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Leo Eberl - One of the best experts on this subject based on the ideXlab platform.
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Copper resistance genes of Burkholderia cenocepacia H111 identified by transposon sequencing.
Environmental microbiology reports, 2020Co-Authors: Steven Higgins, Marta Pinto-carbó, Stefano Gualdi, Leo EberlAbstract:Copper is an essential element but in excess is highly toxic and therefore cytoplasmic levels must be tightly controlled. Member of the genus Burkholderia are highly resistant to various heavy metals and are often isolated from acidic soils where copper bioavailability is high. In this study, we employed transposon sequencing (Tn-Seq) to identify copper resistance genes in Burkholderia cenocepacia H111. We identified a copper efflux system that shares similarities with the plasmid-based copper detoxification systems found in Escherichia coli and Pseudomonas syringae. We also found that several of the identified resistance determinants are involved in maintaining the integrity of the cell envelope, suggesting that proteins located in the outer membrane and periplasmic space are particularly sensitive to copper stress. Given that several of the resistance genes are required for the repair and turnover of misfolded proteins, we suggest that copper toxicity is caused by protein damage rather than by oxidative stress.
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Ein neues Signalmolekül in Burkholderia cenocepacia
BIOspektrum, 2019Co-Authors: Christian Jenul, Simon Sieber, Karl Gademann, Leo EberlAbstract:Many social behaviours of bacteria are regulated by quorum sensing through the production and perception of structurally diverse signal molecules. The opportunistic pathogen Burkholderia cenocepacia uses classic N-acyl-homoserinlactones and cis-2-unsatturated fatty acids for communication. A recent study has identified an additional signal, valdiazen, which carries an unusual diazenium diolate group. Genomic information suggests that valdiazen-like compounds constitute a new class of signal molecules.
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Key Players and Individualists of Cyclic-di-GMP Signaling in Burkholderia cenocepacia
Frontiers in microbiology, 2019Co-Authors: Anja Richter, Leo Eberl, Angela Suppiger, Nadine Schmid, Mustafa Fazli, Rebecca Shilling, Michael Givskov, Tim Tolker-nielsenAbstract:Burkholderia cenocepacia H111 is an opportunistic pathogen associated with chronic lung infections in cystic fibrosis patients. Biofilm formation, motility and virulence of B. cenocepacia are regulated by the second messenger cyclic di-guanosine monophosphate (c-di-GMP). In the present study, we analyzed the role of all 25 putative c-di-GMP metabolizing proteins of B. cenocepacia H111 with respect to motility, colony morphology, pellicle formation, biofilm formation, and virulence. We found that RpfR is a key regulator of c-di-GMP signaling in B. cenocepacia, affecting a broad spectrum of phenotypes under various environmental conditions. In addition, we identified Bcal2449 as a regulator of B. cenocepacia virulence in Galleria mellonella larvae. While Bcal2449 consists of protein domains that may catalyze both c-di-GMP synthesis and degradation, only the latter was essential for larvae killing, suggesting that a decreased c-di-GMP level mediated by the Bcal2449 protein is required for virulence of B. cenocepacia. Finally, our work suggests that some individual proteins play a role in regulating exclusively motility (CdpA), biofilm formation (Bcam1160) or both (Bcam2836).
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Identification of AHL- and BDSF-Controlled Proteins in Burkholderia cenocepacia by Proteomics
Methods in molecular biology (Clifton N.J.), 2017Co-Authors: Yilei Liu, Gabriella Pessi, Katharina Riedel, Leo EberlAbstract:We used comparative proteome analysis to determine the target genes of the two quorum sensing (QS) circuits in the opportunistic pathogen Burkholderia cenocepacia: the N-acyl homoserine lactone (AHL)-based CepIR system and the BDSF (B urkholderia diffusible signal factor, cis-2-dodecenoic acid)-based RpfFR system. In this book chapter, we focus on the description of the practical procedure we currently use in the laboratory to perform a sensitive GeLC-MS/MS shotgun proteomics experiment; we also briefly describe the downstream bioinformatic data analysis.
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NtrC-dependent control of exopolysaccharide synthesis and motility in Burkholderia cenocepacia H111.
