scholarly journals Integrated Regulation of Acetoin Fermentation by Quorum Sensing and pH in Serratia plymuthica RVH1

2011 ◽  
Vol 77 (10) ◽  
pp. 3422-3427 ◽  
Author(s):  
Pieter Moons ◽  
Rob Van Houdt ◽  
Bram Vivijs ◽  
Chris M. Michiels ◽  
Abram Aertsen
Keyword(s):  
Quorum Sensing ◽  
Bacterial Species ◽  
Homoserine Lactone ◽  
Positive Control ◽  
Negative Control ◽  
Serratia Plymuthica ◽  
Content Type ◽  
Environmental Signals ◽  
Mixed Acid ◽  
External Stimuli

ABSTRACTDuring fermentation of sugars, a number of bacterial species are able to switch from mixed acid production to acetoin and 2,3-butanediol production in order to avoid lethal acidification of their environment, although the regulation of this switch is only poorly understood. In this study, we report the identification of thebudABstructural operon, involved in acetoin production inSerratia plymuthicaRVH1, and its activation by a LysR-type regulator encoded bybudR, immediately upstream of this operon. In addition, the regulation ofbudRtranscription was elucidated and found to be subject to negative control by BudR itself and to positive control by external stimuli such asN-(3-oxohexanoyl)-l-homoserine lactone (OHHL) quorum sensing signaling molecules and acetate. Interestingly, however, we observed that induction ofbudRtranscription by OHHL or acetate did not require BudR, indicating the involvement of additional regulatory factors in relaying these environmental signals to thebudRpromoter.

scholarly journals Quorum Sensing in a Methane-Oxidizing Bacterium

2016 ◽  
Vol 199 (5) ◽  
Author(s):  
Aaron W. Puri ◽  
Amy L. Schaefer ◽  
Yanfen Fu ◽  
David A. C. Beck ◽  
E. Peter Greenberg ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Greenhouse Gas ◽  
Bacterial Species ◽  
Homoserine Lactone ◽  
Sole Source ◽  
Biosynthetic Gene Cluster ◽  
Freshwater Ecosystems ◽  
Dependent Manner ◽  
Content Type ◽  
Methane Oxidizer

ABSTRACT Aerobic methanotrophic bacteria use methane as their sole source of carbon and energy and serve as a major sink for the potent greenhouse gas methane in freshwater ecosystems. Dissecting the molecular details of how these organisms interact in the environment may increase our understanding of how they perform this important ecological role. Many bacterial species use quorum sensing (QS) systems to regulate gene expression in a cell density-dependent manner. We have identified a QS system in the genome of Methylobacter tundripaludum, a dominant methane oxidizer in methane enrichments of sediment from Lake Washington (Seattle, WA). We determined that M. tundripaludum produces primarily N-3-hydroxydecanoyl-l-homoserine lactone (3-OH-C10-HSL) and that its production is governed by a positive feedback loop. We then further characterized this system by determining which genes are regulated by QS in this methane oxidizer using transcriptome sequencing (RNA-seq) and discovered that this system regulates the expression of a putative nonribosomal peptide synthetase biosynthetic gene cluster. Finally, we detected an extracellular factor that is produced by M. tundripaludum in a QS-dependent manner. These results identify and characterize a mode of cellular communication in an aerobic methane-oxidizing bacterium. IMPORTANCE Aerobic methanotrophs are critical for sequestering carbon from the potent greenhouse gas methane in the environment, yet the mechanistic details of chemical interactions in methane-oxidizing bacterial communities are not well understood. Understanding these interactions is important in order to maintain, and potentially optimize, the functional potential of the bacteria that perform this vital ecosystem function. In this work, we identify a quorum sensing system in the aerobic methanotroph Methylobacter tundripaludum and use both chemical and genetic methods to characterize this system at the molecular level.

scholarly journals Signal Integration in Quorum Sensing Enables Cross-Species Induction of Virulence in Pectobacterium wasabiae

