Table 2.
Different processes in the root-microorganism association during phytoremediation of HMs in water.
| Microorganism | Process | Reference |
|---|---|---|
| PGPR (Paenibacillus mucilaginosus, Sinorhizobium meliloti) | Increase the bioavailability of metals | [134] |
| PGPR (Pseudomonas spp.) | Increase water uptake in roots, increasing HM mobilization | [135] |
| PGPR (Stenotrophomonas maltophilia) | Reduce toxicity of HMs, increasing bioaccumulation factor (BF) | [136] |
| PGPR (non specified) | Transformation of HMs into less toxic compounds for faster uptake | [137] |
| PGPR (Planomicrobium chinense, Bacillus cereus) | Increase biomass gain and root growth during HM stress | [138] |
| PGPR (Bacillus spp.) | Reduction in oxidative stress, increasing metabolite production | [139] |
| Chryseobacterium sp. | Creation of antagonistic metabolites to improve resistance to pathogens | [140] |
| PGPR (Pseudomonas fluorescence, Bacillus subtilis) | Increase HM uptake, especially Pb and Ni | [141] |
PGPR have shown positive interactions with plant roots during physiological stress, from inducing metabolite production to enhancing biomass production [142], and even the way in which nutrients are recycled has similar mechanisms in water and soil [110], although some processes, such as the fate of metabolites, can vary between terrestrial and aquatic systems [111]. Nevertheless, dynamics on water may express different interactions and may be studied in future research.