Miscanthus × giganteus Phytoremediation of Soil Contaminated with Trace Elements as Influenced by the Presence of Plant Growth-Promoting Bacteria

The phytoremediation of industrial crops is becoming popular for the revitalization of land contaminated by trace elements (TEs). This approach combines biomass production with the improvement of soil health. To implement phytoremediation and derive sufficient dry biomass, crop production must be adequately supported by agricultural practices, including the application of bioinoculants. The current study aims to test the influence of several plant growth-promoting bacteria (PGPB), isolated from TEs-contaminated soil—i.e., Stenotrophomonas maltophilia KP-13, Bacillus altitudinis KP-14, and Pseudomonas fluorescens KP-16 and their consortia on the phytoremediation of the industrial crop M. × giganteus cultivated in the same TEs-contaminated soil. Contrary to expectations, the effects of PGPB on the biomass harvest were low. The most significant increase was detected in leaf biomass treated with a consortium of tested PGPBs. More significant effects were detected in the uptake of individual TEs. The phytoparameters of translocation factor, comprehensive bioconcentration index and uptake index were used to characterize the behavior of the TEs; Cr; Mn; Ni; Cu; Zn; Sr; V; and Pb in the presence of isolates. Plants treated with PGPB strains accumulated minimal concentrations of Cu and Pb in their aboveground biomass, while a tendency for Zn accumulation in the leaves and stems, and Sr accumulation in the leaves was observed. The obtained results reveal the combinations of isolates that lead to the minimal uptake of TEs into the stems and the simultaneous increase in DW. This study provides more insight into the leading factors of phytoremediation supported by PGPB and can be helpful when M. × giganteus is grown on TEs-contaminated soils of different origins.