Bioaccumulation of Pb, Ni and Cd by Bacillus cereus isolated from Lake Qarun, Egypt, using the spatial technique

Abstract

The present study aimed to investigate the metal bioaccumulation capability of heavy metal-resistant bacterium isolated from Lake Qarun. Physico-chemical parameters and heavy metals of Lake Qarun water were evaluated using the EUREKA Manta2 device and Atomic Absorption Spectroscopy (ASS), respectively. Geostatistical analyses were used for the spatial representation of the investigated parameters. The bacterial isolate was identified as Bacillus cereus, using the MALDI-TOF MS platform, exhibited notable resistance to higher levels of lead (Pb⁺²), cadmium (Cd⁺²) and nickel (Ni⁺²) at 1700, 175 and 80 mg/l, respectively. Furthermore, this isolate showed a high capacity to remove Pb⁺² (59.9%), Ni⁺² (83%) and Cd⁺² (79.4%) The impact of specific physicochemical factors, including temperature, pH, initial metal concentration, and incubation period, was also evaluated concerning bioaccumulation. The optimal pH for the removal of Pb, Ni and Cd was found to be 7. The bacterium exhibited maximum accumulation capacity after 96 h of incubation with each metal while maintaining a temperature of 37ºC. The transmission electron microscope revealed that metals were predominantly observed both extracellularly and intracellularly, concomitant with alterations in cellular morphology. The bioaccumulation capacity (removal efficiency) for each metal by bacteria exhibited a notable swiftness, which presents a potential advantage in the context of treating contaminated sites on a large scale.