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Rita S. Valente ◽  
Pol Nadal-Jimenez ◽  
André F. P. Carvalho ◽  
Filipe J. D. Vieira ◽  
Karina B. Xavier
Keyword(s):  
Signal Transduction ◽  
Quorum Sensing ◽  
Plant Pathogen ◽  
Bacterial Species ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Interspecies Interactions ◽  
Major Factors

ABSTRACT Bacterial communities can sense their neighbors, regulating group behaviors in response to cell density and environmental changes. The diversity of signaling networks in a single species has been postulated to allow custom responses to different stimuli; however, little is known about how multiple signals are integrated and the implications of this integration in different ecological contexts. In the plant pathogen Pectobacterium wasabiae (formerly Erwinia carotovora), two signaling networks—the N-acyl homoserine lactone (AHL) quorum-sensing system and the Gac/Rsm signal transduction pathway—control the expression of secreted plant cell wall-degrading enzymes, its major virulence determinants. We show that the AHL system controls the Gac/Rsm system by affecting the expression of the regulatory RNA RsmB. This regulation is mediated by ExpR2, the quorum-sensing receptor that responds to the P. wasabiae cognate AHL but also to AHLs produced by other bacterial species. As a consequence, this level of regulation allows P. wasabiae to bypass the Gac-dependent regulation of RsmB in the presence of exogenous AHLs or AHL-producing bacteria. We provide in vivo evidence that this pivotal role of RsmB in signal transduction is important for the ability of P. wasabiae to induce virulence in response to other AHL-producing bacteria in multispecies plant lesions. Our results suggest that the signaling architecture in P. wasabiae was coopted to prime the bacteria to eavesdrop on other bacteria and quickly join the efforts of other species, which are already exploiting host resources. IMPORTANCE Quorum-sensing mechanisms enable bacteria to communicate through small signal molecules and coordinate group behaviors. Often, bacteria have various quorum-sensing receptors and integrate information with other signal transduction pathways, presumably allowing them to respond to different ecological contexts. The plant pathogen Pectobacterium wasabiae has two N-acyl homoserine lactone receptors with apparently the same regulatory functions. Our work revealed that the receptor with the broadest signal specificity is also responsible for establishing the link between the main signaling pathways regulating virulence in P. wasabiae. This link is essential to provide P. wasabiae with the ability to induce virulence earlier in response to higher densities of other bacterial species. We further present in vivo evidence that this novel regulatory link enables P. wasabiae to join related bacteria in the effort to degrade host tissue in multispecies plant lesions. Our work provides support for the hypothesis that interspecies interactions are among the major factors influencing the network architectures observed in bacterial quorum-sensing pathways. IMPORTANCE Quorum-sensing mechanisms enable bacteria to communicate through small signal molecules and coordinate group behaviors. Often, bacteria have various quorum-sensing receptors and integrate information with other signal transduction pathways, presumably allowing them to respond to different ecological contexts. The plant pathogen Pectobacterium wasabiae has two N-acyl homoserine lactone receptors with apparently the same regulatory functions. Our work revealed that the receptor with the broadest signal specificity is also responsible for establishing the link between the main signaling pathways regulating virulence in P. wasabiae. This link is essential to provide P. wasabiae with the ability to induce virulence earlier in response to higher densities of other bacterial species. We further present in vivo evidence that this novel regulatory link enables P. wasabiae to join related bacteria in the effort to degrade host tissue in multispecies plant lesions. Our work provides support for the hypothesis that interspecies interactions are among the major factors influencing the network architectures observed in bacterial quorum-sensing pathways.

scholarly journals LuxR- and LuxI-Type Quorum-Sensing Circuits Are Prevalent in Members of the Populus deltoides Microbiome

2013 ◽  
Vol 79 (18) ◽  
pp. 5745-5752 ◽  
Author(s):  
Amy L. Schaefer ◽  
Colin R. Lappala ◽  
Ryan P. Morlen ◽  
Dale A. Pelletier ◽  
Tse-Yuan S. Lu ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Populus Deltoides ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Bacterial Isolates ◽  
Content Type ◽  
Eastern Cottonwood ◽  
Bacterial Signaling ◽  
Signal Production ◽  
Plant Signals

