Sorption Mechanism and Optimization Study for the Bioremediation of Pb(II) and Cd(II) Contamination by Two Novel Isolated Strains Q3 and Q5 of Bacillus sp.

Abstract

The use of bacterial strains as agents in bioremediation processes could reduce the harmfulness of potential toxic elements (PTEs) from water and soil with low or even no impact on the natural ecosystems. In this study, two new metal resistant-bacterial strains (Q3 and Q5) of Bacillus sp. were isolated from a sulfurous spring and their potential (as pure cultures or mixed) to remove Pb(II) and Cd(II) from an aqueous matrix was evaluated and optimized using response surface methodology (RSM). The optimal conditions for Cd(II) removal from all tested strains combinations were observed at an initial pH 5, a temperature of 38 °C, and an initial Cd(II) concentration of 50 mg L−1, while the performance of bacterial strains on Pb(II) removal was strongly correlated to initial pH and temperature conditions. Moreover, the efficiency of bacterial strains in removing both PTEs, Pb(II) and Cd(II), from an aqueous matrix was considerably higher when they were used as a mixed culture rather than pure. According to field emission SEM (FESEM) and EDS analysis, the two bacterial strains showed different mechanisms in removing Cd(II): Bacillus sp. Q5 bio-accumulated Cd(II) in its periplasmic space, whereas Bacillus sp. Q3 bio-accumulated Cd(II) on its cell surface. On the other hand, Pb(II) is removed by chemical precipitation (lead sulfide) induced by both Bacillus sp. Q3 and Q5. This study discloses new aspects of Pb(II) and Cd(II) bioremediation mechanisms in Bacillus species that can be extremely useful for designing and operating novel PTEs bioremediation processes.

Bioremediation of Heavy Metals by the Genus Bacillus

“…One way of bioremediation may be the use of bacteria of the genus Bacillus [ 8 , 17 , 18 , 19 , 20 , 21 ]. They are Gram-positive, spore-forming, rod-shaped, and aerobic or facultative anaerobes.…”

Phosphate transporter genes: genome-wide identification and characterization in Camelina sativa

“…There is a hypothesis that PHTs are involved in maintaining ionic balance in the cytoplasm, which probably increases the resistance of plants to stress. Under the stress of the heavy metal such as cadmium, various mechanisms have been proposed that transporters and cellular pumps play an important role in reducing the toxicity and maintaining the ionic balance (Heidari et al, 2020b;Heidari and Panico, 2020). It seems that PHT genes are involved in response to cadmium stress in C. sativa.…”

Valorization of Agro-industrial Discards in Fermentation for the Production of Cellulase Enzyme

“…The properties and activity of the material depends on the presence of the functional groups such as carboxyl, hydroxyl, phenols, amide, acylamino, and phosphate. 24,25 All through the FTIR analysis, the energy from infrared radiation was absorbed by the covalent bonds present in the functional groups and it caused the bonds to be stretched. This leads to the stretching in OH bonds to increase the sharpness or broadness on the peaks in the spectrum.…”