Arsenic sequestration by manganese-oxidizing Acinetobacter sp

Abstract

This paper presents the potential of manganese (Mn)-oxidizing bacteria in removing arsenic from synthetic solution. Mnoxidizing bacterium was isolated from arsenic and manganese contaminated ground water from district Ballia (UP), India. The bacterium was identified as Acinetobacter sp. by the Institue of Microbial Technology, Chandigarh, India. Synthetic solution of Mn (25 ppm) was treated with Acinetobacter sp. (20 mg/mL) biomass in neutral pH (7.0) at ambient temperature. Acinetobacter sp. was found efficient to oxidize 44.04% (11.01 ppm) Mn within 2 h. Kinetics of Mn oxidation showed that maximum velocity (Vmax) for Mn oxidation was 16.69 μM mg-1 h-1, while kinetic constant (Km) was found to be 1.09 mM. Mn oxidation by Acinetobacter sp. follows the Michalis-Menten kinetics. Free and immobilized cells of Mn-oxide laden Acinetobacter sp. was used for removal of arsenite [As(III)] from arsenite contaminated water. Free and immobilized cells of Mn-oxide (11.01 ppm) laden Acinetobacter sp. biomass (20 mg/mL) was effective in removing of 0.760 ppm arsenite within 30 min and 3.39 ppm arsenite within 15 min from 5 ppm As(III) containing synthetic solution at pH 7. The immobilized cells of Mn-oxide laden Acinetobacter sp. were found to be 4.46 times more effective for the removal of As(III) as compared to the free cells.