Effect of aluminum in Bacillus megaterium nickel resistance and removal capability

The increasing water pollution by heavy metals is considered an alarming situation worldwide, due to the adverse impact they cause in ecosystems and human health. Although conventional techniques are available to diminish the metal concentration present in water bodies, they offer disadvantages, like inefficient metal removal, toxic sludge generation, and high operating costs. In contrast, biotechnological approaches may render a viable alternative, since they offer lower environmental impacts and operating costs, and also higher removal efficiencies when metals are present in small concentrations. It has been shown that the simultaneous presence of more than one metal can generate synergistic, additive or antagonistic effects, thus affecting their removal, and it has been previously demonstrated that B. megaterium strain MNSH1-9K-1 possesses the ability to remove metals present in liquid and solid wastes. Therefore, the goal of the present work was to study B. megaterium MNSH1-9K-1 Ni resistance and removal properties in liquid medium, and to evaluate the variation of these abilities in the presence of another toxic metal, namely Al, which is also commonly found in liquid wastes. To this end, B. megaterium was grown in LB medium with the addition of Ni and/or Al at diverse concentrations, and both metal resistance and Ni removal capabilities were assayed by viable count, and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), respectively. The results obtained strongly suggest that B. megaterium MNSH1-9K-1 presents more susceptibility to Ni than to Al, and that Ni removal is enhanced by the presence of Al.