Usage des sidérophores produits par Pseudomonas dans la bioremédiation des sols pollués par les métaux lourds

Abstract

The issue of soils contaminated by heavy metals is the result of the past, and as well frequently still of an industrial present, small concerned around the release of toxic components within the soil, making many sites potentially contaminated and unsafe to public and animal health. There are several technologies for disinfecting of soils contaminated with heavy metals, including the one chosen in this theoretical analysis: bioremediation. The resistance of Pseudomonas to Cd, Zn and Cu, was studied using three different media TMM, LB and nutrient agar (NA) by observing the zones of inhibition. The maximum tolerable heavy metal concentrations for P. aeruginosa were (1800 M, 1600 M and 1400 M) for Cu, Zn and Cd respectively. Siderophores represent interesting molecules for mobilizing toxic metals in soils where the mechanisms for the production of siderophores and the transport of siderophore-metal complexes are the best known. The detection and estimation of siderophore was studied using the CAS test. Pseudomonas sp. excreted 43.22% siderophore, while P. fluorescens and P. putida produced 87 and 83% siderophore units respectively in SM medium. Metal bioremediation and evaluation of the metal-siderophore complex were studied using CAS agar containing various metal ions (1mM metal in 10mM HCl). The change in color of the modified CAS from blue to orange indicated the chelating of these metal ions. P. aeruginosa adsorbed over 90% of the added heavy metal ions, and absorbing 90.16% of ZnCl2, the siderophores were evaluated for their efficiency in removing heavy metal ions from the soil matrix using the succinate medium where the estimation was made by atomic absorption spectrophotometer, heavy metal concentrations were significantly reduced in an effluent sample where P. fluorescens reduced 37% Cu2+, 32% of Zn2+ and 29% of Cd2+ and therefore proved to be very effective in removing these heavy metals.