ABSTRACTWe are interested in the root microbiome of the fast-growing Eastern cottonwood tree,Populus deltoides. There is a large bank of bacterial isolates fromP. deltoides, and there are 44 draft genomes of bacterial endophyte and rhizosphere isolates. As a first step in efforts to understand the roles of bacterial communication and plant-bacterial signaling inP. deltoides, we focused on the prevalence of acyl-homoserine lactone (AHL) quorum-sensing-signal production and reception in members of theP. deltoidesmicrobiome. We screened 129 bacterial isolates for AHL production using a broad-spectrum bioassay that responds to many but not all AHLs, and we queried the available genome sequences of microbiome isolates for homologs of AHL synthase and receptor genes. AHL signal production was detected in 40% of 129 strains tested. Positive isolates included members of theAlpha-,Beta-, andGammaproteobacteria. Members of theluxIfamily of AHL synthases were identified in 18 of 39 proteobacterial genomes, including genomes of some isolates that tested negative in the bioassay. Members of theluxRfamily of transcription factors, which includes AHL-responsive factors, were more abundant thanluxIhomologs. There were 72 in the 39 proteobacterial genomes. Some of theluxRhomologs appear to be members of a subfamily of LuxRs that respond to as-yet-unknown plant signals rather than bacterial AHLs. Apparently, there is a substantial capacity for AHL cell-to-cell communication in proteobacteria of theP. deltoidesmicrobiota, and there are alsoProteobacteriawith LuxR homologs of the type hypothesized to respond to plant signals or cues.

scholarly journals The Quorum-Sensing Molecules Farnesol/Homoserine Lactone and Dodecanol Operate via Distinct Modes of Action in Candida albicans

2011 ◽  
Vol 10 (8) ◽  
pp. 1034-1042 ◽  
Author(s):  
Rebecca A. Hall ◽  
Kara J. Turner ◽  
James Chaloupka ◽  
Fabien Cottier ◽  
Luisa De Sordi ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Quorum Sensing ◽  
Signaling Pathway ◽  
Homoserine Lactone ◽  
Burkholderia Cenocepacia ◽  
Camp Signaling ◽  
Mammalian Host ◽  
Content Type ◽  
Hyphal Development ◽  
Natural Flora

ABSTRACTLiving as a commensal,Candida albicansmust adapt and respond to environmental cues generated by the mammalian host and by microbes comprising the natural flora. These signals have opposing effects onC. albicans, with host cues promoting the yeast-to-hyphal transition and bacteria-derived quorum-sensing molecules inhibiting hyphal development. Hyphal development is regulated through modulation of the cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway, and it has been postulated that quorum-sensing molecules can affect filamentation by inhibiting the cAMP pathway. Here, we show that both farnesol and 3-oxo-C12-homoserine lactone, a quorum-sensing molecule secreted byPseudomonas aeruginosa, block hyphal development by affecting cAMP signaling; they both directly inhibited the activity of theCandidaadenylyl cyclase, Cyr1p. In contrast, the 12-carbon alcohol dodecanol appeared to modulate hyphal development and the cAMP signaling pathway without directly affecting the activity of Cyr1p. Instead, we show that dodecanol exerted its effects through a mechanism involving theC. albicanshyphal repressor, Sfl1p. Deletion ofSFL1did not affect the response to farnesol but did interfere with the response to dodecanol. Therefore, quorum sensing inC. albicansis mediated via multiple mechanisms of action. Interestingly, our experiments raise the possibility that theBurkholderia cenocepaciadiffusible signal factor, BDSF, also mediates its effects via Sfl1p, suggesting that dodecanol's mode of action, but not farnesol or 3-oxo-C12-homoserine lactone, may be used by other quorum-sensing molecules.

scholarly journals Disruption of Quorum Sensing and Virulence inBurkholderia cenocepaciaby a Structural Analogue of thecis-2-Dodecenoic Acid Signal

