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Impact of rhamnolipid addition on two Phenanthrene (PHE) spiked soils: sorption, degradation kinetics and Phenanthrene degrading bacteria

Abstract : Polycyclic aromatic hydrocarbons (PAHs) are persistent toxic pollutants which present geo-accumulation characteristics. They are more or less strongly sequestrated in soils, and the effectiveness of bioremediation processes is closely linked to their bioavailability for the soils degrading bacterial communities. Rhamnolipids are glycolipidic biosurfactants produced by Pseudomonas aeruginosa, which are used in bioremediation processes because of their ability to remobilize PAHs bounded to soil particles. In this study, the objective was to study the impact of addition of biosurfactants, and especially rhamnolipid, (i) on phenanthrene (PHE) sorption to soil, (ii) on PHE degradation kinetics and (iii) on PHE degrading bacteria on two dissimilar soils (P V soil having markedly higher contents of clays and organic matter (OM) than PPY soil). (i) Sorption isotherms were performed with PHE on both soils, with or without rhamnolipid addition. To compare, isotherms were also realized with a cyclolipopeptidic biosurfactant (produced by Pseudomonas fluorescens PFa7b). (ii) Degradation kinetics were performed on both soils spiked with PHE (300 mg/kg) in triplicates, and PHE dissipation was monitored for 60 days. Remaining PHE in soils was analyzed after microwave-assisted extraction and analyzed by GC-MS. (iii) To assess the impact of rhamnolipid addition on PHE degrading bacteria, DNA stable isotope probing (SIP) method was used. Two sets of microcosms were established, and spiked at 300 mg/kg with 12 C PHE or 13 C PHE, with and without rhamnolipid addition. The 12 C PHE microcosms allowed us to control PHE dissipation and to fix sampling dates (after 20% and 80% PHE dissipation) for DNA analyzes in 13 C PHE microcosms. After microbial DNA extraction and quantification, a separation of 12 C and 13 C labelled DNA allowed us to characterize bacteria having consumed 13 C PHE. K d partition coefficients, obtained from sorption isotherms, were quite similar in the two soils, showing that in the first sorption phase, bioavailability of PHE did not depend on clays and OM contents in soils. By contrast, rhamnolipid allowed a greater desorption of PHE from PPY soil than from Pv soil, showing that PHE was more easy to mobilize by biosurfactants from soils poorer in clays and OM. Comparatively to rhamnolipid, the cyclolipopeptidic biosurfactant had no impact on PHE desorption from soil.
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Submitted on : Wednesday, May 6, 2020 - 11:46:20 AM
Last modification on : Wednesday, October 14, 2020 - 4:05:44 AM

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  • HAL Id : hal-02557225, version 1

Citation

Marc Crampon, Josselin Bodilis, Aurélie Cebron, Fabrice Bureau, Franck Le Derf, et al.. Impact of rhamnolipid addition on two Phenanthrene (PHE) spiked soils: sorption, degradation kinetics and Phenanthrene degrading bacteria. International Conference on Environmental Pollution and Remediation (ICEPR, 14, 2014)), Aug 2014, Prague, Czech Republic. ⟨hal-02557225⟩

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