Rhamnolipids Modulate Swarming Motility Patterns of<i>Pseudomonas aeruginosa</i>

Caiazza, Nicky C.; Shanks, Robert M. Q.; O’Toole, George A.

doi:10.1128/jb.187.21.7351-7361.2005

Cited by 404 publications

(489 citation statements)

References 54 publications

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“…Recently, it has been suggested that the precursor of rhamnolipids, 3-(3-hydroxyalkanoyloxy)alkanoic acid, is required for surface wettability and rhamnolipids for modulating Ps. aeruginosa swarming behavior (29,31). Our results add a class of biosurfactant molecules to this list.…”

Section: Oh-(slc)-hsl Produced By Cini In R Etli Decreases Viscosmentioning

confidence: 99%

Quorum signal molecules as biosurfactants affecting swarming in Rhizobium etli

Daniels

Reynaert

Hoekstra

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

140

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Swarming motility is suggested to be a social phenomenon that enables groups of bacteria to coordinately and rapidly move atop solid surfaces. This multicellular behavior, during which the apparently organized bacterial populations are embedded in an extracellular slime layer, has previously been linked with biofilm formation and virulence. Many population density-controlled activities involve the activation of complex signaling pathways using small diffusible molecules, also known as autoinducers. In Gramnegative bacteria, quorum sensing (QS) is achieved primarily by means of N-acylhomoserine lactones (AHLs). Here, we report on a dual function of AHL molecules in controlling swarming behavior of Rhizobium etli, the bacterial symbiotic partner of the common bean plant. The major swarming regulator of R. etli is the cinIR QS system, which is specifically activated in swarming cells by its cognate AHL and other long-chain AHLs. This signaling role of long-chain AHLs is required for high-level expression of the cin and rai QS systems. Besides this signaling function, the long-chain AHLs also have a direct role in surface movement of swarmer cells as these molecules possess significant surface activity and induce liquid flows, known as Marangoni flows, as a result of gradients in surface tension at biologically relevant concentrations. These results point to an as-yet-undisclosed direct role of long-chain AHL molecules as biosurfactants.cell-cell signaling ͉ motility ͉ quorum sensing

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Section: Oh-(slc)-hsl Produced By Cini In R Etli Decreases Viscosmentioning

confidence: 99%

Quorum signal molecules as biosurfactants affecting swarming in Rhizobium etli

Daniels

Reynaert

Hoekstra

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

140

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“…Swarming is dependent on the combination of the polar flagellum, type IV pili and rhamnolipid production (Caiazza et al, 2005;Kohler et al, 2000). This type of motility is almost completely absent in the oxyR mutant grown on CAA medium (Fig.…”

Section: Oxyr Is Required For Swarming Motility and Rhamnolipid Produmentioning

confidence: 99%

The Pseudomonas aeruginosa oxidative stress regulator OxyR influences production of pyocyanin and rhamnolipids: protective role of pyocyanin

et al. 2010

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The LysR-type transcriptional regulator (LTTR) OxyR orchestrates the defence of the opportunistic pathogen Pseudomonas aeruginosa against reactive oxygen species. In previous work we also demonstrated that OxyR is needed for the utilization of the ferrisiderophore pyoverdine, stressing the importance of this regulator. Here, we show that an oxyR mutant is unable to swarm on agar plates, probably as a consequence of absence of production of rhamnolipid surfactant molecules. Another obvious phenotypic change was the increased production of the phenazine redox-active molecule pyocyanin in the oxyR mutant. As already described, the oxyR mutant could not grow in LB medium, unless high numbers of cells (>108 ml−1) were inoculated. However, its growth in Pseudomonas P agar (King's A), a medium inducing pyocyanin production, was like that of the wild-type, suggesting a protective action of this redox-active phenazine compound. This was confirmed by the restoration of the capacity to grow in LB medium upon addition of pure pyocyanin. Although both rhamnolipid and pyocyanin production are controlled by quorum sensing, no obvious changes were observed in the production of N-acylhomoserine lactones or the Pseudomonas quinolone signal (PQS). Complementation of rhamnolipid production and motility, and restoration of normal pyocyanin levels, was only possible when the oxyR gene was in single copy, while pyocyanin levels were increased when oxyR was present in a multicopy vector. Conversely, plating efficiency was increased only when the oxyR gene was present in multicopy, but not when in single copy in the chromosome, due to lower expression of oxyR compared with the wild-type, suggesting that some phenotypes are differently affected in function to the levels of OxyR molecules in the cell. Analysis of transcripts of oxidative stress-response enzymes showed a strong decrease of katB, ahpC and ahpB expression in the oxyR mutant grown in LB, but this was not the case when the mutant was grown on P agar, suggesting that the OxyR dependency for the transcription of these genes is not total.

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“…The CSF samples were taken from different individuals than those who provided the serum samples. The average age of AD patients was 75 years (56-85), of MCI patients 70 years , and of controls 73.3 years (68)(69)(70)(71)(72)(73)(74)(75)(76)(77)(78)(79)(80)(81). Each sample was assayed in duplicate.…”

Section: The Elisa Methods For Rls Immunodetection In Csf From Ad Patimentioning

confidence: 99%

Rhamnolipids, Microbial Virulence Factors, in Alzheimer’s Disease

Andreadou

Pantazaki

Daniilidou

et al. 2017

JAD

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Abstract. Alzheimer's disease (AD) has been attributed to chronic bacterial infections. The recognition of human microbiota as a substantial contributor to health and disease is relatively recent and growing. During evolution, mammals live in a symbiotic state with myriads of microorganisms that survive at a diversity of tissue micro-surroundings. Microbes produce a plethora of secretory products [amyloids, lipopolysaccharides, virulence factors rhamnolipids (RLs), toxins, and a great number of neuroactive compounds]. The contribution of infectious microbial components to the pathophysiology of the human central nervous system including AD is considered potentially substantial, but the involvement of the RLs has never been reported. Here, RLs were isolated from serum and identified through various conventional methods including the colorimetric orcinol method, thin-layer chromatography, attenuated total reflection Fourier transform infrared (ATR-FTIR), and dot blot using antibodies against RLs. Dot blot demonstrated elevated RL levels in sera of AD patients compared to controls (p = 0.014). Moreover, ELISA showed similarly elevated RL levels in cerebrospinal fluid of both AD (0.188 versus 0.080) (p = 0.04) and mild cognitive impairment (0.188 versus 0.129) (p = 0.088) patients compared to healthy, and are wellcorrelated with the AD stages severity assessed using the Mini-Mental State Examination. These results provide conclusive evidence for the newly-reported implication of RLs in AD, adding it to the list of bacterial components, opening new avenues for AD investigation. Moreover, they strengthen and vindicate the divergence of research toward the exploration of bacterial involvement in AD generation and progression.

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Rhamnolipids Modulate Swarming Motility Patterns ofPseudomonas aeruginosa

Cited by 404 publications

References 54 publications

Quorum signal molecules as biosurfactants affecting swarming in Rhizobium etli

Quorum signal molecules as biosurfactants affecting swarming in Rhizobium etli

The Pseudomonas aeruginosa oxidative stress regulator OxyR influences production of pyocyanin and rhamnolipids: protective role of pyocyanin

Rhamnolipids, Microbial Virulence Factors, in Alzheimer’s Disease

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