2019 ◽  
Vol 85 (8) ◽  
Author(s):  
Chaoyu Cui ◽  
Shihao Song ◽  
Chunxi Yang ◽  
Xiuyun Sun ◽  
Yutong Huang ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Bacterial Infections ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Burkholderia Cenocepacia ◽  
Enoic Acid ◽  
Acyl Homoserine Lactone ◽  
Structural Analogue ◽  
Content Type ◽  
Signal Production

ABSTRACTQuorum sensing (QS) signals are widely used by bacterial pathogens to control biological functions and virulence in response to changes in cell population densities.Burkholderia cenocepaciaemploys a molecular mechanism in which thecis-2-dodecenoic acid (namedBurkholderiadiffusiblesignalfactor [BDSF]) QS system regulatesN-acyl homoserine lactone (AHL) signal production and virulence by modulating intracellular levels of cyclic diguanosine monophosphate (c-di-GMP). Thus, inhibition of BDSF signaling may offer a non-antibiotic-based therapeutic strategy against BDSF-regulated bacterial infections. In this study, we report the synthesis of small-molecule mimics of the BDSF signal and evaluate their ability to inhibit BDSF QS signaling inB. cenocepacia. A novel structural analogue of BDSF, 14-Me-C16:Δ2(cis-14-methylpentadec-2-enoic acid), was observed to inhibit BDSF production and impair BDSF-regulated phenotypes inB. cenocepacia, including motility, biofilm formation, and virulence, while it did not inhibit the growth rate of this pathogen. 14-Me-C16:Δ2also reduced AHL signal production. Genetic and biochemical analyses showed that 14-Me-C16:Δ2inhibited the production of the BDSF and AHL signals by decreasing the expression of their synthase-encoding genes. Notably, 14-Me-C16:Δ2attenuated BDSF-regulated phenotypes in variousBurkholderiaspecies. These findings suggest that 14-Me-C16:Δ2could potentially be developed as a new therapeutic agent against pathogenicBurkholderiaspecies by interfering with their QS signaling.IMPORTANCEBurkholderia cenocepaciais an important opportunistic pathogen which can cause life-threatening infections in susceptible individuals, particularly in cystic fibrosis and immunocompromised patients. It usually employs two types of quorum sensing (QS) systems, including thecis-2-dodecenoic acid (BDSF) system andN-acyl homoserine lactone (AHL) system, to regulate virulence. In this study, we have designed and identified an unsaturated fatty acid compound (cis-14-methylpentadec-2-enoic acid [14-Me-C16:Δ2]) that is capable of interfering withB. cenocepaciaQS signaling and virulence. We demonstrate that 14-Me-C16:Δ2reduced BDSF and AHL signal production inB. cenocepacia. It also impaired QS-regulated phenotypes in variousBurkholderiaspecies. These results suggest that 14-Me-C16:Δ2could interfere with QS signaling in manyBurkholderiaspecies and might be developed as a new antibacterial agent.

scholarly journals The Formation of Streptococcus mutans Persisters Induced by the Quorum-Sensing Peptide Pheromone Is Affected by the LexA Regulator

2015 ◽  
Vol 197 (6) ◽  
pp. 1083-1094 ◽  
Author(s):  
Vincent Leung ◽  
Dragana Ajdic ◽  
Stephanie Koyanagi ◽  
Céline M. Lévesque
Keyword(s):  
Quorum Sensing ◽  
Streptococcus Mutans ◽  
Bacterial Species ◽  
Regulatory System ◽  
Bacterial Survival ◽  
Chronic Infections ◽  
Persister Cells ◽  
Gene Encoding ◽  
Content Type ◽  
Peptide Pheromone

