Significance of treated agrowaste residue and autochthonous inoculates (Arbuscular mycorrhizal fungi and Bacillus cereus) on bacterial community structure and phytoextraction to remediate soils contaminated with heavy metals

Abstract In this study, we analyzed the impact of treatments such as Aspergillus niger -treated sugar beet waste (SB), PO 4 3 - fertilization and autochthonous inoculants [arbuscular mycorrhizal (AM) fungi and Bacillus cereus ], on the bacterial community structure in a soils contaminated with heavy metals as well as, the effectiveness on plant growth ( Trifolium repens ). The inoculation with AM fungi in SB amended soil, increased plant growth similarly to PO 4 3 - addition, and both treatments matched in P acquisition but bacterial biodiversity estimated by denaturing gradient gel electrophoresis of amplified 16S rDNA sequences, was more stimulated by the presence of the AM fungus than by PO 4 3 - fertilization. The SB amendment plus AM inoculation increased the microbial diversity by 233% and also changed (by 215%) the structure of the bacterial community. The microbial inoculants and amendment used favoured plant growth and the phytoextraction process and concomitantly modified bacterial community in the rhizosphere; thus they can be used for remediation. Therefore, the understanding of such microbial ecological aspects is important for phytoremediation and the recovery of contaminated soils.