Does virulence assessment of Vibrio anguillarum using sea bass (Dicentrarchus labrax) larvae correspond with genotypic and phenotypic characterization?

Background: Vibriosis is one of the most ubiquitous fish diseases caused by bacteria belonging to the genus Vibrio such as Vibrio (Listonella) anguillarum. Despite a lot of research efforts, the virulence factors and mechanism of V. anguillarum are still insufficiently known, in part because of the lack of standardized virulence assays. Methodology/Principal Findings: We investigated and compared the virulence of 15 V. anguillarum strains obtained from different hosts or non-host niches using a standardized gnotobiotic bioassay with European sea bass (Dicentrarchus labrax L.) larvae as model hosts. In addition, to assess potential relationships between virulence and genotypic and phenotypic characteristics, the strains were characterized by random amplified polymorphic DNA (RAPD) and repetitive extragenic palindromic PCR (rep-PCR) analyses, as well as by phenotypic analyses using Biolog's Phenotype MicroArray (TM) technology and some virulence factor assays. Conclusions/Significance: Virulence testing revealed ten virulent and five avirulent strains. While some relation could be established between serotype, genotype and phenotype, no relation was found between virulence and genotypic or phenotypic characteristics, illustrating the complexity of V. anguillarum virulence. Moreover, the standardized gnotobiotic system used in this study has proven its strength as a model to assess and compare the virulence of different V. anguillarum strains in vivo. In this way, the bioassay contributes to the study of mechanisms underlying virulence in V. anguillarum

Current and emerging trends in techniques for plant pathogen detection

Plant pathogenic microorganisms cause substantial yield losses in several economically important crops, resulting in economic and social adversity. The spread of such plant pathogens and the emergence of new diseases is facilitated by human practices such as monoculture farming and global trade. Therefore, the early detection and identification of pathogens is of utmost importance to reduce the associated agricultural losses. In this review, techniques that are currently available to detect plant pathogens are discussed, including culture-based, PCR-based, sequencing-based, and immunology-based techniques. Their working principles are explained, followed by an overview of the main advantages and disadvantages, and examples of their use in plant pathogen detection. In addition to the more conventional and commonly used techniques, we also point to some recent evolutions in the field of plant pathogen detection. The potential use of point-of-care devices, including biosensors, have gained in popularity. These devices can provide fast analysis, are easy to use, and most importantly can be used for on-site diagnosis, allowing the farmers to take rapid disease management decisions

In vivo expression technology (IVET) for studying niche-specific gene expression by plant- and soil-colonizing bacteria

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Combinatie chemische desinfectie en UV bestrijdt bacteriën en

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Chemische en microbiologische waterverontreiniging: een risico voor de consument? Een laatste update

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Azotobacter vinelandii: a Pseudomonas in disguise?

Azotobacter vinelandii is a widely distributed free-living soil bacterium. This Gram-negative, strictly aerobic bacterium has many interesting features, including the ability to grow on a wide variety of carbohydrates, alcohols and organic acids, alginate production and nitrogen fixation. Sequence analysis of P. stutzeri genes that are specifically activated in the rice rhizosphere revealed high sequence similarity to A. vinelandii genes. These observations and the availability of a genome sequence of A. vinelandii and several Pseudomonas species urged us to inspect the phylogenetic relationship of A. vinelandii to Pseudomonas sensu stricto. Our in silico data strongly suggest that A. vinelandii belongs to the genus Pseudomonas sensu stricto.status: publishe

Tetragenococcus

In 1990 the genus Tetragenococcus was created after reclassification of the halophilic lactic acid bacterium (LAB) Pediococcus halophilus as T. halophilus. Tetragenococci are typical LAB in that they are Gram-positive, catalase negative, and oxidase negative. Physiologically, tetragenococci are distinguished from other LAB mainly by their high salt tolerance and ability to grow at high pH values. Presently, the genus comprises a limited number of species, including T. halophilus, T. koreensis, T. muriaticus, T. osmosphilus and T. solitarius. Based on both physiological and genetic characteristics as well as on the origin of the strains, the species T. halophilus was further subdivided into two subspecies, including T. halophilus subsp. halophilus and T. halophilus subsp. flandriensis for strains isolated from salt-rich and sugar-rich environments, respectively. In this chapter, both phenotypical and genotypical characteristics of the genus are outlined, with a detailed description of each species comprising the genus. In addition, emphasis is put on the industrial relevance of the genus.status: publishe

Application of in vivo expression technology (IVET) for the study of rice colonization by the endophytic nitrogen-fixing bacterium Pseudomonas stutzeri A15

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Evaluation of the cold chain of fresh-cut endive from farmer to plate

In this study, the cold chain and its impact on food stuff microbiology was evaluated for fresh-cut endive. A survey was carried out to analyze endive temperature throughout the supply chain from producer, via processor and distributor to the restaurant. Data loggers accompanying the endive on its route provided a temperature profile of the endive. The effect of the outdoor temperature on initial cooling was evaluated and critical points regarding cold chain management in the supply chain were identified. Our experiments indicate that the cold chain is generally properly maintained. In parallel with temperature monitoring, indicator microorganisms were assessed at different points in the supply chain to examine the effects of endive temperature, temperature fluctuations, and the outdoor temperature on microbial food safety. Small temperature fluctuations in the supply chain had a small effect on the total level of aerobic mesophilic bacteria. However, at the best before-date, total coliforms and Enterobacteriaceae levels were significantly higher in endive samples subject to temperature fluctuations in the supply chain, compared to endive stored in optimal conditions. To our knowledge, this is the first study that combines microbiological analysis with the temperature profile of fresh-cut produce in a realistic food supply chain.status: publishe