A Novel Robust Screening Assay Identifies Strains as Reliable Antagonists of the Root-Knot Nematode .

Forty-four bacterial strains isolated from greenhouse soil and beetroots were tested for their antagonistic activity against the plant-parasitic root-knot nematode (RKN) , which causes significant yield losses in a number of important crops worldwide. Through a novel combination of in vitro and on planta screening assays, spp. 105 and 108 were identified as the most promising bacterial isolates.

Spontaneous Resistance of Against Bacteriophage Y2 Affects Infectivity of Multiple Phages.

Broad application of antibiotics gave rise to increasing numbers of antibiotic resistant bacteria. Therefore, effective alternatives are currently investigated. Bacteriophages, natural predators of bacteria, could work as such an alternative.

Bacteriophage S6 requires bacterial cellulose for Erwinia amylovora infection.

Bacteriophages are highly selective in targeting bacteria. This selectivity relies on the specific adsorption of phages to the host cell surface. In this study, a Tn5 transposon mutant library of Erwinia amylovora, the causative agent of fire blight, was screened to identify bacterial receptors required for infection by the podovirus S6.

Priority Effects in the Apple Flower Determine If the Siderophore Desferrioxamine Is a Virulence Factor for Erwinia amylovora CFBP1430.

Iron is crucial for bacterial growth and virulence. Under iron-deficiency bacteria produce siderophores, iron chelators that facilitate the iron uptake into the cell via specific receptors. Erwinia amylovora, the causative agent of fire blight, produces hydroxamate-type desferrioxamine siderophores (DFO).

Conjugation Dynamics of Self-Transmissible and Mobilisable Plasmids into O157:H7 on Rosettes.

Many antibiotic resistance genes present in human pathogenic bacteria are believed to originate from environmental bacteria. Conjugation of antibiotic resistance conferring plasmids is considered to be one of the major reasons for the increasing prevalence of antibiotic resistances. A hotspot for plasmid-based horizontal gene transfer is the phyllosphere, i.

Pseudomonas orientalis F9 Pyoverdine, Safracin, and Phenazine Mutants Remain Effective Antagonists against Erwinia amylovora in Apple Flowers.

The recently characterized strain F9, an isolate from apple flowers in a Swiss orchard, exhibits antagonistic traits against phytopathogens. At high colonization densities, it exhibits phytotoxicity against apple flowers. F9 harbors biosynthesis genes for the siderophore pyoverdine as well as for the antibiotics safracin and phenazine.

F9: A Potent Antagonist against Phytopathogens with Phytotoxic Effect in the Apple Flower.

In light of public concerns over the use of pesticides and antibiotics in plant protection and the subsequent selection for spread of resistant bacteria in the environment, it is inevitable to broaden our knowledge about viable alternatives, such as natural antagonists and their mode of action. The genus is known for its metabolic versatility and genetic plasticity, encompassing pathogens as well as antagonists. We characterized strain F9, an isolate from apple flowers in a Swiss orchard, and determined its antagonistic activity against several phytopathogenic bacteria, in particular , the causal agent of fire blight.

Role of the type VI secretion systems during disease interactions of Erwinia amylovora with its plant host.

Background: Type VI secretion systems (T6SS) are widespread among Gram-negative bacteria and have a potential role as essential virulence factors or to maintain symbiotic interactions. Three T6SS gene clusters were identified in the genome of E. amylovora CFBP 1430, of which T6SS-1 and T6SS-3 represent complete T6SS machineries, while T6SS-2 is reduced in its gene content.

Complete genome sequence of P3B5, a candidate for microbial phyllo-remediation of hydrocarbon-contaminated sites.

is a Gram negative, motile gammaproteobacterium belonging to the order and the family . We isolated strain P3B5 from the phyllosphere of basil plants ( L.).

Fe2+ chelator proferrorosamine A: a gene cluster of Erwinia rhapontici P45 involved in its synthesis and its impact on growth of Erwinia amylovora CFBP1430.

Proferrorosamine A (proFRA) is an iron (Fe2+) chelator produced by the opportunistic plant pathogen Erwinia rhapontici P45. To identify genes involved in proFRA synthesis, transposon mutagenesis was performed. The identified 9.

A duplex-PCR method for species- and pathovar-level identification and detection of the quarantine plant pathogen Xanthomonas arboricola pv. pruni.

