Postdoc - Effects of chlordecone (kepone) pollution on structure and composition of river biofilms

Exopolymers are ubiquitous component of aquatic ecosystems primarily composed of carbohydrates, proteins and lipids. They have multiple roles in aquatic systems but their most striking feature is perhaps their ability to bind most of the pollutants making them available for bioaccumulation in aquatic food webs. EPS generally contains high molecular weight compounds with charged functional groups, which serve as natural adsorptive and adhesive source, providing binding sites for other charged particles/molecules including several pollutants (Bhaskar and Bhosle 2006).

Thus, properties and behaviour of river biofilm cannot be studied without taking into account these complex polymers, mainly because they trap most of the pollutants but also because they enhance the cohesion of river sediments and their capacity to resist erosion and to pollutants resuspension/ flocculation. Surface adhesive capacity, which is partly controlled by the flow regime, also depends on biological factors such as structure and composition of biofilm polymers. Analyzing how different levels of chlordecone interact to influence the development, diversity, activity, and functioning of microbial communities may help in understanding the holistic properties determining surface adhesion and pollution retention.

Profile: The candidates should be microbiologists or biogeochemists with a strong background in the study of epilithic biofilms. They must be ideally familiar with chromatography techniques (notably GC and GC-MS for monosaccharides and fatty acids identification). They should have knowledge on EPS measurement, their degradations (exo-enzymatic activities) and properties. Experience in chorum sensing will be an asset. A field mission (Guadeloupe) is scheduled at the beginning of the contract.

The successful candidate will be requested to complete the following tasks:

- Measure of surface adhesion of biofilms in both laboratory experiments and natural epilithic biofilm - Analysis of fatty acids, monosaccharides composition, induced by different concentration of chlordecone using GC and GCMS

- Measure of total and colloidal carbohydrate and protein concentrations by colorimetry

- Measure of β-D-glucoside and N-terminal peptidic bonds degradation by bacteria

- Writing publications

- The post-doc will begin in September 2012 for a duration of 12 months. The net salary will be € 1900-2100 / month.

Deadline for submission of applications: June 1st 2012. Result in late June.

The successful candidate will be hosted in the RESAQUA research group (Structure modelling and functioning of aquatic food webs http://www.mnhn.fr/mnhn/UMR7208/equipe5/equipe5uk.php).

This group is composed of 5 associate professors, 3 fulltime researchers and one engineer. The main laboratory, part of BOREA research unit (UMR CNRS 7208 http://www.mnhn.fr/mnhn/UMR7208/umrboreauk.php), is situated at the National Museum of Natural History (Paris).

Contact: Hubas Cedric: tel : +33 (1)40795745, hubas@mnhn.fr, or Tarik Meziane: meziane@mnhn.fr