Rhizosphere microbiome of plants used in phytoremediation of mine tailing dams.

ABSTRACT

Rhizospheric microbial communities improve the effectiveness of hyperaccumulators in the phytoremediation of heavy metals. However, limited access to tailing dams and inadequate assessment of plants' phytoremediation potential limit the characterization of native accumulators, hindering the effectiveness of local remediation efforts. This study evaluates the heavy metal sequestration potentials of Pennisetum purpureum, Leucaena leucocephala, and Pteris vittata and their associated rhizospheric microbial communities at the Marlu and Pompora tailing dams in Ghana. The results indicate shoot hyperaccumulation of Cd (334.5 ± 6.3 mg/kg) and Fe (10,647.0 ± 12.6 mg/kg) in P. purpureum and L. leucocephala, respectively. Analysis of rhizospheric bacterial communities revealed the impact of heavy metal contamination on bacterial community composition, associating Fe and Cd hyperaccumulation with Bacillus, Arthrobacter, and Sphingomonas species. This study reports the hyperaccumulation potentials of L. leucocephala and P. purpureum enhanced by associated rhizosphere bacterial communities, suggesting their potential application as an environmentally friendly remediation process of heavy metals contaminated lands.

The novelty of this study is the report of the heavy metal accumulation potentials of the fast-growing herbaceous plants Leucaena leucocephala and Pennisetum purpureum at abandoned gold mine tailing dams in Ghana. Substantial amounts of Cd (334.5 mg/kg) and Fe (10,647.0 mg/kg) were accumulated in P. purpureum and L. leucocephala shoots, indicating their hyperaccumulation potentials. The concentration of heavy metal levels in the rhizosphere influenced the bacterial community structure, with the abundance of Bacillus, Arthrobacter, and Sphingomonas linked to hyperaccumulation. The outcome of this study supports the utilization of L. leucocephala and P. purpureum in the phytoremediation of lands contaminated with heavy metals.