PLOS ONE, 2017Co-Authors: Yilei Liu, Martina Lardi, Alessandro Pedrioli, Leo Eberl, Gabriella PessiAbstract:Burkholderia cenocepacia is a versatile opportunistic pathogen that survives in a wide variety of environments, which can be limited in nutrients such as nitrogen. We have previously shown that the sigma factor σ54 is involved in the control of nitrogen assimilation and virulence in B. cenocepacia H111. In this work, we investigated the role of the σ54 enhancer binding protein NtrC in response to nitrogen limitation and in the pathogenicity of H111. Of 95 alternative nitrogen sources tested the ntrC showed defects in the utilisation of nitrate, urea, L-citrulline, acetamide, DL-lactamide, allantoin and parabanic acid. RNA-Seq and phenotypic analyses of an ntrC mutant strain showed that NtrC positively regulates two important phenotypic traits: exopolysaccharide (EPS) production and motility. However, the ntrC mutant was not attenuated in C. elegans virulence.
Miguel A. Valvano - One of the best experts on this subject based on the ideXlab platform.
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Complete Genome Sequence of Burkholderia cenocepacia K56-2, an Opportunistic Pathogen.
Microbiology resource announcements, 2020Co-Authors: Inmaculada García-romero, Miguel A. ValvanoAbstract:Burkholderia cenocepacia K56-2, an opportunistic bacterium for people with cystic fibrosis (CF), belongs to the Burkholderia cepacia complex (Bcc) and is consistently used as a model pathogen. We describe here the closed genome sequence for this strain, which will help advance research in B. cenocepacia biology and omics studies.
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Interferon-gamma-activated macrophages infected with Burkholderia cenocepacia process and present bacterial antigens to T-cells by class I and II major histocompatibility complex molecules.
Emerging microbes & infections, 2020Co-Authors: Roberto Rosales-reyes, Vianney Ortiz-navarrete, Paola Garza-villafuerte, Daniela Vences-vences, Daniel F. Aubert, Rubi Aca-teutle, Laura C. Bonifaz, Julio Cesar Carrero-sánchez, Alfonso Olivos-garcía, Miguel A. ValvanoAbstract:Burkholderia cenocepacia is an emerging opportunistic pathogen for people with cystic fibrosis and chronic granulomatous disease. Intracellular survival in macrophages within a membrane-bound vacuo...
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Burkholderia cenocepacia Lipopolysaccharide Modification and Flagellin Glycosylation Affect Virulence but Not Innate Immune Recognition in Plants
mBio, 2015Co-Authors: Maryam Khodai-kalaki, Ángel G. Andrade, Yasmine Fathy Mohamed, Miguel A. ValvanoAbstract:ABSTRACT Burkholderia cenocepacia causes opportunistic infections in plants, insects, animals, and humans, suggesting that “virulence” depends on the host and its innate susceptibility to infection. We hypothesized that modifications in key bacterial molecules recognized by the innate immune system modulate host responses to B. cenocepacia. Indeed, modification of lipopolysaccharide (LPS) with 4-amino-4-deoxy-l-arabinose and flagellin glycosylation attenuates B. cenocepacia infection in Arabidopsis thaliana and Galleria mellonella insect larvae. However, B. cenocepacia LPS and flagellin triggered rapid bursts of nitric oxide and reactive oxygen species in A. thaliana leading to activation of the PR-1 defense gene. These responses were drastically reduced in plants with fls2 (flagellin FLS2 host receptor kinase), Atnoa1 (nitric oxide-associated protein 1), and dnd1-1 (reduced production of nitric oxide) null mutations. Together, our results indicate that LPS modification and flagellin glycosylation do not affect recognition by plant receptors but are required for bacteria to establish overt infection. IMPORTANCE Virulence and pathogenicity are properties ascribed to microbes, which actually require careful consideration of the host. Using the term “pathogen” to define a microbe without considering its host has recently been debated, since the microbe9s capacity to establish a niche in a given host is a critical feature associated with infection. Opportunistic bacteria are a perfect example of microbes whose ability to cause disease is intimately related to the host9s ability to recognize and respond to the infection. Here, we use the opportunistic bacterium Burkholderia cenocepacia and the host plant Arabidopsis thaliana to investigate the role of bacterial surface molecules, namely, lipopolysaccharide and flagellin, in contributing to infection and also in eliciting a host response. We reveal that both molecules can be modified by glycosylation, and although the modifications are critical for the bacteria to establish an infection, they do not impact the host9s ability to recognize the pathogen.
