Effect of aluminum in Bacillus megaterium nickel resistance and removal capability

Abstract

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.

Bioremoval of Different Heavy Metals by the Resistant Fungal StrainAspergillus niger

“…Different microorganisms that are heavy metals resistant have been isolated from different contaminated sites: screening the resistance to lead, cadmium, copper, and zinc of five fungal species isolated from soils: Emericella quadrilineata , A. niger , Macrophomina phaseolina , R. stolonifer , and Aspergillus fumigatus , and the most resistant fungal species (1 g/L of metals) was R. stolonifer followed by M. phaseolina which showed resistance with all the metals, while A. niger, A. fumigatus , and E. quadrilineata were more sensitive to these heavy metals [ 11 ], the fungus P. ostreatus HAAS grew very well in 500 mg/L of lead, and concentrations of 30 mg/L of cadmium and 200 mg/L of chromium appeared to inhibit the growth of the fungus [ 12 ], B. megaterium strain MNSH1-9K-1 tolerate up to 200 ppm of each nickel and vanadium [ 13 ], Alcaligenes sp. BAPb.1, grow in the presence of 1000 mg/L of lead (II), 600 mg/L of copper (II), 600 mg/L of zinc (II), 400 mg/L of nickel (II) and chromium(VI) [ 15 ], Penicillium sp., Trichoderma sp., and Alternaria sp., isolated from the farmland of the “Tanque Tenorio”, grow with 500–2000 mg/L of lead (II) [ 16 ], A. niger has been growing in the presence of different concentrations of metals like nickel, cobalt, iron, magnesium, and manganese [ 27 ], and the yeast Candida tropicalis , isolated from wastewater from industrial area of Sheikhupura, which is grown in 2.5 g/L of cadmium (II), zinc (II) (1.4 g/L), nickel (II) (1 g/L), Mercury (II) (1.4 g/L), copper (II) (1 g/L), chromium (VI) (1.2 g/L), and lead (II) (1 g/L) [ 28 ].…”

“…Dead fungal cells can be effective metal accumulators, and there is evidence that some biomass-based cleanup processes are economically viable [ 2 , 4 ]. The tolerance of some fungal species to heavy metals, as well as the physiological response to them, has been also determined [ 2 , 11 – 13 ]. The removal of heavy metal ions, using fungus as biosorbents, was previously investigated [ 2 , 4 , 12 , 17 – 20 ].…”

“…Different public institutions have developed investigations to establish the magnitude of this problem and have proposed strategies to contribute to the solution of the same, focusing on the use of biological alternatives that result in a lower alteration of the environment, specifically through the use of microorganisms for the removal of heavy metals or biosorption [ 11 ]. There are many reports of the isolation of resistant microorganisms to heavy metals and the use of microbial biomass for the removal of heavy metals, from industrial wastewater and/or contaminated water: the resistance and removal of Rhizopus stolonifer to lead, cadmium, copper, and zinc [ 11 ], the tolerance and removal mechanisms of heavy metals (lead, cadmium, and chromium), by the fungus Pleurotus ostreatus HAAS [ 12 ], Bacillus megaterium nickel resistance and her capacity of removal [ 13 ], heavy metal susceptibility and removal potential (mercury, copper, and lead) of Rhodotorula mucilaginosa [ 14 ], the resistance of Alcaligenes sp. BAPb.1 to lead (II), copper (II), zinc (II), nickel (II), and chromium (VI), and his capacity for removal of lead (II) [ 15 ], the isolation and identification of fungi and yeast resistant to lead (II) [ 16 ], the resistance and removal of chromium (VI) by Aspergillus niger [ 17 ], the removal of different heavy metals by A. niger [ 18 ], the removal of lead, cadmium, copper, and nickel by A. niger [ 19 ], the removal of aluminum, iron, lead, and zinc by A. niger during the bioleaching process [ 12 ], and the removal of copper (II), manganese (II), zinc (II), nickel (II), iron (III), lead (II), and cadmium (II) by immobilized cells of A. niger [ 20 ], with highly satisfactory results.…”