Optical Algal Biosensor using Alkaline Phosphatase for Determination of Heavy Metals

International audienceA biosensor is constructed to detect heavy metals from inhibition of alkaline phosphatase (AP) present on the external membrane of Chlorella vulgaris microalgae. The microalgal cells are immobilized on removable membranes placed in front of the tip of an optical fiber bundle inside a homemade microcell. C. vulgaris was cultivated in the laboratory and its alkaline phosphatase activity is strongly inhibited in the presence of heavy metals. This property has been used for the determination of those toxic compounds

Co-encapsulation of Daphnia magna and microalgae in silica matrices, a stepping stone toward a portable microcosm

We report on the first silica encapsulation of a metazoan (Daphnia magna), with a high initial viability (96% of the population remained active 48 h after encapsulation). Moreover, the co-encapsulation of this crustacean and microalgae (Pseudokirchneriella subcapitata) was achieved, creating inside a silica monolith, the smallest microcosm developed to present. This artificial ecosystem in a greatly diminished scale isolated inside a silica nanoporous matrix could have applications in environmental monitoring, allowing ecotoxicity studies to be carried out in portable devices for on-line and in situ pollution level assessment.Fil: Perullini, Ana Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Orias, Frédéric. Université Claude Bernard Lyon 1; FranciaFil: Durrieu, Claude. Université Claude Bernard Lyon 1; FranciaFil: Jobbagy, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Aldabe, Sara Alfonsina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Optical whole-cell biosensor using Chlorella vulgaris designed for monitoring herbicides

International audienceAn optical biosensor was designed for determination of herbicides as aquatic contaminants. Detection was obtained with immobilised Chlorella vulgaris microalgae entrapped on a quartz microfibre filter and placed in a five-membrane-home-made-flow cell. The algal chlorophyll fluorescence modified by the presence of herbicides was collected at the tip of an optical fibre bundle and sent to a fluorimeter. A continuous culture was set up to produce algal cells in reproducible conditions for measurement optimisation. Effects of flow rate, algal density, temperature, and pH on the biosensor response to atrazine were studied. Reversibility and detection limits were determined for DNOC and atrazine, simazine, isoproturon, diuron. Detection of photosystem II (PSII) herbicides was achieved at sub-ppb concentration level

Synchronous-scan fluorescence of algal cells for toxicity assessment of heavy metals and herbicides.

International audienceSynchronous-scan spectrofluorometry was applied to Chlorella vulgaris cells to assess the toxicity of heavy metals and herbicides in water. Simultaneous scan of both the excitation and emission spectra was done at a constant wavelength difference Deltalambda (20-140 nm) between the emission and excitation wavelengths in the range of 420-700 nm emission, where a peak of fluorescence was observed. Its position depends on Deltalambda. Fluorescence measurements were conducted with algal cells in suspension in water and immobilized in a translucent silica matrix. The influence of toxic chemicals was tested with cadmium as a heavy metal and with atrazine, diuron, DNOC and paraquat as herbicides. The toxic effect of those chemicals mainly results in a quenching of algal cells fluorescence by reducing their photosynthetic activity

A Bi-enzymatic Whole-Cell Algal Biosensor for Monitoring Waste Water Pollutants

International audienceTwo algal whole cells biosensors are developed to measure specific toxicity of freshwater pollutants. Both optical and conductometric biosensors are based on inhibition of algal alkaline phosphatase (AP) and esterase activities. Chlorella vulgaris cells are immobilised on a membrane placed in front of an optical fiber bundle for optical sensing or deposited on the surface of an electrode for conductometric sensing. Phosphatase activity of the biosensor is strongly inhibited by heavy metal ions (60% loss of activity is obtained after 10 ppb Cd2+ and Zn2+ with 20 min exposure time), as equally observed with a microplate reader. Inhibition of esterase activity (EA) is actually achieved with organophosphorous pesticides such as methyl paraoxon. The biosensors exhibit a response time of about 5 min. These pollutants can be detected down to 10 ppb after being in contact with the biosensor for 30 min. The biosensor can be used up to 20 days with 90% remaining activity

Évaluation de l'impact des rejets urbains de temps de pluie sur le compartiment algal des écosystèmes aquatiques (Mise au point d'outils pour la surveillance des milieux récepteurs)