A PCR-based method was developed for the stone fruit quarantine pathogen Xanthomonas arboricola pv. pruni (Xap), which provides rapid, sensitive and specific in planta detection and isolate identification. Primers specific for Xap were identified using random amplified polymorphic DNA (RAPD).

Genomic and phenotypic characterization of a nonpigmented variant of Pantoea vagans biocontrol strain C9-1 lacking the 530-kb megaplasmid pPag3.

A 530-kb megaplasmid pPag3 contributing 10.8% of the total genome of Pantoea vagans biocontrol strain C9-1 was sequenced. A rare nonpigmented variant C9-1W was obtained and shown to have lost pPag3, but retained all other plasmids (pPag1, pPag2).

Broad spectrum microarray for fingerprint-based bacterial species identification.

Background: Microarrays are powerful tools for DNA-based molecular diagnostics and identification of pathogens. Most target a limited range of organisms and are based on only one or a very few genes for specific identification. Such microarrays are limited to organisms for which specific probes are available, and often have difficulty discriminating closely related taxa.

Pilot study to evaluate microarray hybridization as a tool for Salmonella enterica serovar Typhimurium strain differentiation.

In developed countries, Salmonella enterica subspecies 1 serovars Enteritidis and Typhimurium range among the most common causes of bacterial food-borne infections. The surveillance and typing of epidemic Salmonella strains are important tools in epidemiology. Usually, Salmonella enterica subspecies 1 serovars are differentiated by serotyping for diagnostic purposes.

Irp9, encoded by the high-pathogenicity island of Yersinia enterocolitica, is able to convert chorismate into salicylate, the precursor of the siderophore yersiniabactin.

The Irp9 protein of Yersinia enterocolitica participates in the synthesis of salicylate, the precursor of the siderophore yersiniabactin. In Pseudomonas species, salicylate synthesis is mediated by two enzymes: isochorismate synthase and isochorismate pyruvate-lyase. Both enzymes are required for complementation of a Yersinia irp9 mutant.

The SopEPhi phage integrates into the ssrA gene of Salmonella enterica serovar Typhimurium A36 and is closely related to the Fels-2 prophage.

Salmonella spp. are enteropathogenic gram-negative bacteria that use a large array of virulence factors to colonize the host, manipulate host cells, and resist the host's defense mechanisms. Even closely related Salmonella strains have different repertoires of virulence factors.

Transfer of the core region genes of the Yersinia enterocolitica WA-C serotype O:8 high-pathogenicity island to Y. enterocolitica MRS40, a strain with low levels of pathogenicity, confers a yersiniabactin biosynthesis phenotype and enhanced mouse virulence.

The high-pathogenicity island (HPI) of yersiniae encodes an iron uptake system represented by its siderophore yersiniabactin (Ybt). The HPI is present in yersiniae with high levels of pathogenicity--i.e.

Functional analysis of yersiniabactin transport genes of Yersinia enterocolitica.

Yersinia enterocolitica O:8, biogroup (BG) IB, strain WA-C carries a high-pathogenicity island (HPI) including iron-repressible genes (irp1-9, fyuA) for biosynthesis and uptake of the siderophore yersiniabactin (Ybt). The authors report the functional analysis of irp6,7,8, which show 98-99% similarity to the corresponding genes ybtP,Q,X on the HPI of Yersinia pestis. It was demonstrated that irp6,7 are involved in ferric (Fe)-Ybt utilization and mouse virulence of Y.

Cloning and characterization of the gene encoding periplasmic 2',3'-cyclic phosphodiesterase of Yersinia enterocolitica O:8.

The gene encoding periplasmic 2',3'-cyclic phosphodiesterase in Yersinia enterocolitica O:8 (designated cpdB), was cloned and expressed in Escherichia coli. This enzyme enables Y. enterocolitica to grow on 2',3'-cAMP as a sole source of carbon and energy.

The yersiniabactin biosynthetic gene cluster of Yersinia enterocolitica: organization and siderophore-dependent regulation.

The ability to synthesize and uptake the Yersinia siderophore yersiniabactin is a hallmark of the highly pathogenic, mouse-lethal species Yersinia pestis, Y. pseudotuberculosis, and Y. enterocolitica 1B.