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A markerless deletion method for genetic manipulation of Burkholderia cenocepacia and other multidrug-resistant gram-negative bacteria.
Methods in molecular biology (Clifton N.J.), 2014Co-Authors: Daniel F. Aubert, Mohamad A. Hamad, Miguel A. ValvanoAbstract:Genetic manipulation of multidrug-resistant bacteria is often difficult and hinders progress in understanding their physiology and pathogenesis. This book chapter highlights advances in genetic manipulation of Burkholderia cenocepacia, which are also applicable to other members of the Burkholderia cepacia complex and multidrug-resistant gram-negative bacteria of other genera. The method detailed here is based on the I-SceI homing endonuclease system, which can be efficiently used for chromosomal integration, deletion, and genetic replacement. This system creates markerless mutations and insertions without leaving a genetic scar and thus can be reused successively to generate multiple modifications in the same strain.
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Activation of the Pyrin Inflammasome by Intracellular Burkholderia cenocepacia
Journal of immunology (Baltimore Md. : 1950), 2012Co-Authors: Mikhail A. Gavrilin, Miguel A. Valvano, Basant A. Abdulrahman, Daniel F. Aubert, Anwari Akhter, Dalia H. A. Abdelaziz, Mahmoud M. Mostafa, Jaykumar Grandhi, Arwa Abu Khweek, Mark D. WewersAbstract:Burkholderia cenocepacia is an opportunistic pathogen that causes chronic infection and induces progressive respiratory inflammation in cystic fibrosis patients. Recognition of bacteria by mononuclear cells generally results in the activation of caspase-1 and processing of IL-1β, a major proinflammatory cytokine. In this study, we report that human pyrin is required to detect intracellular B. cenocepacia leading to IL-1β processing and release. This inflammatory response involves the host adapter molecule ASC and the bacterial type VI secretion system (T6SS). Human monocytes and THP-1 cells stably expressing either small interfering RNA against pyrin or YFP–pyrin and ASC (YFP–ASC) were infected with B. cenocepacia and analyzed for inflammasome activation. B. cenocepacia efficiently activates the inflammasome and IL-1β release in monocytes and THP-1. Suppression of pyrin levels in monocytes and THP-1 cells reduced caspase-1 activation and IL-1β release in response to B. cenocepacia challenge. In contrast, overexpression of pyrin or ASC induced a robust IL-1β response to B. cenocepacia, which correlated with enhanced host cell death. Inflammasome activation was significantly reduced in cells infected with T6SS-defective mutants of B. cenocepacia, suggesting that the inflammatory reaction is likely induced by an as yet uncharacterized effector(s) of the T6SS. Together, we show for the first time, to our knowledge, that in human mononuclear cells infected with B. cenocepacia, pyrin associates with caspase-1 and ASC forming an inflammasome that upregulates mononuclear cell IL-1β processing and release.
Pamela A. Sokol - One of the best experts on this subject based on the ideXlab platform.
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Quorum sensing systems influence Burkholderia cenocepacia virulence
Future microbiology, 2012Co-Authors: Sujatha Subramoni, Pamela A. SokolAbstract:Burkholderia cepacia complex strains communicate using N-acyl homoserine lactones and BDSF-dependent quorum sensing (QS) systems. Burkholderia cenocepacia QS systems include CepIR, CciIR, CepR2 and BDSF. Analysis of CepR, CciIR, CepR2 and RpfF (BDSF synthase) QS regulons revealed that these QS systems both independently regulate and coregulate many target genes, often in an opposing manner. The role of QS and several QS-regulated genes in virulence has been determined using vertebrate, invertebrate and plant infection models. Virulence phenotypes are strain and model dependent, suggesting that different QS-regulated genes are important depending on the strain and type of infection. QS inhibitors in combination with antibiotics can reduce biofilm formation and virulence in infection models.
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Burkholderia cenocepacia zinc metalloproteases influence resistance to antimicrobial peptides.
