sensing inhibitors (QSIs) and QQ enzymes play a significant role in this regard either by interference with the signal generation, ...