Osmotic stress and phosphate limitation alter production of cell-to-cell signal molecules and rhamnolipid biosurfactant by Pseudomonas aeruginosa

Bazire, Alexis; Dheilly, Alexandra; Diab, Farès; Morin, Danièle; Jebbar, Mohamed; Haras, Dominique; Dufour, Alain

doi:10.1016/j.femsle.2005.09.029

Cited by 50 publications

(47 citation statements)

References 26 publications

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“…A 2 4 full factorial experimental design was used, with three central points to determine error, made up of 19 experiments ( Table 1). The factors studied were select based on the literature [4,[24][25][26][27][28]. The minimum and maximum ranges of the variables investigated and the full experimental plan with respect to their values are listed in Table 1.…”

Section: Effect Of Variables On Surface Tensionmentioning

confidence: 99%

Biosurfactant production by Pseudomonas aeruginosa MSIC02 in cashew apple juice using a 24 full factorial experimental design

Rocha

Mendes

Giro

et al. 2014

CI&CEQ

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In this work, the production of biosurfactants from cashew apple juice by Pseudomonas aeruginosa MSIC02 was investigated by carrying out a 2 4 full factorial experimental design, using temperature, glucose concentration from cashew apple juice, phosphorous concentration and cultivation time as variables. The response variable was the percentage of reduction in surface tension in the cell-free culture medium, since it indicates the surface-active agent production. Maximum biosurfactant production, equivalent to a 58% reduction in surface tension, was obtained at 37 °C, with glucose concentration of 5.0 g/L and no phosphorous supplementation. Surface tension reduction was significant, since low values were observed in the cell-free medium (27.50 dyn/cm), indicating that biosurfactant was produced. The biosurfactant emulsified different hydrophobic sources and showed stability in the face of salinity, exposure to high temperatures and extreme pH conditions. These physiochemical properties demonstrate the potential for using biosurfactants produced by P. aeruginosa MSIC02 in various applications.

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Section: Effect Of Variables On Surface Tensionmentioning

confidence: 99%

Biosurfactant production by Pseudomonas aeruginosa MSIC02 in cashew apple juice using a 24 full factorial experimental design

Rocha

Mendes

Giro

et al. 2014

CI&CEQ

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“…PQS is also produced in the absence of a functional las system (14), and, unlike the other two signals, PQS is not produced maximally until the stationary phase of growth (13). Furthermore, each signaling system can also be affected by environmental conditions, such as the availability of nutrients like iron, phosphate, and certain amino acids (16,(19)(20)(21)(22). The interplay between these systems allows P. aeruginosa to integrate information from multiple signals and alter gene expression accordingly.…”

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confidence: 99%

CysB Negatively Affects the Transcription of pqsR and Pseudomonas Quinolone Signal Production in Pseudomonas aeruginosa

et al. 2015

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Pseudomonas aeruginosa is a Gram-negative bacterium that is ubiquitous in the environment, and it is an opportunistic pathogen that can infect a variety of hosts, including humans. During the process of infection, P. aeruginosa coordinates the expression of numerous virulence factors through the production of multiple cell-to-cell signaling molecules. The production of these signaling molecules is linked through a regulatory network, with the signal N-(3-oxododecanoyl) homoserine lactone and its receptor LasR controlling the induction of a second acyl-homoserine lactone signal and the Pseudomonas quinolone signal (PQS). LasR-mediated control of PQS occurs partly by activating the transcription of pqsR, a gene that encodes the PQS receptor and is necessary for PQS production. We show that LasR interacts with a single binding site in the pqsR promoter region and that it does not influence the transcription of the divergently transcribed gene, nadA. Using DNA affinity chromatography, we identified additional proteins that interact with the pqsR-nadA intergenic region. These include the H-NS family members MvaT and MvaU, and CysB, a transcriptional regulator that controls sulfur uptake and cysteine biosynthesis. We show that CysB interacts with the pqsR promoter and that CysB represses pqsR transcription and PQS production. Additionally, we provide evidence that CysB can interfere with the activation of pqsR transcription by LasR. However, as seen with other CysB-regulated genes, pqsR expression was not differentially regulated in response to cysteine levels. These findings demonstrate a novel role for CysB in influencing cell-to-cell signal production by P. aeruginosa. IMPORTANCEThe production of PQS and other 4-hydroxy-2-alkylquinolone (HAQs) compounds is a key component of the P. aeruginosa cellto-cell signaling network, impacts multiple physiological functions, and is required for virulence. PqsR directly regulates the genes necessary for HAQ production, but little is known about the regulation of pqsR. We identified CysB as a novel regulator of pqsR and PQS production, but, unlike other CysB-controlled genes, it does not appear to regulate pqsR in response to cysteine. This implies that CysB functions as both a cysteine-responsive and cysteine-unresponsive regulator in P. aeruginosa. Pseudomonas aeruginosa is a Gram-negative bacterium that is ubiquitous in the environment, due in part to its metabolic versatility that allows it to obtain the nutrients needed for growth from a wide variety of compounds (1). P. aeruginosa is also an opportunistic pathogen that can infect plants, nematodes, insects, and mammals (2-5). With regard to humans, it can cause a wide range of diseases and is a major cause of health care-associated illnesses and devastating chronic infections in cystic fibrosis patients (6, 7). In order to thrive under such a diverse range of conditions, P. aeruginosa utilizes complex regulatory networks to control gene expression. These networks include global regulatory systems that can direct l...