Microbiology, 2009Co-Authors: Cora Kooi, Pamela A. SokolAbstract:Burkholderia cenocepacia secretes two zinc-dependent metalloproteases, designated ZmpA and ZmpB. Previously, ZmpA and ZmpB have been shown to cleave several proteins important in host defence. In this study, the ability of ZmpA and ZmpB to digest and inactivate antimicrobial peptides involved in innate immunity was examined. ZmpB but not ZmpA cleaved β-defensin-1. ZmpA but not ZmpB cleaved the cathelicidin LL-37. Both enzymes cleaved elafin and secretory leukocyte inhibitor, which are antimicrobial peptides as well as neutrophil elastase inhibitors. Both ZmpA and ZmpB cleaved protamine, a fish antimicrobial peptide, and a zmpA zmpB mutant was more sensitive to protamine killing than the parental strain. ZmpA or ZmpB cleavage of elafin inactivated its anti-protease activity. The effect of ZmpA and ZmpB on the neutrophil proteases elastase and cathepsin G was also examined but neither enzyme was active against these host proteases. These studies suggest that ZmpA and ZmpB may influence the resistance of B. cenocepacia to host antimicrobial peptides as well as alter the host protease/anti-protease balance in chronic respiratory infections.
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Identification of potential CepR regulated genes using a cep box motif-based search of the Burkholderia cenocepacia genome.
BMC microbiology, 2006Co-Authors: Catherine E. Chambers, Erika I. Lutter, Michelle B. Visser, Peggy P Y Law, Pamela A. SokolAbstract:Background The Burkholderia cenocepacia CepIR quorum sensing system has been shown to positively and negatively regulate genes involved in siderophore production, protease expression, motility, biofilm formation and virulence. In this study, two approaches were used to identify genes regulated by the CepIR quorum sensing system. Transposon mutagenesis was used to create lacZ promoter fusions in a cepI mutant that were screened for differential expression in the presence of N-acylhomoserine lactones. A bioinformatics approach was used to screen the B. cenocepacia J2315 genome for CepR binding site motifs.
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Functional Analysis of the Burkholderia cenocepacia ZmpA Metalloprotease
Journal of bacteriology, 2005Co-Authors: Cora Kooi, C. R. Corbett, Pamela A. SokolAbstract:Burkholderia cenocepacia ZmpA is expressed as a preproenzyme typical of thermolysin-like proteases such as Pseudomonas aeruginosa LasB and Bacillus thermoproteolyticus thermolysin. The zmpA gene was expressed using the pPRO-EXHTa His6 tag expression system, which incorporates a six-His tag at the N-terminal end of the protein, and recombinant ZmpA was purified using Ni-nitrilotriacetic acid affinity chromatography. Upon refolding of the recombinant His6-pre-pro-ZmpA (62 kDa), the fusion protein was autoproteolytically cleaved into 36-kDa (mature ZmpA) and 27-kDa peptides. Site-directed mutagenesis was employed to infer the identity of the active site residues of ZmpA and to confirm that the enzyme undergoes autoproteolytic cleavage. Oligonucleotide mutagenesis was used to replace H465 with G465 or A465, E377 with A377 or D377, or H380 with P380 or A380. Mutagenesis of H465, E377, or H380 resulted in the loss of both autocatalytic activity and proteolytic activity. ZmpA with either substitution in H380 was not detectable in B. cenocepacia cell extracts. The activity of the recombinant ZmpA was inhibited by EDTA and 1,10 phenanthroline, indicating that it is a zinc metalloprotease. ZmpA, however, was not inhibited by phosphoramidon, a classical inhibitor of the thermolysin-like proteases. The refolded mature ZmpA enzyme was proteolytically active against various substrates including hide powder azure, type IV collagen, fibronectin, neutrophil α-1 proteinase inhibitor, α2-macroglobulin, and gamma interferon, suggesting that B. cenocepacia ZmpA may cause direct tissue damage to the host or damage to host tissues through a modulation of the host's immune system.
