Biosorption and bioaccumulation of heavy metals on dead and living biomass of Bacillus sphaericus

The tolerance to As, Hg, Co, Fe and Cr was determined in different Colombian Bacillus sphaericus native strains, as well as the biosorption and bioaccumulation in living biomass. In addition, biosorption of Cr in dead cells was also determined. Living cells of the two most tolerant strains had the capacity to accumulate between 6 and 47% of Co, Hg, Fe and As. Living and dead cells of B. sphaericus OT4b31 showed a biosorption of 25 and 44.5% of Cr respectively, while B. sphaericus IV(4)10 showed a biosorption of 32 and 45%. These results are due to the absence of an active metabolism in dead cells and to the pH adjustment. S-layer proteins may possibly have the ability to entrap metallic ions, either on living or dead cells. This can be an interesting alternative for bioremediation processes of heavy metals. (C) 2009 Elsevier B.V. All rights reserved.