Multiple metal resistance and antioxidant enzyme production by Klebsiella pneumoniae PbS₃A₂ isolated from industrial effluent

Heavy metal ions produced by industrialization are the major source of pollution that affect both humans and other animals in different ways. In the current study, lead-resistant gram-negative Klebsiella pneumoniae strain PbS₃A₂ was isolated from industrial effluent around the Chokera, in Faisalabad, Pakistan. The minimum inhibitory concentration revealed that K. pneumoniae PbS₃A₂ can resist Pb up to 20 mM and other toxic heavy metal ions including 3 mM (Zn²⁺), 2 mM (Ni²⁺), 4 mM (Cu²⁺), 6 mM (Cd²⁺), 8 mM (As³⁺), with the resistance order as (Pb > As > Cd > Cu > Zn > Ni). Lead stress triggered a significant rise in the production of antioxidant enzymes including Superoxide dismutase (247%) Glutathione S-transferase (50%), and ascorbate peroxidase (17%) as well as a considerable decrease was observed in peroxidase (46%), and catalase (5%). Metal ions can be trapped by functional groups such as phosphate, carboxyl, and amide groups that are fully engaged in Pb adsorption were shown by FTIR as well as intracellular accumulation confirmed by scanning electron microscopy and energy dispersive X-ray. From the obtained results, K. pneumoniae may be a potential candidate for lead bioremediation of industrial effluent.