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Quorum-Sensing Mutations Affect Attachment and Stability of Burkholderia cenocepacia Biofilms
Applied and environmental microbiology, 2005Co-Authors: Kerry L. Tomlin, Pamela A. Sokol, Rebecca J. Malott, Gordon Ramage, Douglas G. Storey, Howard CeriAbstract:Biofilm formation in Burkholderia cenocepacia has been shown to rely in part on acylhomoserine lactone-based quorum sensing. For many other bacterial species, it appears that both the initial adherence and the later stages of biofilm maturation are affected when quorum sensing pathways are inhibited. In this study, we examined the effects of mutations in the cepIR and cciIR quorum-sensing systems of Burkholderia cenocepacia K56-2 with respect to biofilm attachment and antibiotic resistance. We also examined the role of the cepIR system in biofilm stability and structural development. Using the high-throughput MBEC assay system to produce multiple equivalent biofilms, the biomasses of both the cepI and cepR mutant biofilms, measured by crystal violet staining, were less than half of the value observed for the wild-type strain. Attachment was partially restored upon providing functional gene copies via multicopy expression vectors. Surprisingly, neither the cciI mutant nor the double cciI cepI mutant was deficient in attachment, and restoration of the cciI gene resulted in less attachment than for the mutants. Meanwhile, the cciR mutant did show a significant reduction in attachment, as did the cciR cepIR mutant. While there was no change in antibiotic susceptibility with the individual cepIR and cciIR mutants, the cepI cciI mutant biofilms were more sensitive to ciprofloxacin. A significant increase in sensitivity to removal by sodium dodecyl sulfate was seen for the cepI and cepR mutants. Flow cell analysis of the individual cepIR mutant biofilms indicated that they were both structurally and temporally impaired in attachment and development. These results suggest that biofilm structural defects might be present in quorum-sensing mutants of B. cenocepacia that affect the stability and resistance of the adherent cell mass, providing a basis for future studies to design preventative measures against biofilm formation in this species, an important lung pathogen of cystic fibrosis patients.
Tom Coenye - One of the best experts on this subject based on the ideXlab platform.
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low iron induced small rna brrf regulates central metabolism and oxidative stress responses in Burkholderia cenocepacia
bioRxiv, 2019Co-Authors: Andrea Sass, Tom CoenyeAbstract:Abstract BrrF is a Fur-regulated small RNA highly upregulated in Burkholderia cenocepacia under conditions of iron depletion. Its computationally predicted targets include iron-containing enzymes of the tricarboxylic acid (TCA) cycle such as aconitase and succinate dehydrogenase, as well as iron-containing enzymes responsible for the oxidative stress response, such as superoxide dismutase and catalase. Phenotypic and gene expression analysis of BrrF deletion and overexpression mutants show that the regulation of these genes is BrrF-dependent. Expression of acnA, fumA, sdhA and sdhC was downregulated during iron depletion in the wild type strain, but not in a BrrF deletion mutant. TCA cycle genes not predicted as target for BrrF were not affected in the same manner by iron depletion. Likewise, expression of sodB and katB was dowregulated during iron depletion in the wild type strain, but not in a BrrF deletion mutant. BrrF overexpression reduced aconitase and superoxide dismutase activities and increased sensitivity to hydrogen peroxide. All phenotypes and gene expression changes of the BrrF deletion mutant could be complemented by overexpressing BrrF in trans. Overall, BrrF acts as a regulator of central metabolism and oxidative stress response, possibly as an iron-sparing measure to maintain iron homeostasis under conditions of iron starvation. Importance Regulatory small RNAs play an essential role in maintaining cell homeostasis in bacteria in response to environmental stresses such as iron starvation. Prokaryotes generally encode a large number of RNA regulators, yet their identification and characterisation is still in its infancy for most bacterial species. Burkholderia cenocepacia is an opportunistic pathogen with high innate antimicrobial resistance, which can cause the often fatal cepacia syndrome in individuals with cystic fibrosis. In this study we characterise a small RNA which is involved in the response to iron starvation, a condition that pathogenic bacteria are likely to encounter in the host.
