A quick rhizobacterial selection tests for the remediation of copper contaminated soils

Aims: The main objective of the study is to develop and improve quick bacterial tests to select the best candidates for the bioaugmentation of metal-contaminated soil, coupled with phytoextraction.

Methods and results: Bacteria isolates (181) were selected from a collection originated from a Cu-contaminated sediment, on the basis of several miniaturized biochemical tests adapted to the copper contamination. Amongst them, we used a growth soil based-medium to select metal-tolerant bacteria, and their ability to grow and mobilize metals by mean of metabolites (siderophores, organic acids) was also assessed.

Conclusion: The result of the bacterial selection tests showed differences in presence or absence of copper, especially for phosphate-solubilizing strains which ability decreased by 53% in the presence of copper hydroxide phosphate as compared to the standard tricalcium phosphate test. A promising Pseudomonas putida was selected from the collection.

Significance and impact of the study: The study underlined the importance of choosing significant selection tests regarding the nature of the metal occurring in the soil to be cleaned-up to assess the real potential of each bacterial strain for subsequent soil bioaugmentation purposes.