The presence of multidrug-tolerant persister cells within microbial populations has been implicated in the resiliency of bacterial survival against antibiotic treatments and is a major contributing factor in chronic infections. The mechanisms by which these phenotypic variants are formed have been linked to stress response pathways in various bacterial species, but many of these mechanisms remain unclear. We have previously shown that in the cariogenic organismStreptococcus mutans, the quorum-sensing peptide CSP (competence-stimulating peptide) pheromone was a stress-inducible alarmone that triggered an increased formation of multidrug-tolerant persisters. In this study, we characterized SMU.2027, a CSP-inducible gene encoding a LexA ortholog. We showed that in addition to exogenous CSP exposure, stressors, including heat shock, oxidative stress, and ofloxacin antibiotic, were capable of triggering expression oflexAin an autoregulatory manner akin to that of LexA-like transcriptional regulators. We demonstrated the role of LexA and its importance in regulating tolerance toward DNA damage in a noncanonical SOS mechanism. We showed its involvement and regulatory role in the formation of persisters induced by the CSP-ComDE quorum-sensing regulatory system. We further identified key genes involved in sugar and amino acid metabolism, the clustered regularly interspaced short palindromic repeat (CRISPR) system, and autolysin from transcriptomic analyses that contribute to the formation of quorum-sensing-induced persister cells.

scholarly journals Quorum Sensing Influences Burkholderia thailandensis Biofilm Development and Matrix Production

2016 ◽  
Vol 198 (19) ◽  
pp. 2643-2650 ◽  
Author(s):  
Boo Shan Tseng ◽  
Charlotte D. Majerczyk ◽  
Daniel Passos da Silva ◽  
Josephine R. Chandler ◽  
E. Peter Greenberg ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Matrix Material ◽  
Close Relative ◽  
Wild Type ◽  
Flow Conditions ◽  
Burkholderia Thailandensis ◽  
Content Type ◽  
Biofilm Development

ABSTRACTMembers of the genusBurkholderiaare known to be adept at biofilm formation, which presumably assists in the survival of these organisms in the environment and the host. Biofilm formation has been linked to quorum sensing (QS) in several bacterial species. In this study, we characterizedBurkholderia thailandensisbiofilm development under flow conditions and sought to determine whether QS contributes to this process.B. thailandensisbiofilm formation exhibited an unusual pattern: the cells formed small aggregates and then proceeded to produce mature biofilms characterized by “dome” structures filled with biofilm matrix material. We showed that this process was dependent on QS.B. thailandensishas three acyl-homoserine lactone (AHL) QS systems (QS-1, QS-2, and QS-3). An AHL-negative strain produced biofilms consisting of cell aggregates but lacking the matrix-filled dome structures. This phenotype was rescued via exogenous addition of the three AHL signals. Of the threeB. thailandensisQS systems, we show that QS-1 is required for proper biofilm development, since abtaR1mutant, which is defective in QS-1 regulation, forms biofilms without these dome structures. Furthermore, our data show that the wild-type biofilm biomass, as well as the material inside the domes, stains with a fucose-binding lectin. ThebtaR1mutant biofilms, however, are negative for fucose staining. This suggests that the QS-1 system regulates the production of a fucose-containing exopolysaccharide in wild-type biofilms. Finally, we present data showing that QS ability during biofilm development produces a biofilm that is resistant to dispersion under stress conditions.IMPORTANCEThe saprophyteBurkholderia thailandensisis a close relative of the pathogenic bacteriumBurkholderia pseudomallei, the causative agent of melioidosis, which is contracted from its environmental reservoir. Since most bacteria in the environment reside in biofilms,B. thailandensisis an ideal model organism for investigating questions inBurkholderiaphysiology. In this study, we characterizedB. thailandensisbiofilm development and sought to determine if quorum sensing (QS) contributes to this process. Our work shows thatB. thailandensisproduces biofilms with unusual dome structures under flow conditions. Our findings suggest that these dome structures are filled with a QS-regulated, fucose-containing exopolysaccharide that may be involved in the resilience ofB. thailandensisbiofilms against changes in the nutritional environment.

scholarly journals Alginate Oligosaccharide-Induced Modification of the lasI-lasR and rhlI-rhlR Quorum-Sensing Systems in Pseudomonas aeruginosa