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involvement of toxin antitoxin modules in Burkholderia cenocepacia biofilm persistence
Pathogens and Disease, 2014Co-Authors: Heleen Van Acker, H.j.c.f. Nelis, Andrea Sass, Inne Dhondt, Tom CoenyeAbstract:Biofilms are involved in the recalcitrance of infections due to the presence of persister cells. Although the molecular basis of persistence is still largely unknown, toxin-antitoxin modules (TA) are thought to play a role in this process. In this study, we investigated whether TA modules contribute to persistence toward antibiotics in Burkholderia cenocepacia J2315. Sixteen pairs of genes were identified based on their apparent similarity to TA modules. Overexpression of the putative toxins had various effects on growth, persistence, and biofilm formation. Toxins, whose overexpression resulted in growth inhibition, often increased the number of surviving persisters; in contrast, overexpression of putative toxins showing no effects on growth had no positive influence on the number of surviving persisters. Furthermore, the expression of the TA modules was compared between treated and untreated sessile and planktonic wild-type cultures. For 10 toxin-encoding genes, the expression was higher in untreated sessile cells than in untreated planktonic cells. Nine toxin-encoding genes were upregulated after treatment with tobramycin, but none after treatment with ciprofloxacin. These results indicate that most, but not all TA modules contribute to persistence in B. cenocepacia J2315 and that this contribution depends on the mode of growth and the antibiotic used.
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Involvement of toxin–antitoxin modules in Burkholderia cenocepacia biofilm persistence
Pathogens and disease, 2014Co-Authors: Heleen Van Acker, H.j.c.f. Nelis, Andrea Sass, Inne Dhondt, Tom CoenyeAbstract:Biofilms are involved in the recalcitrance of infections due to the presence of persister cells. Although the molecular basis of persistence is still largely unknown, toxin-antitoxin modules (TA) are thought to play a role in this process. In this study, we investigated whether TA modules contribute to persistence toward antibiotics in Burkholderia cenocepacia J2315. Sixteen pairs of genes were identified based on their apparent similarity to TA modules. Overexpression of the putative toxins had various effects on growth, persistence, and biofilm formation. Toxins, whose overexpression resulted in growth inhibition, often increased the number of surviving persisters; in contrast, overexpression of putative toxins showing no effects on growth had no positive influence on the number of surviving persisters. Furthermore, the expression of the TA modules was compared between treated and untreated sessile and planktonic wild-type cultures. For 10 toxin-encoding genes, the expression was higher in untreated sessile cells than in untreated planktonic cells. Nine toxin-encoding genes were upregulated after treatment with tobramycin, but none after treatment with ciprofloxacin. These results indicate that most, but not all TA modules contribute to persistence in B. cenocepacia J2315 and that this contribution depends on the mode of growth and the antibiotic used.
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Antibacterial activity of a lectin-like Burkholderia cenocepacia protein.
MicrobiologyOpen, 2013Co-Authors: Maarten G. K. Ghequire, Tom Coenye, Evelien De Canck, Pierre Wattiau, Iris Van Winge, Remy Loris, René De MotAbstract:Bacteriocins of the LlpA family have previously been characterized in the γ-proteobacteria Pseudomonas and Xanthomonas. These proteins are composed of two MMBL (monocot mannose-binding lectin) domains, a module predominantly and abundantly found in lectins from monocot plants. Genes encoding four different types of LlpA-like proteins were identified in genomes from strains belonging to the Burkholderia cepacia complex (Bcc) and the Burkholderia pseudomallei group. A selected recombinant LlpA-like protein from the human isolate Burkholderia cenocepacia AU1054 displayed narrow-spectrum genus-specific antibacterial activity, thus representing the first functionally characterized bacteriocin within this β-proteobacterial genus. Strain-specific killing was confined to other members of the Bcc, with mostly Burkholderia ambifaria strains being susceptible. In addition to killing planktonic cells, this bacteriocin also acted as an antibiofilm agent.
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Evaluation of the efficacy of disinfection procedures against Burkholderia cenocepacia biofilms
Journal of Hospital Infection, 2008Co-Authors: Elke Peeters, H.j.c.f. Nelis, Tom CoenyeAbstract:In the present study we evaluated the efficacy of various procedures recommended for the disinfection of respiratory equipment and other materials in cystic fibrosis, using both planktonic and sessile Burkholderia cenocepacia cells. A modified European Suspension Test was performed to determine the effects of the disinfection procedures on planktonic cells. The ability of the treatments to kill sessile cells and to remove biofilm biomass was evaluated using two resazurin-based viability assays and a crystal violet staining on biofilms grown and treated in 96-well microtitre plates. The effect of chlorhexidine and hydrogen peroxide treatments on the viability of sessile B. cenocepacia cells was clearly reduced compared to the effects on planktonic cells. Treatments with low concentrations of sodium hypochlorite (0.05%, 5 min) and acetic acid (1.25%, 15 min) also resulted in insufficient reductions in the number of viable sessile cells. There was no relation between the ability of the disinfectants to remove biofilm biomass and their potential to kill biofilm cells. In conclusion, our study indicates that testing of the efficacy of disinfectants should be performed on both planktonic and sessile cells, with particular attention to their effects on cellular viability.
