Drivers to improve metal(loid) phytoextraction with a focus on microbial degradation of dissolved organic matter in soils

Abstract

Bioaugmentation of soils can increase the mobilization of metal(loid)s from the soil-bearing phases. However, once desorbed, these metal(loid)s are mostly complexed to the dissolved organic matter (DOM) in the soil solution, which can restrict their availability to plants (roots mainly taking up the free forms) and then the phytoextraction performances. Firstly the main drivers influencing phytoextraction are reminded, then the review focuses on the DOM role. After having reminding the origin, the chemical structure and the lability of DOM, the pool of stable DOM (the most abundant in the soil) most involved in the complexation of metal(loid)s is addressed in particular by focusing on carboxylic and/or phenolic groups and factors controlling metal(loid) complexation with DOM. Finally, this review addresses the ability of microorganisms to degrade metal(loid)-DOM complexes as an additional lever for increasing the pool of free metal(loid) ions, and then phytoextraction performances, and details the origin of microorganisms and how they are selected. The development of innovative processes including the use of these DOM-degrading microorganisms is proposed in perspectives.

NOVELTY STATEMENT

This review focuses on the available drivers to increase the pool of free (i.e. phytoavailable) metal(loid)s in the soil solution, with a specific focus on the ability of microorganisms to degrade dissolved organic matter for enriching this pool, and then to substantially improve phytoextraction performance.

Keywords:

• Bacteria
• bioaugmentation
• carboxylic acid groups
• complexing agent
• phenolic groups
• phytomanagement

Acknowledgements

INRAE BIOGECO is member of the COST Action PlantMetals and the INRAE Ecotox network.

Disclosure statement

The authors report there are no competing interests to declare.

Additional information

Funding

This work was supported by France’s Pays de la Loire Regional Council and by ADEME (under the VITALICUIVRE project).