La gestion des eaux pluviales constitue un défi important à relever dans les villes du monde entier : aujourd hui on ne compte plus les problèmes d inondation et de pollution, problèmes chroniques qui tendent à s amplifier à mesure que l urbanisation grandit en parallèle du changement climatique. Une gestion durable de ces eaux est au cœur des enjeux du XXIe siècle et afin de faire face à ces problèmes le Ministère de l Écologie et du Développement Durable a engagé une opération de recherche sur cette thématique. Parmi les problèmes posés par les eaux pluviales, notre étude se focalise sur les rejets urbains de temps de pluie (RUTP). Ces rejets constituent un apport important et imprévisible de nombreux polluants pour les masses d eaux réceptrices. La pollution des RUTP est étudiée depuis de nombreuses années et, alors que les connaissances en la matière s affinent, il n existe à l heure actuelle aucune étude de grande ampleur permettant d identifier l impact des RUTP sur les écosystèmes récepteurs. Notre travail a consisté à étudier l impact environnemental de différents échantillons de RUTP collectés sur 3 sites d assainissement pluvial de l agglomération lyonnaise. Pour cela nous avons sélectionné des bioindicateurs pertinents, les microalgues d eau douce, organismes unicellulaires à la base des chaînes trophiques et très sensibles aux polluants présents dans les RUTP. Nous avons réalisé des bioessais écotoxicologiques connus de la littérature et contribué au développement de nouveaux indicateurs de toxicité complémentaires. De plus nous avons cherché à adapter ces bioessais pour permettre leur utilisation sur le terrain. En parallèle nous avons travaillé à l amélioration d un biocapteur enzymatique à cellules algales. Ses performances ont été évaluées sur des échantillons de RUTP avant d œuvrer à la construction d une station automatisée qui nous a permis de réaliser des mesures directement sur les sites d assainissement (on line monitoring). Ce travail contribue à mettre en évidence l impact important des RUTP sur le milieu récepteur tout en confirmant le caractère hétérogène de ce type d effluent et l intérêt des dispositifs de surveillance in situ.The stormwater management constitutes an important challenge for cities around the world: today there are countless problems of flooding and pollution, chronic problems that tend to amplify as urbanization grows. Sustainable management of these waters is at the heart of defies of the twenty-first century and to address these problems the Ministry of Ecology and Sustainable Development has launched a research operation. Among problems posed by stormwater, our study focuses on urban wet weather discharges (UWWD). These releases are an important and unpredictable contribution of many pollutants to the receiving water bodies. UWWD's pollution has been studied for many years and, while knowledge in the field matures, there is at present no large-scale study to identify the impact of UWWD on the receiving ecosystems. Our work consist in studying the impact of different UWWD samples collected at 3 storm sanitation sites of Lyon on the environment. We have relevant bioindicators, freshwater microalgae, unicellular organisms at the base of the trophic chain and very sensitive to pollutants present in the UWWD. We have undertaken ecotoxicological bioassays known from the literature and contributed to the development of new indicators of toxicity. Furthermore, we seek to adapt these bioassays to allow their use in the field. In parallel, we have worked to improve an enzyme biosensor algal cell. We evaluated its performances on samples of UWWD and then we built an automated measuring station to make measurements directly on the remediation site (online monitoring).VILLEURBANNE-DOC'INSA-Bib. elec. (692669901) / SudocSudocFranceF

Algal biosensors for aquatic ecosystems monitoring

International audienceThe harmful effect of toxic chemicals on natural ecosystems has led to an increasing demand for early-warning systems to detect those toxicants at very low concentrations levels. Whole-cell biosensors based either on chlorophyll fluorescence or enzyme (phosphatase and esterase) inhibition are constructed for real-time detection and on-line monitoring. Results show that these devices are sensitive to heavy metals and pesticides. The system allows the cells to operate in their natural environment which favours long term stability and reflects the toxic action mechanism providing therefore an ecological interest

Ecotoxicological risk assessment linked to infilling quarries with treated dredged seaport sediments

International audienceThe dredged sediments of polluted seaports now raise complex management problems since it is no longer possible to discharge them into the sea. This results in the need to manage them on land, raising other types of technical, economic and environmental problems. Regarding the technical and economic dimensions, traditional waste treatment methods have proved to be poorly adapted, due to very high costs and low absorbable volumes. In this context, filling quarries in coastal areas with treated sediments could represent an interesting alternative for these materials. Nevertheless, for the environmental dimension, it is necessary to demonstrate that this possibility is harmless to inland ecosystems. Consequently, a specific ecotoxicological risk assessment methodology has been formulated and tested on three sediments taken from seaboards of France, in view to providing an operational and usable tool for the prior validation of any operation to fill quarries with treated seaport sediments. This method incorporates the formulation of a global conceptual model of the scenario studied and the definition of protocols for each of its steps: the characterisation of exposures (based on a simulation of sediment deposit), the characterisation of effects (via the study of sediments ecotoxicity), and the final ecotoxicological risk assessment performed as a calculation of a risk quotient. It includes the implementation in parallel of two types of complementary approach: the "substances" approach derived from the European methodology for assessing new substances placed on the market, and the "matrix" approach which is similar to methods developed in France to assess ecological risks in other domains (waste management, polluted site management, ...). The application of this dual approach to the three sediments tested led to conclude with reliability that the project to deposit sediments "1" and "2" presented a low risk for the peripheral aquatic ecosystems while sediment "3" presented a high risk

Les concessions d'exploitation forestière menacent-elles les tourbières en République démocratique du Congo ?

peer reviewed[No abstract available

Association d'une enzyme de la glycolyse (La glyceraldehyde-3-phosphate dehydrogenase) avec les microtubules

SIGLECNRS TD 15475 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc