The Fate of Lead (Pb) in Multitrophic Interactions Among Bacteria, Fungi, and Bacterivorous Soil Nematodes

Abstract

AbstractContamination of potentially toxic metals poses threats to living organisms due to prolonged existence in an ecosystem. The effects of toxic metals on soil microbes have broadly been reported but the study on interactions among soil micro‐ and macro‐organisms under metal stress needs to be elaborated. In current study, the immobilization of lead (Pb) is investigated by using five resistant microbial strains; (2) Bacillus cereus, (1) Bacillus subtilis, (1) Brevundimonas naejangsanensis, and (1) fungal strain Fusarium equiseti isolated from contaminated soil of Hattar, Pakistan. Bacterial and fungal strains and their consortia are tested in the presence/absence of nematodes for Pb immobilization in a medium containing 250 mg L−1 Pb. Single bacterial strains immobilize Pb up to 72%, while in the presence of nematodes, bacterial immobilization potential decreases. An increased Pb immobilization up to 185 mg L−1 is found when bacterial and fungal consortia are inoculated with nematodes. The maximum 80% Pb immobilization is found in bacterial–bacterial combinations with nematodes. This study, reveals that inoculation of bacterial–bacterial consortia in the presence of nematodes enhanced bacterial growth via feeding resulting in higher Pb immobilization. These resistant microbial strains can thus be used to treat contaminated sites for better ecosystem functioning.