Modulation of Arabidopsis thaliana growth by volatile substances emitted by Pseudomonas and Serratia strains.

Many volatile compounds secreted by bacteria play an important role in the interactions of microorganisms, can inhibit the growth of phytopathogenic bacteria and fungi, can suppress or stimulate plant growth and serve as infochemicals presenting a new type of interspecies communication. In this work, we investigated the effect of total pools of volatile substances and individual volatile organic compounds (VOCs) synthesized by the rhizosphere bacteria Pseudomonas chlororaphis 449 and Serratia plymuthica IC1270, the soil-borne strain P. fluorescens B-4117 and the spoiled meat isolate S.

SprI/SprR Quorum Sensing System of 94.

In this study, we investigated the quorum sensing (QS) regulatory system of the psychrotrophic strain 94 isolated from spoiled refrigerated meat. The strain produced several -acyl--homoserine-lactone (AHL) QS signal molecules, with -(3-oxo-hexanoyl)--homoserine lactone and -(3-hydroxy-hexanoyl)--homoserine lactone as two main types. The and genes encoding an AHL synthase and a receptor regulatory protein, respectively, were cloned and sequenced.

Regulation of GacA in Pseudomonas chlororaphis Strains Shows a Niche Specificity.

The GacS/GacA two-component system plays a central role in the regulation of a broad range of biological functions in many bacteria. In the biocontrol organism Pseudomonas chlororaphis, the Gac system has been shown to positively control quorum sensing, biofilm formation, and phenazine production, but has an overall negative impact on motility. These studies have been performed with strains originated from the rhizosphere predominantly.

Successful hematopoietic cell transplantation in a patient with X-linked agammaglobulinemia and acute myeloid leukemia.

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency characterized by marked reduction in all classes of serum immunoglobulins and the near absence of mature CD19(+) B-cells. Although malignancy has been observed in patients with XLA, we present the first reported case of acute myeloid leukemia (AML) in a patient with XLA. We also demonstrate the complete correction of the XLA phenotype following allogeneic hematopoietic cell transplantation for treatment of the patient's leukemia.

Pseudomonas aeruginosa activates the quorum sensing LuxR response regulator through secretion of 2-aminoacetophenone.

In this study we identify a volatile compound produced by Pseudomonas aeruginosa, which can specifically activate the LuxR quorum-sensing response regulator of Vibrio fischeri. Comparative gas-chromatography analysis between P. aeruginosa wild type and a ΔlasR mutant strain implied that the active volatile is 2-aminoacetophenone.

Silencing the mob: disrupting quorum sensing as a means to fight plant disease.

Bacteria are able to sense their population's density through a cell-cell communication system, termed 'quorum sensing' (QS). This system regulates gene expression in response to cell density through the constant production and detection of signalling molecules. These molecules commonly act as auto-inducers through the up-regulation of their own synthesis.

Insect repellents and contact urticaria: differential response to DEET and picaridin.

Topical insect repellent is commonly used throughout the world. Active ingredients typically include N,N-diethyl-meta-toluamide (DEET) or picaridin. Reactions to topical repellents have ranged from contact dermatitis to urticaria.

Association of natural killer cell dysfunction and recurrent Stevens-Johnson syndrome in a pediatric patient.

Stevens-Johnson syndrome (SJS) is a debilitating condition involving the skin and mucous membranes. It is commonly the result of adverse drug reactions but can also be caused by infections. A predisposition to recurrent viral infections, such as in the case of natural killer (NK) cell dysfunction, may manifest with virally induced SJS.

Signal transducer and activator of transcription 3 mutation with invasive eosinophilic disease.

Hyper-IgE syndrome (HIES), or Jobs disease, is a rare immunologic disorder characterized by the triad of staphylococcal abscesses, pneumonia with pneumatocele formation, and elevated IgE. It has been shown to have multiple modes of inheritance, autosomal dominant being more common than autosomal recessive, with sporadic cases as well. A mutation in signal transducer and activator of transcription 3 (STAT3) gene has been linked to the development of the sporadic and dominant forms of HIES.

The rate of epinephrine administration associated with allergy skin testing in a suburban allergy practice from 1997 to 2010.

Allergy skin testing is considered a safe method for testing for IgE-mediated allergic responses although anaphylactic events can occur. Reported rates of anaphylaxis per patient are not consistent and range from 0.008 to 4%.

