Effect of the bacterial pyoverdine siderophore on the phytoextraction of cesium from illite

Radioactive Cs contamination is a major concern in case of a nuclear accident such as the Fukushima accident in 2011. Remediation methods have been proposed including soil washing, removal and landfill disposal, which have many drawbacks such as high cost and non-conservation of soil resources. Hence, innovative remediation methods are being developed, for instance in situ bioremediation such as phytoextraction. In this framework, we investigated the Cs uptake from illite by red clover associated with the bacterial pyoverdine siderophore. Dialysis membranes were used to prevent a direct contact between pyoverdine and plants. The results show an increase of Cs extraction from illite in the presence of pyoverdine, mainly due to illite alteration and dissolution of Al, Fe and Si. In the presence of pyoverdine, the red clover extracted 5.6 times more Cs from illite in comparison with the experiment without pyoverdine. Here, we demonstrate that Cs phytoextraction enhanced by bacterial by-products may constitute a relevant solution to speed up phytoextraction rate.