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“…In P. aeruginosa the impact of the rhl QS on the biosynthesis of the secondary metabolites pyocyanin and rhamnolipids is well documented (42). However, the production of these secondary metabolites also seems to be dependent on environmental cues (3,62). A link between QS and iron homeostasis was suggested previously (5,11,21,24,25,52,60).…”

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confidence: 99%

RhlR Expression inPseudomonas aeruginosaIs Modulated by thePseudomonasQuinolone Signal via PhoB-Dependent and -Independent Pathways

Jensen¹,

Löns²,

Zaoui³

et al. 2006

J Bacteriol

148

147

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The expression of virulence determinants in Pseudomonas aeruginosa is coordinately regulated in response to both the social environment-commonly referred to as quorum sensing-and to environmental cues. In this study we have dissected the various independent regulation levels for pyocyanin production, which is influenced by the homoserine lactone-and Pseudomonas quinolone signal (PQS)-mediated quorum-sensing systems as well as by iron and phosphate availability. We demonstrate that the phosphate regulon is involved in the transcriptional activation of rhlR and the augmentation of PQS and pyocyanin production under phosphate limitation. However, we also observed an enhancement of rhlR transcription under low-iron medium conditions and after the addition of PQS that was independent of the phosphate regulon. These results highlight the complexity of secondary metabolite production in P. aeruginosa via environmental cues and the quorumsensing system.Bacterial organisms that elaborate traits tailored to their surroundings have better chances of surviving the pressures of unfavorable environmental conditions and host defenses. The outstanding capability of Pseudomonas aeruginosa for adaptation is reflected by the large number of putative transcriptional regulators (53), as bacterial differentiation is often controlled by transcription factors whose activity is influenced by local cues. Moreover, it has been recognized that environmental signals (33) as well as the social surrounding control bacterial virulence factor production. Cell-density-dependent gene regulation is commonly referred to as quorum sensing (QS) (20). QS is based on the release of soluble communicator molecules that trigger the transcription of QS-dependent genes when the bacterial population has reached a certain cell density. Many of these genes are involved in bacterial pathogenicity (9,19,39,40,50). Three chemically distinct signal molecules have been identified so far in P. aeruginosa. Two of these are acyl-homoserine lactones (AHL): a butyryl-homoserine lactone and a 3-oxo-dodecanoyl homoserine lactone, which together with their corresponding transcriptional activator proteins (R proteins) comprise the two hierarchically organized QS systems las and rhl (8,27,38,41,44) and control the expression of over 200 genes (23,48,57). The third signal molecule is 2-heptyl-3-hydroxy-4-quinolone (43). This Pseudomonas quinolone signal (PQS) interacts with the las and the rhl systems. While the las system seems to induce the production of PQS, exogenous PQS up-regulates the expression of the rhl system (15, 16, 31). In P. aeruginosa the impact of the rhl QS on the biosynthesis of the secondary metabolites pyocyanin and rhamnolipids is well documented (42). However, the production of these secondary metabolites also seems to be dependent on environmental cues (3,62). A link between QS and iron homeostasis was suggested previously (5,11,21,24,25,52,60). Moreover, PQS was shown to exhibit an iron-chelating activity, and PQS-dependent rhlR induction seems to be ...

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Osmotic stress and phosphate limitation alter production of cell-to-cell signal molecules and rhamnolipid biosurfactant by Pseudomonas aeruginosa

Cited by 50 publications

References 26 publications

Biosurfactant production by Pseudomonas aeruginosa MSIC02 in cashew apple juice using a 24 full factorial experimental design

Biosurfactant production by Pseudomonas aeruginosa MSIC02 in cashew apple juice using a 24 full factorial experimental design

CysB Negatively Affects the Transcription of pqsR and Pseudomonas Quinolone Signal Production in Pseudomonas aeruginosa

RhlR Expression inPseudomonas aeruginosaIs Modulated by thePseudomonasQuinolone Signal via PhoB-Dependent and -Independent Pathways

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