Gabriella Pessi - One of the best experts on this subject based on the ideXlab platform.
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Identification of AHL- and BDSF-Controlled Proteins in Burkholderia cenocepacia by Proteomics
Methods in molecular biology (Clifton N.J.), 2017Co-Authors: Yilei Liu, Gabriella Pessi, Katharina Riedel, Leo EberlAbstract:We used comparative proteome analysis to determine the target genes of the two quorum sensing (QS) circuits in the opportunistic pathogen Burkholderia cenocepacia: the N-acyl homoserine lactone (AHL)-based CepIR system and the BDSF (B urkholderia diffusible signal factor, cis-2-dodecenoic acid)-based RpfFR system. In this book chapter, we focus on the description of the practical procedure we currently use in the laboratory to perform a sensitive GeLC-MS/MS shotgun proteomics experiment; we also briefly describe the downstream bioinformatic data analysis.
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NtrC-dependent control of exopolysaccharide synthesis and motility in Burkholderia cenocepacia H111.
PLOS ONE, 2017Co-Authors: Yilei Liu, Martina Lardi, Alessandro Pedrioli, Leo Eberl, Gabriella PessiAbstract:Burkholderia cenocepacia is a versatile opportunistic pathogen that survives in a wide variety of environments, which can be limited in nutrients such as nitrogen. We have previously shown that the sigma factor σ54 is involved in the control of nitrogen assimilation and virulence in B. cenocepacia H111. In this work, we investigated the role of the σ54 enhancer binding protein NtrC in response to nitrogen limitation and in the pathogenicity of H111. Of 95 alternative nitrogen sources tested the ntrC showed defects in the utilisation of nitrate, urea, L-citrulline, acetamide, DL-lactamide, allantoin and parabanic acid. RNA-Seq and phenotypic analyses of an ntrC mutant strain showed that NtrC positively regulates two important phenotypic traits: exopolysaccharide (EPS) production and motility. However, the ntrC mutant was not attenuated in C. elegans virulence.
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σ54-Dependent Response to Nitrogen Limitation and Virulence in Burkholderia cenocepacia Strain H111
Applied and environmental microbiology, 2015Co-Authors: Martina Lardi, Alessandro Pedrioli, Leo Eberl, Angela Suppiger, Claudio Aguilar, Ulrich Omasits, Gerardo Cárcamo-oyarce, Nadine Schmid, Christian H. Ahrens, Gabriella PessiAbstract:Members of the genus Burkholderia are versatile bacteria capable of colonizing highly diverse environmental niches. In this study, we investigated the global response of the opportunistic pathogen Burkholderia cenocepacia H111 to nitrogen limitation at the transcript and protein expression levels. In addition to a classical response to nitrogen starvation, including the activation of glutamine synthetase, PII proteins, and the two-component regulatory system NtrBC, B. cenocepacia H111 also upregulated polyhydroxybutyrate (PHB) accumulation and exopolysaccharide (EPS) production in response to nitrogen shortage. A search for consensus sequences in promoter regions of nitrogen-responsive genes identified a σ54 consensus sequence. The mapping of the σ54 regulon as well as the characterization of a σ54 mutant suggests an important role of σ54 not only in control of nitrogen metabolism but also in the virulence of this organism.
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Genome Sequence of Burkholderia cenocepacia H111, a Cystic Fibrosis Airway Isolate
Genome Announcements, 2014Co-Authors: Aurélien Carlier, Gabriella Pessi, Christian Jenul, Kirsty Agnoli, Angela Suppiger, Nadine Schmidt, Burkhard Tümmler, Marta Pinto-carbó, Leo EberlAbstract:The Burkholderia cepacia complex (BCC) is a group of related bacterial species that are commonly isolated from environmental samples. Members of the BCC can cause respiratory infections in cystic fibrosis patients and immunocompromised individuals. We report here the genome sequence of Burkholderia cenocepacia H111, a well-studied model strain of the BCC.