Expression of an entire bacterial operon in plants.

Multigene expression is required for metabolic engineering, i.e. coregulated expression of all genes in a metabolic pathway for the production of a desired secondary metabolite.

Cracking the shell on egg-hypersensitive patients and egg-containing vaccines.

Hens' eggs are a common food in the American diet. They are consumed as a primary food source and added as an ingredient to other foods. In individuals who are hypersensitive to eggs, egg-containing foods can cause mild to severe allergic reactions if ingested.

Quorum-sensing quenching by rhizobacterial volatiles.

We show that volatile organic compounds (VOCs) produced by rhizospheric strains Pseudomonas fluorescens B-4117 and Serratia plymuthica IC1270 may act as inhibitors of the cell-cell communication quorum-sensing (QS) network mediated by N-acyl homoserine lactone (AHL) signal molecules produced by various bacteria, including strains of Agrobacterium, Chromobacterium, Pectobacterium and Pseudomonas. This quorum-quenching effect was observed when AHL-producing bacteria were treated with VOCs emitted by strains B-4117 and IC1270 or with dimethyl disulfide (DMDS), the major volatile produced by strain IC1270. LC-MS/MS analysis revealed that treatment of strains Pseudomonas chlororaphis 449, Pseudomonas aeruginosa PAO1 or Ps.

Broad-range antagonistic rhizobacteria Pseudomonas fluorescens and Serratia plymuthica suppress Agrobacterium crown gall tumours on tomato plants.

Aim: To examine the biocontrol activity of broad-range antagonists Serratia plymuthica IC1270, Pseudomonas fluorescens Q8r1-96 and P. fluorescens B-4117 against tumourigenic strains of Agrobacterium tumefaciens and A. vitis.

[Involvement of the global regulators GrrS, RpoS, and SplIR in formation of biofilms in Serratia plymuthica].

Most bacteria exist in the natural environment as biofilms, multicellular communities attached to hard surfaces. Biofilms have a characteristic architecture and are enclosed in the exopolymer matrix. Bacterial cells in biofilms are extremely resistant to antibacterial factors.

Characterization of ACC deaminase from the biocontrol and plant growth-promoting agent Trichoderma asperellum T203.

1-aminocyclopropane-1-carboxylate (ACC) deaminase activity was evaluated in the biocontrol and plant growth-promoting fungus Trichoderma asperellum T203. Fungal cultures grown with ACC as the sole nitrogen source showed high enzymatic activity. The enzyme encoding gene (Tas-acdS) was isolated, and an average 3.

[Structure and expression of gene vfr in Pseudomonas chlororaphis 449].

Gene vfr previously described only in Pseudomonas aeruginosa was cloned, identified, and sequenced in cells of Pseudomonas chlororaphis 449; its localization in the chromosome was determined. Amino acid sequence of the protein encoded by gene vfr in P. chlororaphis 449 was shown to have a 83% identity with the Vfr protein of P.

Quorum-sensing effects in the antagonistic rhizosphere bacterium Serratia plymuthica HRO-C48.

The rhizosphere-associated bacterium Serratia plymuthica HRO-C48 is not only able to suppress symptoms caused by soil-borne pathogens but is also able to stimulate growth of plants. Detailed knowledge about the underlying mechanisms and regulation are crucial for the application in biocontrol strategies. To analyse the influence of N-acyl homoserine lactone (AHL)-mediated communication on the biocontrol activity, the AHL-degrading lactonase AiiA was heterologously expressed in the strain, resulting in abolished AHL production.

[Quorum sensing systems of regulation, synthesis of phenazine antibiotics, and antifungal (corrected) activity in rhizospheric bacterium Pseudomonas chlororaphis 449].

Strain Pseudomonas chlororaphis 449, an antagonist of a broad spectrum of phytopathogenic microorganisms isolated from the maize rhizosphere, was shown to produce three phenazine antibiotics: phenazine-1-carboxylic acid (PCA), 2-hydroxylphenazine-1-carboxylic acid (2-OH-PCA), and 2-hydroxylphenazine (2-OH-PHZ). Two Quorum Sensing (QS) systems of regulation were identified: PhzIR and CsaI/R. Genes phzI and csaI were cloned and sequenced.