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Quorum Sensing and Essential Oils
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Isabel Charlotte Soede, Gerhard Buchbauer
Research showed that antagonists of natural AHLs can reduce the pathogenicity by means of confirmation-modification of CviR of C. violaceum on the nematode Caenorhabditis elegans, allowing the presumption that QSI may also reduce virulence in of C. violaceum in human infections. One well-studied gene product controlled by QS in C. violaceum is the purple pigment violacein. The violacein gene cluster consists out of four genes: vioABCD, whereas the vioA promotor is directly controlled by CviR. To detect QS inhibition, different strains of C. violaceum are being used; they are listed in the “Materials and Methods” section (Mcclean et al., 1997; August et al., 2000).
Molecular docking, quorum quenching effect, antibiofilm activity and safety profile of silver-complexed sulfonamide on Pseudomonas aeruginosa
Published in Biofouling, 2021
Fallon dos Santos Siqueira, Camilla Filippi dos Santos Alves, Alencar Kolinski Machado, Josiéli Demétrio Siqueira, Thiago dos Santos, Caren Rigon Mizdal, Kelly Schneider Moreira, Diogo Teixeira Carvalho, Pauline Codernonsi Bonez, Carolina Gonzalez Urquhart, Roberto Christ Vianna Santos, Michele Rorato Sagrillo, Lenice de Lourenço Marques, Davi Fernando Back, Marli Matiko Anraku de Campos
Inhibition of QS was evaluated according to Burt et al. (2014), with some modifications. The production of violacein, the violet pigment produced by Chromobacterium violaceum (ATCC 12472), was quantitatively determined as a result of QS activity. Initially, the MIC for the microorganism was determined. Then, 1 ml of the subinhibitory concentration of the silver-complexed sulfonamide was added to portions of 2 ml C. violaceum brain heart infusion (BHI) inoculated (adjusted to OD 600 nm) and incubated for 24 h. After incubation, a 2 ml sample was centrifuged for 5 min at 3,000 rpm, and the supernatant was discarded. After discarding the violacein, the pellet was resuspended in 150 µl of BHI, to which 150 µl of 10% sodium dodecyl sulfate (SDS) were added to lyse the bacteria. After 5 min at room temperature, 675 µl of water-saturated n-butanol were added, and the mixture vortexed to dissolve the violacein and centrifuged for 5 min at 13,000 g. The supernatant was transferred to a 96-well plate, and the OD was measured at 540 nm on a plate reader. A blank reading (sterile BHI) was subtracted from the measurements. The assay was performed in triplicate for each concentration of the compound evaluated. The absorbances obtained in the wells treated with the compound were compared with the absorbance of the positive control.
Inhibitory effect of norharmane on Serratia marcescens NJ01 quorum sensing-mediated virulence factors and biofilm formation
Published in Biofouling, 2021
Huai-Zhi Luo, Jin-Wei Zhou, Bing Sun, Huan Jiang, Shi Tang, Ai-Qun Jia
C. violaceum ATCC 12472 and C. violaceum CV026 were used as two biomarker strains for the screening of QSIs (Sybiya Vasantha Packiavathy et al. 2012). The ILEE was subjected to qualitative analysis to determine the QSI against C. violaceum ATCC 12472. C. violaceum ATCC 12472 was cultivated in the presence or absence of ILEE (0.5, 1.0, 1.5 and 2.0 mg ml−1) at 28 °C and 180 rpm for 24 h in 96-well microplate. The quantitative analysis of violacein was performed with C. violaceum CV026. In this analysis, C. violaceum CV026 was cultivated with 10 μM C6-HSL and ILEE at different concentrations (0.5, 1.0, 1.5 and 2.0 mg ml−1) at 28 °C and 180 rpm for 24 h. The same amount of DMSO was added as the negative control. Then 1 ml of each culture was centrifuged at 13,800 × g for 5 min to remove the supernatant. Cell pellets were resuspended with the same volume of DMSO and re-centrifuged. The supernatant was determined at 585 nm using a microplate reader.
Aspergillus ochraceopetaliformis SSP13 modulates quorum sensing regulated virulence and biofilm formation in Pseudomonas aeruginosa PAO1
Published in Biofouling, 2018
Subhaswaraj Pattnaik, Tanveer Ahmed, Sampath Kumar Ranganathan, Dinakara Rao Ampasala, V. Venkateswara Sarma, Siddharha Busi
From the MIC determination, it was observed that at the concentration of 1,000 μg ml−1 and beyond that no turbidity was observed. Hence, 1,000 μg ml−1 was used as the MIC and three sub-MIC concentrations (250, 500, and 750 μg ml−1) were used for further studies. In the present study, the quantitative violacein inhibition assay was performed as a preliminary assay to assess the anti-QS property of A. ochraceopetaliformis SSP13 extract against C. violaceum as a biomarker strain. A. ochraceopetaliformis SSP13 extract significantly inhibited the production of violacein by C. violaceum compared to the control with 75.99 ± 1.4, 84.01 ± 2.62, and 94.00 ± 4.07% inhibition at 250, 500, and 750 μg ml−1, respectively (Figure 1a). The production of violacein was significantly reduced with a concomitant increase in sub-MIC levels of A. ochraceopetaliformis SSP13 extract. The present result is in accordance with a previous report where concentration dependent violacein inhibition was observed (Vasavi et al. 2016). Pyocyanin, an important virulence factor produced by P. aeruginosa PAO1 imparts severe oxidative damage to the lungs and impairment of ciliary functions in the host. The sub-MIC concentrations of A. ochraceopetaliformis SSP13 extract significantly inhibited the production of pyocyanin as compared to the control with 67.98 ± 5.47, 81.14 ± 3.62, and 87.69 ± 5.02% inhibition at 250, 500, and 750 μg ml−1, respectively (Figure 1a). Such inhibition is significantly higher than the levels reported in previous studies (O’Brien and Fothergill 2017; Zhou et al. 2017).