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Alison A. Jack ◽  
Saira Khan ◽  
Lydia C. Powell ◽  
Manon F. Pritchard ◽  
Konrad Beck ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Laser Scanning ◽  
Homoserine Lactone ◽  
Laser Scanning Microscopy ◽  
Extracellular Dna ◽  
Mass Spectrometry Analysis ◽  
Confocal Laser ◽  
Steric Interaction ◽  
Content Type

ABSTRACT Pseudomonas aeruginosa plays a major role in many chronic infections. Its ability to readily form biofilms contributes to its success as an opportunistic pathogen and its resistance/tolerance to antimicrobial/antibiotic therapy. A low-molecular-weight alginate oligomer (OligoG CF-5/20) derived from marine algae has previously been shown to impair motility in P. aeruginosa biofilms and disrupt pseudomonal biofilm assembly. As these bacterial phenotypes are regulated by quorum sensing (QS), we hypothesized that OligoG CF-5/20 may induce alterations in QS signaling in P. aeruginosa . QS regulation was studied by using Chromobacterium violaceum CV026 biosensor assays that showed a significant reduction in acyl homoserine lactone (AHL) production following OligoG CF-5/20 treatment (≥2%; P < 0.05). This effect was confirmed by liquid chromatography-mass spectrometry analysis of C 4 -AHL and 3-oxo-C 12 -AHL production (≥2%; P < 0.05). Moreover, quantitative PCR showed that reduced expression of both the las and rhl systems was induced following 24 h of treatment with OligoG CF-5/20 (≥0.2%; P < 0.05). Circular dichroism spectroscopy indicated that these alterations were not due to steric interaction between the AHL and OligoG CF-5/20. Confocal laser scanning microscopy (CLSM) and COMSTAT image analysis demonstrated that OligoG CF-5/20-treated biofilms had a dose-dependent decrease in biomass that was associated with inhibition of extracellular DNA synthesis (≥0.5%; P < 0.05). These changes correlated with alterations in the extracellular production of the pseudomonal virulence factors pyocyanin, rhamnolipids, elastase, and total protease ( P < 0.05). The ability of OligoG CF-5/20 to modify QS signaling in P. aeruginosa PAO1 may influence critical downstream functions such as virulence factor production and biofilm formation.

scholarly journals Antimicrobial Activity of an Amnion-Chorion Membrane to Oral Microbes

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Haroon Ashraf ◽  
Kerri Font ◽  
Charles Powell ◽  
Michael Schurr
Keyword(s):  
Bacterial Species ◽  
Healing Process ◽  
Antimicrobial Properties ◽  
Positive Control ◽  
Negative Control ◽  
Collagen Membrane ◽  
Wound Healing Process ◽  
Bacterial Strains ◽  
Oral Microbes ◽  
Negative Controls

Objective. The aim of this study was to evaluate wound biomodification by assessing antimicrobial properties present within a human-derived composite amnion-chorion membrane (ACM). Methods. Membranes analyzed were the human-derived ACM BioXclude™ and the porcine-derived collagen membrane Bio-Gide®. Paper discs with and without tetracycline served as positive and negative controls, respectively. The same number of colony-forming units per milliliter for each bacterial species (Aggregatibacter actinomycetemcomitans, Streptococcus mutans, and Streptococcus oralis) was inoculated on each of the discs. Discs from each group were removed at 12 and 24 hours and sonicated to remove the bacteria off the membranes. A serial dilution was performed to quantify bacterial growth. Results. The ACM inhibited growth at all time points, with all bacterial strains, identical to the negative control tetracycline discs. The collagen membrane and positive controls did not inhibit growth of any of the bacterial species throughout the 24-hour study period. P<0.05 for microbial growth on ACM or negative control vs. either collagen membrane or positive control. Conclusion. ACM was proven to be as bactericidal as paper discs inoculated with tetracycline at its minimum bactericidal concentration. The ACM bactericidal property may be beneficial in the early wound healing process.

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