Bioreporter pseudomonas fluorescens HK44 immobilized in a silica matrix

The bioluminescent bioreporter Pseudomonas fluorescens HK44, the whole cell bacterial biosensor that responds to naphthalene and its metabolites via the production of visible light, was immobilized into a silica matrix by the sol-gel technique. The bioluminescence intensities were measured in the maximum of the bioluminescence band at X = 500 nm. The immobilized cells (>105 cells per g silica matrix) produced light after induction by salicylate (cone. > 10 g/l), naphthalene and aminobenzoic acid. The bioluminescence intensities induced by 2,3-dihydroxynaphthalene 3-hydroxybenzoic acid and 4-hydroxybenzoic acid were comparable to a negative control. The cells in the silica layers on glass slides produced light in response to the presence of an inductor at least 8 months after immobilization, and >50 induction cycles. The results showed that these test slides could be used as assays for the multiple determination of water pollution

Maîtrise et modélisation de température des produits réfrigérés dans la chaîne du froid

This study was obtained in the frame of a two year French-Czech research project (1998-1999) with participation of Czech manufacturers. The main objective was to identify and evaluate the critical points in the cold chain of chilled products by temperature monitoring and by modelling. The experimentation was focused on ambient and product temperatures measurement during various steps in the cold chain i.e. preparation, cold storage and transfer etc. The modelling was focused on heat transfers in order to predict product temperature exposed in different ambient conditions. The experiments were carried out in the Czech Republic on two products : crème patissière cake and sliced ham. The results of cake examination are presented in this paper. The experimental results show that the product temperature was too high during certain steps. The heat transfer modelling carried out on cake shows a good agreement between the experimental and calculated data. It allows to present to manufacturers the important effect of ambient conditions on product temperature which is a deciding factor for food safety.Cette étude est obtenue dans le cadre du projet de recherche en commun de 2 ans (1998-1999) entre la France et la République Tchèque avec la participation des industriels tchèques. L'objectif principal de cette étude est d'identifier et d'évaluer les points critiques dans la chaîne du froid des produits réfrigérés à l'aide de l'expérimentation de suivi de température et de modélisation. L'expérimentation est menée en mesurant la température de l'air ambiant et du produit pendant différentes étapes de la chaîne du froid, c'est-à-dire préparation, stockage et transfert, etc. La modélisation des transferts thermiques est réalisée afin de prédire la température du produit soumis à différentes conditions ambiantes. L'expérimentation a été menée en République tchèque sur 2 produits : crème pâtissière et jambon en tranches. Le résultat expérimental montre que la température du produit est trop élevée à certaines étapes. La modélisation des transferts thermiques réalisée sur la crème patissière montre un bon accord entre la température expérimentale et calculée et permet ainsi de présenter aux industriels l'importance des conditions ambiantes sur la température des produits, facteurs déterminants dans la qualité sanitaire

Novel roles for genetically modified plants in environmental protection

Transgenic plants of environmental benefit typically consist of plants that either reduce the input of agrochemicals into the environment or make the biological remediation of contaminated areas more efficient. Examples include the construction of species that result in reduced pesticide use and of species that contain genes for either the degradation of organics or the increased accumulation of inorganics. Cutting-edge approaches, illustrated by our own work, focus on the applicability of genetically modified (GM) plants that produce insect pheromones or that are specifically tailored to the phytoremediation of cadmium or PCBs. This paper discusses the role that the next generation of GM plants might play in preventing and reducing chemical contamination and in converting contaminated sites into safe agricultural or recreational land